The apparent diffusion coefficient (ADC) on 3-T MRI differentiates myometrial invasion depth and histological grade in patients with endometrial cancer.

Abstract

Diffusion-weighted magnetic resonance imaging (DW-MRI) with apparent diffusion coefficient (ADC) measurement provides additional information about tumor microstructure with potential relevance for staging and predicting aggressive disease in patients with endometrial cancer (EC). To determine whether ADC values in EC diverge according to the tumor's histologic grade and myometrial invasion depth. A sample of 48 pathologically confirmed cases of EC were reviewed retrospectively. The sample was distributed as follows: G1 (n = 9); G2 (n = 18); G3 (n = 21); with myometrial invasion <50% (n = 31); and with myometrial invasion ≥50% (n = 17). DW images were performed at 3.0T with b factors of 0-1000/mm2. The region of interest (ROI) was defined within the tumor with T1-weighted and T2-weighted imaging and copied manually to an ADC map. The tumor's grade and myometrial invasion's depth were determined by postoperative histopathological tests. The means of ADCmin and ADCmean values were significantly lower for patients with G2 and G3 endometrial tumors than G1. The same tendency was observed in myometrial invasion, as both ADCmin and ADCmean values were lower for patients with deep than for those with superficial myometrial invasion. The cut-off values of the ADCmin and ADCmean that predicted high-grade tumors were 0.69 × 10-3 mm2/s and 0.82 × 10-3 mm2/s, respectively, while those for myometrial infiltration were 0.70 × 10-3 mm2/s (ADCmin) and 0.88 × 10-3 mm2/s (ADCmean). ADCmin and ADCmean values correlated with histologic tumor grade and myometrial invasion depth; therefore, it is suggested that ADC on MRI may be a useful indicator to predict malignancy of ECs.