Novel perioperative imaging with 18F-FDG PET/CT and intraoperative 18F-FDG detection using a handheld gamma probe in recurrent ovarian cancer

Radiation source detection for the accurate location of lymph node metastases using robotic forceps-type coincidence radiation detector

PURPOSE

We have developed a forceps-type coincidence radiation detector for supporting lymph node dissection in esophageal cancer treatment. For precise detecting, this study aims to measure the 2D point-spread function of the detector at three difference tip angles, to devise a method to determine the position of a point source using the 2D point-spread function.

METHOD

The 2D sensitivity distribution on the surface of the detector was investigated to assess sensitivity variation caused by differences in the relative positions of the detector and radiation source. Based on the results, we identified the peak sensitivity value and proposed a detection method using this value. We evaluated the effectiveness of the proposed method by detecting radiation source location using this simulated distribution.

RESULT

From the radiation sensitivity distribution measurements, we observed a gradual decrease in radiation detection sensitivity from the center toward the edges of the detector surface. Additionally, we verified that the peak sensitivity value was attainable. Through the basic verification of the detection method, we confirmed that the radiation source location could be detected within a maximum error of 1.4 mm.

CONCLUSION

We developed a peak value search method aimed at mitigating sensitivity variations by leveraging the sensitivity distribution across the detector surface. The proposed device is thought to be able to quantitatively evaluate the desired target assuming that the field of view could be limited to the area clamped by the detector. As a next research step, more precise search methods should be verified in an environment resembling the one of the target clinical uses.

Method for co-registration of high-resolution specimen PET-CT with histopathology to improve insight into radiotracer distributions

BACKGROUND

As the spatial resolution of positron emission tomography (PET) scanners improves, understanding of radiotracer distributions in tissues at high resolutions is important. Hence, we propose a method for co-registration of high-resolution ex vivo specimen PET images, combined with computed tomography (CT) images, and the corresponding specimen histopathology.

METHODS

We applied our co-registration method to breast cancer (BCa) specimens of patients who were preoperatively injected with 0.8 MBq/kg [18 F]fluorodeoxyglucose ([18F]FDG). The method has two components. First, we used an image acquisition scheme that minimises and tracks tissue deformation: (1) We acquired sub-millimetre (micro)-PET-CT images of ±2 mm-thick lamellas of the fresh specimens, enclosed in tissue cassettes. (2) We acquired micro-CT images of the same lamellas after formalin fixation to visualise tissue deformation. (3) We obtained 1 hematoxylin and eosin (H&E) stained histopathology section per lamella of which we captured a digital whole slide image (WSI). Second, we developed an automatic co-registration algorithm to improve the alignment between the micro-PET-CT images and WSIs, guided by the micro-CT of the fixated lamellas. To estimate the spatial co-registration error, we calculated the distance between corresponding microcalcifications in the micro-CTs and WSIs. The co-registered images allowed to study standardised uptake values (SUVs) of different breast tissues, as identified on the WSIs by a pathologist.

RESULTS

We imaged 22 BCa specimens, 13 cases of invasive carcinoma of no special type (NST), 6 of invasive lobular carcinoma (ILC), and 3 of ductal carcinoma in situ (DCIS). While the cassette framework minimised tissue deformation, the best alignment between the micro-PET-CT images and WSIs was achieved after deformable co-registration. We found an overall average co-registration error of 0.74 ± 0.17 mm between the micro-PET images and WSIs. (Pre)malignant tissue (including NST, ILC, and DCIS) generally showed higher SUVs than healthy tissue (including healthy glandular, connective, and adipose tissue). As expected, inflamed tissue and skin also showed high uptake.

CONCLUSIONS

We developed a method to co-register micro-PET-CT images of surgical specimens and WSIs with an accuracy comparable to the spatial resolution of the micro-PET images. While currently, we only applied this method to BCa specimens, we believe this method is applicable to a wide range of specimens and radiotracers, providing insight into distributions of (new) radiotracers in human malignancies at a sub-millimetre resolution.

