Comparison of T1rho and T2 Mapping of Knee Articular Cartilage in an Asymptomatic Population.
To analyze subregional differences in T1rho (T1ρ) and T2 values and their correlation in asymptomatic knee cartilage, and to evaluate angular dependence with magic angles.



Six asymptomatic volunteers underwent knee MRI with T1ρ and T2 mapping. T1ρ and T2 values were measured by two radiologists independently, at nine subregions in the medial femoral condyle (MFC) cartilage, at angles of ± 0°, 15°, 35°, 55°, 75° respective to a vertical line (B0) bisecting the width of the distal femur, and at two locations in the patella. Subregional values of T1ρ and T2 were analyzed and significant differences in three divided portions of the MFC (anterior, central, and posterior) were statistically evaluated. Correlation between T1ρ and T2 and angular dependence with magic angles were also assessed for statistical significance.



T1ρ values were lowest at +15° and highest at -55°. T2 values were lowest at +75° and highest at +35°. Both T1ρ and T2 were higher in superior patella than inferior patella. T1ρ showed significant differences in the three divided portions of the MFC, while T2 showed significant differences only between central and posterior portions. There was a weak correlation between T1ρ and T2 (r= 0.217,p= 0.127). T1ρ showed more angular dependence than T2.



T1ρ and T2 showed different subregional values and angular dependence in asymptomatic knee cartilage with a weak correlation. Awareness of these differences will aid in assessment of cartilage in a specific subregion of the knee.
Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul 08308, Korea.
Min A
MA
Yoon
Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul 08308, Korea.
Suk-Joo
SJ
Hong
Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul 08308, Korea.
A Lan
AL
Im
Department of Radiology, Korea University Anam Hospital, Korea University College of Medicine, Seoul 02841, Korea.
Chang Ho
CH
Kang
Department of Radiology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan 15355, Korea.
Baek Hyun
BH
Kim
Siemens Healthcare, Seoul 03737, Korea.
In Seong
IS
Kim
D000328:Adult; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D011446:Prospective Studies
Cartilage; Knee; MRI; Magic angle; T1rho; T2 mapping