Whole-body magnetic resonance imaging for detection of malignant disease: A head-to-head-comparison with whole-body 18F-FDG-PET/CT as the reference standard

The combined use of 18 F-FDG-PET and computed tomography (CT) scans is an integrated part of diagnosing and staging patients with suspected malignancy or other pathologies. Magnetic resonance imaging (MRI) has proven its use as a non-ionizing imaging alternative for identifying potential malignancy in specific organs. Objective: To investigate the clinical value of whole-body MRI in detection of suspicious lesions, we compared 1.5T MRI findings to those obtained from a whole-body 18 F-FDG-PET/CT scan, the latter serving as the reference standard. Finally, the findings were compared with histology if available. Materials and methods: Twenty-five patients (9 women and 16 men, mean age SD: 64.5 11.8 years; range: 3485 years) with suspected malignancy or other pathologies were enrolled. All patients were scanned using both modalities. Imaging included the head, torso and extremities. Images were scored blinded by experienced readers: two radiologists and two nuclear medicine physicians. Statistical tests included weighted kappa for measuring interobserver reliability and Wilcoxon signed-rank test for detection differences between paired observations. Results and discussion: Interobserver reliability between each pair of specialists was fair-to-strong (Weighted kappa). Statistically significant differences between the findings of the two modalities were found in the colon (p=0.016), soft tissues of the extremities (p=0.002) and skeleton of the extremities (p=0.008). Twelve patients had histology available. WB-MRI and whole-body 18 F-FDG-PET/CT found 10 of these cases (sensitivity: 83.3%, 95% CI: 55.2%-95.3%). Conclusion: The diagnostic value of WB-MRI equaled whole-body 18 F-FDG-PET/CT. The MRI approach could therefore be considered in patients unsuitable for 18 F-FDG-imaging e.g. younger patients, during pregnancy or dysregulated diabetics.