Partial nephrectomy margin imaging using structured illumination microscopy

Abstract

Partial nephrectomy (PN) is the recommended procedure over radical nephrectomy (RN) for patients with renal masses less than 4 cm in diameter (Stage T1a). Patients with less than 4 cm renal masses can also be treated with PN, but have a higher risk for positive surgical margins (PSM). PSM, when present, are indicative of poor clinical outcomes. The current gold-standard histopathology method is not well-suited for the identification of PSM intraoperatively due to processing time and destructive nature. Here, video-rate structured illumination microscopy (VR-SIM) was investigated as a potential tool for PSM detection during PN. A clinical image atlas assembled from ex vivo renal biopsies provided diagnostically useful images of benign and malignant kidney, similar to permanent histopathology. VR-SIM was then used to image entire parenchymal margins of tumor resection covering up to >1800× more margin surface area than standard histology. Aided by the image atlas, the study pathologist correctly classified all parenchymal margins as negative for PSM with VR-SIM, compared to standard postoperative pathology. The ability to evaluate large surgical margins in a short time frame with VR-SIM may allow it to be used intraoperatively as a "safety net" for PSM detection, allowing more patients to undergo PN over RN.

Keywords: cancer; margin imaging; partial nephrectomy; renal cell carcinoma; structured illumination microscopy.