Reliability of 18F-FDG PET Metabolic Parameters Derived Using Simultaneous PET/MRI and Correlation With Prognostic Factors of Invasive Ductal Carcinoma: A Feasibility Study

OBJECTIVE. The objective of our study was to correlate semiquantitative PET parameters- standardized uptake value (SUV) and total lesion glycolysis (TLG)-derived in simultaneous PET/MRI using MRI-based attenuation correction with clinical and histopathologic prognostic factors in patients with breast cancer. MATERIALS AND METHODS. Eighty-two invasive ductal carcinomas in 69 women were included in the study. All the subjects underwent whole-body (WB) PET/MRI (supine WB mode) and dedicated PET/MRI of the breast (prone breast imaging mode) for staging on a simultaneous PET/MRI system. The SUV and TLG values were calculated from F-18-FDG PET data using MRI-based attenuation correction (2-point Dixon sequence for tissue segmentation). Relationships between SUV and TLG values and clinical and histopathologic parameters (i.e., tumor size, tumor grade, Ki-67 status, and hormonal receptor expression status) were evaluated using Spearman correlation coefficient analysis. RESULTS. A significant correlation was observed between mean SUV (SUVmean) and maximum SUV (SUVmax) values derived with WB PET and regional PET of the breasts performed simultaneously with MRI (r = 0.88 and 0.89, respectively). A significant difference (p < 0.05) was observed in SUVmean, SUVmax, and TLG values between the grades and molecular subtypes of breast cancer. High SUVmean, SUVmax, and TLG values were found to correlate with larger tumor size (p < 0.01), higher proliferation index (p < 0.05), higher grade (p < 0.01), and triple-negative hormonal receptor status (p < 0.01, p < 0.05). CONCLUSION. Semiquantitative FDG parameters derived with MRI-based attenuation correction in simultaneous PET/MRI are reliable and correlate with clinicopathologic features such as grade as well as subtype and thus could be used in the prognostication of breast cancer.