Comparison of Reproducibility of Manual and Sphere Contour Methods for the Measurement of Vascularization in Cervical Carcinoma Using the Virtual Organ Computer‐Aided Analysis II System

Objective. The purpose of this study was to investigate the reproducibility of virtual organ computer‐aided analysis II software (GE Healthcare, Milwaukee, WI), an integrated tool for 3‐dimensional power Doppler angiography (3D‐PDA), in measuring vascularization of cervical carcinoma under manual and automatic sphere contour modes. Methods. Eighty patients with cervical carcinoma were prospectively examined by observer 1 using transvaginal 3D‐PDA. For each patient, measurements of the vascularization index, flow index, and vascularization‐flow index were repeated twice under both manual and automatic sphere contour modes. Forty patients were randomly selected for another round of examination by observer 2 under the same setting. The reproducibility of vascularization measurements was assessed by the intraclass correlation coefficient (intra‐CC), interclass correlation coefficient (inter‐CC), and 95% limits of agreement (LOAs). Various analysis of variance models were used to estimate the contribution of each factor (observer, contour mode, and patient) to measurement variance. Results. For each observer, the manual contour mode outperformed the automatic sphere contour mode in reproducibility (intra‐CC, 0.96 to 0.99 versus 0.77 to 0.94). In addition, repeated measurements of the manual mode had a smaller SD and a narrower LOA. For the manual contour mode, interobserver agreement was comparable with intraobserver agreement (inter‐CC, 0.91 to 0.98, versus intra‐CC, 0.96 to 0.99). However, the interobserver agreement was significantly smaller than the intraobserver agreement for the automatic sphere contour mode (inter‐CC, 0.51 to 0.85, versus intra‐CC, 0.77 to 0.94; P = .001). Conclusions. The manual contour mode for 3D‐PDA vascular measurements has better interobserver and intraobserver reproducibility than the automatic sphere contour mode. It is especially useful for measuring tumor tissues with irregular shapes and vascularity.