BACKGROUND: Ovarian thecoma-fibroma groups (OTFGs) are uncommon sex cord-stromal neoplasms. Ultrasound (US) is one of the imaging modalities frequently used to evaluate pelvic masses. It has the advantages of safety, convenience, and noninvasive diagnosis. However, there are still shortcomings in accurately diagnosing OTFGs. The present study aimed to describe the conventional ultrasound and high-frame-rate contrast-enhanced ultrasound (HiFR-CEUS) characteristics of OTFGs and to compare the diagnostic efficacy of these 2 methods and their combination to improve the diagnosis of OTFGs. METHODS: The study included 68 patients diagnosed with ovarian tumors with complete US images from January 2021 to December 2023. Based on pathology results, there were 35 OTFGs and 33 non-OTFGs. All patients underwent preoperative conventional US and HiFR-CEUS. A 3×2 Chi-squared test and paired Chi-squared test were used to compare the diagnostic concordance of the 3 methods to diagnose OTFGs. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of these 3 methods were calculated to determine their efficacy for diagnosing OTFGs. RESULTS: Among the 35 OTFGs, 77.1% tumors (27/35) showed hypoechogenicity in solid parts, with granular or linear hyperechogenicity. All tumors with recorded color Doppler signals (27/27) had no-to-sparse vascularization (color score 1-2). HiFR-CEUS showed typical linear perfusion in the OTFG tumors
94.3% tumors (33/35) showed hypoenhancement at the peak intensity, as compared to the surrounding myometrium. Seven patients (7/35, 20.0%) had cystic lesions with no internal enhancement. The combination of conventional US and HiFR-CEUS showed the highest diagnostic efficacy for diagnosing OTFGs [sensitivity: 97%, specificity: 100%, accuracy: 99%, PPV: 100%, NPV: 97%, area under the curve (AUC): 0.99] as compared to conventional US (sensitivity: 23%, specificity: 100%, accuracy: 60%, PPV: 100%, NPV: 55%, AUC: 0.61) and HiFR-CEUS (sensitivity: 94%, specificity: 97%, accuracy: 96%, PPV: 97%, NPV: 94%, AUC: 0.96). CONCLUSIONS: Most of the OTFGs showed characteristic linear perfusion in HiFR-CEUS. The combination of conventional US and HiFR-CEUS greatly improved the diagnosis rate of OTFGs. In summary, the combination of conventional US and HiFR-CEUS has significant value in the accurate diagnosis of OTFGs.