Yong Lu MD, PhD, Presenter: Nothing to Disclose

Xiaoyi Ding MD, Abstract Co-Author: Nothing to Disclose

Kemin Chen MD, PhD, Abstract Co-Author: Nothing to Disclose

Quantitative magnetic resonance imaging (MRI) techniques have been developed for noninvasive assessment of the structure of articular cartilage. In the present study, normal adult patellar cartilages were investigated to reveal the effect of cartilage load to T2 relaxation time and volumetric changes.  

Ten adult volunteers were included for the study. Inclusion criteria for all subjects were younger than 30 years; no clinical knee symptoms as well as no cartilage or subchondral  abnormalities in routine knee MRI. MRI of the knee joint was performed on a 3.0 T system using a dedicated knee coil. T1-weighted 3D high-spatial-resolution volumetric fat-suppressed spoiled gradient-echo (SPGR) sequence dedicated to cartilage volume measurement. Sagittal 2D dual-echo fast spin echo (FSE) sequence was used for measuring T2 relaxation time. The patellar cartilage margin was defined by using a gradient peak method, and volume was measured semiautomatically. The cartilage volume was normalized to minimize variation due to joint size. The sagittal T2 maps were generated by using functool software and the linear profile tool was used to reveal the superficial and deep patellar cartilage T2 relaxation time variation. All the volunteers were requested prostration for 30 mins before the first knee MR scans; the second scans were performed after squatting 20 times. The central patellar superficial and deep cartilage T2 relaxation time variations and total patellar cartilage volumes before and after exercises were compared.  

In the mixed effect model, the patellar cartilages exhibited significantly higher (t=12.43, P =0.013) T2 relaxation times after exercises compared to static controls. But the superficial and deep T2 relaxation time variations did not show significant changes (t=3.583, P>0.05). Applying the mixed effect model, no significant (t=2.859, P>0.05) cartilage volume changes were found compare the results of two scans.  

The cartilage load could influence the matrix orientation of the collagen network, but which is aequalis and steady in normal deep and superficial region. Cartilage T2 relaxation time changes were more sensitive than volumetric variants.  

The load influence would be included in the cartilage longitudial evaluation.Cartilage T2 relaxation time and volumetric measurement may be useful in quantifying early OA related changes.

Lu, Y, Ding, X, Chen, K, Human Patellar CartilageT2 Relaxation Time and Volumetric Changes in Response to Physical Exercise.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6017973.html