Imaging of lumpectomy surface with large field-of-view confocal laser scanning microscopy 'Histolog® scanner' for breast margin assessment in comparison with conventional specimen radiography

PURPOSE

The Histolog® Scanner (SamanTree Medical SA, Lausanne, Switzerland) is a large field-of-view confocal laser scanning microscope designed to allow intraoperative margin assessment by the production of histological images ready for assessment in the operating room. We evaluated the feasibility and the performance of the Histolog® Scanner (HS) to correctly identify infiltrated margins in clinical practice of lumpectomy specimens. It was extrapolated if the utilization of the HS has the potential to reduce infiltrated margins and therefore reduce re-operation rates in patients undergoing breast conserving surgery (BCS) due to a primarily diagnosed breast cancer including ductal carcinoma in situ.

METHODS

This is a single-center, prospective, non-interventional, diagnostic pilot study including 50 consecutive patients receiving BCS. The complete surface of the specimen was scanned using the HS intraoperatively. The surgery and the intraoperative margin assessment of the specimen was performed according to the clinical routine consisting of conventional specimen radiography as well as the clinical impression of the surgeon. Three surgeons and an experienced pathologist assessed the scans produced by the HS for cancer cells on the surface. The potential of the HS to correctly identify involved margins was compared to the results of the conventional specimen radiography alone as well as the clinical routine. The histopathological report served as the gold standard.

RESULTS

50 specimens corresponding to 300 surfaces were scanned by the HS. The mean sensitivity of the surgeons to identify involved margins with the HS was 37.5% ± 5.6%, the specificity was 75.2% ± 13.0%. The assessment of resection margins by the pathologist resulted in a sensitivity of 37.5% and a specificity of 81.0%, while the local clinical routine resulted in a sensitivity of 37.5% and a specificity of 78.2%.

CONCLUSION

Acquisition of high-resolution histological images using the HS was feasible in clinical practice. Sensitivity and specificity were comparable to clinical routine. With more specific training and experience on image interpretation and acquisition, the HS may have the potential to enable more accuracy in the margin assessment of BCS specimens.

Comparison of narrow band and fluorescence molecular imaging to improve intraoperative tumour margin assessment in oral cancer surgery

OBJECTIVE

New techniques have emerged to aid in preventing inadequate margins in oral squamous cell carcinoma (OSCC) surgery, but studies comparing different techniques are lacking. Here, we compared narrow band imaging (NBI) with fluorescence molecular imaging (FMI), to study which intraoperative technique best assesses the mucosal tumour margins.

MATERIALS AND METHODS

NBI was performed in vivo and borders were marked with three sutures. For FMI, patients received 75 mg of unlabelled cetuximab followed by 15 mg cetuximab-800CW intravenously-two days prior to surgery. The FMI borders were defined on the excised specimen. The NBI borders were correlated with the FMI outline and histopathology.

RESULTS

Sixteen patients were included, resulting in 31 NBI and 30 FMI measurements. The mucosal border was delineated within 1 mm of the tumour border in 4/31 (13 %) of NBI and in 16/30 (53 %) FMI cases (p = 0.0008), and within 5 mm in 23/31 (74 %) of NBI and in 29/30 (97 %) of FMI cases (p = 0.0048). The median distance between the tumour border and the imaging border was significantly greater for NBI (3.2 mm, range -6.1 to 12.8 mm) than for FMI (0.9 mm, range -3.0 to 7.4 mm; p = 0.028). Submucosal extension and previous irradiation reduced NBI accuracy.

CONCLUSION

Ex vivo FMI performed more accurately than in vivo NBI in mucosal margin assessment, mainly because NBI cannot detect submucosal extension. NBI adequately identified the mucosal margin especially in early-stage and not previously irradiated tumours, and may therefore be preferable in these tumours for practical and cost-related reasons.

Planning target volume margin assessment for online adaptive MR-guided dose-escalation in rectal cancer on a 1.5 T MR-Linac

PURPOSE

This study assessed the margins needed to cover tumor intrafraction motion during an MR-guided radiotherapy (MRgRT) dose-escalation strategy in intermediate risk rectal cancer.

METHODS

Fifteen patients with rectal cancer were treated with neoadjuvant short-course radiotherapy, 5x5 Gy, according to an online adaptive workflow on a 1.5 T MR-linac. Per patient, 26 3D T2 weighted MRIs were made; one reference scan preceding treatment and five scans per treatment fraction. The primary tumor was delineated on each scan as gross tumor volume (GTV). Target coverage margins were assessed by isotropically expanding the reference GTV until more than 95% of the voxels of the sequential GTVs were covered. A margin with a coverage probability threshold of 90% was defined as adequate. Intra- and interfraction margins to cope with the movement of the GTV in the period between scans were calculated to indicate the target volume margins. Furthermore, the margin needed to cover GTV movement was calculated for different time intervals.

