Accuracy of Liver Lesion Assessment using Automated Measurement and Segmentation Software in Biphasic Multislice CT (MSCT)

Purpose: To assess the accuracy of liver lesion measurement using automated measurement and segmentation software depending on the vascularization level. Materials and Methods: Arterial and portal venous phase multislice CT (MSCT) was performed for 58 patients. 94 liver lesions were evaluated and classified according to vascularity (hypervascular: 13 hepatocellular carcinomas, 20 hemangiomas; hypovascular: 31 metastases, 3 lymphomas, 4 abscesses; liquid: 23 cysts). The RECIST diameter and volume were obtained using automated measurement and segmentation software and compared to corresponding measurements derived visually by two experienced radiologists as a reference standard. Statistical analysis was performed using the Wilcoxon test and concordance correlation coefficients. Results: Automated measurements revealed no significant difference between the arterial and portal venous phase in hypovascular (mean RECIST diameter: 31.4 vs. 30.2 mm; p=0.65; kappa=0.875) and liquid lesions (20.4 vs. 20.1 mm; p=0.1; kappa=0.996). The RECIST diameter and volume of hypervascular lesions were significantly underestimated in the portal venous phase as compared to the arterial phase (30.3 vs. 26.9 mm, p=0.007, kappa=0.834; 10.7 vs. 7.9 ml, p=0.0045, kappa=0.752). Automated measurements for hypovascular and liquid lesions in the arterial and portal venous phase were concordant to the reference standard. Hypervascular lesion measurements were in line with the reference standard for the arterial phase (30.3 vs. 32.2 mm, p=0.66, kappa=0.754), but revealed a significant difference for the portal venous phase (26.9 vs. 32.1 mm; p=0.041; kappa=0.606). Conclusion: Automated measurement and segmentation software provides accurate and reliable determination of the RECIST diameter and volume in hypovascular and liquid liver lesions. Hypervascular lesions are prone to be underestimated with regard to size in the portal venous phase and therefore should preferentially be segmented in the arterial phase.