Assessment of the axial resolution of a compact gamma camera with coded aperture collimator

PURPOSE

Handheld gamma cameras with coded aperture collimators are under investigation for intraoperative imaging in nuclear medicine. Coded apertures are a promising collimation technique for applications such as lymph node localization due to their high sensitivity and the possibility of 3D imaging. We evaluated the axial resolution and computational performance of two reconstruction methods.

METHODS

An experimental gamma camera was set up consisting of the pixelated semiconductor detector Timepix3 and MURA mask of rank 31 with round holes of 0.08 mm in diameter in a 0.11 mm thick Tungsten sheet. A set of measurements was taken where a point-like gamma source was placed centrally at 21 different positions within the range of 12-100 mm. For each source position, the detector image was reconstructed in 0.5 mm steps around the true source position, resulting in an image stack. The axial resolution was assessed by the full width at half maximum (FWHM) of the contrast-to-noise ratio (CNR) profile along the z-axis of the stack. Two reconstruction methods were compared: MURA Decoding and a 3D maximum likelihood expectation maximization algorithm (3D-MLEM).

RESULTS

While taking 4400 times longer in computation, 3D-MLEM yielded a smaller axial FWHM and a higher CNR. The axial resolution degraded from 5.3 mm and 1.8 mm at 12 mm to 42.2 mm and 13.5 mm at 100 mm for MURA Decoding and 3D-MLEM respectively.

CONCLUSION

Our results show that the coded aperture enables the depth estimation of single point-like sources in the near field. Here, 3D-MLEM offered a better axial resolution but was computationally much slower than MURA Decoding, whose reconstruction time is compatible with real-time imaging.

Concordance between freehand SPECT and conventional scintigraphy for sentinel lymph node detection in breast cancer

INTRODUCTION

Freehand SPECT can be a useful imaging technique for preoperative planning of sentinel lymph node biopsy (SLNB) as it allows localization of the sentinel node by 3D and real-time tomographic imaging and determines its depth after a few minutes of scanning. The aim of the study was to evaluate the correlation between the number of detected SNs between freehand SPECT images and lymphoscintigraphy (LS).

MATERIALS AND METHODS

100 patients with a diagnosis of invasive breast cancer and no clinical evidence of lymph node involvement prospectively underwent SLNB. The preoperative study included freehand SPECT imaging at 15min after injection and LS imaging at 25 and 60-90min after injection (early and late). The observed agreement was analyzed and a concordance study was performed between the number of SNs detected with freehand SPECT and LS.

RESULTS

The observed agreement in the detection of SNs between freehand SPECT and early LS was 72%; between freehand SPECT and late LS was 85%; and between early and late LS was 87%. In the concordance study, there was moderate concordance between freehand SPECT and early LS (kappa coefficient: 0.42); moderate-high concordance between freehand SPECT and late LS (kappa coefficient: 0.60); and moderate-high concordance between early and late LS (kappa coefficient: 0.70), with no significant differences between them (p-value=0.16).

CONCLUSION

Freehand SPECT showed a moderate-high concordance with conventional imaging studies and could be a valid alternative for the presurgical study of SLNB in breast cancer.

[Salvage lymphadenectomy for recurrent prostate cancer]

Prostate-specific membrane antigen (PSMA)-based positron emission tomography (PET) imaging allows early detection of metastases in patients with biochemical recurrence. Salvage lymphadenectomy became a widely used method of metastasis-directed treatment. Retrospective analyses show that a low prostate-specific antigen (PSA) value and presence of no more than two affected lymph nodes within the pelvis are factors associated with a good outcome. In all, 40-80% of patients achieve a complete biochemical response with a mean time without biochemical recurrence of 8 months and a prolonged treatment-free interval. About 10% of patients with a complete biochemical response will live without recurrence after 10 years. The utilization of PSMA-radioguided surgery increases the likelihood of intraoperative detection of suspicious affected lymph nodes. Complications can mostly be avoided by prudent patient selection and surgical expertise.

Steerable DROP-IN radioguidance during minimal-invasive non-robotic cervical and endometrial sentinel lymph node surgery

PURPOSE

The recently introduced tethered DROP-IN gamma probe has revolutionized the way robotic radioguided surgery is performed, fully exploiting the nature of steerable robotic instruments. Given this success, the current first-in-human study investigates if the DROP-IN can also provide benefit in combination with steerable non-robotic instruments during conventional laparoscopic surgery, showing equivalence or even benefit over a traditional rigid gamma probe.

METHODS

The evaluation was performed in ten patients during laparoscopic cervical (n = 4) and endometrial (n = 6) cancer sentinel lymph node (SLN) procedures. Surgical guidance was provided using the hybrid, or bi-modal, SLN tracer ICG-99mTc-nanocolloid. SLN detection was compared between the traditional rigid laparoscopic gamma probe, the combination of a DROP-IN gamma probe and a steerable laparoscopic instrument (LaproFlex), and fluorescence imaging.

RESULTS

The gynecologists experienced an enlarged freedom of movement when using the DROP-IN + LaproFlex combination compared to the rigid laparoscopic probe, making it possible to better isolate the SLN signal from background signals. This did not translate into a change in the SLN find rate yet. In both cervical and endometrial cancer combined, the rigid probe and DROP-IN + LaproFlex combination provided an equivalent detection rate of 96%, while fluorescence provided 85%.

CONCLUSION

We have successfully demonstrated the in-human use of steerable DROP-IN radioguidance during laparoscopic cervical and endometrial cancer SLN procedures, expanding the utility beyond robotic procedures. Indicating an improved surgical experience, these findings encourage further investigation and consideration on a path towards routine clinical practice and improved patient outcome.

TRIAL REGISTRATION

HCB/2021/0777 and NCT04492995; https://clinicaltrials.gov/study/NCT04492995.

A Multicentre Clinical Trial Evaluating a Drop-in Gamma Probe for Minimally Invasive Sentinel Lymph Node Dissection in Prostate Cancer

BACKGROUND

This study evaluated the safety and performance of a drop-in gamma probe for prostate cancer (PCa) sentinel lymph node biopsy (SeLNB) in a prospective, open-label, multicentre, single-arm clinical trial.

OBJECTIVE

The main objective was to determine the sentinel lymph node (SeLN) detection rate with the drop-in gamma probe system. The secondary objectives were overall performance and safety.

DESIGN, SETTING, AND PARTICIPANTS

At three European centres, patients received an ultrasound-guided systemic and tumour-targeted injection of [99mTc]Tc-nanocolloid followed by planar lymphoscintigraphy and/or single-photon emission computerised tomography. The next day, manual laparoscopic or robot-assisted radical prostatectomy was performed, including SeLN dissection (SeLND) and extended pelvic lymph node dissection (ePLND).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

SeLNs were detected with the drop-in probe and a rigid laparoscopic gamma probe (RLGP). The primary endpoint of the study was the SeLND rate defined as the percentage of patients with at least one SeLN detected in vivo by the drop-in probe. The secondary endpoints included diagnostic performance, ease of SeLN detection, number of SeLNs detected, and safety. The first two patients at each site (six in total) were used for familiarisation.

RESULTS AND LIMITATIONS

A total of 27 patients were included in the main analysis. SENSEI successfully detected at least one SeLN in all 27 patients, resulting in a detection rate of 100% (95% confidence interval 87.2-100%). The total number of SeLNs identified with SENSEI was 85 (median three SeLNs per patient, range 1-6); of these 85 SeLNs, 12 were located outside of the ePLND template. In the nine patients in whom the RLGP was used, SENSEI detected two SeLNs that could not be detected with the RLGP due to manoeuvrability restrictions. Ten of the 27 patients were pN1; four patients had a false-negative SeLNB. No adverse events or complications were related to the use of the drop-in probe.

CONCLUSIONS

The study demonstrated that the drop-in gamma probe meets the performance and safety requirements for SeLNB in PCa. The device provided improved manoeuvrability and SeLN detection compared with the conventional RLGP.

PATIENT SUMMARY

A novel device was tested for detecting sentinel lymph nodes during minimally invasive surgery for prostate cancer. In this first evaluation, the performance and safety of the device were evaluated positively.

Delphi consensus project on prostate-specific membrane antigen (PSMA)-targeted surgery-outcomes from an international multidisciplinary panel

PURPOSE

Prostate-specific membrane antigen (PSMA) is increasingly considered as a molecular target to achieve precision surgery for prostate cancer. A Delphi consensus was conducted to explore expert views in this emerging field and to identify knowledge and evidence gaps as well as unmet research needs that may help change practice and improve oncological outcomes for patients.

METHODS

One hundred and five statements (scored by a 9-point Likert scale) were distributed through SurveyMonkey®. Following evaluation, a consecutive second round was performed to evaluate consensus (16 statements; 89% response rate). Consensus was defined using the disagreement index, assessed by the research and development project/University of California, Los Angeles appropriateness method.

RESULTS

Eighty-six panel participants (72.1% clinician, 8.1% industry, 15.1% scientists, and 4.7% other) participated, most with a urological background (57.0%), followed by nuclear medicine (22.1%). Consensus was obtained on the following: (1) The diagnostic PSMA-ligand PET/CT should ideally be taken < 1 month before surgery, 1-3 months is acceptable; (2) a 16-20-h interval between injection of the tracer and surgery seems to be preferred; (3) PSMA targeting is most valuable for identification of nodal metastases; (4) gamma, fluorescence, and hybrid imaging are the preferred guidance technologies; and (5) randomized controlled clinical trials are required to define oncological value. Regarding surgical margin assessment, the view on the value of PSMA-targeted surgery was neutral or inconclusive. A high rate of "cannot answer" responses indicates further study is necessary to address knowledge gaps (e.g., Cerenkov or beta-emissions).

CONCLUSIONS

This Delphi consensus provides guidance for clinicians and researchers that implement or develop PSMA-targeted surgery technologies. Ultimately, however, the consensus should be backed by randomized clinical trial data before it may be implemented within the guidelines.

Sentinel lymph node procedure in early-stage vulvar cancer: Correlation of lymphoscintigraphy with surgical outcome and groin recurrence

INTRODUCTION

In early-stage vulvar squamous cell carcinoma (VSCC) a sentinel lymph node (SLN) procedure is regarded successful if at least one SLN is removed with minimal residual radioactivity. An inguinofemoral lymphadenectomy is considered if not all SLNs visualized on lymphoscintigraphy can be found, with subsequent increased morbidity. We correlated lymphoscintigraphy findings with surgical outcome and groin recurrence with focus on number of SLNs found.