RESULTS

The required margins to cover inter- and intrafraction GTV motion were 17 mm and 6 mm, respectively. Analysis based on time intervals between scans showed smaller margins were needed for adequate GTV coverage as time intervals became shorter, with a 4 mm margin required for a procedure of 15 min or less.

CONCLUSION

The shorter the treatment time, the smaller the margins needed to cover for the GTV movement during an online adaptive MRgRT dose-escalation strategy for intermediate risk rectal cancer. When time intervals between replanning and the end of dose delivery could be reduced to 15 min, a 4 mm margin would allow adequate target coverage.

Intraoperative fluorescence imaging with aminolevulinic acid detects grossly occult breast cancer: a phase II randomized controlled trial

BACKGROUND

Re-excision due to positive margins following breast-conserving surgery (BCS) negatively affects patient outcomes and healthcare costs. The inability to visualize margin involvement is a significant challenge in BCS. 5-Aminolevulinic acid hydrochloride (5-ALA HCl), a non-fluorescent oral prodrug, causes intracellular accumulation of fluorescent porphyrins in cancer cells. This single-center Phase II randomized controlled trial evaluated the safety, feasibility, and diagnostic accuracy of a prototype handheld fluorescence imaging device plus 5-ALA for intraoperative visualization of invasive breast carcinomas during BCS.

METHODS

Fifty-four patients were enrolled and randomized to receive no 5-ALA or oral 5-ALA HCl (15 or 30 mg/kg). Forty-five patients (n = 15/group) were included in the analysis. Fluorescence imaging of the excised surgical specimen was performed, and biopsies were collected from within and outside the clinically demarcated tumor border of the gross specimen for blinded histopathology.

RESULTS

In the absence of 5-ALA, tissue autofluorescence imaging lacked tumor-specific fluorescent contrast. Both 5-ALA doses caused bright red tumor fluorescence, with improved visualization of tumor contrasted against normal tissue autofluorescence. In the 15 mg/kg 5-ALA group, the positive predictive value (PPV) for detecting breast cancer inside and outside the grossly demarcated tumor border was 100.0% and 55.6%, respectively. In the 30 mg/kg 5-ALA group, the PPV was 100.0% and 50.0% inside and outside the demarcated tumor border, respectively. No adverse events were observed, and clinical feasibility of this imaging device-5-ALA combination approach was confirmed.

CONCLUSIONS

This is the first known clinical report of visualization of 5-ALA-induced fluorescence in invasive breast carcinoma using a real-time handheld intraoperative fluorescence imaging device.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT01837225 . Registered 23 April 2013.

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.

A Standardized Framework for Fluorescence-Guided Margin Assessment for Head and Neck Cancer Using a Tumor Acidosis Sensitive Optical Imaging Agent

Purpose

Intra-operative management of the surgical margin in patients diagnosed with head and neck squamous cell carcinoma (HNSCC) remains challenging as surgeons still have to rely on visual and tactile information. Fluorescence-guided surgery using tumor-specific imaging agents can assist in clinical decision-making. However, a standardized imaging methodology is lacking. In this study, we determined whether a standardized, specimen-driven, fluorescence imaging framework using ONM-100 could assist in clinical decision-making during surgery.

Procedures

Thirteen patients with histologically proven HNSCC were included in this clinical study and received ONM-100 24 ± 8 h before surgery. Fluorescence images of the excised surgical specimen and of the surgical cavity were analyzed. A fluorescent lesion with a tumor-to-background ratio (TBR) > 1.5 was considered fluorescence-positive and correlated to standard of care (SOC) histopathology.

Results

All six tumor-positive surgical margins were detected immediately after excision using fluorescence-guided intra-operative imaging. Postoperative analysis showed a median TBR (±IQR) of the fluorescent lesions on the resection margin of 3.36 ± 1.62. Three fluorescence-positive lesions in the surgical cavity were biopsied and showed occult carcinoma and severe dysplasia, and a false-positive fluorescence lesion.

Conclusion

Our specimen-driven fluorescence framework using a novel, pH-activatable, fluorescent imaging agent could assist in reliable and real-time adequate clinical decision-making showing that a fluorescent lesion on the surgical specimen with a TBR of 1.5 is correlated to a tumor-positive resection margin. The binary mechanism of ONM-100 allows for a sharp tumor delineation in all patients, giving the surgeon a clinical tool for real-time margin assessment, with a high sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11307-021-01614-z.

