Objective To investigate the correlation of magnetic resonance imaging （MRI） with histopathologica changes, and to evaluate T2 mapping in assessing muscle trauma in a rabbit model of muscle injury. Methods We divided 35 rabbits into seven groups that each represented a different time point after intramuscular hemorrhage and muscle injury. Hemorrhage was created by injecting autologous blood into the left legs, and muscle injury was created by scalpel incision of the biceps femoris of the right legs. At different time points, the rabbits underwent Tl-weighted imaging and T2-weighted imaging （TzWl and T2Wl） and T2 mapping. T2 relaxation times were measured, and the corresponding samples were evaluated for pathological changes. Results After 2 h, the intramuscular hemorrhage model demonstrated an increased signal intensity on both TlWl and T2Wl. Histological examination showed erythrocytes within the muscle bundle. On days 1 and 3, the MRI signals were decreased, and there were no significant changes after day 7. From 2 h to 3 days, the muscle-injury model showed a high signal on both TzWl and T2Wl. Corresponding pathological changes included rupture and edema of muscle fibers, and inflammation. The abnormal signals were reduced on day 7. After day 14, the T2Wl intensity remained high. TlWl showed no abnormal changes, but some models showed a high signal, representing fresh bleeding and fatty tissue. T2 relaxation times were significantly different between the central and marginal regions, and between the marginal and normal regions. Conclusion MRI clearly demonstrates intramuscular hemorrhage and muscle injury, which correlate well with histopathological changes. Tz mapping is useful in assessing the extent of injury.
YAN DongZHANG JingLIANG WeiSUN JingLIU Bao YueTIAN WeiCHENG Xiao Guang
Objective Using MR T2-mapping and histopathologic score for articular cartilage to evaluate the effect of structural changes in subchondral bone on articular cartilage. Methods Twenty-four male Beagle dogs were randomly divided into a subchondral bone defect group （n = 12） and a bone cement group （n = 12）. Models of subchondral bone defectin the medial tibial plateau and subchondral bone filled with bone cement were constructed. In all dogs, the left knee joint was used as the experimental sideand the right knee as the sham side. The T2 value for articular cartilage at the medial tibial plateau was measured at postoperative weeks 4, 8, 16, and 24. The articular cartilage specimens were stained with hematoxylin and eosin, and evaluated using the Mankin score. Results There was a statistically significant difference （P 〈 0.05） in Mankin score between the bone defect group and the cement group at postoperative weeks 16 and 24. There was a statistically significant difference in the T2 values between the bone defect group and its sham group （P 〈 0.05） from week 8, and between the cement group and its sham group （P 〈 0.05） from week 16. There was significant difference in T2 values between the two experimental groups at postoperative week 24 （P 〈 0.01）. The T2 value for articular cartilage was positively correlated with the Mankin score （ρ = 0.758, P 〈 0.01）. Conclusion Structural changes in subchondral bone can lead to degeneration of the adjacent articular cartilage. Defects in subchondral bone cause more severe degeneration of cartilage than subchondral bone filled with cement. The T2 value for articular cartilage increases with the extent of degeneration. MR T2-mapping images and the T2 value for articular cartilage can indicate earlycartilage degeneration.
YAN DongLIU Tong XiLIU Bao YueWANG LingQIAN Zhan HuaCHENG Xiao GuangLI Kun Cheng
目的分析北京城区与农村老年人群的股骨近段骨密度(bone mineral density,BMD)与骨结构参数差异。方法回顾性分析2012年12月1日至2013年12月1日接受髋部定量CT(quantitative computed tomography,QCT)扫描的174名50~70岁的北京居民的相关临床资料,根据居住地分为城区组(n=118)(男性46名、女性72名)和农村组(n=56)(男性31名、女性25名)。统计学分析由QCT测得的股骨颈体积骨密度(femoral neck volumetric bone mineral density,FN v BMD)、全髋体积骨密度(total hip volumetric bone mineral density,TH v BMD)、股骨颈面积骨密度(femoral neck areal bone mineral density,FN a BMD)、股骨大粗隆面积骨密度(trochanter areal bone mineral density,TR a BMD)、股骨粗隆间面积骨密度(intertrochanter areal bone mineral density,IT a BMD)和全髋面积骨密度(total hip areal bone mineral density,TH a BMD)等参数以及股骨近段骨强度(hip strength analysis,HSA)参数,包括股骨颈干角(neck shaft angle,NSA)、颈宽度(femur neck width,FNW)、髋轴长(hip axis length,HAL)、股骨颈横截面惯性矩(cross-sectional moment of inertia,CSMI)、股骨颈横截面面积(cross-sectional area,CSA)、曲率比率(buckling ratio,BR)、平均骨皮质厚度(averaged cortical thickness,ACT)、截面模数(section modulus,SM)等在两组人群中的差异。结果城乡男女身高比较,差异均无统计学差异(P>0.05),城区老年男性体质量(73.66±12.63)kg显著高于农村男性(67.8±9.58)kg(P<0.05);城乡男性之间的FN v BMD、TH v BMD、FN a BMD、TR a BMD、IT a BMD、TH a BMD、NSA、FNW、HAL、CSMI、CSA、BR、ACT、SM各项指标差异均无统计学意义;农村女性HAL显著高于城区女性HAL(109.41 mm vs 104.23 mm),差异有统计学意义(P<0.05);其余骨密度及骨结构参数比较,差异无统计学意义(P>0.05)。结论除老年女性HAL城乡之间存在差异外,本研究人群股骨近段QCT骨密度与骨结构参数无城乡差别。