METHODS

This study concerns a retrospective cohort of 171 women treated for early-stage VSCC who underwent a SLN procedure between 2000 and 2020. The risk of groin recurrence was compared after either a successful or complete SLN procedure, i.e. removal of all SLNs that were visualized on lymphoscintigraphy.

RESULTS

In 13 (7.6%) groins of 171 patients SLN visualization on lymphoscintigraphy failed. In 230 of the 246 (93.5%) groins in which a SLN was visualized, at least one SLN was found during surgery. In 224 of the 246 (91.1%) groins the SLN procedure was regarded either successful (n = 14) or complete (n = 210). An isolated groin recurrence was documented in 5 out of 192 (2.6%, 95%-CI; 0.34 to 4.9) SLN-negative groins after a median follow-up of 47.0 months. All recurrences were noted in the complete SLN group (5/180 groins). The difference with the successful SLN group (0/12 groins) was not significant.

CONCLUSION

Risk of groin recurrence was 2.6% after SLN negative biopsy in early-stage VSCC. The risk appeared not increased if at least one SLN was found with minimal residual radioactivity, in case more SLNs were visualized on lymphoscintigraphy.

Radioguided surgery of mesenchymal tumors with 125I seeds

INTRODUCTION

Radioguided surgery uses radioactive substances to identify and remove hard-to-locate lesions. Mesenchymal tumors constitute a heterogeneous group of neoplasms derived from the mesoderm, including benign lesions and malignant sarcomas. The aim of this study was to evaluate the ability of 125I radioactive seeds to guide intraoperative localization of mesenchymal tumors, analyzing the complication rates and evaluating the margins of the surgical specimens retrieved.

METHODS

Retrospective observational study of all consecutive patients undergoing radioguided surgery of a mesenchymal tumor with a 125I radioactive seed from January 2012 to January 2020 at a tertiary referral center in Spain. The seed was inserted percutaneously guided by ultrasound or computed tomography in an outpatient setting.

RESULTS

Fifteen lesions were resected in 11 interventions in 11 patients, recovering all lesions marked (100%) with a 125I seed. The lesions included areas of benign fibrosis (26.7%), cellular angiofibroma (6.7%), desmoid tumor (20%), solitary fibrous tumor (13.3%), chondrosarcoma (6.7%), and pleomorphic sarcoma (26.7%), with a high rate of recurrent tumors (60%). There was only one complication (6.7%) due to the seed falling within the surgical bed. According to the UICC classification of residual tumors, 80% of the lesions resulted in an R0 resection, 6.7% were R1 resections, and 13.3% were R2 resections.

CONCLUSION

Radioguided surgery is an accurate technique for the resection of hard-to-locate mesenchymal tumors.

Radioguided surgery with β decay: A feasibility study in cervical cancer

PURPOSE

Radioguided surgery (RGS) is a technique that helps the surgeon to achieve a tumour resection as complete as possible, by means of the intraoperative detection of particles emitted by a radiotracer that bounds to tumoural cells. This study aimed to investigate the applicability of β-RGS for tumour resection and margin assessment in cervical cancer patients preoperatively injected with [18F]FDG, by means of Monte Carlo simulations.

METHODS

Patients were retrospectively included if they had a recurrent or persistent cervical cancer, underwent preoperative PET/CT to exclude distant metastases and received radical surgery. All PET/CT images were analysed extracting tumour SUVmax, background SUVmean and tumour-to-non-tumour ratio. These values were used to obtain the expected count rate in a realistic surgical scenario by means of a Monte Carlo simulation of the β probe, assuming the injection of 2 MBq/kg of [18F]FDG 60 min before surgery.

RESULTS

Thirty-eight patients were included. A measuring time of ∼2-3 s is expected to be sufficient for discriminating the tumour from background in a given lesion, being this the time the probe has to be over the sample in order to be able to discriminate tumour from healthy tissue with a sensitivity of ∼99% and a specificity of at least 95%.

CONCLUSION

This study presents the first step towards a possible application of our β-RGS technique in cervical cancer. Results suggest that this approach to β-RGS could help surgeons distinguish tumour margins from surrounding healthy tissue, even in a setting of high radiotracer background activity.

State of the Art in Prostate-specific Membrane Antigen-targeted Surgery-A Systematic Review

Context

Identifying malignant tissue and leaving adjacent structures undisturbed constitute an ongoing challenge in prostate cancer (PCa) surgery. Image and radioguided surgical technologies targeting the prostate-specific membrane antigen (PSMA) receptor may facilitate identification and removal of diseased tissue.

Objective

To perform a systematic review of the clinical studies on PSMA-targeted surgery.

Evidence acquisition

The MEDLINE (OvidSP), Embase.com, and Cochrane Library databases were searched. Identified reports were critically appraised according to the Idea, Development, Exploration, Assessment, Long-term framework criteria. The risk of bias (RoB) was assessed as per the Risk Of Bias In Non-randomized Studies-of Interventions tool. The strengths and limitations of the techniques and corresponding oncological outcomes were extracted as areas of interest. Data were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Evidence synthesis

In total, 29 reports were selected, including eight prospective studies, 12 retrospective analyses, and nine case reports, all with a high or an unclear RoB. In 72.4% of studies, PSMA targeting was achieved via radioguided surgery (RGS), predominantly using ^99mTc-PSMA-I&S (66.7%). Hybrid approaches that complement RGS with optical guidance are emerging. The majority of studies retrieved were pilot studies with a short follow-up. In 13 reports, salvage lymph node surgery was discussed (44.8%). In 12 more recent reports (41.4%), PSMA targeting was studied in primary PCa surgery (50.0% lymph nodes and 50.0% surgical margins), and four studied both primary and salvage surgery (13.8%). Overall, specificity was higher than sensitivity (median 98.9% and 84.8%, respectively). Oncological outcomes were discussed only in reports on the use of ^99mTc-PSMA-I&S in salvage surgery (median follow-up of 17.2 mo). A decline in prostate-specific antigen level of >90% ranged from 22.0% to 100.0%, and biochemical recurrence ranged from 50.0% to 61.8% of patients.

Conclusions

In PSMA-targeted surgery, most studies address salvage PSMA-RGS using ^99mTc-PSMA-I&S. Available evidence suggests that the specificity of intraoperative PSMA targeting is higher than the sensitivity. The studies that included follow-up did not yet objectify a clear oncological benefit. Lacking solid outcome data, PSMA-targeted surgery remains investigational.

Patient summary

In this paper, we review recent advances in prostate-specific membrane antigen (PSMA)-targeted surgery, which is used to help identify and remove prostate cancer. We found good evidence to suggest that PSMA targeting helps identify prostate cancer during surgery. The oncological benefits have yet to be investigated further.

Prostate-specific Membrane Antigen-radioguided Surgery Facilitates Pelvic Lymph Node Dissection During Radical Prostatectomy for the Treatment of Locally Advanced Prostate Cancer with Regional Lymph Node Metastases

Lymph node metastases (LNMs) are common in intermediate- to high-risk prostate cancer (PC) and may be missed during extended pelvic lymph node dissection (ePLND). Here we report on the use of prostate-specific membrane antigen (PSMA)-radioguided surgery (RGS) during open radical prostatectomy (RP) with ePLND to resect locoregional LNMs identified on preoperative PSMA positron emission tomography (PET). Preoperative PSMA PET showed 78 LNMs in 35 patients undergoing RP with ePLND and RGS between January 2018 and June 2020. In 14 patients (40%), LNMs were located outside the ePLND template. RGS achieved resection of PSMA-positive LNMs in 33/35 patients (94%). On univariable analysis, lower metastatic burden with up to two PSMA-positive LNMs on preoperative PET was associated with better postoperative outcomes. Limitations include the retrospective analysis and the small sample size. RGS facilitates resection of PSMA-positive LNs in patients treated with RP. Our data indicate a favorable treatment outcome in patients with low metastatic LN burden on preoperative PSMA PET. PATIENT SUMMARY: We investigated the use of radioactive guidance to remove lymph nodes affected by prostate cancer during surgical removal of the prostate. This approach can help to identify cancerous lymph nodes that might otherwise be missed and could lead to better survival outcomes.

Synthesis and preclinical evaluation of novel 99mTc-labeled PSMA ligands for radioguided surgery of prostate cancer

BACKGROUND

Radioguided surgery (RGS) has recently emerged as a valuable new tool in the management of recurrent prostate cancer (PCa). After preoperative injection of a ^99mTc-labeled prostate-specific membrane antigen (PSMA) inhibitor, radioguided intraoperative identification and resection of lesions is facilitated by means of suitable γ-probes. First clinical experiences show the feasibility of RGS and suggest superiority over conventional lymph node dissection in recurrent PCa. However, commonly used [^99mTc]Tc-PSMA-I&S exhibits slow whole-body clearance, thus hampering optimal tumor-to-background ratios (TBR) during surgery. We therefore aimed to develop novel ^99mTc-labeled, PSMA-targeted radioligands with optimized pharmacokinetic profile to increase TBR at the time of surgery.

METHODS

Three ^99mTc-labeled N4-PSMA ligands were preclinically evaluated and compared to [^99mTc]Tc-PSMA-I&S. PSMA affinity (IC₅₀) and internalization were determined on LNCaP cells. Lipophilicity was assessed by means of the distribution coefficient logD_7.4 and an ultrafiltration method was used to determine binding to human plasma proteins. Biodistribution studies and static µSPECT/CT-imaging were performed at 6 h p.i. on LNCaP tumor-bearing CB17-SCID mice.

RESULTS

The novel N4-PSMA tracers were readily labeled with [^99mTc]TcO₄^- with RCP > 95%. Comparable and high PSMA affinity was observed for all [^99mTc]Tc-N4-PSMA-ligands. The ligands showed variable binding to human plasma and medium to low lipophilicity (logD_7.4 - 2.6 to - 3.4), both consistently decreased compared to [^99mTc]Tc-PSMA-I&S. Biodistribution studies revealed comparable tumor uptake among all [^99mTc]Tc-N4-PSMA-ligands and [^99mTc]Tc-PSMA-I&S, while clearance from most organs was superior for the novel tracers. Accordingly, increased TBR were achieved. [^99mTc]Tc-N4-PSMA-12 showed higher TBR than [^99mTc]Tc-PSMA-I&S for blood and all evaluated tissue. In addition, a procedure suitable for routine clinical production of [^99mTc]Tc-N4-PSMA-12 was established. Labeling with 553 ± 187 MBq was achieved with RCP of 98.5 ± 0.6% (n = 10).