Intraoperative [18F]FDG flexible autoradiography for tumour margin assessment in breast-conserving surgery: a first-in-human multicentre feasibility study

Introduction

In women undergoing breast-conserving surgery (BCS), 20–25% require a re-operation as a result of incomplete tumour resection. An intra-operative technique to assess tumour margins accurately would be a major advantage. A novel method for intraoperative margin assessment was developed by applying a thin flexible scintillating film to specimens—flexible autoradiography (FAR) imaging. A single-arm, multi-centre study was conducted to evaluate the feasibility of intraoperative [¹⁸F]FDG FAR for the assessment of tumour margins in BCS.

Methods

Eighty-eight patients with invasive breast cancer undergoing BCS received ≤ 300 MBq of [¹⁸F]FDG 60–180 min pre-operatively. Following surgical excision, intraoperative FAR imaging was performed using the LightPath^® Imaging System. The first 16 patients were familiarisation patients; the remaining 72 patients were entered into the main study. FAR images were analysed post-operatively by three independent readers. Areas of increased signal intensity were marked, mean normalised radiances and tumour-to-tissue background (TBR) determined, agreement between histopathological margin status and FAR assessed and radiation dose to operating theatre staff measured. Subgroup analyses were performed for various covariates, with thresholds set based on ROC curves.

Results

Data analysis was performed on 66 patients. Intraoperative margin assessment using FAR was completed on 385 margins with 46.2% sensitivity, 81.7% specificity, 8.1% PPV, 97.7% NPV and an overall accuracy of 80.5%, detecting both invasive carcinoma and DCIS. A subgroup analysis based on [¹⁸F]FDG activity present at time of imaging revealed an increased sensitivity (71.4%), PPV (9.3%) and NPV (98.4%) in the high-activity cohort with mean tumour radiance and TBR of 126.7 ± 45.7 photons/s/cm²/sr/MBq and 2.1 ± 0.5, respectively. Staff radiation exposure was low (38.2 ± 38.1 µSv).

Conclusion

[¹⁸F]FDG FAR is a feasible and safe technique for intraoperative tumour margin assessment. Further improvements in diagnostic performance require optimising the method for scintillator positioning and/or the use of targeted radiopharmaceuticals.

Trial registration: Identifier: NCT02666079. Date of registration: 28 January 2016. URL: https://clinicaltrials.gov/ct2/show/NCT02666079.

ISRCTN registry: Reference: ISRCTN17778965. Date of registration: 11 February 2016. URL: http://www.isrctn.com/ISRCTN17778965.

Diagnostic accuracy of resection margin in specimen radiography: digital breast tomosynthesis versus full-field digital mammography

OBJECTIVE

We investigated the accuracy of digital breast tomosynthesis compared to full-field digital mammography for evaluating tumor-free resection margins in the intraoperative specimen during breast-conserving surgery, reducing re-excision rates.

MATERIALS AND METHODS

In total, 170 patients, with proven breast cancer and eligible for breast-conserving surgery, were enrolled. Intraoperative specimens underwent digital mammography and digital breast tomosynthesis. Two breast radiologists, with ten years of experience in breast imaging, in batch mode, evaluated tumor-free resection margins and the distance between the margins and lesion. Histopathological findings were considered the standard of reference.

RESULTS

We used the correlation analysis to evaluate the agreement between measures of tumor-free resection margins obtained with digital mammography and the true value (histopathological findings), and between digital breast tomosynthesis and histopathological findings. The size evaluation determined by digital breast tomosynthesis was more accurately correlated with that found by pathology; the calculated Pearson's correlation coefficient of digital breast tomosynthesis and digital mammography to the pathologically determined tumor-free resection margins were 0.92 and 0.79 in CC view and 0.92 and 0.72 in LL view, respectively. Compared with the pathologically determined tumor-free resection margins, the size determined by both imaging modalities was, on average, overestimated. Bland-Altman analysis showed an excellent inter readers agreement.

CONCLUSIONS

Digital breast tomosynthesis is more accurate in assessment of margin status than digital mammography; it could be a more accurate technique than full-field digital mammography for the intraoperative delineating of tumor resection margins.

Performance of a novel protease-activated fluorescent imaging system for intraoperative detection of residual breast cancer during breast conserving surgery

Purpose

Safe breast cancer lumpectomies require microscopically clear margins. Real-time margin assessment options are limited, and 20–40% of lumpectomies have positive margins requiring re-excision. The LUM Imaging System previously showed excellent sensitivity and specificity for tumor detection during lumpectomy surgery. We explored its impact on surgical workflow and performance across patient and tumor types.