Innovations in dedicated PET instrumentation: from the operating room to specimen imaging

This review casts a spotlight on intraoperative positron emission tomography (PET) scanners and the distinctive challenges they confront. Specifically, these systems contend with the necessity of partial coverage geometry, essential for ensuring adequate access to the patient. This inherently leans them towards limited-angle PET imaging, bringing along its array of reconstruction and geometrical sensitivity challenges. Compounding this, the need for real-time imaging in navigation systems mandates rapid acquisition and reconstruction times. For these systems, the emphasis is on dependable PET image reconstruction (without significant artefacts) while rapid processing takes precedence over the spatial resolution of the system. In contrast, specimen PET imagers are unburdened by the geometrical sensitivity challenges, thanks to their ability to leverage full coverage PET imaging geometries. For these devices, the focus shifts: high spatial resolution imaging takes precedence over rapid image reconstruction. This review concurrently probes into the technical complexities of both intraoperative and specimen PET imaging, shedding light on their recent designs, inherent challenges, and technological advancements.

Radioguided Occult Lesion Localization for Gynecologic Tumor Relapses: Development of a Technique

PURPOSE OF THE REPORT

Excision of peritoneal or nodal isolated recurrences frequently involves performing a surgery on a previously operated area, which is more difficult to achieve with minimally invasive approaches. Our aim was to describe the technical aspects, feasibility, and complications derived from the application of the radioguided occult lesions localization (ROLL) in gynecologic oncology recurrence excision.

PATIENTS AND METHODS

All consecutive patients bearing localized relapses of a gynecologic tumor that were considered candidates for surgical excision were assessed to undergo a ROLL procedure. Radiotracer (99mTc-albumin macroaggregate) injection of the lesions was performed by ultrasonography or CT guidance. Relapses were localized using a gamma probe by minimally invasive surgery when located in the abdomen, or percutaneously when located in the groin. Intraoperative and early (up to postoperative day 30) complications were prospectively recorded.

RESULTS

A total of 8 patients underwent the procedure. The median age was 59 years (range, 35-87 years). Four patients had abdominal relapses, whereas 4 patients presented groin relapses. The mean operative time was 120 minutes (range, 30-190 minutes), whereas the median estimated blood loss was 5 mL (range, 0-150 mL). All the targeted lesions were successfully removed. No intraoperative complications were reported. One postoperative complication (inguinal lymphocele) was recorded.

CONCLUSIONS

ROLL surgery constitutes a new approach for isolated recurrences in gynecological tumors.

Handheld PET Probe for Pediatric Cancer Surgery

Simple Summary

Positron emission tomography (PET)/computed tomography (CT) scans are widely used as a form of full body imaging and allow for the early detection of small, asymptomatic tumors that may represent cancer metastasis or recurrence. Tissue diagnosis is critical in determining the choice of ongoing targeted therapy for pediatric patients with solid tumors. These small tumors may be difficult to localize in the operating room, especially in a re-operative or radiated area of the body. An adjunct such as a PET probe, used to guide intra-operative dissection, is the ideal tool to assist in cases where an occult tumor requires an excisional biopsy.

Abstract

18F-fluorodeoxyglucose (FDG) is a glucose analog that acts as a marker for glucose uptake and metabolism. FDG PET scans are used in monitoring pediatric cancers. The handheld PET probe localization of FDG-avid lesions is an emerging modality for radio-guided surgery (RGS). We sought to assess the utility of PET probe in localizing occult FDG-avid tumors in pediatric patients. PET probe functionality was evaluated by using a PET/CT scan calibration phantom. The PET probe was able to detect FDG photon emission from simulated tumors with an expected decay of the radioisotope over time. Specificity for simulated tumor detection was lower in a model that included background FDG. In a clinical model, eight pediatric patients with FDG-avid primary, recurrent or metastatic cancer underwent a tumor excision, utilizing IV FDG and PET probe survey. Adequate tissue for diagnosis was present in 16 of 17 resected specimens, and pathology was positive for malignancy in 12 of the 17 FDG-avid lesions. PET probe gamma counts per second were higher in tumors compared with adjacent benign tissue in all operations. The median ex vivo tumor-to-background ratio (TBR) was 4.0 (range 0.9–12). The PET probe confirmed the excision of occult FDG-avid tumors in eight pediatric patients.

