Endometrial cancer: correlation of apparent diffusion coefficient with tumor grade, depth of myometrial invasion, and presence of lymph node metastases

OBJECTIVE. The objective of our study was to investigate whether apparent diffusion coefficient (ADC) values of endometrial cancer differ from those of normal endometrium and myometrium and whether they vary according to histologic tumor grade, the depth of myometrial invasion, or lymph node status. SUBJECTS AND METHODS. Seventy patients with histologically proved endometrial cancer and 36 control subjects with normal endometrium were enrolled in this prospective study. T2-weighted, dynamic T1-weighted, and diffusion-weighted images with b values of 0 and 1000 s/mm2 were obtained of all patients. The ADC values of endometrial cancer, normal endometrium, and normal myometrium were recorded. Tumor grade, the depth of myometrial invasion, and lymph node status were assessed at postoperative histopathologic analysis. RESULTS. The mean (± SD) ADC value (10-3 mm2/s) of endometrial cancer (0.77 ± 0.12) was significantly lower than that of normal endometrium (1.31 ± 0.11, p < 0.0001) and normal myometrium (1.52 ± 0.21, p < 0.0001), with no overlap between the two former distributions. There was no significant difference between ADC values of endometrial cancer tissue in patients with tumor grade 1 (0.79 ± 0.08, n = 14), grade 2 (0.76 ± 0.14, n = 40), or grade 3 (0.75 ± 0.12, n = 16) (p = 0.67); in patients with deep (0.77 ± 0.13, n = 18) and those with superficial (0.76 ± 0.12, n = 52) myometrial invasion (p = 0.87); and in patients with (0.78 ± 0.10, n = 6) and those without (0.75 ± 0.14, n = 39) lymph node metastases (p = 0.64). CONCLUSION. ADC values allow normal endometrium to be differentiated from endometrial carcinoma; however, they do not correlate with histologic tumor grade, the depth of myometrial invasion, or whether lymph node metastases are present. © American Roentgen Ray Society.