正常膝关节软骨MRI T_1ρ序列表现初步研究

目的比较正常膝关节软骨MRIT1ρ和三维抑脂扰相梯度回波(3D-FS-SPGR)序列表现,研究T1ρ序列应用于软骨评估的可行性;评估软骨深层与浅层MRIT1ρ值的差异。方法选择经临床和影像确认的26例成年志愿者,其中男性11例,女性15例;年龄15~65岁,平均年龄31.69岁。分析其T1ρ和3D-FS-SPGR序列MRI成像表现。将膝关节软骨划分为髌软骨、髁间窝、股骨内外侧髁、胫骨内外侧平台6个部分。测量相同层面与位置的T1ρ第一回波和3D-FS-SPGR图像上软骨、软骨下骨、背景噪声的信号强度,比较两者的软骨与软骨下骨对比度比(CNR)和软骨信噪比(SNR)。选取6个部位软骨最厚处,把该处软骨厚度等分为深层和浅层,分别测量同像素感兴趣区(ROI)的T1ρ值。对以上数据进行配对t检验,以P0.05为差异有统计学意义。结果①膝关节T1ρ序列第一回波图像上的CNR均值和SNR均值均高于同一部位的3D-FSSPGR序列,CNR 29.88±10.00 vs 12.08±3.08(t=23.09,P=0.000),SNR 34.70±11.16 vs 14.18±3.46(t=23.929,P=0.000);②正常膝关节软骨深层均值(29.12±8.07)ms,浅层均值(43.23±6.78)ms,浅层T1ρ值显著高于深层表现(t=-24.687,P=0.000)。结论 T1ρ序列可用于软骨临床评估,浅层软骨胶原纤维排列较深层更为致密。     

膝关节软骨负荷运动前后磁共振T_2时间与容积变化研究

目的通过比较分析负荷运动前后膝关节软骨磁共振T2时间和软骨容积变化,探讨利用T2时间和容积变化反映负荷作用下软骨形态变化的可行性。方法选择20例健康志愿者,其中男性16例,女性4例;年龄为20.1~30.4岁,平均年龄25.7岁。在同等运动负荷前后进行软骨T2mapping序列成像,测量股骨内外侧髁、胫骨平台和髌软骨T2时间;以三维脂肪抑制快速扰相梯度回波(3D-FS-SPGR)序列扫描并采用最大信号强度投影法(MIP)重建后测量髌软骨及股骨髁软骨容积。比较负荷前后软骨T2时间变化、软骨容积差异,并分析软骨容积与T2时间变化间的相关性。结果运动前与运动后髌软骨T2时间最长,胫骨外侧平台最短;运动后不同部位软骨T2时间均降低(P=0.000),股骨内侧髁软骨下降幅度最大(t=-27.96,P=0.000);运动后膝关节软骨容积减小(P=0.000),股骨髁软骨容积变化程度(t=-86.71,P=0.000)大于髌软骨(t=-9.42,P=0.000);软骨容积与T2时间变化间无线性相关性(P0.05)。结论运动后膝关节软骨各部位T2时间和局部软骨容积均减少,但软骨容积与T2时间变化间无相关性;软骨T2mapping和软骨容积变化磁共振成像技术对评价负荷作用下软骨形态变化有一定的意义。     