One-by-One Comparison of Lymph Nodes Between 18F-FDG Uptake and Pathological Diagnosis in Esophageal Cancer

Esophagectomy with extended lymph node (LN) dissection is a standard treatment for resectable esophageal cancer to prevent recurrence, but severe, potentially life-threatening postoperative complications are still important issues. Accurate diagnosis of LN metastases would enable the decision to dissect or leave the LNs in regions with high risk of complications. Advancements in intraoperative gamma probe and radioactivity detectors have made intraoperative navigation surgery possible using a radiotracer as a marker. ¹⁸F-FDG is one such candidate markers, and the diagnostic power of FDG through counting the radioactivity close to each LN should be elucidated.

Intraoperative biophotonic imaging systems for image-guided interventions

Biophotonic imaging has revolutionized the operation room by providing surgeons intraoperative image-guidance to diagnose tumors more efficiently and to resect tumors with real-time image navigation. Among many medical imaging modalities, near-infrared (NIR) light is ideal for image-guided surgery because it penetrates relatively deeply into living tissue, while nuclear imaging provides quantitative and unlimited depth information. It is therefore ideal to develop an integrated imaging system by combining NIR fluorescence and gamma-positron imaging to provide surgeons with highly sensitive and quantitative detection of diseases, such as cancer, in real-time without changing the look of the surgical field. The focus of this review is to provide recent progress in intraoperative biophotonic imaging systems, NIR fluorescence imaging and intraoperative nuclear imaging devices, and their future perspectives for image-guided interventions.

Normal Variants and Pitfalls Encountered in PET Assessment of Gynecologic Malignancies

Combined PET/computed tomography is used for oncological indications. PET/computed tomography benefits from the metabolic information of PET and the anatomic localization of computed tomography. The integrated scanner provides data with accurate registration of anatomy and molecular information. Many physiologic conditions, normal variants, and benign lesions within the pelvis and the body can cause confusion and uncertainty. False-negative results owing to low 18F-fluorodeoxyglucose uptake from the tumor can produce diagnostic challenges and inaccurate conclusions. This article reviews normal variants and potential pitfalls encountered in PET assessment of gynecologic malignancies to provide useful information for the referring and reporting physicians.

Advancing Precision Nuclear Medicine and Molecular Imaging for Lymphoma

PET with fluorodeoxyglucose F 18 (¹⁸F FDG-PET) is a meaningful biomarker for the detection, targeted biopsy, and treatment of lymphoma. This article reviews the evolution of ¹⁸F FDG-PET as a putative biomarker for lymphoma and addresses the current capabilities, challenges, and opportunities to enable precision medicine practices for lymphoma. Precision nuclear medicine is driven by new imaging technologies and methodologies to more accurately detect malignant disease. Although quantitative assessment of response is limited, such technologies will enable a more precise metabolic mapping with much higher definition image detail and thus may make it a robust and valid quantitative response assessment methodology.

Feasibility of a multimodal (18)F-FDG-directed lymph node surgical excisional biopsy approach for appropriate diagnostic tissue sampling in patients with suspected lymphoma

Background

¹⁸F-FDG PET/CT imaging is widely utilized in the clinical evaluation of patients with suspected or documented lymphoma. The aim was to describe our cumulative experience with a multimodal ¹⁸F-FDG-directed lymph node surgical excisional biopsy approach in patients with suspected lymphoma.

