Comparative study between 18FDG-PET/CT and whole body MRI DWIBS in the assessment of recurrent breast cancer (Prospective, Comparative, Cross‑sectional Study Design) Mahmoud Rezk1, M.D. Ibrahim Nasr2, MD. Ismail Ali3, MD. Heba Abdelhamed, MD 1Department of Radiology, National Cancer Institute, Cairo, Egypt, 2,4Department of Oncology and Nuclear Medicine, Faculty of Medicine, Zagazig University, 3Department of Radiology, Faculty Of medicine Zagazig University. Indian J. Nucl. Med., Jan 2019 (In press) Abstract Aim: To assess the diagnostic performance of fluorodeoxyglucose positron emission tomography [18FDG-PET/CT] compared to whole body diffusion weighted imaging with background body signal suppression [MR DWIBS] in lesions detection for patients with recurrent breast cancer. Methodology: Twenty three patients with local or distant breast cancer recurrence by clinical, laboratory or conventional imaging underwent both 18FDG-PET/CT and WB-MRI/DWIBS. Whole body 18FDG-PET/CT was performed using standard technique. WB-MRI/DWIBS acquired sequences were whole body diffusion weighted imaging (DWI) with short tau inversion recovery (STIR), coronal T1 and coronal STIR. Both 18FDG-PET/CT and WB-MRI/DWIBS were independently interpreted using visual qualitative and quantitative analysis. Both pathological findings and combined clinical/ radiological follow up data were used as a reference standard. Sensitivity, specificity, PPV, NPV and overall accuracy were done for both techniques.Results: 18FDG-PET/CT correctly diagnosed 158/185 lesions (95 malignant and 63 benign) versus 149/185 lesions for MR-DWIBS (92 malignant and 57 benign) with overall accuracy 85.4% for PET/CT versus 80.5% for MR-DWIBS. PET/CT demonstrated higher specificity and sensitivity indices than MR-DWIBS in the detection of the nodal and distant lesions, while the latter displayed higher sensitivity in diagnosis of local breast lesions. The overall sensitivity, specificity, negative predictive value and positive predictive value of PET/CT were 84.8%,86.3%,90.4% and 78.7% versus 82.1 %, 78.0%, 85.2% and 74.0% for MR-DWIBS. A high degree of agreement was existed between PET/CT and MR-DWIBS. Conclusion: 18FDG-PET/CT is more sensitive and has superiority in assessment of nodal and distant lesions than DWIBS that have potential superior role in assessment of local breast lesions. DWIBS has a promising and helpful complementary tool for 18FDG-PET/ CT in evaluation of patients with proven malignancies. Key word: breast, 18FDG-PET/-CT, WB-MRI, DWIBS