CONCLUSION

High tumor accumulation and favorable clearance from blood and non-target tissue make [^99mTc]Tc-N4-PSMA-12 an attractive tracer for RGS, possibly superior to currently established [^99mTc]Tc-PSMA-I&S. Its GMP-production according to a method presented here and first clinical investigations with this novel radioligand is highly recommended.

Prostate-specific membrane antigen Radioguided Surgery to Detect Nodal Metastases in Primary Prostate Cancer Patients Undergoing Robot-assisted Radical Prostatectomy and Extended Pelvic Lymph Node Dissection: Results of a Planned Interim Analysis of a Prospective Phase 2 Study

BACKGROUND

Extended pelvic nodal dissection (ePLND) represents the gold standard for nodal staging in prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) radioguided surgery (RGS) could identify lymph node invasion (LNI) during robot-assisted radical prostatectomy (RARP).

OBJECTIVE

To report the planned interim analyses of a phase 2 prospective study (NCT04832958) aimed at describing PSMA-RGS during RARP.

DESIGN, SETTING, AND PARTICIPANTS

A phase 2 trial aimed at enrolling 100 patients with intermediate- or high-risk cN0cM0 PCa at conventional imaging with a risk of LNI of >5% was conducted. Overall, 18 patients were enrolled between June 2021 and March 2022. Among them, 12 patients underwent PSMA-RGS and represented the study cohort.

SURGICAL PROCEDURE

All patients received ⁶⁸Ga-PSMA positron emission tomography (PET)/magnetic resonance imaging; ^99mTc-PSMA-I&S was synthesised and administered intravenously the day before surgery, followed by single-photon emission computed tomography/computed tomography. A Drop-In gamma probe was used for in vivo measurements. All positive lesions (count rate ≥2 compared with background) were excised and ePLND was performed.

MEASUREMENTS

Side effects, perioperative outcomes, and performance characteristics of robot-assisted PSMA-RGS for LNI were measured.

RESULTS AND LIMITATIONS

Overall, four (33%), six (50%), and two (17%) patients had intermediate-risk, high-risk, and locally advanced PCa. Overall, two (17%) patients had pathologic nodal uptake at PSMA PET. The median operative time, blood loss, and length of stay were 230 min, 100 ml, and 5 d, respectively. No adverse events and intraoperative complications were recorded. One patient experienced a 30-d complication (Clavien-Dindo 2; 8.3%). Overall, three (25%) patients had LNI at ePLND. At per-region analyses on 96 nodal areas, sensitivity, specificity, positive predictive value, and negative predictive value of PSMA-RGS were 63%, 99%, 83%, and 96%, respectively. On a per-patient level, sensitivity, specificity, positive predictive value, and negative predictive values of PSMA-RGS were 67%, 100%, 100%, and 90%, respectively.

CONCLUSIONS

Robot-assisted PSMA-RGS in primary staging is a safe and feasible procedure characterised by acceptable specificity but suboptimal sensitivity, missing micrometastatic nodal disease.

PATIENT SUMMARY

Prostate-specific membrane antigen radioguided robot-assisted surgery is a safe and feasible procedure for the intraoperative identification of nodal metastases in cN0cM0 prostate cancer patients undergoing robot-assisted radical prostatectomy with extended pelvic lymph node dissection. However, this approach might still miss micrometastatic nodal dissemination.

Feasibility of a drop-in γ-probe for radioguided sentinel lymph detection in early-stage cervical cancer

Background

Minimally invasive radioguided sentinel lymph node (SLN) procedures, increasingly performed with robot-assisted laparoscopy, can benefit from using a drop-in γ-probe instead of the conventional rigid laparoscopic γ-probe. We evaluated the safety and feasibility of a tethered drop-in γ-probe system for SLN detection in patients with early-stage cervical cancer.

Methods

Ten patients with FIGO stage IA – IB2 or IIA1 cervical cancer scheduled for robot-assisted laparoscopic SLN procedure were included. All patients underwent preoperative 240 MBq technetium-99m nanocolloid (^99mTc) injection and SPECT/CT imaging. Intraoperatively the tethered drop-in γ-probe SENSEI® (Lightpoint Medical Ltd, Chesham, UK) was used for probe guided SLN detection, subsequently confirmed by the standard rigid laparoscopic γ-probe. Sentinel lymph node detection rates and anatomical SLN location were assessed. Surgeon questionnaires were used to assess usability.

Results

In all patients at least one SLN was successfully resected under guidance of the drop-in γ-probe (overall detection rate: 100%). Bilateral SLN detection rate with the drop-in γ-probe was 80%. Of the two patients with unilateral SLN detection only, one presented with an atypical SLN location at the aortic bifurcation that was detected only on SPECT/CT. The other patient had failed unilateral ^99mTc uptake. Combined use of preoperative SPECT/CT and drop-in γ-probe resulted in a bilateral detection rate of 90%. Similar to the drop-in γ-probe, overall and bilateral SLN detection rate of the rigid γ-probe was 100% and 80%, respectively. No significant discrepancy existed between the count rate of the drop-in and rigid laparoscopic γ-probe (p = 0.69). In total 21 SLN’s were detected with the drop-in γ-probes including all three tumor positive nodes. Because of wristed articulation of the robotic tissue grasper and possibility of autonomous probe control by the surgeon, maneuverability and control with the drop-in γ-probe were highly rated in surgeon questionnaires. No adverse events related to the intervention occurred.

Conclusions

Sentinel lymph node detection with a drop-in γ-probe is safe and feasible in patients with early-stage cervical cancer. Use of the drop-in γ-probe enhances maneuverability and surgical autonomy during robot-assisted SLN detection.

Trial registration Netherlands Trial Registry, NL9358. Registered 23 March 2021, https://www.trialregister.nl/trial/9358.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00907-w.

Survey of the Radioguided Surgery Working Group (GTCRG-RGSWG) of the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM): Radioguided localization of non-palpable breast lesions with or without indication for selective sentinel node biopsy: ROLL, SNOLL and 125I seeds

OBJECTIVE

To know the current status of the technique of radioguided localisation of non-palpable breast lesions with or without indication for selective sentinel node biopsy -ROLL, SNOLL and ¹²⁵I seeds- by conducting a national survey developed by the Working Group on Radioguided Surgery (GTCRG) of the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM).

MATERIAL AND METHODS

In October 2020, the form was sent in digital format to the different nuclear medicine services in Spain. A response time of 2 months with an overtime of 15 days was given. The number of ROLL/SNOLL procedures in each centre and the methodology used were obtained, including important technical details. In addition, a specific section on ¹²⁵I seeds was included. The results were automatically downloaded into an Excel 2007 spreadsheet for subsequent analysis with the same program.

RESULTS

The survey was answered by 55 centres; 21 use wire-guided localisation while the remaining 34 use different radioguided surgery techniques (RGS) for the localisation of non-palpable breast lesions, with the results itemized into thirteen sections. The commonly used tracer dose is 111 MBq for the ROLL technique and 222 MBq for the SNOLL technique, with a volume of 0.2 ml. The most common protocol is the two-day protocol. 26% of centres performing CRG use ¹²⁵I seeds for both breast lesion and suspicious/pathological node detection, with the time between implantation and removal being about 3 days, with subsequent radiological control in most cases.

CONCLUSION

The survey shows the relevance of radioguided surgery in the management of breast cancer patients at different stages of the disease, with disparity in the implementation of new techniques and tools, which responds to the multiple healthcare realities of Nuclear Medicine services.

Interventional nuclear medicine's contribution to molecularly targeted precision surgery

The surgical approach to different pathologies, not only oncological, has evolved. As Veronesi's group has coined very graphically, we are moving from "maximum tolerable treatments to minimum effective treatments" and this journey cannot be carried out in any other way than through a multidisciplinary and multimodality approach. Multidisciplinary, because collaboration between surgeons, oncologists, radiologists, nuclear physicians, pathologists, and all those involved in patient follow-up is necessary, and multimodality, because we must move towards precision surgery tailored to each patient in which, on the part of Nuclear Medicine, hybrid imaging (SPECT/CT and PET/CT), bimodal tracers, the use of new allies such as ultrasound or our own adaptation to robotic surgery have a great deal to say. A wide range of possibilities is built on the solid foundation of preoperative scintigraphy, which makes it possible to identify the target tissues and whose knowledge prior to surgery allows the necessary surgical approach to be considered for each patient.

Robot-assisted Prostate-specific Membrane Antigen-radioguided Salvage Surgery in Recurrent Prostate Cancer Using a DROP-IN Gamma Probe: The First Prospective Feasibility Study

BACKGROUND

It has been proven that intraoperative prostate-specific membrane antigen (PSMA)-targeted radioguidance is valuable for the detection of prostate cancer (PCa) lesions during open surgery. Rapid extension of robot-assisted, minimally invasive surgery has increased the need to make PSMA-radioguided surgery (RGS) robot-compliant.

OBJECTIVE

To evaluate whether the miniaturized DROP-IN gamma probe facilitates translation of PSMA-RGS to robotic surgery in men with recurrent PCa.

DESIGN, SETTING, AND PARTICIPANTS

This prospective feasibility study included 20 patients with up to three pelvic PCa recurrences (nodal or local) on staging PSMA positron emission tomography (PET) after previous curative-intent therapy.

SURGICAL PROCEDURE

Robot-assisted PSMA-RGS using the DROP-IN gamma probe was carried out 19-23 h after intravenous injection of ^99mtechnetium PSMA-Investigation & Surgery (^99mTc-PSMA-I&S).

MEASUREMENTS

The primary endpoint was the feasibility of robot-assisted PSMA-RGS. Secondary endpoints were a comparison of the radioactive status (positive or negative) of resected specimens and final histopathology results, prostate-specific antigen (PSA) response following PSMA-RGS, and complications according to the Clavien-Dindo classification.

RESULTS AND LIMITATIONS

Using the DROP-IN probe, 19/21 (90%) PSMA-avid lesions could be resected robotically. On a per-lesion basis, the sensitivity and specificity of robot-assisted PSMA-RGS was 86% and 100%, respectively. A prostate-specific antigen (PSA) reduction of >50% and a complete biochemical response (PSA <0.2 ng/ml) were seen in 12/18 (67%) and 4/18 (22%) patients, respectively. During follow-up of up to 15 mo, 4/18 patients (22%) remained free of biochemical recurrence (PSA ≤0.2 ng/ml). One patient suffered from a Clavien-Dindo grade >III complication.

