Objective: To determine whether resistance index values obtained by color Doppler ultrasound contribute to the accuracy in diagnosing ovarian malignancies.
Methods: Four hundred ten patients with ovarian neoplasms referred for color Doppler ultrasound evaluation were enrolled, excluding patients examined during the luteal phase. Resistance index of the intra-tumor arteries was measured by color Doppler ultrasound. The corresponding clinical and histopathologic information was recorded. For statistical determinations, we used the Yates corrected chi 2 analysis, Fisher exact test, Student t test, and linear regression analysis.
Results: Satisfactory intra-tumor artery waveforms were obtained in 96.1% (99 of 103) of ovarian malignancies. Resistance index values varied at 0.23-0.82. Regression analysis of resistance index values on tumor size and amount of ascites demonstrated a linear association (R = 0.498 and 0.362, respectively; P < .01 in both). If we regard a resistance index of 0.4 as a cutoff value, the overall sensitivity and specificity in detecting malignancy were 68.0 and 97.4%, respectively. Primary ovarian malignancies exhibited significantly more false negatives (30 of 79) than malignancies metastasized to the ovary (three of 24) (P = .018). Malignancies containing mainly cystic components exhibited more false negatives (20 of 41) than did tumors with primarily solid components (13 of 62) (P < .01). Significantly more false negatives were encountered in malignancies with larger diameters (greater than 10 cm) compared to smaller ones (27 of 63 versus six of 40; P < .01), and in malignancies accompanied by considerable ascites (greater than 1000 mL) (13 of 25 versus 20 of 78; P < .05).
Conclusions: Tumor origin, size, component nature, and amount of ascites contributed to the accuracy in diagnosing ovarian malignancies using resistance index values obtained by color Doppler ultrasound.