Diagnostic and Prognostic Value of Pretreatment SUV in 18F-FDG/PET in Breast Cancer: Comparison with Apparent Diffusion Coefficient from Diffusion-Weighted MR Imaging

In oncology, the apparent diffusion coefficient (ADC) measured by diffusion-weighted MR imaging (DWI) and the standardized uptake value (SUV) from F-18-FDG PET have similar clinical applications. The purpose of this study was to assess the correlation between the ADC and SUV and compare their potential in the diagnosis and prediction of prognosis in breast tumors. Methods: Seventy-nine female patients (age range, 19-69 y; average, 49.1 y) with 83 pathologically proven breast tumors were recruited. The diagnoses consisted of 70 malignant breast tumors (65 cases of invasive ductal carcinoma, 1 of medullary carcinoma, 1 of mucinous carcinoma, 1 of squamous cell carcinoma, and 2 of micropapillary carcinoma) and 13 benign breast tumors (4 cases of fibroadenoma, 4 of mastopathy, 3 of adenosis with atypia, and 2 of benign phyllodes tumor). All patients underwent mammary gland MR imaging with DWI and 18F-FDG PET within a 2-wk interval. The patients' ADCs and SUVs were measured within the tumor by DWI and F-18-FDG PET, respectively. For the malignant tumors, we evaluated the relationships among ADC, SUV, histopathologic appearance, and long-term prognosis. Results: A significant difference (P < 0.05) was observed in both parameters (ADC and SUV) between the benign and malignant breast tumors, and the difference was more significant when we introduced a new parameter, SUV/ADC. There was a weak inverse correlation between ADC and SUV (r = -0.36; P = 0.06) among the total tumors; however, this correlation was not significant within the group of malignant tumors. High SUV was found to correlate with larger tumor size, higher nuclear grade, and the triple-negative hormonal receptor profile. High ADC was revealed to be correlated with negative progesterone receptor and positive human epidermal growth factor receptor 2 profile. Higher SUVs also showed a correlation with poor prognosis. No correlation was seen between ADC and prognosis. Conclusion: Both SUV and ADC are helpful parameters in differentiating benign from malignant breast tumors. The use of SUV and ADC in combination may help in the diagnosis because of their inverse relationship. High preoperative SUV was associated with poor prognosis, but the contribution of ADC to prognosis prediction was small.