CONCLUSIONS

The DROP-IN probe helps in realizing robot-assisted PSMA-RGS. The procedure is technically feasible for intraoperative detection of nodal or local PSMA-avid PCa recurrences.

PATIENT SUMMARY

A device called the DROP-IN probe facilitates minimally invasive, robot-assisted surgery guided by radioactive tracers in patients with recurrent prostate cancer. This procedure holds promise for improving the intraoperative identification and removal of prostate cancer lesions.

Possible Role of Circulating Tumour Cells for Prediction of Salvage Lymph Node Dissection Outcome in Patients with Early Prostate Cancer Recurrence

Promising oncological results have been reported for salvage lymph node dissection (SLND) with prostate-specific membrane antigen–radioguided surgery (PSMA-RGS) in patients with prostate cancer (PCa) recurrence. We performed a proof-of-principle study assessing circulating tumour cells (CTCs) as a prognostic marker in patients undergoing SLND. Twenty consecutive patients with recurrent PCa treated with PSMA-RGS during April–July 2019 for PSMA-positive LNs were evaluated. Preoperative CTC counts were assessed using the US Food and Drug Administration–approved CellSearch system. Biochemical recurrence (BCR)-free survival (BFS) and therapy-free survival (TFS) were evaluated using the Kaplan-Meier method. Overall, three patients (15%) were CTC-positive. Postoperatively, CTC-positive patients had more pathologically positive LNs (median 8 vs 2) without a difference in overall LN count. During median follow-up of 10.1 mo, 14 patients experienced BCR and five received further therapy. In Kaplan-Meier analyses, median BFS was 1.4 versus 4.3 mo and median TFS was 10.3 mo versus not reached for CTC-positive versus CTC-negative patients. The main limitations are the small number of patients, the retrospective design, and short follow-up. Our pilot study suggests that CTC-positive patients seem to have worse pathological and short-term oncological outcomes. Therefore, further validation of this biomarker for treatment decision-making before local salvage therapy could be of value.

Patient summary

We looked at outcomes for lymph node dissection in patients with recurrence of prostate cancer. We found that outcomes appear to be worse when circulating tumour cells (CTCs) can be measured in the blood preoperatively. We conclude that detection of CTCs indicates spread of tumour cells via the blood, which may limit the benefit of lymph node dissection. Thus, CTCs should be investigated in further studies as a potential marker to help in selecting patients who could benefit from lymph node dissection if their prostate cancer recurs.

Radioguided Surgery in Insulinoma Using 68Ga Labeled Exendin-4: a Case Report

Laparoscopic resection of tumor is often performed for benign and small insulinomas, or for those located in the body or tail of the pancreas. The precise preoperative and intraoperative localization of the insulinoma is critical to minimize the surgical intervention. Conventional imaging studies, i.e., MRI, CT, and endoscopic ultrasound have limited sensitivity due to the small size of the insulinomas. Angiography, intraarterial calcium stimulation, and venous sampling are invasive procedures with concomitant risk for complications. Exendin-4 PET/CT scan has shown to be of great value in preoperative localization of insulinomas. In the absence of the traditional gold standard, i.e., intraoperative ultrasound with manual palpation, in laparoscopic surgery, a simple enucleation procedure might not be possible. Gamma probe-assisted surgery is a new method of diagnosis and treatment which allows a small area of tissue to be identified and removed, while a large area of the organ or the system remains unaffected. We present a case of a 34-year-old man with clinical suspicion of insulinoma with negative conventional imaging and successful lesion localization with ⁶⁸Ga-Exendin-4 PET/CT scan in the pancreatic body, who underwent laparoscopic enucleation of the lesion with the aid of a hand-held gamma detecting probe.

Use of wire guided localisation and radio-guided occult lesion localisation for non-palpable breast lesions: A systematic literature review and meta-analysis of current evidence

Breast cancer screening has seen an increase in the detection of non-palpable breast lesions. Wire guided localisation (WGL) and Radio-guided occult lesion localisation (ROLL) are well established modalities of localisation of non-palpable breast lesions in the UK. We aimed to compare the outcomes of WGL and ROLL in this updated meta-analysis. We searched Cochrane Central Register of Controlled Trials (CENTRAL), and LILACS using free text search words as well as relevant MESH-terms. We also searched Medline (02/03/2021), Embase and registers of clinical trials, abstracts of scientific meetings, reference lists of included studies and contacted experts in the field. Outcomes considered were re-excision rates, margin involvement, specimen volume and weight, accurate localisation of lesions and operative time. We assessed the risk of bias in included studies and performed random effects meta-analyses using Review Manager (version 5.3). Heterogeneity was estimated using the I²-statistic. Nine included studies enrolled 1096 patients undergoing localization in breast surgery (534 in WGL and 562 in ROLL). There was a statistically significant benefit in favour of ROLL for non-involved resection margins (OR 0.60; 95% CI, 0.44-0.97); based on seven studies. Nine trials assessed operative time favouring ROLL (OR 1.95; 95% CI, 0.27-3.63). No significant difference in re-excision rates was reported (OR 1.42; 95% CI, 0.83-2.43) based on seven studies. Current evidence favourably supports ROLL, compared to WGL, with respect to margin involvement, localisation and operative time in the treatment of non-palpable breast lesions.

Occupational radiation exposure of radiopharmacy-, nuclear medicine-, and surgical personnel during use of [99mTc]Tc-PSMA-I&S for prostate cancer surgery

Aim: The aim of this study was to estimate and subsequently measure the occupational radiation exposure for all personnel involved in the production, administration, imaging, or surgery with [^99mTc]Tc-PSMA-I&S, which has been introduced for identification of tumor-positive lymph nodes during salvage prostate cancer surgery Materials and Methods: The effective dose was estimated and subsequently measured with electronic personal dosimeters for the following procedures and personnel: labeling and quality control by the radiopharmacy technician, syringe preparation by the nuclear medicine laboratory technician, patient administration by the nuclear medicine physician, patient imaging by the nuclear medicine imaging technician, and robot-assisted laparoscopic salvage lymph node dissection attended by an anesthesiology technician, scrub nurse, surgical nurse, and surgeon. The dose rate of the patient was measured immediately after administration of [^99mTc]Tc-PSMA-I&S, after imaging, and after surgery. Results: The estimated dose per procedure ranged from 1.59x10-10 µSv (imaging technician) to 9.74 µSv (scrub nurse). The measured effective dose ranged from 0 to 5 µSv for all personnel during one procedure with [^99mTc]Tc-PSMA-I&S. The highest effective dose was received by the scrub nurse (3.2±1.3 µSv), whilst the lowest dose was measured for the surgical nurse (0.2±0.5 µSv). If a single scrub nurse would perform as much as 100 procedures with [^99mTc]Tc-PSMA-I&S in a year, the total effective dose would be 3.2x10-1 mSv/year. Immediately after administration, the dose rate at 50 cm from the patient was 18.5±1.6 µSv/h, which dropped to 1.8±0.3 µSv/h after imaging the following day and reducing even further to 0.56±0.33 µS/h after surgery. Conclusion: The effective dose for personnel involved in handling [^99mTc]Tc-PSMA-I&S is comparable to that of other ^99mTc-radiopharmaceuticals and therefore safe for imaging and radioguided surgery.

Role of a portable gamma-camera with optical view for margins assessment of pulmonary nodules resected by radioguided surgery

PURPOSE

Radioguided occult lesion localization (ROLL) of pulmonary nodules is an alternative to hook-wire. Both required of a histological margin assessment. The activity emerging from the radiotracer allows to obtain an intraoperative scintigraphic image of the surgical specimen by a portable gamma-camera (PGC) fitted with an optical view, which provides information about the localization of the nodule in relation to the margins. The aim of this study was to evaluate the intraoperative use of a PGC for margin assessment of pulmonary nodules.

METHODS

ROLL technique was used in 38 nodules (36 pulmonary, 1 chest wall, and 1 pleural nodules). A PGC intraoperative image of the surgical specimen was obtained in 32. Scintigraphic results were compared to the histological assessment. Other factors, such as nodule size, distance from the pleural surface, or distance covered by the needle, were considered as possible factors for non-centered lesions.

RESULTS

PGC images showed that the lesion was in contact with the margins in 8/32 cases and centered in 24. In all cases in which the lesion was considered as centered by the PGC, the margins were free of involvement (NPV 100%), although the PPV is low.

CONCLUSIONS

The use of a PGC for margin assessment after pulmonary nodule resection is feasible and provides a high NPV in our series. In addition, the short intraoperative time required for its use makes the PGC a useful tool for providing supplementary information to histopathologic results. Further studies from different surgical teams are required for an external validation.

The Click-On gamma probe, a second-generation tethered robotic gamma probe that improves dexterity and surgical decision-making

Purpose

Decision-making and dexterity, features that become increasingly relevant in (robot-assisted) minimally invasive surgery, are considered key components in improving the surgical accuracy. Recently, DROP-IN gamma probes were introduced to facilitate radioguided robotic surgery. We now studied if robotic DROP-IN radioguidance can be further improved using tethered Click-On designs that integrate gamma detection onto the robotic instruments themselves.

Methods

Using computer-assisted drawing software, 3D printing and precision machining, we created a Click-On probe containing two press-fit connections and an additional grasping moiety for a ProGrasp instrument combined with fiducials that could be video tracked using the Firefly laparoscope. Using a dexterity phantom, the duration of the specific tasks and the path traveled could be compared between use of the Click-On or DROP-IN probe. To study the impact on surgical decision-making, we performed a blinded study, in porcine models, wherein surgeons had to identify a hidden ⁵⁷Co-source using either palpation or Click-On radioguidance.

Results

When assembled onto a ProGrasp instrument, while preserving grasping function and rotational freedom, the fully functional prototype could be inserted through a 12-mm trocar. In dexterity assessments, the Click-On provided a 40% reduction in movements compared to the DROP-IN, which converted into a reduction in time, path length, and increase in straightness index. Radioguidance also improved decision-making; task-completion rate increased by 60%, procedural time was reduced, and movements became more focused.

Conclusion

The Click-On gamma probe provides a step toward full integration of radioguidance in minimal invasive surgery. The value of this concept was underlined by its impact on surgical dexterity and decision-making.

