Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Rheumatol Int. 2012 Sep;32(9):2867-75. doi: 10.1007/s00296-011-2140-3. Epub 2011 Sep 1.
T1ρ magnetic resonance imaging (MRI) can be used to map proteoglycan (PG) loss in cartilage. Here, we used T1ρ MRI to map cartilage degradation in osteoarthritis (OA) and rheumatoid arthritis (RA). Tissue samples were obtained from five RA patients and 14 OA patients following total knee arthroplasty (TKA). Three parameters were measured: First, macroscopic grading of cartilage sample tissues was performed on a 5-grade scale (G0: normal, G1: swelling, G2: superficial fibrillation, G3: deep fibrillation, G4: subchondral bone exposure). Second, semi-quantitative values of PG were assessed by measuring the optical density of Safranin-O-stained paraffin sections that had been digitally photographed. Third, cartilage was divided into superficial and deep layers and the T1ρ values were quantified. T1ρ values of OA and RA in the superficial layers showed significant differences between groups (G0/1 and G0/2 for OA; G0/2 and G1/2 for RA). In the deep layers, T1ρ values of OA and RA also differed significantly between groups. In both the superficial and deep layers, there was a significant correlation between the mean T1ρ values and macroscopic grading (P < 0.01 for OA, P < 0.001 for RA). We found a negative correlation between the score of Safranin-O staining and T1ρ values (r = -0.61 for OA, r = -0.79 for RA). In addition, RA subjects had significantly higher T1ρ values than OA subjects of similar morphologic grade. In conclusion, T1ρ MRI is able to detect and map the early stages of cartilage degradation in OA and RA. This method is reliable and useful for the evaluation of macromolecular changes in arthritic cartilage.
T1ρ 磁共振成像（MRI）可用于绘制软骨中蛋白聚糖（PG）的损失。在这里，我们使用 T1ρ MRI 来绘制骨关节炎（OA）和类风湿关节炎（RA）中的软骨降解。从接受全膝关节置换术（TKA）的 5 名 RA 患者和 14 名 OA 患者中获得组织样本。测量了三个参数：首先，对软骨样本组织进行了 5 级宏观分级（G0：正常，G1：肿胀，G2：浅表纤维化，G3：深层纤维化，G4：软骨下骨暴露）。其次，通过测量已数字化拍摄的番红 O 染色石蜡切片的光密度来评估 PG 的半定量值。第三，将软骨分为浅层和深层，并量化 T1ρ 值。OA 和 RA 在浅层中的 T1ρ 值在组间显示出明显差异（OA 中的 G0/1 和 G0/2；RA 中的 G0/2 和 G1/2）。在深层中，OA 和 RA 的 T1ρ 值在组间也有明显差异。在浅层和深层中，平均 T1ρ 值与宏观分级之间均存在显著相关性（OA 为 P<0.01，RA 为 P<0.001）。我们发现番红 O 染色评分与 T1ρ 值之间呈负相关（OA 为 r=-0.61，RA 为 r=-0.79）。此外，RA 患者的 T1ρ 值明显高于形态学相似的 OA 患者。总之，T1ρ MRI 能够检测和绘制 OA 和 RA 中软骨降解的早期阶段。该方法可靠且可用于评估关节炎软骨中大分子的变化。