医用臭氧对骨关节炎关节软骨作用的病理-磁共振成像实验研究

目的 通过病理-磁共振成像(MRI)对照研究,评价医用臭氧对骨关节炎动物模型的关节软骨的修复作用.方法 新西兰大白兔36只,分为正常对照组、模型对照组、10mg/L臭氧关节腔内注射组、30mg/L臭氧关节腔内注射组、10mg/L臭氧自血回输组、30mg/L臭氧自血回输组,每组6只兔.采用Ⅱ型胶原蛋白酶关节腔内注射法诱导骨关节炎模型,造模4周后进行臭氧干预.比较各组关节软骨的MRI表现,测量其关节软骨的平均厚度及信号强度,与病理学改变对照分析,并对MRI表现与Mankin评分进行直线相关及回归分析.结果 模型对照组、各臭氧干预组的膝关节软骨平均厚度及信号强度较正常对照组变薄和降低(均P<0.05).病理结果显示关节软骨表面粗糙,裂隙形成并基质失染,模型对照及臭氧干预各组的Mankin评分均高于正常对照组(均P<0.05),而模型组与各臭氧干预组间的关节软骨平均厚度、信号强度及Mankin评分差异均无统计学意义(均P>0.05).关节软骨平均厚度与信号强度呈正的直线相关(r=0.561,P=0.000);关节软骨平均厚度及信号强度与Mankin评分呈负的直线相关(r=-0.727、-0.590,均P=0.000);关节软骨平均厚度与Mankin评分存在线性回归关系(Y=18.582-0.035X,R~2=0.528).结论 关节软骨损伤的MRI表现与病理有较好的相关性,中低浓度的医用臭氧经关节腔内注射及自血回输对骨关节炎动物模型的关节软骨可能均无修复作用.     

T_2 mapping评价关节软骨损伤及修复的研究进展

T2mapping是近年来发展的MRI新技术,能间接反应关节软骨结构及组织学成分的变化,发现关节软骨形态学变化之前的组织学改变。笔者就T2mapping成像原理、软骨损伤的组织学表现,以及成像影响因素等方面作一综述,重点介绍了T2mapping在软骨损伤、退变、修复等方面的研究进展,并展望了T2mapping未来发展前景。     

软骨下骨量变化与软骨退变的相关性

背景：关节软骨与软骨下骨在骨关节炎病变进程中的相互作用机制目前尚未完全阐明。软骨下骨量改变在骨关节炎病理进程中亦发挥重要作用。 目的：分析2种手术方式及2种蛋白酶诱导建立兔膝关节骨关节炎动物模型的效果,以及软骨下骨量变化与关节软骨退变的相关性。 方法：32只新西兰大白兔随机分为4组：Hulth模型组、前交叉韧带切断模型组、Ⅱ型胶原蛋白酶组及木瓜蛋白酶组,每组8只,右膝关节造模,左膝关节作为自身对照。造模后0,4,8周行DXA扫描,8周行MRI扫描后处死实验动物,取双侧膝关节制作病理组织学切片,比较各组膝关节影像学表现、大体形态及病理变化,并采用Mankin评分进行定量分析。 结果与结论：造模后0,4,8周实验侧膝关节骨密度进行性降低,骨量降低程度Hulth模型组>前交叉韧带切断模型组>Ⅱ型胶原蛋白酶组>木瓜蛋白酶组。MRI显示实验侧股骨内外髁关节软骨厚度变薄,厚度Hulth模型组<前交叉韧带切断模型组<Ⅱ型胶原蛋白酶组<木瓜蛋白酶组。大体标本、组织切片观察及Mankin评分显示手术建模组骨关节炎程度较药物组重,Hulth模型组病变最重,木瓜蛋白酶组最轻。结果说明关节内手术及关节腔内注射蛋白酶均能建立骨关节炎动物模型;手术造模可复制出中晚期骨关节炎,药物诱导可产生骨关节炎早期改变。骨关节炎病变严重程度与软骨下骨骨密度呈负相关;关节软骨退变和软骨下骨改变相互关联,病变进行性发展。     

