Pulmonary Nodules in Patients with Primary Malignancy: Comparison of Hybrid PET/MR and PET/CT Imaging
Abstract
Radial volumetric interpolated breath-hold examination free-breathing MR imaging with simultaneously acquired PET data has high sensitivity in the detection of fluorodeoxyglucose-avid nodules and nodules with a diameter of at least 0.5 cm.
Purpose
To assess diagnostic sensitivity of radial T1-weighted gradient-echo (radial volumetric interpolated breath-hold examination [VIBE]) magnetic resonance (MR) imaging, positron emission tomography (PET), and combined simultaneous PET and MR imaging with an integrated PET/MR system in the detection of lung nodules, with combined PET and computed tomography (CT) as a reference.
Materials and Methods
In this institutional review board–approved HIPAA-compliant prospective study, 32 patients with tumors who underwent clinically warranted fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT followed by PET/MR imaging were included. In all patients, the thorax station was examined with free-breathing radial VIBE MR imaging and simultaneously acquired PET data. Presence and size of nodules and FDG avidity were assessed on PET/CT, radial VIBE, PET, and PET/MR images. Percentage of nodules detected on radial VIBE and PET images was compared with that on PET/MR images by using generalized estimating equations. Maximum standardized uptake value (SUVmax) in pulmonary nodules with a diameter of at least 1 cm was compared between PET/CT and PET/MR imaging with Pearson rank correlation.
Results
A total of 69 nodules, including 45 FDG-avid nodules, were detected with PET/CT. The sensitivity of PET/MR imaging was 70.3% for all nodules, 95.6% for FDG-avid nodules, and 88.6% for nodules 0.5 cm in diameter or larger. PET/MR imaging had higher sensitivity than PET for all nodules (70.3% vs 61.6%, P = .002) and higher sensitivity than MR imaging for FDG-avid nodules (95.6% vs 80.0%, P = .008). There was a significantly strong correlation between SUVmax of pulmonary nodules obtained with PET/CT and that obtained with PET/MR imaging (r = 0.96, P < .001).
Conclusion
Radial VIBE and PET data acquired simultaneously with PET/MR imaging have high sensitivity in the detection of FDG-avid nodules and nodules 0.5 cm in diameter or larger, with low sensitivity for small non–FDG-avid nodules.
© RSNA, 2013
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Article History
Received March 10, 2013; revision requested March 28; revision received April 25; accepted May 2; final version accepted May 10.Published online: Sept 2013
Published in print: Sept 2013