Radioguided surgery with iodine-125 seeds in breast cancer patients treated with neoadjuvant chemotherapy

OBJECTIVE

To evaluate the use of radioactive iodine-125 seed (RIS) in breast and/or axillary surgery, in patients with breast cancer treated with neoadjuvant chemotherapy (NAC).

MATERIAL AND METHODS

Prospective study between January 2016 and June 2020. 80 women T1-3,N0-2,M0: 30 RIS marking the breast tumor, 36 both the tumor and the biopsied positive axillary node, and 14 only the axilla. Age: 54.7±11.4 years. Tumor size: 34.1±14.6mm. Histological type: invasive ductal carcinoma 90.0%. Molecular subtypes: luminal-A 23.8%, luminal-B/HER2- 33.7%, luminal-B/HER2+ 18.8%, HER2+ 7.5%, basal-like 16,2%.

RESULTS

Of the 66 patients with RIS marking of the tumor (51 pre-NAC, 15 post-NAC), 92.1% had tumor-free surgical margins, with a specimen volume of 126.7±111.2 cm3. Of the 5 second local excisions, in 3 the resection margin was involved (1 mastectomy). Of the 50 patients N1 with RIS marking (MLN), 44 pre-NAC and 6 post-NAC, MLN was identified in 97.2%: negative 23, positive 26. In 45/50 patients, sentinel node biopsy (SNB) was performed and it was identified in 93.3%: negative 26, positive 16. In 1 case RIS was not placed correctly and SNB was not identified due to non-migration. In 61.9% of the patients, MLN was among the SNB identified in the surgery. In 5 patients with mismatched SNB and MLN, the pathological result of the SNB was negative and the MLN was positive. Axillary lymph node dissection was performed in 53.8% of the patients.

CONCLUSION

RIS allow to perform breast-conserving surgery and improve detection of residual axillary disease in patients treated with NAC.

Salvage Surgery in Patients with Local Recurrence After Radical Prostatectomy

BACKGROUND

Since the introduction of prostate-specific membrane antigen (PSMA) positron emission tomography (PET) imaging, isolated local recurrence after radical prostatectomy (RP) can be delineated accurately.

OBJECTIVE

To describe and evaluate surgical technique, biochemical response, and therapy-free survival (TFS) after salvage surgery in patients with local recurrence in the seminal vesicle bed.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively assessed 40 patients treated with open salvage surgery in two centres (11/2014-02/2020). All patients presented with biochemical recurrence (BCR) after RP with a singular local recurrence at PSMA PET imaging. Thirty-three (82.5%) patients received previous salvage radiation therapy.

SURGICAL PROCEDURE

Open salvage surgery with PSMA radioguidance.

MEASUREMENTS

Prostate-specific antigen (PSA) nadir and percentage of patients with complete biochemical response (cBR) without further treatment (PSA < 0.2 ng/ml) after 6-16 wk were assessed. BCR-free survival and TFS were calculated using Kaplan-Meier estimates. Clavien-Dindo complications were evaluated.

RESULTS AND LIMITATIONS

Prior to salvage surgery, median PSA was 0.9 ng/ml (interquartile range [IQR]: 0.5-1.7 ng/ml). Postoperatively, median PSA nadir was 0.1 ng/ml (IQR: 0-0.4 ng/ml). In 31 (77.5%) patients, cBR was observed. During the median follow-up of 24.4 months, 22 (55.0%) patients experienced BCR and 12 (30.0%) received further therapy. At 1 yr of follow-up, BCR-free survival rate was 62.2% and TFS rate was 88.3%. Three (7.5%) Clavien-Dindo grade III complications were observed. The main limitations are the retrospective design, short follow-up, and lack of a control group.

CONCLUSIONS

Salvage surgery of local recurrence within the seminal vesicle bed is feasible. It may present an opportunity in selected, locally recurrent patients to prolong BCR-free survival and increase TFS. Further studies are needed to confirm our findings.

PATIENT SUMMARY

We looked at the outcomes from prostate cancer patients with locally recurrent disease after radical prostatectomy and radiotherapy. We found that surgery in well-selected patients may be an opportunity to prolong treatment-free survival.

A CT-based radiomics model to detect prostate cancer lymph node metastases in PSMA radioguided surgery patients

PURPOSE

In recurrent prostate carcinoma, determination of the site of recurrence is crucial to guide personalized therapy. In contrast to prostate-specific membrane antigen (PSMA)-positron emission tomography (PET) imaging, computed tomography (CT) has only limited capacity to detect lymph node metastases (LNM). We sought to develop a CT-based radiomic model to predict LNM status using a PSMA radioguided surgery (RGS) cohort with histological confirmation of all suspected lymph nodes (LNs).

METHODS

Eighty patients that received RGS for resection of PSMA PET/CT-positive LNMs were analyzed. Forty-seven patients (87 LNs) that received inhouse imaging were used as training cohort. Thirty-three patients (62 LNs) that received external imaging were used as testing cohort. As gold standard, histological confirmation was available for all LNs. After preprocessing, 156 radiomic features analyzing texture, shape, intensity, and local binary patterns (LBP) were extracted. The least absolute shrinkage and selection operator (radiomic models) and logistic regression (conventional parameters) were used for modeling.

RESULTS

Texture and shape features were largely correlated to LN volume. A combined radiomic model achieved the best predictive performance with a testing-AUC of 0.95. LBP features showed the highest contribution to model performance. This model significantly outperformed all conventional CT parameters including LN short diameter (AUC 0.84), LN volume (AUC 0.80), and an expert rating (AUC 0.67). In lymph node-specific decision curve analysis, there was a clinical net benefit above LN short diameter.

CONCLUSION

The best radiomic model outperformed conventional measures for detection of LNM demonstrating an incremental value of radiomic features.

A DROP-IN Gamma Probe for Robot-assisted Radioguided Surgery of Lymph Nodes During Radical Prostatectomy

BACKGROUND

The DROP-IN gamma probe was introduced to overcome the restricted manoeuvrability of traditional laparoscopic gamma probes. Through enhanced manoeuvrability and surgical autonomy, the DROP-IN promotes the implementation of radioguided surgery in the robotic setting.

OBJECTIVE

To confirm the utility and safety profile of the DROP-IN gamma probe and to perform a comparison with the traditional laparoscopic gamma probe and fluorescence guidance.

DESIGN, SETTING, AND PARTICIPANTS

Twenty-five prostate cancer patients were scheduled for a robot-assisted sentinel lymph node (SN) procedure, extended pelvic lymph node dissection, and prostatectomy at a single European centre.

SURGICAL PROCEDURE

After intraprostatic injection of indocyanine green (ICG)-^99mTc-nanocolloid (n = 12) or ^99mTc-nanocolloid + ICG (n = 13), SN locations were defined using preoperative imaging. Surgical excision of SNs was performed under image guidance using the DROP-IN gamma probe, the traditional laparoscopic gamma probe, and fluorescence imaging.

MEASUREMENTS

Intraoperative SN detection was assessed for the different modalities and related to anatomical locations. Patient follow-up was included (a median of 18 mo).

RESULTS AND LIMITATIONS

Overall, 47 SNs were pursued in vivo by the DROP-IN gamma probe, of which 100% were identified. No adverse events related to its use were observed. In vivo fluorescence imaging identified 91% of these SNs. The laparoscopic gamma probe identified only 76% of these SNs, where the detection inaccuracies appeared to be related to specific anatomical regions.

CONCLUSIONS

Owing to improved manoeuvrability, the DROP-IN probe yielded improved SN detection rates compared with the traditional gamma probe and fluorescence imaging. These findings underline that the DROP-IN technology provides a valuable tool for radioguided surgery in the robotic setting.

PATIENT SUMMARY

Radioguided robot-assisted surgery with the novel DROP-IN gamma probe is feasible and safe. It enables more efficient intraoperative identification of sentinel lymph nodes than can be achieved with a traditional laparoscopic gamma probe. The use of the DROP-IN probe in combination with fluorescence imaging allows for a complementary optical confirmation of node localisations.

Feasibility study on the use of CMOS sensors as detectors in radioguided surgery with β-- emitters

Radioguided surgery (RGS) is a medical practice which thanks to a radiopharmaceutical tracer and a probe allows the surgeon to identify tumor residuals up to a millimetric resolution in real-time. The employment of β^- emitters, instead of γ or β⁺, reduces background from healthy tissues, administered activity to the patient, and medical exposure. In a previous work the possibility of using a CMOS Imager (Aptina MT9V011), initially designed for visible light imaging, to detect β^- from ⁹⁰Y or ⁹⁰Sr sources has been established. Because of its possible application as counting probe in RGS, the performances of MT9V011 in clinical-like conditions were studied.¹ Through horizontal scans on a collimated ⁹⁰Sr source of different sizes (1, 3, 5, 7 mm), we have determined relationships between scan fit parameters and the source dimension, namely A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter, are determined. Horizontal scan measurements on a source, interposing collimators of different size, aim to determine relationships or correlations between scan fit parameters and source dimension. A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter are determined. In order to get closer to clinical conditions, agar-agar phantoms containing ⁹⁰Y with different dimensions and activities were prepared. A ⁹⁰Y phantom is characterized by a central spot and a ring all around, for simulating both signal (tumor) and background (surrounding healthy tissue). The relationship found between scan maximum and ⁹⁰Sr source diameter is then exploited to extract the concentration ratio between spot and external ring of the ⁹⁰Y phantom. This observable, defined as the ratio between the tumor and the nearby healthy tissues uptake simulates the Tumor-to-Non-tumor Ratio (TNR). With the aim of evaluating the sensor's ability to discriminate signal from background relying on the significance parameter, a further ⁹⁰Y phantom, featuring a well-known and clinical-like activity will mimic the signal only condition. This result is used to extrapolate to different source sizes, after having estimated the background for various TNR. The obtained significance values suggest that the MT9V011 sensor is capable of distinguishing a signal from an estimated background, depending on the interplay among TNR, acquisition time and tumor diameter.

Diagnosis and radio-guided surgery of lung nodules

The detection of pulmonary nodules has increased in recent decades due to the introduction of lung cancer screening programs and the massively use of routine chest computed tomography in patients with malignant neoplasms. Percutaneous biopsy of these nodules does not always characterize them, so sometimes a surgical biopsy is necessary, which often requires a presurgical localization. The radioguided occult lesion localization (ROLL) described for breast lesions was first applied in the resection of pulmonary nodules in 2000, becoming an alternative to other presurgical localization techniques such as hook-wire. The technique provides high detection rate with minimal morbidity, enhancing multidisciplinary work with specialists in Radiology and Chest Surgery. The present paper describes the different pre-surgical localization techniques currently available, the methodological procedure of the ROLL technique and the collected results in 20 years of experience.

