Knee Articular Cartilage in an Asymptomatic Population : Comparison of T1rho and T2 Mapping

Transcription

1 TR_002 Technical Reports Knee Articular Cartilage in an Asymptomatic Population : Comparison of T1rho and T2 Mapping Min A Yoon 1,*, Suk-Joo Hong 1, Chang Ho Kang 2, Baek Hyun Kim 3 1 Korea University Guro Hospital, Republic of Korea 2 Korea University Anam Hospital 3 Korea University Ansan Hospital * Corresponding author : mina11360@gmail.com

2 Nothing to disclose

3 Introduction Hyaline articular cartilage Chondrocyte 4% Water (65-85%) Extracellular matrix type II collagen (15-20%) proteoglycan (3-10%) MAGNETOM Flash 2/2012

4 Biochemical MRI T1rho (T1ρ) T2 spin-lattice relaxation time in the rotating frame a time constant for transverse magnetization decay in a very weak B1 field strength produced by spin-lock RF pulse positive association with the severity of knee osteoarthritis sensitive to changes in proteoglycan content in in articular cartilage spin-spin relaxation related to dipolar interaction of water proton in ECM sensitive for collagen and water content and orientation elevated in knee osteoarthritis

5 Introduction Magic angle effect regions of tightly bound collagen at of the main magnetic field (Bo) maximal at relatively short TE

6 Introduction Inconsistent results on magic angle effects on T2 and T1ρ in knee cartilage strong orientation dependence of T2 Grunder et al, Magn Reson Med 1998;39: , Mlynárik et al, Magn Reson Imaging 1996;14: substantially less orientation effect in vivo knee cartilage T2 Mosher et al, AJR Am J Roentgenol 2001;177: elimination of laminar appearance at magic angle due to reduced dipolar interaction with spin-lock technique Akella et al, Magn Reson Med 2004;52: magic angle may be cause of higher T1ρ in the patella Buck et al, AJR Am J Roentgenol 2011;196:W

7 Purpose Analyze subregional differences in T1ρ and T2 values in the medical femoral condyle and patella Correlation of T1ρ and T2 in asymptomatic knee cartilage Evaluate angular dependence with magic angles on cartilage T1ρ and T2 mapping

8 Material and Methods Six healthy adult volunteers 4M and 2F; mean, 32.3 yrs; range, yrs 3.0T MR scanner (Magnetom Trio, A Tim, Siemens Medical Solutions) T1ρ mapping truefisp-based 2D T1ρ pulse sequence time of spin lock (TSL) = 0, 10, 20, 30, 40 ms, spin lock frequency = 500 Hz, TR/TE = 8/4 ms T2 mapping multi-echo spin echo sequence TR = 2000 ms, TE = 10, 20, 30, 40, 50, 59, 69, 79 ms

9 Material and Methods Image Analysis T1ρ and T2 quantification Two independent review by musculoskeletal radiologists Manually drawn ROIs (2-3mm 2 ) Nine anatomical subregions in the medial femoral condyle Two locations in the center of the patella

10 Nine anatomical subregions in the medial femoral condyle, At angles of ± 0 o, 15 o, 35 o, 55 o, 75 o respective to a vertical line (B0) bisecting the width of the distal femur Perpendicular to a horizontal line crossing the posterior margin of MFC cartilage B0 T2 map T1rho map

11 Material and Methods Statistical Analysis Intraclass correlation coefficients (ICC) Inter-reader agreement Kruskal-Wallis test and post-hoc Tukey s test significant differences between T1ρ and T2 values in three divided MFC portions (anterior: -75 o, 55 o, 35 o, central: -15 o, 0 o, 15 o, and posterior: 35 o, 55 o, 75 o ) and patella Pearson s rank correlation correlation between T1ρ and T2 values Wilcoxon signed-rank test evaluation of angular dependence with magic angle influence between values of anatomical subregions in the MFC and values at ±55 o

12 Results T1ρ lowest at +15 o, highest at -55 o superior patella>inferior patella lowest in the central portion of the MFC highest in the anterior portion of the MFC

