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Quantitative [18F]-Naf-PET-MRI Analysis for the Evaluation of Dynamic Bone Turnover in a Patient with Facetogenic Low Back Pain
Published on: August 8, 2019
PET/MRI of metabolic activity in osteoarthritis: A feasibility study
Feliks Kogan1, Audrey P Fan1, Emily J McWalter2
1Department of Radiology, Stanford University, Stanford, California, USA.
Purpose:
To evaluate positron emission tomography / magnetic resonance imaging (PET/MRI) knee imaging to detect and characterize osseous metabolic abnormalities and correlate PET radiotracer uptake with osseous abnormalities and cartilage degeneration observed on MRI.
Materials And Methods:
Both knees of 22 subjects with knee pain or injury were scanned at one timepoint, without gadolinium, on a hybrid 3.0T PET-MRI system following injection of 18 F-fluoride or 18 F-fluorodeoxyglucose (FDG). A musculoskeletal radiologist identified volumes of interest (VOIs) around bone abnormalities on MR images and scored bone marrow lesions (BMLs) and osteophytes using a MOAKS scoring system. Cartilage appearance adjacent to bone abnormalities was graded with MRI-modified Outerbridge classifications. On PET standardized uptake values (SUV) maps, VOIs with SUV greater than 5 times the SUV in normal-appearing bone were identified as high-uptake VOI (VOIHigh ). Differences in 18 F-fluoride uptake between bone abnormalities, BML, and osteophyte grades and adjacent cartilage grades on MRI were identified using Mann-Whitney U-tests.
Results:
SUVmax in all subchondral bone lesions (BML, osteophytes, sclerosis) was significantly higher than that of normal-appearing bone on MRI (P < 0.001 for all). Of the 172 high-uptake regions on 18 F-fluoride PET, 63 (37%) corresponded to normal-appearing subchondral bone on MRI. Furthermore, many small grade 1 osteophytes (40 of 82 [49%]), often described as the earliest signs of osteoarthritis (OA), did not show high uptake. Lastly, PET SUVmax in subchondral bone adjacent to grade 0 cartilage was significantly lower compared to that of grades 1-2 (P < 0.05) and grades 3-4 cartilage (P < 0.001).
Conclusion:
PET/MRI can simultaneously assess multiple early metabolic and morphologic markers of knee OA across multiple tissues in the joint. Our findings suggest that PET/MR may detect metabolic abnormalities in subchondral bone, which appear normal on MRI.
Level Of Evidence:
2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;45:1736-1745.
