Ex vivo 3D scanning and specimen mapping in anatomic pathology

How far are we off? Analyzing the accuracy of surgical margin relocation in the head and neck

BACKGROUND

Positive surgical margin rates remain high in head and neck cancer surgery. Relocation is challenging given the complex, three-dimensional (3D) anatomy.

METHODS

Prospective, multi-institutional study to determine accuracy of head and neck surgeons and pathologists relocating margins on virtual 3D specimen models using written descriptions from pathology reports. Using 3D models of 10 head and neck surgical specimens, each participant relocated 20 mucosal margins (10 perpendicular, 10 shave).

RESULTS

A total of 32 participants, 23 surgeons and 9 pathologists, marked 640 margins. Of the 320 marked perpendicular margins, 49.7% were greater than 1 centimeter from the true margin with a mean relocation error of 10.2 mm. Marked shave margins overlapped with the true margin a mean 54% of the time, with no overlap in 44 of 320 (13.8%) shave margins.

CONCLUSIONS

Surgical margin relocation is imprecise and challenging even for experienced surgeons and pathologists. New communication technologies are needed.

How Often is Cancer Present in Oral Cavity Re-resections After Initial Positive Margins?

OBJECTIVE

To evaluate the rate at which carcinoma is present in the re-resection specimen following initial positive margins during head and neck cancer surgery and its impact on oncologic outcomes.

STUDY DESIGN

Retrospective chart review.

METHODS

A single institution retrospective chart review of patients that underwent curative-intent surgery for oral cavity cancer was performed. Final pathology reports were reviewed to identify patients with initial positive margins who underwent re-resection during the same operation. Initial positive margin was defined as severe dysplasia, carcinoma in situ (CIS), or carcinoma. Cox proportional hazards and Kaplan-Meier analyses were used to assess for associations with survival outcomes.

RESULTS

Among 1873 total patients, 190 patients (10.1%) had initial positive margins and underwent re-resection during the same surgery. Additional carcinoma, CIS, or severe dysplasia was found in 29% of re-resections, and 31% of patients with initial positive margins had final positive margins. Half of the patients with a final positive margin had a positive margin at an anatomic site different than the initial positive margin that was re-resected. The median follow-up was 636 days (range 230-1537). Re-resection with cancer and final positive margin status was associated with worse overall survival (OS; p = 0.044 and p = 0.05, respectively). However, only age, T4 disease, and surgery for recurrent oral cavity cancer were independently associated with OS (p < 0.001, p = 0.005, and p = 0.001, respectively).

CONCLUSIONS

Fewer than a third of oral cavity re-resections contain further malignancy, which may suggest that surgeons have difficulty relocating the site of initial positive margin. Final positive margins are often at anatomic sites different than the initial positive margin.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:717-724, 2024.

Intraoperative margin assessment for basal cell carcinoma with deep learning and histologic tumor mapping to surgical site

Successful treatment of solid cancers relies on complete surgical excision of the tumor either for definitive treatment or before adjuvant therapy. Intraoperative and postoperative radial sectioning, the most common form of margin assessment, can lead to incomplete excision and increase the risk of recurrence and repeat procedures. Mohs Micrographic Surgery is associated with complete removal of basal cell and squamous cell carcinoma through real-time margin assessment of 100% of the peripheral and deep margins. Real-time assessment in many tumor types is constrained by tissue size, complexity, and specimen processing / assessment time during general anesthesia. We developed an artificial intelligence platform to reduce the tissue preprocessing and histological assessment time through automated grossing recommendations, mapping and orientation of tumor to the surgical specimen. Using basal cell carcinoma as a model system, results demonstrate that this approach can address surgical laboratory efficiency bottlenecks for rapid and complete intraoperative margin assessment.

Virtual 3D Specimen Mapping in Head & Neck Oncologic Surgery

OBJECTIVES

Virtual 3D specimen mapping of oncologic surgical specimens provides a visual record of the specimen and margin sampling sites which can be utilized in a variety of cancer care settings. Our objective was to perform a retrospective review of head and neck surgical oncology cases where the specimen was mapped post-operatively and to evaluate the utility of these 3D specimen maps amongst the multidisciplinary cancer care team.

METHODS

A retrospective review of our 3D specimen model biorepository was performed. Surgical specimens were 3D scanned and then graphically annotated (or "mapped") during routine pathologic processing. The resulting 3D specimen maps were distributed to the multidisciplinary oncologic care team. Final margin status and any use of the 3D specimen maps were recorded.

