Simultaneous whole-body and breast 18F-FDG PET/MRI examinations in patients with breast cancer: a comparison of apparent diffusion coefficients and maximum standardized uptake values

Purpose To compare standardized uptake value (SUV) and apparent diffusion coefficient (ADC) values acquired using a PET/MRI scanner in breast cancer patients. Materials and methods Whole-body PET/MRI and breast PET/MRI were performed in 108 consecutive patients. Ninety-four patients who had a total of 100 breast cancers were analyzed. SUVmax and ADCmean acquired using breast PET/MRI were compared with pathologic prognostic factors. Results All the lesions were visually detectable using PET and diffusion-weighted imaging (DWI) on breast PET/MRI; however, lesions were visually undetectable on whole-body DWI in 13 patients (13%) or on whole-body PET in 7 patients (7%). An analysis of ADCmean and SUVmax demonstrated a statistically significant correlation between whole-body imaging and breast imaging (rho = 0.613, p < 0.001 and rho = 0.928, p < 0.001, respectively). In a univariate analysis, SUVmax was significantly correlated with HER2 status (p < 0.001), Ki-67 (p = 0.014), tumor size (p = 0.0177), and nuclear grade (p = 0.0448). In multiple regression analysis, only tumor size (p = 0.00701) was shown to independently influence SUVmax. Conclusion Prone breast imaging was more sensitive than whole-body PET/MRI for detection of breast cancers. Both SUVmax and ADCmean showed limited correlation with pathologic prognostic factors.