Anatomic Kidney Segmentation System to Describe Tumor Location for Nephron-sparing Surgery

==inizio abstract==

Background: Current nephrometry systems provide objective information about various characteristics of small renal masses, except precise anatomic location.
Objective: To propose a system based on segmental renal anatomy to objectively report location of clinical T1 masses for partial nephrectomy (PN) surgery planning.
Design, setting and participants: The kidney was sub-divided into 12 standard anatomic segments, based on computed tomography images (1mm slice thickness). In 103 patients (105 cT1 tumors) three blinded radiologists (A, B, C) prospectively reported anatomic segmental tumor location, size, exophytic growth pattern, proximity to collecting system and any visualized intra-renal tumor-feeding arteries.
Intervention: PN was performed in 98 patients; in these patients, segmental tumor location was assigned and correlated with peri-operative outcomes.
Measurements and statistical analysis: Baseline, perioperative, and postoperative data were collected prospectively. Kappa statistics were used to measure the inter-rater agreements.
Results and Limitations: Tumor location could be assigned according to the defined anatomic segments in all cases. Median tumor size was 2.8 cm (range, 0.6-5.8). Inter-observer concordance was : A vs B 0.82 (95%CI: 0.74-0.90); A vs C 0.89 (95%CI: 0.83-0.95); B vs C 0.84(95%CI: 0.76-0.92). One, 2, 3 and 4 anatomic segments were involved by the tumor in 23%, 39%, 17% and 21% of cases. Tumor-feeding arteries were identifiable in 80 patients (76%). Segmental tumor location correlated with tumor size (p=0.007), distance from collecting system (p<0.001), number of tumor-feeding arteries (p=0.001) and estimated blood loss during PN (p=0.03). Limitations of the study include the small number of patients and lack of external validation. Conclusions: Anatomic kidney segmentation (AKS) system is an objective and reproducible radiologic method for universally reporting tumor location according to 12 anatomic segments. This novel AKS system could serve as an adjunct to current nephrometry systems. ==fine abstract==