Methods

We performed IRB-approved, prospective, non-randomized studies in breast cancer lumpectomy procedures. The LUM Imaging System uses LUM015, a protease-activated fluorescent imaging agent that identifies residual tumor in the surgical cavity walls. Fluorescent cavity images were collected in real-time and analyzed using system software.

Results

Cavity and specimen images were obtained in 55 patients injected with LUM015 at 0.5 or 1.0 mg/kg and in 5 patients who did not receive LUM015. All tumor types were distinguished from normal tissue, with mean tumor:normal (T:N) signal ratios of 3.81–5.69. T:N ratios were 4.45 in non-dense and 4.00 in dense breasts (p = 0.59) and 3.52 in premenopausal and 4.59 in postmenopausal women (p = 0.19). Histopathology and tumor receptor testing were not affected by LUM015. Falsely positive readings were more likely when tumor was present < 2 mm from the adjacent specimen margin. LUM015 signal was stable in vivo at least 6.5 h post injection, and ex vivo at least 4 h post excision.

Conclusions

Intraoperative use of the LUM Imaging System detected all breast cancer subtypes with robust performance independent of menopausal status and breast density. There was no significant impact on histopathology or receptor evaluation.

Efficacy of intraoperative specimen radiography as margin assessment tool in breast conserving surgery

PURPOSE

To explore the ability of intraoperative specimen radiography (SR) to correctly identify positive margins in patients receiving breast conserving surgery (BCS). To assess whether the reoperation rate can be reduced by using this method.

METHODS

This retrospective study included 470 consecutive cases receiving BCS due to a primarily diagnosed breast cancer. SR was carried out in two planes, assessing the specimen regarding the presence of the lesion and its relation to all margins. If indicated, re-excision of selective orientations was advised. Under consideration of gross inspection and the SR-findings, it was up to the surgeon whether to perform re-resections. The recommendations for re-excision were, separately for each orientation, compared to the histopathological results, serving as gold standard.

RESULTS

Intraoperative SR was performed in 470 cases, thus 2820 margins were assessed. Of those, 2510 (89.0%) were negative and 310 (11.0%) positive. SR identified 2179 (77.3%) margins correctly as negative, whereas 331 (11.7%) clear margins were misjudged as positive. Of 310 infiltrated margins, SR identified 114 (4.0%) correctly, whereas 196 (7.0%) infiltrated margins were missed. This resulted in a sensitivity/specificity of 36.8%/86.8% and PPV/NPV of 25.6%/91.8%. Through targeted re-resections positive margins could be reduced by 31.0% [310 to 214 (7.6%)]. On case level, the rate of secondary procedures could be reduced by 37.0% [from 162 to 102 (21.7%)].

CONCLUSIONS

SR is a helpful tool to identify infiltrated margins and to reduce the rate of secondary surgeries by recommending targeted re-excisions of according orientations in order to obtain a final negative margin status.

Intraoperative margin assessment of human breast tissue in optical coherence tomography images using deep neural networks

Assessing the surgical margin during breast lumpectomy operations can avoid the need for additional surgery. Optical coherence tomography (OCT) is an imaging technique that has been proven to be efficient for this purpose. However, to avoid overloading the surgeon during the operation, automatic cancer detection at the surface of the removed tissue is needed. This work explores automated margin assessment on a sample of patient data collected at the Pathology Department, Severance Hospital (Seoul, South Korea). Some methods based on the spatial statistics of the images have been developed, but the obtained results are still far from human performance. In this work, we investigate the possibility to use deep neural networks (DNNs) for real time margin assessment, demonstrating performance significantly better than the reported literature and close to the level of a human expert. Since the goal is to detect the presence of cancer, a patch-based classification method is proposed, as it is sufficient for detection, and requires training data that is easier and cheaper to collect than for other approaches such as segmentation. For that purpose, we train a DNN architecture that was proved to be efficient for small images on patches extracted from images containing only cancer or only normal tissue as determined by pathologists in a university hospital. As the number of available images in all such studies is by necessity small relative to other deep network applications such as ImageNet, a good regularization method is needed. In this work, we propose to use a recently introduced function norm regularization that attempts to directly control the function complexity, in contrast to classical approaches such as weight decay and DropOut. As neither the code nor the data of previous results are publicly available, the obtained results are compared with reported results in the literature for a conservative comparison. Moreover, our method is applied to locally collected data on several data configurations. The reported results are the average over the different trials. The experimental results show that the use of DNNs yields significantly better results than other techniques when evaluated in terms of sensitivity, specificity, F1 score, G-mean and Matthews correlation coefficient. Function norm regularization yielded higher and more robust results than competing regularization methods. We have demonstrated a system that shows high promise for (partially) automated margin assessment of human breast tissue, Equal error rate (EER) is reduced from approximately 12% (the lowest reported in the literature) to 5% - a 58% reduction. The method is computationally feasible for intraoperative application (less than 2 s per image) at the only cost of a longer offline training time.

