Hybrid FDG-PET/MR compared to FDG-PET/CT in adult lymphoma patients

Purpose The goal of this study is to evaluate the diagnostic performance of simultaneous FDG-PET/MR including diffusion compared to FDG-PET/CT in patients with lymphoma. Methods Eighteen patients with a confirmed diagnosis of non-Hodgkin’s (NHL) or Hodgkin’s lymphoma (HL) underwent an IRB-approved, single-injection/dual-imaging protocol consisting of a clinical FDG-PET/CT and subsequent FDG-PET/MR scan. PET images from both modalities were reconstructed iteratively. Attenuation correction was performed using low-dose CT data for PET/CT and Dixon-MR sequences for PET/MR. Diffusion-weighted imaging was performed. SUV max was measured and compared between modalities and the apparent diffusion coefficient (ADC) using ROI analysis by an experienced radiologist using OsiriX. Strength of correlation between variables was measured using the Pearson correlation coefficient ( r p ). Results Of the 18 patients included in this study, 5 had HL and 13 had NHL. The median age was 51 ± 14.8 years. Sixty-five FDG-avid lesions were identified. All FDG-avid lesions were visible with comparable contrast, and therefore initial and follow-up staging was identical between both examinations. SUV max from FDG-PET/MR [(mean ± sem) (21.3 ± 2.07)] vs. FDG-PET/CT (mean 23.2 ± 2.8) demonstrated a strongly positive correlation [ r s = 0.95 (0.94, 0.99); p