2015 ISAKOS Biennial Congress ePoster #405

Correlation Betweeen Newly Developed 3D Cube Acquisition T1rho And T2 Relaxation Mapping and Histological Assessments in Early Phase Osteoarthritic Cartilage

Takahisa Sasho, MD, PhD, Chiba, Chiba JAPAN
Satoshi Yamaguchi, MD, Chiba JAPAN
Hiroko Hoshi, MD, Chiba JAPAN
Toshihide Sasaki, MD, Chiba JAPAN
Yohei Yamamoto, MD, Chiba, Chiba JAPAN
Yuichi Wada, Prof., Ichihara City JAPAN
Atsuya Watanabe, MD, PhD, Ichihara, Chiba JAPAN

Graduate School of Medicine, Chiba University, Chiba, JAPAN

FDA Status Not Applicable

Summary: 3D T1rho mapping was more adequate to detect early articular cartilage degeneration than 3D T2 mapping.

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Abstract:

Introduction

Several studies have reported detection of very early phase of osteoarthritis (OA) was possible by assessing the quality of cartilage with MRI. For that purpose several imaging techniques have been developed. T1rho mapping and T2 mapping are representative methods. Each of them reflects different biochemical parameters of cartilage. Previous studies revealed that T1rho relaxation time reflected changes in the glycosaminoglycan content in the extracellular matrix, while T2 relaxation time was more sensitive to the cartilage's water content than T1rho and also reflected the presence of collagen anisotropy due to dipolar interaction. 3D Cube® T1 rho and 3D Cube T2 acquisition are modifications of acquiring images and are expected to enable better cartilage assessment but their actual potential have to be addressed.

Objective

To examine correlation of 3D CUBE T1rho and 3D CUBE T2 relaxation time with macroscopic and histological assessment with special reference to lateral compartment cartilage retrieved at the time of total knee arthroplasty (TKA) performed for medial type OA knees.

Methods

Nineteen primary knee OA patients who underwent TKA were involved in the present study. Prior to operations, MRI was taken with 3-T machine (Discovery® MR750 MR System, Research pack 3.0, GE Healthcare, Japan). As the first step for 3D CUBE T1 rho or T2 mapping, mask images were made based on sagittal planes of 3 sequences; i.e; 3D-MERGE (Multiple Echo Recombined Gradient Echo), 3D-SPGR, and 3D-Cube. Then position adjustment and cartilage extraction were followed. 3D T1rho/T2 analyses were done and resultant color contour mapping image were exhibited. At the time of operation, cartilage damage on LFC (lateral femoral condyle), LFCP (LFC posterior), and LTP (lateral tibia plateau) was assessed macroscopically and graded by ICRS (International Cartilage Research Society) articular classification system. Extracted specimens were histologically assessed by OARSI histology score. Three ROIs from each specimen were assessed by mean T1rho/T2 value, ICRS grade, and OARSI score. Then, their correlations were examined. For statistical-analytical approach, Kruskal-Wallis test, and Steel Dwass test for post hoc was used for data analysis among multiple groups. Significance was defined as a p<0.05.

Results

There was no significant difference between any ICRS grades on neither T1rho nor T2 time. T1rho time was significantly different between OARSI grade 1 and 2 at all the three locations (44.55 ± 1.23ms vs 45.91 ± 2.96 on LFC, 49.40 ± 3.90 vs 54.49 ± 2.79 on LFCP, 40.76 ± 2.74 vs 47.94 ± 5.52 on LTP) with p-value of 0.0315, 0.0079, 0.0036 respectively, while T2 time was not.

Conclusion

Our results indicated that 3D T1rho mapping was able to detect early articular cartilage degeneration.