MRI对兔骨性关节炎动物模型软骨损伤的评价

目的 使用脂肪抑制三维稳态进动快速成像(FS-3D-FISP)序列动态观察兔骨性关节炎动物模型,探讨FS-3D-FISP序列对关节软骨损伤的诊断价值.方法 选用雄性新西兰大白兔18只,制作骨性关节炎模型,左膝关节腔注射木瓜蛋白酶0.5 ml,右膝关节腔注射等量无菌生理盐水作为对照.建模后第1、2、4周行膝关节核磁共振检查,扫描序列采用FS-3D-FISP序列,并取双侧股骨髁部和胫骨平台,观察骨关节大体形态和病理改变.按Outerbridge分级法对软骨病变进行MR图像以及大体标本观察,病理评价使用Collins分级.结果 FS-3D-FISP序列成像与大体标本及病理结果相对照,MR分级与大体标本分级之间具有较好的一致性(Kappa值0.806,P值<0.001);MRI软骨病损Ⅰ～Ⅱ级为1组,Ⅲ～Ⅳ级为另1组,与病理I～II级,III～IV级分组进行相关对照分析,2组间(Kappa值0.827,P<0.001)分级一致性较高.结论 FS-3D-FISP能准确评价软骨损伤的程度.     

1.5T MR研究健康人膝关节软骨T_2值空间分布

目的 研究健康成人膝关节软骨T2弛豫时间(T2值)空间分布.方法 1.5T场强下对21名健康男性(年龄24～39岁,平均30岁±4岁)行膝关节矢状位多回波多层面SE序列扫描,使用Profile软件测量股骨非承重软骨的前部、股骨承重软骨、胫骨承重软骨、髌软骨的T2弛豫时间(即T2值),采用方差分析检验各部位软骨深层和浅层T2值、承重软骨和非承重软骨的T2值空间分布的差异.结果 健康人膝关节软骨T2值空间分布呈浅凹形曲线,即近软骨下骨质T2值较高,随后T2值从软骨深层到浅层逐渐增高,并且各层T2值存在差异(F=70.892,P＜0.05).髌软骨T2值空间分布变化最大,股胫关节承重软骨和股骨前部非承重软骨T2值的空间分布变化较平缓.髌软骨深层T2值[(26.56±4.4) ms]明显低于所有软骨深层T2值(P=0.001).股骨外髁承重软骨浅层T2值[(35.2±6.31) ms]明显低于髌软骨[(40.78±3.56) ms]和股骨非承重软骨前部[(42.31±2.4) ms](P=0.002,P=0.000).胫骨外髁承重部软骨浅层T2值[37.11±6.6) ms]明显低于股骨非承重前部(P=0.000).结论 1.5T 场强下健康人膝关节软骨T2值具有特定空间分布,对量化研究退行性骨关节炎和其他关节病变具有参考价值.     

Articular cartilage deformation determined in an intact tibiofemoral joint by displacement‐encoded imaging

This study demonstrates the in vitro displacement and strain of articular cartilage in a cyclically‐compressed and intact joint using displacement‐encoded imaging with stimulated echoes (DENSE) and fast spin echo (FSE). Deformation and strain fields exhibited complex and heterogeneous patterns. The displacements in the loading direction ranged from ?1688 to ?1481 μm in the tibial cartilage and from ?1601 to ?764 μm in the femoral cartilage. Corresponding strains ranged from ?9.8% to 0.7% and from ?4.3% to 0.0%. The displacement and strain precision were determined to be 65 μm and less than 0.2%, respectively. Displacement‐encoded magnetic resonance imaging is capable of determining the nonuniform displacements and strains in the articular cartilage of an intact joint to a high precision. Knowledge of these nonuniform strains is critical for the in situ characterization of normal and diseased tissue, as well as the comprehensive evaluation of repair constructs designed using regenerative medicine. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Rapid estimation of cartilage T2 based on double echo at steady state (DESS) with 3 Tesla

The double‐echo‐steady‐state (DESS) sequence generates two signal echoes that are characterized by a different contrast behavior. Based on these two contrasts, the underlying T2 can be calculated. For a flip‐angle of 90°, the calculated T2 becomes independent of T1, but with very low signal‐to‐noise ratio. In the present study, the estimation of cartilage T2, based on DESS with a reduced flip‐angle, was investigated, with the goal of optimizing SNR, and simultaneously minimizing the error in T2. This approach was validated in phantoms and on volunteers. T2 estimations based on DESS at different flip‐angles were compared with standard multiecho, spin‐echo T2. Furthermore, DESS‐T2 estimations were used in a volunteer and in an initial study on patients after cartilage repair of the knee. A flip‐angle of 33° was the best compromise for the combination of DESS‐T2 mapping and morphological imaging. For this flip angle, the Pearson correlation was 0.993 in the phantom study (～20% relative difference between SE‐T2 and DESS‐T2); and varied between 0.429 and 0.514 in the volunteer study. Measurements in patients showed comparable results for both techniques with regard to zonal assessment. This DESS‐T2 approach represents an opportunity to combine morphological and quantitative cartilage MRI in a rapid one‐step examination. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Delayed gadolinium‐enhanced magnetic resonance imaging (dGEMRIC) of hip joint cartilage in femoroacetabular impingement (FAI): Are pre‐ and postcontrast imaging both necessary?

