Margin Assessment in Renal Surgery Using a Handheld Optical Coherence Tomography Probe

Objective: To assess the use of a handheld optical coherence tomography (OCT) probe for the evaluation of intraoperative surgical margins during partial nephrectomy (PN). Methods: In an initial feasibility study, a radical nephrectomy specimen with a 9-cm tumor was cut into 19 sections, exposing 0 mm (n = 8), 1 mm (n = 6), and 2 mm (n = 5) gross margins. OCT was used to determine the margin width in each specimen. Second, a prospective ex vivo assessment of 15 PN tumor specimens was performed with OCT to determine margin status and to measure the attenuation coefficient of tumor and renal parenchyma. Results: Median OCT margin width measurements for sectioned samples were 0 mm, 0.9 mm (range 0.7-2.9 mm), and 2.7 (range 1.65-2.8 mm) for grossly 0 mm (positive), 1 mm, and 2 mm margins, respectively. The difference between measurements from all margin groups was statistically significant (P <.04). The sensitivity and specificity for identifying positive margins were both 100%. In the PN specimens, OCT correctly found that all specimens had negative margins (within <.0001). Conclusion: We have demonstrated the feasibility of using a handheld OCT probe to assess margins ex vivo during PN. OCT may reduce the need for intraoperative frozen section and aid in minimizing parenchymal excision.