Amide proton transfer MR imaging of endometrioid endometrial adenocarcinoma: Association with histologic grade

Purpose: To evaluate the utility of amide proton transfer (APT) imaging in estimating histologic grades of endometrioid endometrial adenocarcinoma (EEA). Materials and The institutional review board approved this prospective Methods: study. Between June 2012 and March 2016, 32 patients with EEA underwent magnetic resonance (MR) imaging. After their surgical procedures, their EEAs were confirmed pathologically and classified into histologic grades: grade 1 (n = 11), grade 2 (n = 11), and grade 3 (n = 10). The APT signal intensities (SIs) and the mean and minimum apparent diffusion coefficients (ADCs) of the three grades were calculated and compared. Spearman rank correlation coefficient was also calculated between the APT SIs and histologic grades, and between the ADCs and histologic grades. Results: The Spearman correlation coefficient with histologic grade of the APT SIs, the mean ADC, and the minimum ADC were 0.55 (P = .001), 0.03 (P = .84), and 20.30 (P = .09), respectively. The average APT SIs and the mean and minimum ADCs were 2.2% 6 0.2 (standard deviation), 0.9 3 102³ mm²/sec 6 0.2, and 0.6 3 102³ mm²/sec 6 0.1 for grade 1; 3.2% 6 0.3, 0.8 3 102³ mm²/sec 6 0.1, and 0.5 3 102³ mm²/sec 6 0.1 for grade 2; and 3.7% 6 0.3, 0.9 3 102³ mm²/sec 6 0.1, and 0.5 3 102³ mm²/sec 6 0.1 for grade 3, respectively. The APT SIs of grade 3 EEA were significantly higher than those of grade 1 EEA (P = .01), but other pairwise comparisons did not reveal any significant differences (P = .06-.51). The mean and minimum ADCs showed no significant differences among the three histologic grades (P =.13-.51). Conclusion: The APT SI was positively correlated with the histologic grades of EEA.