13 Results T2 lowest at +75 o, highest at +35 o superior patella>inferior patella lowest in the posterior portion highest in the central portion of the MFC

14 Results Significant differences in the three divided portions of the MFC for both T1ρ (p<0.05) No significant differences in three portions of the MFC for T2 (p=0.767) Weak correlation (r=0.217, p=0.127) between T1ρ and T2 values of the MFC and the patellar cartilage

15 Results - Magic angle effects T2 minimal angular dependence with the magic angle effect significant differences between -55 o and (-35 o, +75 o ) T1ρ more angular dependence -55 o and (-35 o, -15 o, 0 o, +15 o, +35 o, +55 o, 75 o ), +55 o and (0 o, +15 o ) (p<0.05) T1ρ T2 Location p(1) p(2) p(1) p(2) -75 o o * o * * o * o * * o * * o * o * o * * p(1) = p-values in comparison to 55 o p(2) = p-values in comparison to 135 o

16 Conclusion Significant subregional variations in T1ρ and T2 values of the MFC and patella cartilage Only T1ρ showed significant differences in the three divided portions of the MFC Lowest in the central and highest in the anterior portion A weak correlation between T1ρ and T2 in the knee articular cartilage T1rho showed more angular dependence than T2

17 Conclusion T1ρ and T2 mappings differences between T1ρ and T2 in asymptomatic knee will aid in assessment of cartilage in a specific subregion of the knee

18 References 1. Li X, Pai A, Blumenkrantz G, Carballido-Gamio J, Link T, Ma B, et al. Spatial distribution and relationship of T1rho and T2 relaxation times in knee cartilage with osteoarthritis. Magn Reson Med 2009;61: Regatte RR, Akella SV, Lonner JH, Kneeland JB, Reddy R. T1rho relaxation mapping in human osteoarthritis (OA) cartilage: comparison of T1rho with T2. J Magn Reson Imaging 2006;23: Li X, Benjamin Ma C, Link TM, Castillo DD, Blumenkrantz G, Lozano J, et al. In vivo T(1rho) and T(2) mapping of articular cartilage in osteoarthritis of the knee using 3 T MRI. Osteoarthritis Cartilage 2007;15: Dunn TC, Lu Y, Jin H, Ries MD, Majumdar S. T2 relaxation time of cartilage at MR imaging: comparison with severity of knee osteoarthritis. Radiology 2004;232: Keenan KE, Besier TF, Pauly JM, Han E, Rosenberg J, Smith RL, et al. Prediction of glycosaminoglycan content in human cartilage by age, T1rho and T2 MRI. Osteoarthritis Cartilage 2011;19: Mlynárik V, Trattnig S, Huber M, Zembsch A, Imhof H. The role of relaxation times in monitoring proteoglycan depletion in articular cartilage. J Magn Reson Imaging 1999;10: Mosher TJ, Dardzinski BJ. Cartilage MRI T2 relaxation time mapping: overview and applications. Semin Musculoskelet Radiol 2004;8: Gründer W, Wagner M, Werner A. MR-microscopic visualization of anisotropic internal cartilage structures using the magic angle technique. Magn Reson Med 1998;39: Mlynárik V, Degrassi A, Toffanin R, Vittur F, Cova M, Pozzi-Mucelli RS. Investigation of laminar appearance of articular cartilage by means of magnetic resonance microscopy. Magn Reson Imaging 1996;14: Mosher TJ, Smith H, Dardzinski BJ, Schmithorst VJ, Smith MB. MR imaging and T2 mapping of femoral cartilage: in vivo determination of the magic angle effect. AJR Am J Roentgenol 2001;177: Akella SV, Regatte RR, Wheaton AJ, Borthakur A, Reddy R. Reduction of residual dipolar interaction in cartilage by spin-lock technique. Magn Reson Med 2004;52: Buck FM, Bae WC, Diaz E, Du J, Statum S, Han ET, et al. Comparison of T1rho measurements in agarose phantoms and human patellar cartilage using 2D multislice spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot techniques at 3 T. AJR Am J Roentgenol 2011;196:W