Ambient Mass Spectrometry in Cancer Research

Ambient ionization mass spectrometry was developed as a sample preparation-free alternative to traditional MS-based workflows. Desorption electrospray ionization (DESI)-MS methods were demonstrated to allow the direct analysis of a broad range of samples including unaltered biological tissue specimens. In contrast to this advantageous feature, nowadays DESI-MS is almost exclusively used for sample preparation intensive mass spectrometric imaging (MSI) in the area of cancer research. As an alternative to MALDI, DESI-MSI offers matrix deposition-free experiment with improved signal in the lower (<500m/z) range. DESI-MSI enables the spatial mapping of tumor metabolism and has been broadly demonstrated to offer an alternative to frozen section histology for intraoperative tissue identification and surgical margin assessment. Rapid evaporative ionization mass spectrometry (REIMS) was developed exclusively for the latter purpose by the direct combination of electrosurgical devices and mass spectrometry. In case of the REIMS technology, aerosol particles produced by electrosurgical dissection are subjected to MS analysis, providing spectral information on the structural lipid composition of tissues. REIMS technology was demonstrated to give real-time information on the histological nature of tissues being dissected, deeming it an ideal tool for intraoperative tissue identification including surgical margin control. More recently, the method has also been used for the rapid lipidomic phenotyping of cancer cell lines as it was demonstrated in case of the NCI-60 cell line collection.

Digital mammography versus digital breast tomosynthesis for detection of breast cancer in the intraoperative specimen during breast-conserving surgery

PURPOSE

To compare the diagnostic ability of specimen radiography using digital mammography (DM) and digital breast tomosynthesis (DBT) for detecting breast cancer and evaluating its extension in the intraoperative specimen.

METHODS

Sixty-five specimens from 65 women (median 62 years; range 34-86) obtained during breast-conserving surgery were prospectively investigated. Specimens underwent DM (25-40 kVp, 12-322 mA s) and DBT (25-34 kVp, 13-137 mA) in two orthogonal planes, anteroposterior (AP) and latero-lateral (LL). Images were interpreted by a radiologist to detect invasive lesions and their extensive intraductal components (EIC) or ductal carcinomas in situ (DCIS); afterwards, they were compared with histopathological findings.

RESULTS

In AP views, 96 % of the invasive lesions were detected by both the methods. Of the EICs, 55 and 65 % were detected by DM and DBT, respectively (P = 0.61). Of the DICSs, 31 and 38 % were detected by DM and DBT, respectively (P > 0.99). In LL views, 71 and 13 % of the invasive lesions were detected by DBT and DM, respectively (P < 0.0001). Of the EICs, 42 and 10 % were detected by DBT and DM, respectively (P = 0.0078). Of the 13 DCISs, 42 and 8 % were detected by DBT and DM, respectively (P = 0.32). The whole lesion and contour could be delineated in 45 % by DBT and in 6.2 % by DM (P < 0.0001).

CONCLUSIONS

DBT could detect breast cancer more accurately than DM in LL views, indicating its potential to more precisely diagnose vertical invasion.

Melanoma Margin Assessment

Primary cutaneous melanoma is treated by excisional surgery and careful histologic assessment of the specimen margins is a crucial component of pathology reporting. Surgical margins may be assessed by conventional transverse (bread-loaf) vertical sections, by en face vertical sections, or by en face oblique sections. Transverse techniques only sample a small percentage of the surgical margin. En face techniques are technically challenging but allow assessment of close to 100% of the margin. Margin assessment for melanoma removed from chronically sun-damage skin is difficult. Melanoma in situ shows contiguous melanocyte growth, nesting, or intraepidermal pagetoid spread. Pitfalls include solar melanocytic hyperplasia, solar lentigines, melanocytic hyperplasia secondary to previous biopsy, lichenoid reactions, and invasive melanoma mimicking scar or benign nevus. En face sections can be used to assess margins for melanoma on sun-damaged skin, and evidence suggests that frozen sections may also be employed by experienced clinicians. Immunohistochemistry is a useful ancillary technique, enabling more accurate identification of in situ melanoma within a surgical margin.