Methods

Thirteen patients (mean age 51 (±16;22–76) years), with suspected new or suspected recurrent lymphoma suggested by ¹⁸F-FDG-avid lesions seen on prior diagnostic whole-body PET/CT imaging, were injected IV with ¹⁸F-FDG prior to undergoing same-day diagnostic lymph node surgical excisional biopsy in the operating room. Various ¹⁸F-FDG detection strategies were used on the day of surgery, including, (1) same-day pre-resection patient PET/CT; (2) intraoperative gamma probe assessment; (3) clinical scanner specimen PET/CT imaging of whole surgically excised tissue specimens; (4) specimen gamma well counts; and/or (5) same-day post-resection patient PET/CT.

Results

Same-day ¹⁸F-FDG injection dose was 14.8 (±2.4;12.5-20.6) millicuries or 548 (±89;463–762) megabecquerels. Sites of ¹⁸F-FDG-avid lesions were 4 inguinal, 3 cervical, 3 abdominal/retroperitoneal, 2 axillary, and 1 gluteal region subcutaneous tissue. Same-day pre-resection patient PET/CT was performed on 6 patients. Intraoperative gamma probe assessment was performed on 13 patients. Clinical scanner PET/CT imaging of whole surgically excised tissue specimens was performed in 10 cases. Specimen gamma well counts were performed in 6 cases. Same-day post-resection patient PET/CT imaging was performed on 8 patients. Time from ¹⁸F-FDG injection to same-day pre-resection patient PET/CT, intraoperative gamma probe assessment, and same-day post-resection patient PET/CT were 76 (±8;64–84), 240 (±63;168–304), and 487 (±104;331–599) minutes, respectively. Time from ¹⁸F-FDG injection to clinical scanner PET/CT of whole surgically excised tissue specimens was 363 (±60;272–446) minutes. Time from ¹⁸F-FDG injection to specimen gamma well counts was 591 (±96;420–689) minutes. Intraoperative gamma probe assessment successfully identified ¹⁸F-FDG-avid lesions in 12/13 patients. Histopathologic evaluation confirmed lymphoma in 12/13 patients and benign disease in 1/13 patients.

Conclusions

A multimodal approach to ¹⁸F-FDG-directed lymph node surgical excisional biopsy for suspected lymphoma is technically feasible for guiding appropriate diagnostic tissue sampling of lymph nodes seen as ¹⁸F-FDG-avid lesions on diagnostic ¹⁸F-FDG PET/CT imaging.

Cerenkov luminescence endoscopy: improved molecular sensitivity with β--emitting radiotracers

Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β(+) or β(-)) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β(-) radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation.

METHODS

The signal-to-noise ratio (SNR) of (90)Y was compared with that of (18)F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR.

RESULTS

γ noise from (18)F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of (90)Y compared with (18)F in phantoms. (90)Y-bound RGD peptide produced a higher tumor-to-background SNR than (18)F in a mouse model.

CONCLUSION

The use of (90)Y for Cerenkov endoscopic imaging enabled superior results compared with an (18)F radiotracer.

Comparison of two threshold detection criteria methodologies for determination of probe positivity for intraoperative in situ identification of presumed abnormal 18F-FDG-avid tissue sites during radioguided oncologic surgery

Background

Intraoperative in situ identification of ¹⁸F-FDG-avid tissue sites during radioguided oncologic surgery remains a significant challenge for surgeons. The purpose of our study was to evaluate the 1.5-to-1 ratiometric threshold criteria method versus the three-sigma statistical threshold criteria method for determination of gamma detection probe positivity for intraoperative in situ identification of presumed abnormal ¹⁸F-FDG-avid tissue sites in a manner that was independent of the specific type of gamma detection probe used.

Methods

From among 52 patients undergoing appropriate in situ evaluation of presumed abnormal ¹⁸F-FDG-avid tissue sites during ¹⁸F-FDG-directed surgery using 6 available gamma detection probe systems, a total of 401 intraoperative gamma detection probe measurement sets of in situ counts per second measurements were cumulatively taken.