A DROP-IN beta probe for robot-assisted 68Ga-PSMA radioguided surgery: first ex vivo technology evaluation using prostate cancer specimens

BACKGROUND

Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. In parallel, a novel approach to achieve sensitive radioguidance using beta-emitting PET isotopes has been proposed. Integration of these two concepts would allow to exploit the use of PET tracers during robot-assisted tumor-receptor-targeted. In this study, we have engineered and validated the performance of a novel DROP-IN beta particle (DROP-INβ) detector.

METHODS

Seven prostate cancer patients with PSMA-PET positive tumors received an additional intraoperative injection of ~ 70 MBq 68Ga-PSMA-11, followed by robot-assisted prostatectomy and extended pelvic lymph node dissection. The surgical specimens from these procedures were used to validate the performance of our DROP-INβ probe prototype, which merged a scintillating detector with a housing optimized for a 12-mm trocar and prograsp instruments.

RESULTS

After optimization of the detector and probe housing via Monte Carlo simulations, the resulting DROP-INβ probe prototype was tested in a robotic setting. In the ex vivo setting, the probe-positioned by the robot-was able to identify 68Ga-PSMA-11 containing hot-spots in the surgical specimens: signal-to-background (S/B) was > 5 when pathology confirmed that the tumor was located < 1 mm below the specimen surface. 68Ga-PSMA-11 containing (and PET positive) lymph nodes, as found in two patients, were also confirmed with the DROP-INβ probe (S/B > 3). The rotational freedom of the DROP-IN design and the ability to manipulate the probe with the prograsp tool allowed the surgeon to perform autonomous beta-tracing.

CONCLUSIONS

This study demonstrates the feasibility of beta-radioguided surgery in a robotic context by means of a DROP-INβ detector. When translated to an in vivo setting in the future, this technique could provide a valuable tool in detecting tumor remnants on the prostate surface and in confirmation of PSMA-PET positive lymph nodes.

Selective Neck Dissection Guided by a Radioactive I125 Seed for Papillary Thyroid Carcinoma Recurrence

Lymph nodes are the most common place of recurrence of papillary thyroid cancer, and surgery can be considered a therapeutic option. The risks of surgery increase with every intervention. We present 3 cases of cervical non palpable thyroid cancer recurrence managed with I125 seed radioguided cervical dissection from 2017 to 2019. Two of the cases had already a thyroidectomy and central compartment lymphadenectomy performed. The seed was placed guided by US on the lesion and its position was confirmed afterwards. The target was successfully localized in 100% of cases. There was no post surgery complications. There was no evidence of recurrence with a mean follow up of 15 months. Radioguided surgery using I125 seed it is a save technique and it offers a precise localization of the non palpable thyroid cancer recurrence.

Application of the ROLL technique as a method of excisional biopsy in oncological pathology

OBJECTIVE

To evaluate the utility of the ROLL (Radioguided Occult Lesion Localization) technique as a method of excisional biopsy in hypermetabolic lesions suspected of malignancy evidenced in [¹⁸F]Fluordeoxiglucose PET/CT scans.

MATERIAL AND METHODS

33 patients were retrospectively evaluated referred for metabolic studies due to tumoral pathology or suspected neoplastic process and presenting hypermetabolic adenopathies with high probability of malignancy. The group consisted of 19 women and 14 men, ranging from 23 to 77 years old. Patients were performed a ROLL technique for localization and removal the selected adenopathies, through the injection of [99mTc] macro-aggregates of albumin guided by ultrasound or CT. A detection probe and a portable gamma camera were used during the surgical procedure.

RESULTS

In 31 patients (94%) the location and removal of the radiolabeled adenopathies was achieved. In one patient the location of the lesion was not possible and a second patient was not operated due to inadequate dose injection confirmed by gammagraphy study. The result of the anatomopathological study of adenopathies resulted in 23 tumor affections and 8 benign processes, including a granulomatous process.

CONCLUSION

The ROLL technique proved its utility as a radioguided excisional biopsy method for the study of lesions suspected of malignancy evidenced in patients undergoing PET/CT studies. The technique allowed to confirm the persistence of oncological process in some cases and the existence of false positives from the imaging study in others, modifying the patients therapeutic management.

Automated synthesis and quality control of [99mTc]Tc-PSMA for radioguided surgery (in a [68Ga]Ga-PSMA workflow)

BACKGROUND

Lymph node dissection is a therapeutic option for prostate cancer patients with a high risk of- or proven lymph node metastases. Radioguided surgery after intravenous injection of [^99mTc]Tc-PSMA could improve the selectivity of lymph node dissection. The aim of this project was to develop an automated synthesis method for [^99mTc]Tc-PSMA, using the disposables and chemicals used at our institute for [⁶⁸Ga]Ga-PSMA labeling. Furthermore, quality control procedures and validation results of the automated production of [^99mTc]Tc-PSMA conform cGMP and cGRPP are presented.

METHODS

[^99mTc]Tc-PSMA is produced fully automatic with a Scintomics synthesis module. Quality control procedures are described and performed for: activity, labeling yield, visual inspection, pH measurement, sterility and endotoxin determination, radionuclide purity, radiochemical purity (^99mTc-colloids, unbound [^99mTc]pertechnetate, and other impurities), and HEPES content. Three batches of [^99mTc]Tc-PSMA were prepared on three separate days for validation and stability testing at 0, 4, 6, and 24 h.

RESULTS

[^99mTc]Tc-PSMA can be successfully manufactured automatically within a [⁶⁸Ga]Ga-PSMA workflow with the addition of only [^99mTc]pertechnetate and stannous chloride. The radiochemical purity after production was highly reproducible (96.3%, 97.6%, and 98.2%) and remained > 90% (required for patient administration) up to 6 h later.

CONCLUSION

A fully automated labeling procedure with corresponding quality control methods for production of [^99mTc]Tc-PSMA is presented, which is validated according to cGMP and cGRPP guidelines and can be implemented in a GMP environment. The produced [^99mTc]Tc-PSMA is stable for up to 6 h. The presented procedure is almost identical to the automated production of [⁶⁸Ga]Ga-PSMA and can therefore be implemented expediently if a workflow for [⁶⁸Ga]Ga-PSMA is already in place.

Recent advances in nuclear and hybrid detection modalities for image-guided surgery

Introduction: Radioguided surgery is an ever-evolving part of nuclear medicine. In fact, this nuclear medicine sub-discipline actively bridges non-invasive molecular imaging with surgical care. Next to relying on the availability of radio- and bimodal-tracers, the success of radioguided surgery is for a large part dependent on the imaging modalities and imaging concepts available for the surgical setting. With this review, we have aimed to provide a comprehensive update of the most recent advances in the field. Areas covered: We have made an attempt to cover all aspects of radioguided surgery: 1) the use of radioisotopes that emit γ, β⁺, and/or β^- radiation, 2) hardware developments ranging from probes to 2D cameras and even the use of advanced 3D interventional imaging solutions, and 3) multiplexing solutions such as dual-isotope detection or combined radionuclear and optical detection. Expert opinion: Technical refinements in the field of radioguided surgery should continue to focus on supporting its implementation in the increasingly complex minimally invasive surgical setting, e.g. by accommodating robot-assisted laparoscopic surgery. In addition, hybrid concepts that integrate the use of radioisotopes with other image-guided surgery modalities such as fluorescence or ultrasound are likely to expand in the future.

125I radioactive seed localization for non-palpable lesions in breast cancer

AIM

Marking of non-palpable breast lesions with ¹²⁵I radioactive seeds is an alternative to the use of the surgical wire. The objective of this work is to present the results that we have obtained using radioactive seed localization compared to the reference technique in our center, the wire localization of non-palpable breast lesions.

MATERIAL AND METHOD

Longitudinal prospective study that includes patients with histological diagnostic of breast cancer, with non-palpable lesions that are candidates to primary surgical treatment by radioactive seed localization (2016-2018) and by wire localization (2015-2016). Histological analysis of the surgical specimen was performed determining the status of surgical margins. The volume of the surgical specimen was calculated.

RESULTS

A total of 146 patients were included, 95 who underwent surgery by radioactive seed localization and 51 by wire localization. The mean cube volume of the specimens were 135.67cm3 vs. 190.77cm3 (p=0.017), respectively. Eleven patients who underwent surgery by radioactive seed localization showed affected margins of the specimen (11.6%), versus 7 (13.2%) of wire localization group (p=0.084). Reintervention was performed in 9 of the patients marked with seeds and in 7 marked with wires (p=0.49).

CONCLUSION

The use of ¹²⁵I radioactive seeds is feasible in non-palpable breast lesions, with a low rate of reintervention and volumes of surgical specimens significantly lower than those obtained by wire localization.

Augmenting camera images with gamma detector data : A novel approach to support sentinel lymph node biopsy

BACKGROUND

Squamous cell carcinoma in the head and neck region is one of the most widespread cancers with high morbidity. Classic treatment comprises the complete removal of the lymphatics together with the cancerous tissue. Recent studies have shown that such interventions are only required in 30% of the patients. Sentinel lymph node biopsy is an alternative method to stage the malignancy in a less invasive manner and to avoid overtreatment. In this paper, we present a novel approach that enables a future augmented reality device which improves the biopsy procedure by visual means.

METHODS

We propose a co-calibration scheme for axis-aligned miniature cameras with pinholes of a gamma ray collimating and sensing device and show results gained by experiments, based on a calibration target visible for both modalities.

RESULTS

Visual inspection and quantitative evaluation of the augmentation of optical camera images with gamma information are congruent with known gamma source landmarks.

CONCLUSIONS

Combining a multi-pinhole collimator with axis-aligned miniature cameras to augment optical images using gamma detector data is promising. As such, our approach might be applicable for breast cancer and melanoma staging as well, which are also based on sentinel lymph node biopsy.

