Auto Localization and Segmentation of Occluded Vessels in Robot-Assisted Partial Nephrectomy Alborz Amir-Khalili 1 , Jean-Marc Peyrat 2 , Julien Abinahed 2 , Osama Al-Alao 3 , Abdulla Al-Ansari 2,3 , Ghassan Hamarneh 4 , and Rafeef Abugharbieh 1 1 BiSICL, University of British Columbia, Vancouver, Canada 2 Qatar Robotic Surgery Centre, Qatar Science & Technology Park, Doha, Qatar 3 Urology Department, Hamad General Hospital, Hamad Medical Corporation, Qatar 4 Medical Image Analysis Lab, Simon Fraser University, Burnaby, Canada Abstract. Hilar dissection is an important and delicate stage in partial nephrectomy during which surgeons remove connective tissue surround- ing renal vasculature. Potentially serious complications arise when vessels occluded by fat are missed in the endoscopic view and are not appro- priately clamped. To aid in vessel discovery, we propose an automatic method to localize and label occluded vasculature. Our segmentation technique is adapted from phase-based video magnification, in which we measure subtle motion from periodic changes in local phase infor- mation albeit for labeling rather than magnification. We measure local phase through spatial decomposition of each frame of the endoscopic video using complex wavelet pairs. We then assign segmentation labels based on identifying responses of regions exhibiting temporal local phase changes matching the heart rate frequency. Our method is evaluated with a retrospective study of eight real robot-assisted partial nephrectomies demonstrating utility for surgical guidance that could potentially reduce operation times and complication rates. 1 Introduction Approximately 30,000 new cases of kidney cancer, generally renal cell carci- noma, are detected each year in the U.S. alone. Kidney resection, also known as a nephrectomy, is the only known effective treatment for this type of local- ized cancer [1]. Robot-assisted partial nephrectomy (RAPN) refers to nephron- sparing techniques performed with surgical robots in which only the cancerous cells are excised while the kidney is reconstructed to retain functionality. The intraoperative aspect of RAPN procedures can be organized into five stages [2]: 1) Bowel mobilization; 2) Hilar dissection and control; 3) Identification and demarcation of tumor margins; 4) Resection of tumor; and 5) Reconstruction of the kidney (renorrhaphy). Hilar dissection stands out as a daunting stage that requires significant expertise since improper clamping due to overlooked accessory renal vessels can cause significant bleeding during resection [3]. Hilar dissection is a delicate procedure during which the surgeon dissects through the Gerota’s fascia and removes the connective tissue that surrounds P. Golland et al. (Eds.): MICCAI 2014, Part I, LNCS 8673, pp. 407–414, 2014. c  Springer International Publishing Switzerland 2014