Results

For the 401 intraoperative gamma detection probe measurement sets, probe positivity was successfully met by the 1.5-to-1 ratiometric threshold criteria method in 150/401 instances (37.4%) and by the three-sigma statistical threshold criteria method in 259/401 instances (64.6%) (P < 0.001). Likewise, the three-sigma statistical threshold criteria method detected true positive results at target-to-background ratios much lower than the 1.5-to-1 target-to-background ratio of the 1.5-to-1 ratiometric threshold criteria method.

Conclusions

The three-sigma statistical threshold criteria method was significantly better than the 1.5-to-1 ratiometric threshold criteria method for determination of gamma detection probe positivity for intraoperative in situ detection of presumed abnormal ¹⁸F-FDG-avid tissue sites during radioguided oncologic surgery. This finding may be extremely important for reshaping the ongoing and future research and development of gamma detection probe systems that are necessary for optimizing the in situ detection of radioisotopes of higher-energy gamma photon emissions used during radioguided oncologic surgery.

18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues

Background

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic ¹⁸F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals.

Methods

¹⁸F-FDG-avid lesions (not surgically manipulated or altered during ¹⁸F-FDG-directed surgery, and visualized both on preoperative and postoperative ¹⁸F-FDG PET/CT imaging) and corresponding background tissues were assessed for ¹⁸F-FDG accumulation on same-day preoperative and postoperative ¹⁸F-FDG PET/CT imaging. Multiple patient variables and ¹⁸F-FDG-avid lesion variables were examined.

Results

For the 32 ¹⁸F-FDG-avid lesions making up the final ¹⁸F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative ¹⁸F-FDG PET/CT scans were 73 (±3, 70-78) and 530 (±79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean ¹⁸F-FDG-avid lesion SUV_max values were 7.7 (±4.0, 3.6-19.5) and 11.3 (±6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUV_max values were 2.3 (±0.6, 1.0-3.2) and 2.1 (±0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUV_max ratios were 3.7 (±2.3, 1.5-9.8) and 5.8 (±3.6, 1.6-16.2), respectively, (P < 0.001).

Conclusions

¹⁸F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for ¹⁸F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the ¹⁸F-FDG-avid lesion SUV_max values, decreased background SUV_max values, and increased lesion-to-background SUV_max ratios seen from preoperative to postoperative ¹⁸F-FDG PET/CT imaging have great potential for allowing for the integrated, real-time use of ¹⁸F-FDG PET/CT imaging in conjunction with ¹⁸F-FDG-directed interventional radiology biopsy and ablation procedures and ¹⁸F-FDG-directed surgical procedures, as well as have far-reaching impact on potentially re-shaping future thinking regarding the “most optimal” injection-to-scan acquisition time interval for all routine diagnostic ¹⁸F-FDG PET/CT oncologic imaging.

Intraoperative imaging

Intraoperative image is a rapidly expanding field encompassing many applications that use a multitude of technologies. Some of the these applications have been in use for many years and are firmly embedded in, and indispensable to, clinical practice (e.g. the use of X-ray to locate foreign bodies during surgery or oocyte retrieval under ultrasound guidance. In others, the application may have been in use in one discipline but not yet fully explored in another. Examples include the use of intraoperative ultrasound with or without contrast enhancement for the detection of hepatic metastases not identified preoperatively, and the effect of such additional information on the ultimate operative procedure. Intraoperative identification of sentinel lymph nodes has been explored in many specialties to a varying extent, with the aim of fine tuning and avoiding unnecessary surgery. In both these instances, we do not know the long-term effect of these interventions on patient survival or quality of life. In this chapter, we will explore the available evidence on these applications and current advances in the new technology in general, with a specific focus on gynaecology.

Intraoperative detection of ¹⁸F-FDG-avid tissue sites using the increased probe counting efficiency of the K-alpha probe design and variance-based statistical analysis with the three-sigma criteria

BACKGROUND

Intraoperative detection of (18)F-FDG-avid tissue sites during 18F-FDG-directed surgery can be very challenging when utilizing gamma detection probes that rely on a fixed target-to-background (T/B) ratio (ratiometric threshold) for determination of probe positivity. The purpose of our study was to evaluate the counting efficiency and the success rate of in situ intraoperative detection of (18)F-FDG-avid tissue sites (using the three-sigma statistical threshold criteria method and the ratiometric threshold criteria method) for three different gamma detection probe systems.