Single Lesion on Prostate-specific Membrane Antigen-ligand Positron Emission Tomography and Low Prostate-specific Antigen Are Prognostic Factors for a Favorable Biochemical Response to Prostate-specific Membrane Antigen-targeted Radioguided Surgery in Recurrent Prostate Cancer

BACKGROUND

Prostate-specific membrane antigen (PSMA)-ligand positron emission tomography (PET) allows detection of metastatic prostate cancer (PC) lesions at low prostate-specific antigen (PSA) values. To facilitate their intraoperative detection during salvage surgery, we recently introduced PSMA-targeted radioguided surgery (RGS).

OBJECTIVE

To describe the outcome of a large cohort of patients treated with PSMA-targeted RGS and to establish prognostic factors.

DESIGN, SETTING, AND PARTICIPANTS

A total of 121 consecutive patients with recurrent PC as defined by PSMA-ligand PET (median PSA: 1.13ng/ml) underwent PSMA-targeted RGS.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The frequency of a complete biochemical response (cBR; PSA <0.2ng/ml) without additional treatment and the duration of biochemical recurrence-free survival (bRFS, time from PSMA-targeted RGS with PSA <0.2ng/ml without further treatment) were evaluated and correlated with preoperatively available clinical variables.

RESULTS AND LIMITATIONS

In almost all patients (120/121, 99%) metastatic tissue could be removed. A cBR was achieved in 77 patients (66%). The chance of cBR was highest in patients with both low preoperative PSA and a single lesion (38/45: 84%). Median bRFS was 6.4mo in the whole patient cohort and 19.8mo for patients with cBR. Significantly longer median bRFS was observed in patients with a low preoperative PSA value (p=0.004, hazard ratio 1.48, 95% confidence interval 1.13-1.93) and with a single lesion in preoperative PSMA-ligand PET (14.0 vs 2.5mo, p=0.002).

CONCLUSIONS

PSMA-targeted RGS leads to a remarkable interval of bRFS in a subset of patients. The frequency of cBR and the duration of bRFS were highest in patients with a low preoperative PSA value and a single lesion on PSMA-ligand PET.

PATIENT SUMMARY

Prostate-specific membrane antigen radioguided surgery delays disease progression in selected patients with recurrent prostate cancer after radical prostatectomy. Patients with a single lesion of recurrence and a low prostate-specific antigen value had the best outcome.

Update on radioguided surgery: from international consensus on sentinel node in head and neck cancer to the advances on gynaecological tumors and localization of non-palpable lesions

The aim of this review is to provide an updated perspective on different fields of radioguided surgery. With reference to the sentinel lymph node biopsy in oral squamous cell carcinoma, we present the results of the interactive debate held at the recent Congress of our specialty about the more relevant aspects of the London Consensus. Drainage peculiarities and indications according to the current guidelines on gynaecological tumours, endometrial and cervical cancer, are detailed and new scenarios for nuclear medicine physicians are presented; robotic surgery and hybrid tracers, for instance. Moreover, the notable growth in radioguided surgery indications for non-palpable lesions, widely used in mammary pathology, make it advisable to update two procedures which have shown satisfying results, such as the solitary pulmonary nodule and the osteoid osteoma.

The EANM practical guidelines for sentinel lymph node localisation in oral cavity squamous cell carcinoma

Purpose

Sentinel lymph node biopsy is an essential staging tool in patients with clinically localized oral cavity squamous cell carcinoma. The harvesting of a sentinel lymph node entails a sequence of procedures with participation of specialists in nuclear medicine, radiology, surgery, and pathology. The aim of this document is to provide guidelines for nuclear medicine physicians performing lymphoscintigraphy for sentinel lymph node detection in patients with early N0 oral cavity squamous cell carcinoma.

Methods

These practice guidelines were written and have been approved by the European Association of Nuclear Medicine (EANM) and the International Atomic Energy Agency (IAEA) to promote high-quality lymphoscintigraphy. The final result has been discussed by distinguished experts from the EANM Oncology Committee, and national nuclear medicine societies. The document has been endorsed by the Society of Nuclear Medicine and Molecular Imaging (SNMMI).

These guidelines, together with another two focused on Surgery and Pathology (and published in specialised journals), are part of the synergistic efforts developed in preparation for the “2018 Sentinel Node Biopsy in Head and Neck Consensus Conference”.

Conclusion

The present practice guidelines will help nuclear medicine practitioners play their essential role in providing high-quality lymphatic mapping for the care of early N0 oral cavity squamous cell carcinoma patients.

Performance of 111In-labelled PSMA ligand in patients with nodal metastatic prostate cancer: correlation between tracer uptake and histopathology from lymphadenectomy

PURPOSE

Intraoperative identification of lymph node (LN) metastases (LNM) detected on preoperative PSMA PET/CT may be facilitated by PSMA radioguided surgery with the use of a gamma probe. We evaluated the uptake of ¹¹¹In-labelled PSMA ligand DKFZ-617 (referred to as ¹¹¹In-PSMA-617) in unaffected LN and LNM at the level of single LN.

METHODS

Six patients with prostate cancer (PCa) with suspicion of LNM on preoperative PSMA PET/CT underwent ¹¹¹In-PSMA-617-guided lymphadenectomy (LA; four salvage LA and two primary LA). ¹¹¹In-PSMA-617 (109 ± 5 MBq). was injected Intravenously 48 h prior to surgery Template LAs were performed in small subregions: common, external, obturator and internal iliac vessels, and presacral and retroperitoneal subregions (n = 4). Samples from each subregion were isolated aiming at the level of single LN. Uptake was measured ex situ using a germanium detector. Receiver operating characteristic (ROC) analysis was performed based on ¹¹¹In-PSMA-617 uptake expressed as standardized uptake values normalized to lean body mass (SUL).

RESULTS

Overall 310 LN (mean 52 ± 19.7) were removed from 74 subregions (mean 12 ± 3.7). Of the 310 LN, 35 turned out to be LNM on histopathology. Separation of the samples from all subregions resulted in 318 single specimens: 182 PCa-negative LN samples with 275 LN, 35 single LNM samples, 3 non-nodal PCa tissue samples and 98 fibrofatty tissue samples. The median SULs of nonaffected LN (0.16) and affected LN (13.2) were significantly different (p < 0.0001). Based on 38 tumour-containing and 182 tumour-free specimens, ROC analysis revealed an area under the curve of 0.976 (95% CI 0.95-1.00, p < 0.0001). Using a SUL cut-off value of 1.136, sensitivity, specificity, positive predictive value, negative predictive value and accuracy in discriminating affected from nonaffected LN were 92.1% (35/38), 98.9% (180/182), 94.6% (35/37), 98.4% (180/183) and 97.7% (215/220), respectively.

CONCLUSION

Ex situ analysis at the level of single LN showed that ¹¹¹In-PSMA-617 had excellent ability to discriminate between affected and nonaffected LN in our patients with PCa. This tracer characteristic is a prerequisite for in vivo real-time measurements during surgery.

Robot-assisted laparoscopic surgery using DROP-IN radioguidance: first-in-human translation

Purpose

Radioguided surgery has been widely used for clinical procedures such as sentinel node resections. In the (robot-assisted) laparoscopic setting radioguidance is realized using laparoscopic gamma probes, which have limited maneuverability. To increase the rotational freedom, a tethered DROP-IN gamma probe was designed. Here we present the first in vivo feasibility study of this technology in prostate cancer patients.

Methods

Ten patients scheduled for a sentinel node procedure received four injections into the prostate with (indocyanine green-)^99mTechnetium-nanocolloid and underwent preoperative imaging (lymphoscintigraphy and SPECT/CT). The DROP-IN probe was inserted via the assistant port, still permitting the insertion and usage of additional laparoscopic tools.

Results

The sentinel nodes were resected using the da Vinci® Si robot under guidance of DROP-IN gamma tracing and fluorescence imaging. The surgeon was able to independently maneuver the DROP-IN probe using the ProGrasp® forceps of the da Vinci® robot and distinguish sentinel nodes from background signal (such as the injection site).

Conclusions

Overall the DROP-IN design proves to be a valuable tool for robot-assisted radioguided surgery approaches.

Radioguided hepatic resection with 18F-DOPA in a patient with metastatic medullary thyroid carcinoma

INTRODUCTION

Medullary carcinoma accounts for 1-2% of all thyroid malignancies. 13-20% of patients present with distant metastasis, with 45% of the cases affecting the liver.

CLINICAL CASE

A 50-year-old woman, diagnosed with medullary thyroid carcinoma, was treated with total thyroidectomy and a modified neck dissection in 1999. Two lymph node recurrences in the neck were treated with surgical resection; during surveillance, she developed elevated calcitonin levels, the recurrence site was identified with ¹⁸F-DOPA PET/CT in the liver. Metabolic activity was not associated with a visible lesion in CT, MRI nor ultrasound. Radioguided surgery with ¹⁸F-DOPA allowed an anatomic resection of segments IVb and V.

DISCUSSION

In patients with medullary carcinoma and elevated calcitonin during surveillance, ¹⁸F-DOPA PET/CT is an option to evaluate the site of recurrence. Radioguided resection was feasible in this patient, whose hepatic recurrence was not visible with any other imaging method.

CONCLUSION

Radioguided hepatic resection with ¹⁸F-DOPA in metastatic medullary thyroid carcinoma is feasible when the recurrence site is not anatomically identified by any other imaging studies.

Novel technology of molecular radio-guidance for lymph node dissection in recurrent prostate cancer by PSMA-ligands

PURPOSE

Recently, prostate-specific membrane antigen-radioguided surgery (PSMA-RGS) has been introduced as a promising new and individual treatment concept in patients with localised recurrent prostate cancer (PC). In the following, we want to review our experience with PSMA-RGS in patients with localised biochemical recurrent PC.

METHODS

A non-systematic review of the literature was carried out with focus on technical and logistical aspects of PSMA-RGS. Furthermore, published data on intraoperative detection of metastatic lesions compared to preoperative PSMA-PET and postoperative histopathology, postoperative complications as well as oncological follow-up data are summarized. Finally, relevant aspects on prerequisites for PSMA-RGS, patient selection, and the potential benefit of additional salvage radiotherapy or potential future applications of robotic PSMA-RGS with drop-in γ-probes are discussed.

RESULTS

First results show that PSMA-RGS is very sensitive and specific in tracking suspicious lesions intraoperatively. Prerequisite for patient selection and localisation of tumour recurrence is a positive Ga-HBED-CC PSMA positron-emission tomography (PET) scan with preferably only singular soft tissue or lymph node recurrence after primary treatment. Furthermore, PSMA-RGS has the potential to positively influence oncological outcome.

