Rapid Volumetric Quantification of Cartilage Biochemistry with MRI

Osteoarthritis (OA) is a chronic, degenerative disease of the joint that is characterized by degeneration affecting all tissues in the joint. A major gap in current osteoarthritis (OA) research is that tissues are studied in isolation, usually in a subjective manner. This work presents a novel technique, PET/MRI, to simultaneously assess early metabolic and structural markers of knee OA across multiple tissues in the joint. ¹⁸F-fluoride PET/MR, a marker of bone remodeling, may detect knee abnormalities unseen on MRI alone and is a promising tool for detection of early metabolic changes in OA. Further, higher ¹⁸F-fluoride uptake corresponds to worse degeneration in the adjacent cartilage, suggesting a spatial relationship between bone remodeling and cartilage health. Use of additional tracers such as ¹⁸F-FDG PET can provide complementary information about inflammatory processes occurring in soft tissues. PET/MR thus can simultaneously assess multiple early metabolic and biochemical markers of knee OA progression across all tissues in the joint. This information may provide new insights into OA pathogenesis and lead to new treatment targets to arrest the onset and progression of OA.

Kogan F, Fan AP, McWalter EJ, Oei EHG, Quon A, Gold GE. PET/MR Imaging of Metabolic Activity in Osteoarthritis: A Feasibility Study. J Magn Reson Imaging. 2017 Jun;45(6):1736-45.

Online Journal Article

¹⁸F-FDG (Top) and ¹⁸F-Fluoride (Bottom) PET SUV maps and corresponding MR images for a 23 male year-old subject. Increased ¹⁸F-FDG uptake (cyan arrow) is observed around the graft that may be indicative of graft impingement or revascularization. Additionally, increased ¹⁸F-Fluoride uptake (magenta arrow) indicative of bone remodeling is seen adjacent to the graft. ¹⁸F-fluoride and ¹⁸F-FDG provide complementary information regarding subchondral bone remodeling and soft tissue inflammation and could potentially be utilized together to study OA degeneration in the entire joint.