METHODS

Of 58 patients undergoing (18)F-FDG-directed surgery for known or suspected malignancy using gamma detection probes, we identified nine (18)F-FDG-avid tissue sites (from amongst seven patients) that were seen on same-day preoperative diagnostic PET/CT imaging, and for which each (18)F-FDG-avid tissue site underwent attempted in situ intraoperative detection concurrently using three gamma detection probe systems (K-alpha probe, and two commercially-available PET-probe systems), and then were subsequently surgical excised.

RESULTS

The mean relative probe counting efficiency ratio was 6.9 (± 4.4, range 2.2-15.4) for the K-alpha probe, as compared to 1.5 (± 0.3, range 1.0-2.1) and 1.0 (± 0, range 1.0-1.0), respectively, for two commercially-available PET-probe systems (P < 0.001). Successful in situ intraoperative detection of 18F-FDG-avid tissue sites was more frequently accomplished with each of the three gamma detection probes tested by using the three-sigma statistical threshold criteria method than by using the ratiometric threshold criteria method, specifically with the three-sigma statistical threshold criteria method being significantly better than the ratiometric threshold criteria method for determining probe positivity for the K-alpha probe (P = 0.05).

CONCLUSIONS

Our results suggest that the improved probe counting efficiency of the K-alpha probe design used in conjunction with the three-sigma statistical threshold criteria method can allow for improved detection of 18F-FDG-avid tissue sites when a low in situ T/B ratio is encountered.

Multimodal imaging and detection approach to 18F-FDG-directed surgery for patients with known or suspected malignancies: a comprehensive description of the specific methodology utilized in a single-institution cumulative retrospective experience

Background

¹⁸F-FDG PET/CT is widely utilized in the management of cancer patients. The aim of this paper was to comprehensively describe the specific methodology utilized in our single-institution cumulative retrospective experience with a multimodal imaging and detection approach to ¹⁸F-FDG-directed surgery for known/suspected malignancies.

Methods

From June 2005-June 2010, 145 patients were injected with ¹⁸F-FDG in anticipation of surgical exploration, biopsy, and possible resection of known/suspected malignancy. Each patient underwent one or more of the following: (1) same-day preoperative patient diagnostic PET/CT imaging, (2) intraoperative gamma probe assessment, (3) clinical PET/CT specimen scanning of whole surgically resected specimens (WSRS), research designated tissues (RDT), and/or sectioned research designated tissues (SRDT), (4) micro PET/CT specimen scanning of WSRS, RDT, and/or SRDT, (5) total radioactivity counting of each SRDT piece by an automatic gamma well counter, and (6) same-day postoperative patient diagnostic PET/CT imaging.

Results

Same-day ¹⁸F-FDG injection dose was 15.1 (± 3.5, 4.6-26.1) mCi. Fifty-five same-day preoperative patient diagnostic PET/CT scans were performed. One hundred forty-two patients were taken to surgery. Three of the same-day preoperative patient diagnostic PET/CT scans led to the cancellation of the anticipated surgical procedure. One hundred forty-one cases utilized intraoperative gamma probe assessment. Sixty-two same-day postoperative patient diagnostic PET/CT scans were performed. WSRS, RDT, and SRDT were scanned by clinical PET/CT imaging and micro PET/CT imaging in 109 and 32 cases, 33 and 22 cases, and 49 and 26 cases, respectively. Time from ¹⁸F-FDG injection to same-day preoperative patient diagnostic PET/CT scan, intraoperative gamma probe assessment, and same-day postoperative patient diagnostic PET/CT scan were 73 (± 9, 53-114), 286 (± 93, 176-532), and 516 (± 134, 178-853) minutes, respectively. Time from ¹⁸F-FDG injection to scanning of WSRS, RDT, and SRDT by clinical PET/CT imaging and micro PET/CT imaging were 389 (± 148, 86-741) and 458 (± 97, 272-656) minutes, 619 (± 119, 253-846) and 661 (± 117, 433-835) minutes, and 674 (± 186, 299-1068) and 752 (± 127, 499-976) minutes, respectively.

