Yasunari Oniki

T1ρ and T2 mapping reveal the in vivo extracellular matrix of articular cartilage

To determine the relationship between changes in the extracellular matrix (ECM) and T1ρ and T2 values in vivo. The ECM is composed of proteoglycan (PG), collagen, and water. It has been unclear which of the ECM constituents affects T1ρ and T2 mapping in living human cartilage.

Articular Cartilage Lesions Increase Early Cartilage Degeneration in Knees Treated by Anterior Cruciate Ligament Reconstruction T1ρ Mapping Evaluation and 1-Year Follow-up

Background: Articular cartilage degeneration can develop after anterior cruciate ligament reconstruction (ACLR). Although radiological studies have identified risk factors for the progression of degenerative cartilage changes in the long term, risk factors in the early postoperative period remain to be documented. Hypothesis: Cartilage lesions that are present at surgery progress to cartilage degeneration in the early phase after ACLR. Study Design: Case series; Level of evidence, 4. Methods: T1ρ is the spin-lattice relaxation in the rotating frame magnetic resonance imaging. Sagittal T1ρ maps of the femorotibial joint were obtained before and 1 year after ACLR in 23 patients with ACL injuries. Four regions of interest (ROIs) were placed on images of the cartilage in the medial and lateral femoral condyle (MFC, LFC) and the medial and lateral tibia plateau (MTP, LTP). Changes in the T1ρ value (milliseconds) of each ROI were recorded, and differences between patients with and without cartilage lesions were evaluated. The relationship between changes in the T1ρ value and meniscal tears was also studied. Results: Arthroscopy at ACLR detected cartilage lesions in 15 MFCs, 7 LFCs, and 2 LTPs. The baseline T1ρ value of the MFC and LFC was significantly higher in patients with cartilage lesions (MFC, 40.7 ms; LFC, 42.2 ms) than in patients without cartilage lesions (MFC, 38.0 ms, P = .025; LFC, 39.4 ms, P = .010). At 1-year follow-up, the T1ρ value of the MFC and LFC was also significantly higher in patients with lesions (MFC, 43.1 ms; LFC, 42.7 ms) than in patients without such lesions (MFC, 39.1 ms, P = .002; LFC, 40.4 ms, P = .023, respectively). In patients with cartilage injury, the T1ρ value of the MFC increased during the year after treatment (P = .002). There was no significant difference in the baseline and follow-up T1ρ value in patients with or without meniscal tears on each side although the T1ρ value of the MFC, MTP, and LFC increased during the first year after surgery regardless of the presence or absence of meniscal injuries. Conclusion: Using T1ρ mapping to detect minimal changes, our study demonstrated that cartilage lesions are related to progressive degenerative cartilage changes during the early phase after ACLR.

T1ρ and T2 mapping of the proximal tibiofibular joint in relation to aging and cartilage degeneration

OBJECTIVE To study the effects of aging and cartilage degeneration of the proximal tibiofibular- and femorotibial joint (PTFJ, FTJ) on the cartilage of the PTFJ using T(1)ρ and T(2) mapping. MATERIALS AND METHODS We performed sagittal T(1)ρ and T(2) mapping of the PTFJ and FTJ on 55 subjects with knee disorders. We placed 3 regions of interest (ROIs) on images of the cartilage in the PTFJ, medial femoral condyle (MFC), and medial tibia plateau (MTP). Correlation analysis was performed for the T(1)ρ and T(2) values of each ROI and the patient age and the osteoarthritic grade of the PTFJ and FTJ. RESULTS The T(1)ρ and T(2) values of the PTFJ were affected neither by aging nor the osteoarthritic grade of the FTJ. Values of the FTJ normalized to PTFJ values were correlated with the osteoarthritic grade of the FTJ in the MFC (r=0.851 and 0.779, respectively) and the MTP (r=0.635 and 0.762, respectively). There was a significant difference in the T(1)ρ but not the T(2) value of the PTFJ and MFC between normal and mildly osteoarthritic cartilage of each joint. CONCLUSION We document that the T(1)ρ and T(2) values of PTFJ cartilage were not affected by aging or cartilage degeneration in the FTJ. The T(1)ρ value of the PTFJ may represent a useful internal standard reference for evaluating early degeneration of the FTJ.

The Effect of Perfusion with UW Solution on the Skeletal Muscle and Vascular Endothelial Exocrine Function in Rat Hindlimbs

BACKGROUND The effect of University of Wisconsin (UW) solution perfusion for extremity preservation is still unknown although it is widely used. The purpose of this study is to examine the effect of UW solution perfusion on skeletal muscle preservation in a rat model. MATERIALS AND METHODS Rat hindlimbs were amputated and either preserved with UW solution perfusion (UW perfusion group) or given no perfusion (no-perfusion group) for 5 h at 25 degrees C. They were then transplanted to other isogeneic rats. ATP in the muscle and serum creatine phosphokinase were measured after 24 h of reperfusion. The vascular endothelial function of the femoral artery rings was measured before and after 24 h of reperfusion in the presence or absence of indomethacin (cyclooxygenase inhibitor) and L-NMMA (nitric oxide synthase inhibitor). TEA (calcium-activated potassium channel inhibitor) was also used to verify the vasodilator function. Reperfusion blood flow was monitored during the first 2 h of reperfusion. RESULTS ATP in the UW perfusion group was significantly decreased after 24 h of reperfusion, while that in the no-perfusion group recovered. Reperfusion blood flow in the UW solution perfusion group was significantly lower than that in the no-perfusion group. Acetylcholine-induced relaxation in the UW perfusion group was significantly reduced before and after 24 h of reperfusion compared to that in the no-perfusion group and was mostly diminished by indomethacin and L-NMMA administration. CONCLUSIONS Skeletal muscle injury is augmented by UW solution perfusion, probably due to deterioration of the vascular endothelial function resulting in blood supply diminution.