Comparison of International Ovarian Tumor Analysis Simple Rules to Society of Radiologists in Ultrasound Guidelines for Detection of Malignancy in Adnexal Cysts.

OBJECTIVE. The purpose of this study was to evaluate the International Ovarian Tumor Analysis (IOTA) simple rules and the Society of Radiologists in Ultrasound (SRU) guidelines for detecting ovarian malignancy in a general population of women presenting to radiology departments with adnexal cystic lesions. MATERIALS AND METHODS. A retrospective multicenter study of ultrasound-detected adnexal cystic lesions with appropriate follow-up was conducted. Lesions were classified into benign, indeterminate, or malignant categories according to criteria based on the IOTA simple rules and the SRU guidelines. The prevalence of nonneoplastic cysts, neoplasms, and malignant tumors was calculated. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated, and ROC analysis for the diagnosis of malignancy was performed. RESULTS. A total of 697 women with 764 cystic lesions were included; 85.2% (651/764) of the lesions were nonneoplastic, 12.2% (93/764) were benign neoplasms, and 2.6% (20/764) were malignant neoplasms. Nearly all malignancies were classified into indeterminate and malignant categories. The prevalence of malignancy in the indeterminate category was 4.8% (7/145) (SRU) to 10.7% (7/65) (IOTA) and in the malignant category was 18.1% (13/72) (SRU) to 34.3% (12/35) (IOTA). Only one malignancy was misclassified as benign by the IOTA simple rules. The sensitivity of the IOTA simple rules for malignancy was 90.0%; specificity, 96.5%; PPV, 29.0%; NPV, 99.8%; and accuracy, 96.4%. The corresponding values for the SRU guidelines were 100%, 89.6%, 14.9%, 100%, and 89.8%. In ROC analysis, the IOTA simple rules were slightly more accurate than the SRU guidelines (AUC, 0.9805 versus 0.9713; p = 0.0003). CONCLUSION. Both imaging characterization methods were sensitive for identifying ovarian malignancies, but the PPV was low among women presenting to radiology departments, and the indeterminate classification harbored one-third of the total malignancies. Exploration of varied clinical settings and inclusion of secondary tests may help to refine these systems.

Indeterminate Adnexal Cysts at US: Prevalence and Characteristics of Ovarian Cancer.

Purpose To assess the prevalence of indeterminate adnexal cysts in women presenting to academic medical centers for pelvic ultrasonography (US), determine the incidence of malignancy, and identify cyst and patient characteristics that are predictive of malignancy. Materials and Methods A multicenter study of US-detected adnexal cysts with appropriate follow-up (surgical pathologic examination, imaging and/or clinical examination) was conducted from January 2008 to June 2012. Indeterminate cysts were classified as category 1 (typical benign appearing cysts >5 cm) or category 2 (cysts with avascular solid components) on the basis of a combination of definitions in the existing literature. The incidence of neoplasms and malignant tumors was calculated. Patient and cyst characteristics associated with neoplasm and malignant tumors were evaluated with the χ2 test or Fisher exact test for categorical variables and the t test for continuous variables. A backward stepwise logistic regression model was performed for two outcomes: (a) the presence of any neoplasm (benign or malignant) and (b) the presence of a malignant tumor. Results There were 1637 women with an adnexal cyst at US; 391 (mean age = 41.8 years ± 13.5.1; range = 17-91 years) had an indeterminate adnexal cyst at US. The prevalence of indeterminate adnexal cysts was 23.9% (391 of 1637; 95% confidence interval [CI]: 0.22, 0.26). Three hundred three indeterminate cysts in 280 women (mean age = 42.9 years ± 14.1; range = 17-88 years) had adequate follow-up. The incidence of ovarian neoplasms (benign and malignant) was 24.8% (75 of 303 cysts; 95% CI: 0.20, 0.30), and the incidence of malignant tumors was 3.6% (11 of 303 cysts; 95% CI: 0.02, 0.06). The proportion of ovarian neoplasms differed between category 1 and category 2 cysts (17.5% [25 of 143 cysts; 95% CI: 0.12, 0.25] vs 31.3% [50 of 160 cysts; 95% CI: 0.24, 0.39], respectively; P = .001). The proportion of malignant tumors differed between categories 1 and 2 cysts (0% [0 of 143 cysts] vs 6.9% [11 of 160 cysts; 95% CI: 0.03, 0.12]; P < .001). The presence of an avascular nodular component was a significant predictor of malignancy at stepwise logistic regression analysis (odds ratio = 2.83; P ≤ .0001; 95% CI: 1.69, 4.70). Conclusion The presence of an avascular nodular component was the most significant predictor of the presence of malignancy in indeterminate adnexal cysts. The risk of malignancy is higher with category 2 cysts than with category 1 cysts. © RSNA, 2018.