The purpose of this study was to assess if delayed gadolinium MRI of cartilage using postcontrast T₁ (T_1Gd) is sufficient for evaluating cartilage damage in femoroacetabular impingement without using noncontrast values (T₁₀). T_1Gd and ΔR₁ (1/T_1Gd ? 1/T₁₀) that include noncontrast T₁ measurements were studied in two grades of osteoarthritis and in a control group of asymptomatic young‐adult volunteers. Differences between T_1Gd and ΔR₁ values for femoroacetabular impingement patients and volunteers were compared. There was a very high correlation between T_1Gd and ΔR₁ in all study groups. In the study cohort with Tonnis grade 0, correlation (r) was ?0.95 and ?0.89 with Tonnis grade 1 and ?0.88 in asymptomatic volunteers, being statistically significant (P < 0.001) for all groups. For both T_1Gd and ΔR₁, a statistically significant difference was noted between patients and control group. Significant difference was also noted for both T_1Gd and ΔR₁ between the patients with Tonnis grade 0 osteoarthritis and those with grade 1 changes. Our results prove a linear correlation between T_1Gd and ΔR₁, suggesting that T_1Gd assessment is sufficient for the clinical utility of delayed gadolinium MRI of cartilage in this setting and additional time‐consuming T₁₀ evaluation may not be needed. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Clinical application of scaffolds for cartilage tissue engineering

The purpose of this paper is to review the basic science and clinical literature on scaffolds clinically available for the treatment of articular cartilage injuries. The use of tissue-engineered grafts based on scaffolds seems to be as effective as conventional ACI clinically. However, there is limited evidence that scaffold techniques result in homogeneous distribution of cells. Similarly, few studies exist on the maintenance of the chondrocyte phenotype in scaffolds. Both of which would be potential advantages over the first generation ACI. The mean clinical score in all of the clinical literature on scaffold techniques significantly improved compared with preoperative values. More than 80% of patients had an excellent or good outcome. None of the short- or mid-term clinical and histological results of these tissue-engineering techniques with scaffolds were reported to be better than conventional ACI. However, some studies suggest that these methods may reduce surgical time, morbidity, and risks of periosteal hypertrophy and post-operative adhesions. Based on the available literature, we were not able to rank the scaffolds available for clinical use. Firm recommendations on which cartilage repair procedure is to be preferred is currently not known on the basis of these studies. Randomized clinical trials and longer follow-up periods are needed for more widespread information regarding the clinical effectiveness of scaffold-based, tissue-engineered cartilage repair.     

bFGF真核表达质粒的构建及骨髓基质细胞转染

目的 探讨bFGF基因转染骨髓基质干细胞的方法 及可行性.方法 构建bFGF基因真核表达质粒,用脂质体法介导转染骨髓基质细胞,通过形态学观察、免疫组化、ELISA法、及RT-PCR方法 检测bFGF基因转染骨髓基质干细胞的成功性,以及转染后骨髓基质干细胞的生物学特性.结果 bFGF基因成功转染骨髓基质干细胞,并能持续稳定的分泌bFGF蛋白,可诱导骨髓基质干细胞向成软骨方向分化.结论 bFGF基因可以转染骨髓基质干细胞,并能诱导骨髓基质干细胞向成软骨方向分化.     

Value of precontrast T1 for dGEMRIC of native articular cartilage

Purpose

To evaluate if the difference between pre‐ and post‐Gd‐DTPA^2‐ relaxation rate (ΔR₁) provides better differentiation of osteoarthritic patients (OA) from healthy subjects (HS) with dGEMRIC, as compared to post‐Gd‐DTPA^2‐ spin‐lattice relaxation time (T_1Gd).

Materials and Methods

Seventeen OA and 14 HS underwent pre‐ and 90 minutes postcontrast (Gd‐DTPA^2‐) magnetic resonance imaging (MRI) of the knee, using inversion recovery fast spin‐echo and/or Lock–Locker sequences for T₁ mapping. Effect sizes for T_1pre, T_1Gd, and ΔR₁ were calculated, and receiver operating characteristic (ROC) curve and regression analysis were also performed to assess the effectiveness of each parameter in the separation of OA and HS.

Results

T_1Gd and ΔR₁ were almost identical in terms of areas under ROC curves (0.903 and 0.914, respectively), and effect sizes (1.34 and 1.31, respectively). These were significantly higher than T_1pre. In addition, a high inverse correlation was observed between ΔR₁ vs. T_1Gd (R = 0.96).

Conclusion

Either T_1Gd or ΔR₁ could be used as an index in the evaluation of native cartilage. However, considering the practical logistical cost involved in terms of time and effort to acquire precontrast T₁ measurements, our data further support the continued use of T_1Gd as the dGEMRIC index in the evaluation of native cartilage. J. Magn. Reson. Imaging 2009;29:494–497. © 2009 Wiley‐Liss, Inc.     

膝关节半月板撕裂的MRI诊断

目的探讨膝关节半月板撕裂的MR I表现及MR I诊断价值。方法行MR I检查并行关节镜检查或手术的患者98例,对其结果进行对照分析。结果在98例196个半月板中,与关节镜检查及手术结果比较,MR I诊断半月板撕裂的准确性为95.9%。结论MR I是诊断膝关节半月板撕裂理想的非创伤性的检查方法。     

鼻尖鼻小柱瓣推进鼻尖延长术

目的单纯假体植入隆鼻只能增加鼻梁高度,很难改善鼻尖上翘,探讨采用鼻尖鼻小柱瓣推进行鼻尖延长术的效果。方法57例鼻梁低平伴鼻尖上翘患者,采用鼻外切口开放式入路,鼻尖鼻小柱瓣向鼻尖推进使皮肤软组织松解,采用自体耳廓软骨鼻尖移植和人工复合型材料植入,进行鼻尖延长整形。结果所有患者切口Ⅰ期愈合,鼻尖平均延长5.2mm,术后效果满意。经过6～12个月的随访,发现瘢痕隐蔽,鼻外形美观,鼻、面关系协调,无其他相关并发症。结论鼻尖鼻小柱瓣推进可有效延长鼻尖,是改善鼻梁低平伴鼻尖上翘的良好方法。