Computerized Liver Volumetry on MRI by Using 3D Geodesic Active Contour Segmentation

OBJECTIVE. Our purpose was to develop an accurate automated 3D liver segmentation scheme for measuring liver volumes on MRI. SUBJECTS AND METHODS. Our scheme for MRI liver volumetry consisted of three main stages. First, the preprocessing stage was applied to T1-weighted MRI of the liver in the portal venous phase to reduce noise and produce the boundary-enhanced image. This boundary- enhanced image was used as a speed function for a 3D fast-marching algorithm to generate an initial surface that roughly approximated the shape of the liver. A 3D geodesic-active-contour segmentation algorithm refined the initial surface to precisely determine the liver boundaries. The liver volumes determined by our scheme were compared with those manually traced by a radiologist, used as the reference standard. RESULTS. The two volumetric methods reached excellent agreement (intraclass correlation coefficient, 0.98) without statistical significance (p = 0.42). The average (+/- SD) accuracy was 99.4% +/- 0.14%, and the average Dice overlap coefficient was 93.6% +/- 1.7%. The mean processing time for our automated scheme was 1.03 +/- 0.13 minutes, whereas that for manual volumetry was 24.0 +/- 4.4 minutes (p < 0.001). CONCLUSION. The MRI liver volumetry based on our automated scheme agreed excellently with reference-standard volumetry, and it required substantially less completion time.