Standardized Uptake Value and Apparent Diffusion Coefficient of Endometrial Cancer Evaluated with Integrated Whole-Body PET/MR: Correlation With Pathological Prognostic Factors

Purpose: To evaluate the correlation between maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADC(min)) of endometrial cancer derived from an integrated positron emission tomography /magnetic resonance (PET/MR) system and to determine their correlation with pathological prognostic factors. Materials and Methods: This prospective study was approved by the Institutional Review Board of the hospital, and informed consent was obtained. Between April and December 2014, 47 consecutive patients with endometrial cancer were enrolled and underwent simultaneous PET/MR examinations before surgery. Thirty-six patients with measurable tumors on PET/MR were included for image analysis. Pearson's correlation coefficient was used to evaluate the correlation between SUVmax and ADCmin of the tumors. The Mann-Whitney U-test was utilized to evaluate relationships between these two imaging biomarkers and pathological prognostic factors. Results: The mean SUVmax and ADC(min) were 14.7 +/- 7.1 and 0.48 +/- 0.13 x 10(-3) mm(2)/s, respectively. A significant inverse correlation was found between SUVmax and ADC(min) (r=-0.53; P=0.001). SUVmax was significantly higher in tumors with advanced stage, deep myometrial invasion, cervical invasion, lymphovascular space involvement, and lymph node metastasis (P< 0.05). ADC(min) was lower in tumors with higher grade, advanced stage, and cervical invasion (P< 0.05). The ratio of SUVmax to ADC(min) was higher in tumors with higher grade, advanced stage, deep myometrial invasion, cervical invasion, lymphovascular space involvement, and lymph node metastasis (P< 0.05). Conclusion: SUVmax and ADC(min) of endometrial cancer derived from integrated PET/MR are inversely correlated and are associated with pathological prognostic factors.