OP20.06: Preoperative prediction of uterine sarcoma using signal intensity at T2 weighted imaging and apparent diffusion coefficient (ADC) on MRI

Abstract

Uterine sarcoma is a rare disease with a poor prognosis, and its preoperative diagnosis is difficult. The author previously presented the finding that a tumour with high tumour-to-subcutaneous fat signal intensity ratio on MRI T2 weighted imaging (TFSIR) and low ADC is highly suspected of sarcoma. However, its sensitivity and specificity are not high enough to diagnose sarcoma. The purpose of this study is to improve the preoperative diagnostic reliability through further investigation of previous and additional cases. MRI was performed in 6 cases (7 tumours) of uterine sarcoma in the last 3 years (sarcoma group), and in 31 cases of leiomyoma in 2015 (myoma group) at the author's hospital. TFSIR and ADC were calculated and compared between 2 groups. The cut-off values of these parameters to predict sarcoma were also calculated. Finally, a preoperative prediction method using both of these parameters was considered through the application to the 40 tumours which were examined in 2016. The sarcoma group had significantly higher TFSIR than the leiomyoma group (p<0.01). The minimum cut-off value of TFSIR to diagnose sarcoma was 0.515 (sensitivity: 100%, specificity: 94%). The sarcoma group had significantly lower ADC values than the leiomyoma group (p<0.01). The maximum cut-off value of ADC to diagnose sarcoma was 1.280 (sensitivity: 86%, specificity: 87%). All tumours with both positive TFSIR and ADC were sarcoma (High Suspicion group). All tumours with negative TFSIR were leiomyoma (Low Suspicion group). Tumours with positive TFSIR and negative ADC included both sarcomas and leiomyomas (Intermediate Suspicion group). Among 40 uterine tumours in 2016, two (5.0%) belonged to the High Suspicion group (all sarcoma), three (7.5%) belonged to the Intermediate Suspicion group (all leiomyoma), and the other 35 tumours (87.5%) belonged to the Low Suspicion group (all leiomyoma). Preoperative prediction of uterine sarcoma is possible using both TFSIR and ADC scores on MRI.