Abstract
To compare 18F-fluordesoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) using a contrast-enhanced T1-weighted (T1w) fat-suppressed (fs) volume-interpolated breath-hold examination (VIBE) sequence with 18F-FDG PET/computed tomography (18F-FDG PET/CT) regarding detection and characterization of lung lesions in oncologic patients. Methods: 121 oncologic patients underwent PET/MRI following PET/CT in a single-injection protocol (260±58 MBq 18F-FDG). Lung lesion detection rates of T1w fs VIBE, PET from 18F-FDG PET/CT, and PET from 18F-FDG PET/MRI were computed in relation to the CT component of PET/CT. Wilcoxon tests assessed differences in lesion contrast (four-point scale) and lesion size between morphologic datasets as well as in image quality (four-point scale), mean and maximum standard uptake values (SUVmean, SUVmax), and dignity ratings (benign/malignant) between 18F-FDG PET/MRI and 18F-FDG PET/CT. Correlations were calculated using Pearson’s coefficients (r) for SUV and size and Spearman’s rank coefficient (ρ) for lesion contrast. Results: Detection rates of T1w fs VIBE, PET from 18F-FDG PET/CT and PET from 18F-FDG PET/MRI regarding 241 lung lesions were 66.8%, 42.7%, and 42.3%, respectively. There was a strong correlation in size (r=0.98) and SUVs (r=0.91) and a moderate correlation concerning lesion contrast (ρ=0.48). Image quality of 18F-FDG PET/MRI was inferior to 18F-FDG PET/CT (p<0.001). Corresponding lung lesions were measured smaller on T1w fs VIBE than on CT (p<0.001). SUVmax and SUVmean from 18F-FDG PET/MRI were significantly higher than from 18F-FDG PET/CT (p<0.001 each). There was no significant difference in lesion contrast (P = 0.11) or dignity ratings (P = 0.076). Conclusion: Performance of 18F-FDG PET/MRI regarding detection and characterization of lung lesions ≥ 10 mm is comparable to 18F-FDG PET/CT. Lesion size, SUV and dignity ratings correlate strongly. However, the overall detection rate of 18F-FDG PET/MRI remains inferior to 18F-FDG PET/CT due to the limited detectability of lesions < 10 mm on T1w fs VIBE. Thus, thoracic staging with 18F-FDG PET/MRI bears a risk of missing small lung metastases.
- Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.