Conclusions

Our multimodal imaging and detection approach to ¹⁸F-FDG-directed surgery for known/suspected malignancies is technically and logistically feasible and may allow for real-time intraoperative staging, surgical planning and execution, and determination of completeness of surgical resection.

PET/CT imaging of clear cell renal cell carcinoma with I labeled chimeric antibody

Clear cell renal cell carcinoma (ccRCC) presents problems for urologists in diagnosis, treatment selection, intraoperative surgical margin analysis, and long term monitoring. In this paper we describe the development of a radiolabeled antibody specific to ccRCC (124I-cG250) and its potential to help urologists manage each of these problems. We believe 124I-cG250, in conjunction with perioperative Positron emission tomography/computed tomography imaging and intraoperative handheld gamma probe use, has the potential to diagnose ccRCC, aid in determining a proper course of treatment (operative or otherwise), confirm complete resection of malignant tissue in real time, and monitor patients post-operatively.

Novel handheld PET probes provide intraoperative localization of PET-avid lymph nodes

INTRODUCTION

The accurate intraoperative localization of malignant nodes can pose a challenge to the surgical oncologist. Positron emission tomography (PET) scanning has significantly increased our ability to detect suspicious lesions. We investigated the ability of a novel, handheld tool to evaluate suspicious nodes intraoperatively and to correlate its findings with those seen on preoperative PET scan.

METHODS

Ten nude rats were inoculated with a lymphogenic mesothelioma tumor line and followed weekly with PET scan studies. When suspicious lymph nodes were found, animals were dissected and the intraoperative amount of tissue radiation was analyzed as "tumor-to-background ratio" (TBR) using the PET probes.

RESULTS

The intraoperative probe was used to guide dissections and select high-risk nodes based on their specific radiotracer uptake. A total of 52 nodes were harvested; eight of these were suspicious on preoperative PET scan studies. Using a TBR of 2.5, the intraoperative probes were able to localize all suspicious nodes previously seen on PET scan. Both gamma (sensitivity: 100%; specificity: 86%; positive predictive value (PPV): 57%; negative predictive value (NPV): 100%) and beta (sensitivity: 88%; specificity: 91%; PPV: 64%; NPV: 98%) probes showed an excellent area under the curve (AUC) in the receiver operating characteristic analysis (ROC). Both probes had an AUC of 0.95 for localizing suspicious nodes on PET scan. Furthermore, the AUC for detecting malignancy for the gamma probe was 0.90 (95% confidence interval (CI), 0.83-0.99), and for the beta probe it was 0.97 (95% CI, 0.94-1.0), suggesting a better performance of the beta probe for detecting malignancy.

CONCLUSIONS

This novel tool may be used synergistically with the PET scan examination to maximize intraoperative nodal selection and sampling.

FDG-PET probe-guided surgery for recurrent retroperitoneal testicular tumor recurrences

AIM

Tumor marker based recurrences of previously treated testicular cancer are generally detected with CT scan. They sometimes cannot be visualized with conventional morphologic imaging. FDG-PET has the ability to detect these recurrences. PET probe-guided surgery, may facilitate the extent of surgery and optimize the surgical resection.

METHODS

Three patients with resectable 2nd or 3rd recurrent testicular cancer based on elevated tumor markers after previous various chemotherapy schedules and resections of residual retroperitoneal tumor masses were included in this study. A diagnostic FDG-PET was performed and a hotspot in previously operated area of the retroperitoneal space in all three patients was visualized. PET probe-guided surgery was performed using a high-energy gamma probe 3 h post-injection of 500 MBq FDG.

