Mikko J. Nissi1, 2, Silvia Mangia1, Shalom Michaeli1, Miika T. Nieminen3, 4
1CMRR and Department of Radiology, University of Minnesota, Minneapolis, MN, United States; 2Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; 3Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; 4Department of Radiology, University of Oulu, Oulu, Finland
Several rotating frame relaxation (RFR) parameters have been recently introduced and applied for quantitative evaluation of articular cartilage. Orientation dependence of adiabatic T1&[rho] and T2&[rho], RAFF as well as CW-T1&[rho] and T2 relaxation times was investigated by imaging at 9.4T at seven different orientations of articular cartilage relative to B0 field. Adiabatic T2&[rho] and RAFF showed significant orientation dependence, whereas adiabatic T1&[rho] was relatively insensitive to orientation. Continuous-wave T1&[rho] at low spin-lock power and T2 were orientation dependent as previously reported. The present findings promote the use of adiabatic T1&[rho] as an orientation-independent biomarker to assess articular cartilage.