RESULTS

A total of 28 cases were included. Virtual 3D specimen maps were utilized by the cancer care team in 8 cases (29%), including 2 positive margin cases, 2 close margin cases, and 4 indeterminate margin cases. 3D specimen maps were used to visualize positive margin sites for pathologist-surgeon communication as a visual reference during tumor board discussions and to inform radiation treatment planning.

CONCLUSION

Post-operative virtual 3D specimen mapping of oncologic specimens creates a permanent visual record of the specimen and the margins sampled and may serve as a beneficial tool for communication amongst the multidisciplinary cancer care team.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:191-197, 2024.

Intraoperative three-dimensional scanning of head and neck surgical defects: Enhanced communication and documentation of harvested supplemental margins

BACKGROUND

We have demonstrated the effectiveness of 3D resection specimen scanning for communicating margin results. We now address the corresponding surgical defect by debuting 3D defect models, which allow for accurate annotations of harvested supplemental margins.

METHODS

Surgical defects were rendered into 3D models, which were annotated to document the precise location of harvested supplemental margins. 3D defect scans were also compared with routine 2D photography and were analyzed for quality, clarity, and the time required to complete the scan.

RESULTS

Forty defects were scanned from procedures including segmental mandibulectomy, maxillectomy, and laryngopharyngectomy. Average duration of defect scan was 6 min, 45 s. In six of ten 2D photographs, the surgeon was unable to precisely annotate the extent of at least one supplemental margin.

CONCLUSION

3D defect scanning offers advantages in that this technique enables documentation of the precise location and breadth of supplemental margins harvested to address margins at-risk.

Augmented-Reality Surgery to Guide Head and Neck Cancer Re-resection: A Feasibility and Accuracy Study

BACKGROUND

Given the complex three-dimensional (3D) anatomy of head and neck cancer specimens, head and neck surgeons often have difficulty relocating the site of an initial positive margin to perform re-resection. This cadaveric study aimed to determine the feasibility and accuracy of augmented reality surgery to guide head and neck cancer re-resections.

METHODS

This study investigated three cadaveric specimens. The head and neck resection specimen was 3D scanned and exported to the HoloLens augmented reality environment. The surgeon manually aligned the 3D specimen hologram into the resection bed. Accuracy of manual alignment and time intervals throughout the protocol were recorded.

RESULTS

The 20 head and neck cancer resections performed in this study included 13 cutaneous and 7 oral cavity resections. The mean relocation error was 4 mm (range, 1-15 mm) with a standard deviation of 3.9 mm. The mean overall protocol time, from the start of 3D scanning to alignment into the resection bed, was 25.3 ± 8.9 min (range, 13.2-43.2 min). Relocation error did not differ significantly when stratified by greatest dimension of the specimen. The mean relocation error of complex oral cavity composite specimens (maxillectomy and mandibulectomy) differed significantly from that of all the other specimen types (10.7 vs 2.8; p < 0.01).

CONCLUSIONS

This cadaveric study demonstrated the feasibility and accuracy of augmented reality to guide re-resection of initial positive margins in head and neck cancer surgery.

Are camera, projector, and camera-projector calibrations different?

Structured light projection systems have become a referent in three-dimensional optical metrology. Calibration of the cameras and projectors of these systems is one of the most critical procedures to achieve high-accuracy measurements. However, the calibration process requires some clarifications for adequate experimental implementation. For instance, it is typically assumed that the calibration of a camera-projector pair differs from calibrating a camera, and the calibration of a projector is possible only with an attached auxiliary camera. This paper presents a unified methodology for camera, projector, and camera-projector calibrations. Experimental results are discussed, providing practical insights into how structured light systems are calibrated. The MATLAB code and data employed in this study are available.

Frozen Section Analysis in Head and Neck Surgical Pathology: A Narrative Review of the Past, Present, and Future of Intraoperative Pathologic Consultation

Frozen section has remained the diagnostic gold standard for intraoperative pathological evaluation of surgical margins for head and neck specimens. While achieving tumor-free margins is of utmost importance to all head and neck surgeons, in practice, there are numerous debates and a lack of standardization for the role and method of intraoperative pathologic consultation. This review serves as a summary guide to the historical and contemporary practice of frozen section analysis and margin mapping in head and neck cancer. In addition, this review discusses current challenges in head and neck surgical pathology, and introduces 3D scanning as a groundbreaking technology to bypass many of the pitfalls in the current frozen section workflow. The ultimate goal for all head and neck pathologists and surgeons should be to modernize practices and take advantage of new technology, such as virtual 3D specimen mapping techniques, that improves the workflow for intraoperative frozen section analysis.