RESULTS

All patients showed extended adhesions and scar tissue in the retroperitoneal area due to the previous surgeries. Pre-operative PET/CT scan showed a good correlation with intra-operative PET probe-guided detection of recurrent lesions. There was a high target to background ratio (TGB) of 5:1 during the procedure. In one patient, a 2 cm large lesion, which did not show on pre-operative FDG-PET scan, was detected with the PET probe. Histopathologic tissue evaluation demonstrated recurrent vital tumor in all PET probe positive lesions.

CONCLUSIONS

PET probe-guided surgery seems to be a promising tool to localize FDG-PET positive lesion in recurrent testicular cancer in hardly accessible surgical locations. PET probe-guided surgery might be a useful technique in surgical oncology for recurrent testicular cancer and has the potential to be applied in surgery of other malignant diseases.

Perioperative (18)F-fluorodeoxyglucose-guided imaging using the becquerel as a quantitative measure for optimizing surgical resection in patients with advanced malignancy

BACKGROUND

(18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) scanning is a widely accepted preoperative tumor imaging modality. Herein, we evaluate the becquerel (Bq) as a potential novel quantitative PET measure for application of surgical specimen imaging.

METHODS

Retrospectively, PET-avid lesions that could be followed from preoperative imaging, confidently identified in the operating room, imaged ex vivo, and correlated with histopathology were included in this study. Bq counts from both in vivo (preoperative) and ex vivo (surgical specimen) PET/CT images were measured and correlated with histopathology.

RESULTS

Fifty-five PET-avid lesions in 37 patients were included. Forty-six of 55 PET-avid lesions identified were found to contain malignancy on histopathology. Mean Bq counts for the PET-avid lesions were significantly higher that the adjacent PET-nonavid areas (background) within both in vivo and ex vivo imaging (P < .001 and P < .001, respectively). When analyzing all 55 lesions, we found significant increases in Bq levels. PET-avid lesions from in vivo to ex vivo images (P < .001) without significant increases in Bq levels in PET-nonavid lesions from in vivo to ex vivo images (P = .06). When comparing Bq levels between the 2 groups (malignant and benign), we found significantly higher Bq counts in the malignant group on in vivo imaging (P = .02) as well as significantly lower Bq counts in FDG-nonavid areas on ex vivo imaging (P = .04) within the malignant group. Significant differences in PET-avid to PET-nonavid Becquerels ratios within both in vivo and ex vivo images (P = .004, P = .002 respectively) were found, with ex vivo ratio being significantly higher (P < .001).

CONCLUSIONS

(18)F-FDG PET/CT imaging using Bqs is the potential to discern malignant lesions from benign tissues within both in vivo and ex vivo scans.

Obtaining adequate surgical margins in breast-conserving therapy for patients with early-stage breast cancer: current modalities and future directions

Inadequate surgical margins represent a high risk for adverse clinical outcome in breast-conserving therapy (BCT) for early-stage breast cancer. The majority of studies report positive resection margins in 20% to 40% of the patients who underwent BCT. This may result in an increased local recurrence (LR) rate or additional surgery and, consequently, adverse affects on cosmesis, psychological distress, and health costs. In the literature, various risk factors are reported to be associated with positive margin status after lumpectomy, which may allow the surgeon to distinguish those patients with a higher a priori risk for re-excision. However, most risk factors are related to tumor biology and patient characteristics, which cannot be modified as such. Therefore, efforts to reduce the number of positive margins should focus on optimizing the surgical procedure itself, because the surgeon lacks real-time intraoperative information on the presence of positive resection margins during breast-conserving surgery. This review presents the status of pre- and intraoperative modalities currently used in BCT. Furthermore, innovative intraoperative approaches, such as positron emission tomography, radioguided occult lesion localization, and near-infrared fluorescence optical imaging, are addressed, which have to prove their potential value in improving surgical outcome and reducing the need for re-excision in BCT.

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.