Comparative T2and T1ρmapping of patellofemoral cartilage under in situ mechanical loading with prospective motion correction.
To demonstrate improved T2and T1ρmapping of patellofemoral cartilage with in situ loading by means of prospective motion correction and to assess load-induced changes in healthy subjects.



Established T2and T1ρmapping sequences were augmented with prospective motion correction based on optical tracking. Protocols were optimized for robust imaging of the patellofemoral cartilage at a field strength of 3T. Subjects were positioned in the scanner with knee flexion and in situ loading of the patellofemoral joint was performed with a pneumatic loading device. In a pilot study on a cohort of 10 healthy subjects, load-induced T2and T1ρchanges were evaluated through measurements with axial loads of 0/20/40 kg.



With prospective motion correction and additional lipid saturation, motion artifacts in patellofemoral cartilage magnetic resonance imaging (MRI) with in situ loading could be notably decreased, as demonstrated for T2mapping. The acquired relaxation maps suggested a T2/T1ρdecrease in superficial cartilage and a T2/T1ρincrease in deep cartilage under loading. However, in the quantitative group evaluation of the lateral patellar facet, only T1ρin superficial cartilage was significantly changed by loading (P ≤ 0.05), while no significant T2differences for the three loading conditions were observed (P ≥ 0.3).



Prospective motion correction enables T2and T1ρmapping of patellofemoral cartilage with in situ loading and a comparison of the two contrasts in terms of their response to mechanical loading. T1ρis a more sensitive marker for load-induced patellar cartilage changes than T2.



3 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:452-460.
Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.
Thomas
T
Lange
Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.
Benjamin R
BR
Knowles
Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.|John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
Michael
M
Herbst
Department of Orthopedic and Trauma Surgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.
Kaywan
K
Izadpanah
Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.
Maxim
M
Zaitsev
D000328:Adult; D016477:Artifacts; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007717:Knee / Q000000981:diagnostic imaging; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D009038:Motion; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging*; D010865:Pilot Projects; D015203:Reproducibility of Results
cartilage; in situ mechanical loading; knee; magnetic resonance imaging; prospective motion correction; relaxation mapping