Novel kidney segmentation system to describe tumour location for nephron-sparing surgery.

Purpose: To propose a novel system based on segmental renal anatomy for objectively reporting location of clinical T1 masses for nephron-sparing surgery.

Methods: The kidney was subdivided into 12 standard segments, based on the computed tomography images. In 103 patients (105 cT1 tumours), three blinded radiologists (A, B, and C) prospectively reported segmental tumour location, size, and tumour-feeding arteries. Baseline, peri-operative, and post-operative data of 98 patients who underwent partial nephrectomy (PN) were prospectively collected, and the correlation between segmental tumour location and peri-operative data was evaluated. Kappa statistics were used to measure the inter-observer agreements.

Results: Tumour location could be assigned to the defined renal segment in all cases. Median tumour size was 2.8 cm (range 0.6-5.8). Inter-observer concordance was as follows: A versus B 0.82 (95% CI 0.74-0.90); A versus C 0.89 (95% CI 0.83-0.95); and B versus C 0.84 (95% CI 0.76-0.92). First, second, third, and fourth segments were involved by the tumour in 23, 39, 17, and 21% of cases, respectively. Number of segments involved by the tumour correlated with tumour size (p = 0.007), number of tumour-feeding arteries (p = 0.001), estimated blood loss during PN (p = 0.03), and trended towards higher post-operative complication rate (p = 0.07). Tumour-feeding arteries were identifiable in 80 patients (76%).

Conclusions: Kidney segmentation (KS) system is an objective and reproducible radiologic method of universally reporting tumour location according to 12 renal segments. By adding descriptive information on tumour characteristics in candidates for nephron-sparing surgery, this novel KS system could serve as an adjunct to current nephrometry systems.