Virtual Liver Resection and Volumetric Analysis of the Future Liver Remnant using Open Source Image Processing Software

BACKGROUND: After extended liver resection, a remnant liver that is too small can lead to postresection liver failure. To reduce this risk, preoperative evaluation of the future liver remnant volume (FLRV) is critical. The open-source OsiriX(®) PAC software system can be downloaded for free and used by nonradiologists to calculate liver volume using a stand-alone Apple computer. The purpose of this study was to assess the accuracy of OsiriX(®) CT volumetry for predicting liver resection volume and FLVR in patients undergoing partial hepatectomy. METHODS: Preoperative contrast-enhanced liver CT scans of patients who underwent partial hepatectomy were analyzed by three observers. Two surgical trainees measured the total liver volume, resection volume, and tumor volume using OsiriX(®), and a radiologist measured these volumes using CT scanner-linked Aquarius iNtuition(®) software. Resection volume was correlated with prospectively determined resection weight, and differences in the measured liver volumes were analyzed. Interobserver variability was assessed using Bland–Altman plots. RESULTS: 25 patients (M/F ratio: 13/12) with a median age of 61 (range, 34–77) years were included. There were significant correlations between the weight and volume of the resected specimens (Pearson’s correlation coefficient: R(2) = 0.95). There were no major differences in total liver volumes, resection volumes, or tumor volumes for observers 1, 2, and 3. Bland–Altman plots showed a small interobserver variability. The mean time to complete liver volumetry for one patient using OsiriX(®) was 19 ± 3 min. CONCLUSIONS: OsiriX(®) liver volumetry performed by surgeons is an accurate and time-efficient method for predicting resection volume and FLRV.