Apparent Diffusion Coefficient of Glial Neoplasms: Correlation with Fluorodeoxyglucose– Positron-Emission Tomography and Gadolinium- Enhanced MR Imaging

BACKGROUND AND PURPOSE: Gd-enhancement provides essential information in the assessment of brain tumors. However, enhancement does not always correlate with histology or disease activity, especially in the setting of current therapies. Our aim was to compare FDG-PET scans to ADC maps and Gd-enhanced MR images in patients with glial neoplasms to assess whether DWI might offer information not available on routine MR imaging sequences and whether such findings have prognos-tic significance. MATERIALS AND METHODS: Institutional review board approval was obtained for this retrospective review, which was conducted in full compliance with HIPAA regulations. Twenty-one patients (11 men and 10 women) with glial tumors underwent FDG-PET and MR imaging, including ADC and Gd-enhancement. Subjectively, regions of interest were drawn around the following areas: 1) increased FDG uptake, 2) decreased signal intensity on ADC maps, and 3) Gd-enhancement. Objectively, FDG-PET and MR images were co-registered, and pixel-by-pixel comparison of ADC to PET values was made for all regions of interest. Correlation coefficients (r values) were calculated for each region of interest. Percentage overlap between regions of interest was calculated for each case. RESULTS: Subjective evaluation showed 60 % of patients with excellent or good correlation betwee