CONCLUSIONS

PSMA-RGS seems to be of high value in patients with localised PC recurrence for exact localisation and resection of oftentimes small metastatic lesions using intraoperative and ex vivo γ-probe measurements. However, patient identification on the basis of Ga-HBED-CC-PSMA PET imaging as well as clinical parameters is crucial to obtain satisfactory results.

Radioguided thyroidectomy for follicular tumors: Multicentric experience

BACKGROUND

The diagnosis of thyroid nodular diseases requires an integrated approach that has been widely established over the past years. This strategy includes: ultrasonography (US) with; implemented Color-Power-Doppler, conventional scintigraphy also with positive indicators, specific pathological studies targeted by immunohistochemically-assays, and the fine needle; aspiration biopsy (FNAB), which, usually, in case of "Follicular Lesions" (10-20%) findings is; unable to distinguish carcinoma from follicular adenoma, then indicating the necessity of surgery to; obtain a correct diagnosis. The aim of this study was to evaluate the role of the scintigraphy with; positive indicators, both preoperatively in diagnostic approach of the thyroid nodules and; intraoperatively as a guide to the extension of the surgical excision.

METHODS

On 4482 Thyroidectomy performed, we selected 360 cases of follicular neoplasms (192; females and 168 males). In the preoperative phase, these patients underwent 99 m Tc-sestaMIBI; scintigraphy with both early (10 min) and late (2 h) image acquisition, which were later; compared to the ones obtained by image subtraction of means 99 m Tc-pertechnetate. Following the; sestamibi administration before intervention, we selected the most up-taking nodularity with the; assistance of a specific surgical probe (Neoprobe), quantifying uptake with relation to the surgical pathology, for an amount of 324 total thyroidectomies and 36 hemi thyroidectomies.

RESULTS

In all cases of multinodular goiter the benign nodules showed an intraoperative low sestamibi uptake whereas follicular carcinomas showed both a high preoperative uptake and, as a; percentage, the highest values of intraoperative uptake; on the other hand, follicular adenomas had; both pre-and intraoperative mean values of uptake. On the contrary, papillary carcinomas only; showed a mild uptake.

CONCLUSIONS

Preoperative sestamibi scintigraphy confirmed its importance in improving the information obtained through different diagnostic investigations. Also intraoperatively, it pointed; out high-risk nodules more accurately. Therefore, radio (Sestamibi) guided surgery could have an; interesting rule in the thyroid follicular lesion treatment.

From interventionist imaging to intraoperative guidance: New perspectives by combining advanced tools and navigation with radio-guided surgery

The integration of medical imaging technologies into diagnostic and therapeutic approaches can provide a preoperative insight into both anatomical (e.g. using computed tomography, magnetic resonance imaging, or ultrasound), as well as functional aspects (e.g. using single photon emission computed tomography, positron emission tomography, lymphoscintigraphy, or optical imaging). Moreover, some imaging modalities are also used in an interventional setting (e.g. computed tomography, ultrasound, gamma or optical imaging) where they provide the surgeon with real-time information during the procedure. Various tools and approaches for image-guided navigation in cancer surgery are becoming feasible today. With the development of new tracers and portable imaging devices, these advances will reinforce the role of interventional molecular imaging.

Hybrid intraoperative imaging techniques in radioguided surgery: present clinical applications and future outlook

PURPOSE

This review aims to summarise the hybrid modality radioguidance techniques currently in clinical use and development, and to discuss possible future avenues of research. Due to the novelty of these approaches, evidence of their clinical relevance does not yet exist. The purpose of this review is to inform nuclear medicine practitioners of current cutting edge research in radioguided surgery which may enter standard clinical practice within the next 5-10 years. Hybrid imaging is of growing importance to nuclear medicine diagnostics, but it is only with recent advances in technology that hybrid modalities are being investigated for use during radioguided surgery. These modalities aim to overcome some of the difficulties of surgical imaging while maintaining many benefits, or providing entirely new information unavailable to surgeons with traditional radioguidance.

METHODS

A literature review was carried out using online reference databases (Scopus, PubMed). Review articles obtained using this technique were citation mined to obtain further references.

RESULTS

In total, 2367 papers were returned, with 425 suitable for further assessment. 60 papers directly related to hybrid intraoperative imaging in radioguided surgery are reported on. Of these papers, 25 described the clinical use of hybrid imaging, 22 described the development of new hybrid probes and tracers, and 13 described the development of hybrid technologies for future clinical use. Hybrid gamma-NIR fluorescence was found to be the most common clinical technique, with 35 papers associated with these modalities. Other hybrid combinations include gamma-bright field imaging, gamma-ultrasound imaging, gamma-β imaging and β-OCT imaging. The combination of preoperative and intraoperative images is also discussed.

CONCLUSION

Hybrid imaging offers new possibilities for assisting clinicians and surgeons in localising the site of uptake in procedures such as in sentinel node detection.

Contribution of SPECT/CT for sentinel node localization in patients with ipsilateral breast cancer relapse

Background

In recent years repeat sentinel node (SN) biopsy has been proven to be feasible in local breast cancer recurrence (LBCR). However, in these patients SNs outside the ipsilateral axilla are frequently observed. This study evaluates the contribution of SPECT/CT for SN localization and surgical adjustment in LBCR patients.

Methods

SN biopsy was performed in 122 LBCR patients (median age 60.5 years, range 24–87), enrolled from August 2006 to July 2015. Median disease-free time lapse was 109.5 months (range 9–365). Axillary lymph node dissection (ALND) had previously been performed in 55 patients, SN biopsy in 44, both techniques in 13 and fine-needle aspiration in 10. Primary breast cancer treatment included radiotherapy in 104 patients (85.3 %) and chemotherapy in 40 (32.8 %). Preoperative lymphatic mapping, using planar scintigraphy (PS) and SPECT/CT included report of SN location according to lymph node territory. In case of a territorial PS-SPECT/CT mismatch, surgery was adjusted according to SPECT/CT findings.

Results

SPECT/CT SN visualization rate was higher than PS (53.3 % vs. 43.4 %, p n.s.) with, in total, 19 additional SN (118 vs. 99, p n.s.). PS-SPECT/CT territory mismatch, found in 60 % (39/65) of patients with SN visualization, led to surgical adjustment in 21.3 % (26/122) of patients. The SN procedure was finally performed in 104 patients resulting in a 65.7 % surgical retrieval rate with a total of 132 removed SNs (1.86/patient). SN metastases were found in 17/71 patients (23.9 %), in 16 of them (94 %) in ipsilateral basins outside the axilla or in the contralateral axilla.

Conclusion

Using SPECT/CT there is a trend to visualize more SNs in LBCR, providing at the same time important anatomical information to adjust intraoperative SN procedures. The addition of SPECT/CT to the standard imaging protocol may lead to better staging mainly in patients presenting drainage outside the ipsilateral axilla.

Current status of ultrasound-guided surgery in the treatment of breast cancer

The primary goal of breast-conserving surgery (BCS) is to obtain tumour-free resection margins. Margins positive or focally positive for tumour cells are associated with a high risk of local recurrence, and in the case of tumour-positive margins, re-excision or even mastectomy are sometimes needed to achieve definite clear margins. Unfortunately, tumour-involved margins and re-excisions after lumpectomy are still reported in up to 40% of patients and additionally, unnecessary large excision volumes are described. A secondary goal of BCS is the cosmetic outcome and one of the main determinants of worse cosmetic outcome is a large excision volume. Up to 30% of unsatisfied cosmetic outcome is reported. Therefore, the search for better surgical techniques to improve margin status, excision volume and consequently, cosmetic outcome has continued. Nowadays, the most commonly used localization methods for BCS of non-palpable breast cancers are wire-guided localization (WGL) and radio-guided localization (RGL). WGL and RGL are invasive procedures that need to be performed pre-operatively with technical and scheduling difficulties. For palpable breast cancer, tumour excision is usually guided by tactile skills of the surgeon performing “blind” surgery. One of the surgical techniques pursuing the aims of radicality and small excision volumes includes intra-operative ultrasound (IOUS). The best evidence available demonstrates benefits of IOUS with a significantly high proportion of negative margins compared with other localization techniques in palpable and non-palpable breast cancer. Additionally, IOUS is non-invasive, easy to learn and can centralize the tumour in the excised specimen with low amount of healthy breast tissue being excised. This could lead to better cosmetic results of BCS. Despite the advantages of IOUS, only a small amount of surgeons are performing this technique. This review aims to highlight the position of ultrasound-guided surgery for malignant breast tumours in the search for better oncological and cosmetic outcomes.

Revolutionizing (robot-assisted) laparoscopic gamma tracing using a drop-in gamma probe technology

In complex (robot-assisted) laparoscopic radioguided surgery procedures, or when low activity lesions are located nearby a high activity background, the limited maneuverability of a laparoscopic gamma probe (LGP; 4 degrees of freedom (DOF)) may hinder lesion identification. We investigated a drop-in gamma probe (DIGP) technology to be inserted via a trocar, after which the laparoscopic surgical tool at hand can pick it up and maneuver it. Phantom experiments showed that distinguishing a low objective from a high background source (1:100 ratio) was only possible with the detector faced >90° from the high background source. Signal-low-objective-to-background ratios of 3.77, 2.01 and 1.84 were found for detector angles of 90°, 135° and 180°, respectively, whereas detector angles of 0° and 45° were unable to distinguish the sources. This underlines the critical role probe positioning plays. We then focused on engineering of the gripping part for optimal DIGP pick-up with a conventional laparoscopic forceps (4 DOF) or a robotic forceps (6 DOF). DIGPs with 0°, 45°, 90°, and 135° -grip orientations were designed, and their maneuverability- and scanning direction were evaluated and compared to a conventional LGP. The maneuverability- and scanning direction of the DIGP was found highest when using the robotic forceps, with the largest effective scanning direction range obtained with the 90° -grip design (0-180° versus 0-111°, 0-140°, and 37-180° for 0°, 45° and 135° -grip designs, respectively). For the laparoscopic forceps, the scan direction directly translated from the angle of the grip design with the advantage that the 135° -gripped DIGP could be faced backwards (not possible with the conventional LGP). In the ex vivo clinical setup, the surgeon rated DIGP pick-up most convenient for the 45°-grip design. Concluding, the DIGP technology was successfully introduced. Optimization of the grip design and grasping angle of the DIGP increased its utility for (robot-assisted) laparoscopic gamma tracing.