基于定量动态负荷下膝关节骨性关节炎软骨MRIT2时间表现研究

目的通过比较膝关节骨性关节炎（OA）病人定量动态负荷前后膝关节软骨T2时间变化情况,分析MRIT2mapping序列反映软骨基质生物力学变化的灵敏度．并验证高磁场条件下人体关节负荷装置的有效性。方法10例膝关节OA病人,其中男性3例．女性7例：年龄4l～66岁．平均年龄57-3岁。依托人体下肢关节力学负荷装置,对其施加膝关节动态负荷。负荷前后行膝关节MRIT2maDping成像,将膝关节轴向负荷区软骨分为4个部位：胫骨平台内、外侧软骨区及股骨内、外侧髁软骨区．分别测量各部位软骨负荷前后的T,时间。对负荷前膝关节内、外侧软骨分级评估进行卡方检验,对同一软骨区动态负荷前后的T2时间进行配对t检验。结果负荷前膝关节内外侧软骨分级差异无统计学意义（P〉0．05）。OA病人负荷前后T2值,胫骨平台内侧软骨区分别为（39．59±4．17）ms、（40．14±4．49）ms（f=0．426,P=0．680）;胫骨平台外侧软骨区（38．85±6．72）ms、（41．25±6．54）ms（t=1．704,P=0．123）：股骨内侧髁软骨区（36．44±5．72）ms、（40．63±4．90）ms（t=1．783,P=0．108）;股骨外侧髁软骨区（39．30±5．78）ms、（46．14±5．03）ms（t=2．826,P=0．020）。结论OA病人负荷后膝关节局部区域软骨区T2时间延长．自行设计的动态加压装置适合在高磁场条件下完成加压及MRI检查,有一定推广意义。     

低场强磁共振在膝关节软骨损伤的诊断价值

目的探讨低场四肢专用MR对膝关节软骨损伤的诊断价值。方法收集我院经关节镜证实膝关节软骨损伤79例,全部病例均行低场强四肢专用MRI常规检查,对照分析膝关节软骨损伤的MRI表现和关节镜结果。结果低场MRI对软骨损伤诊断的敏感性、特异性、准确性分别为84%、86%、85%。结论低场四肢专用MRI对膝关节软骨损伤诊断有一定价值。     

膝关节软骨下立柱式自体骨移植后软骨的变化

目的 通过观察兔膝关节软骨下立柱式自体骨移植的软骨的变化,探讨移植后关节软骨塌陷及软骨退变的原因。方法 ４２只大耳白兔为实验对象,随机分为Ａ、Ｂ两组。分别建立保留不同厚度的关节软骨下大块骨缺损的动物模型,采用立柱式自体额骨移植。分别于术后第１、１２周处死１０只、３２只动物,切取标本。应用光镜、透射电镜,对实验动物的软骨进行形态学观察。结果 Ａ组平均残留软骨下骨的厚度为１．４２ｍｍ,１周时软骨下骨未     

膝关节关节软骨的三维构建

目的:构建膝关节关节软骨的三维模型,为开展膝关节数字医学研究进行模型构建的探索。方法:人体成年新鲜膝关节标本1例,行CT、MRI扫描,利用三维重建软件Mimics及逆向工程软件Geomagic对图像进行三维重建及图像配准,构建膝关节骨、关节软骨结构。结果:利用Mimics 10.01软件构建关节软骨的三维模型,并形成骨-关节软骨复合模型,导入Geomagic软件中与CT构建的骨三维模型相配准,再次导入CT影像中进行逐层微修饰,验证关节软骨分割效果。最终建立具有骨、关节软骨的三维膝关节模型。结论:三维图像重建技术与图像配准技术可将CT、MRI图像两者结合起来,发挥其各自优势,构建出形态较好的膝关节三维模型。     

Diffuse tibiofemoral cartilage change prior to the development of accelerated knee osteoarthritis: Data from the osteoarthritis initiative

We compared the spatial distribution of tibiofemoral cartilage change between individuals who will develop accelerated knee osteoarthritis (KOA) versus typical onset of KOA prior to the development of radiographic KOA. We conducted a longitudinal case–control analysis of 129 individuals from the Osteoarthritis Initiative. We assessed the percent change in tibiofemoral cartilage on magnetic resonance images at 36 informative locations from 2 to 1 year prior to the development of accelerated (n = 44) versus typical KOA (n = 40). We defined cartilage change in the accelerated and typical KOA groups at 36 informative locations based on thresholds of cartilage percent change in a no KOA group (n = 45). We described the spatial patterns of cartilage change in the accelerated KOA and typical KOA groups and performed a logistic regression to determine if diffuse cartilage change (predictor; at least half of the tibiofemoral regions demonstrating change in multiple informative locations) was associated with KOA group (outcome). There was a non‐significant trend that individuals with diffuse tibiofemoral cartilage change were 2.2 times more likely to develop accelerated knee OA when compared with individuals who develop typical knee OA (OR [95% CI] = 2.2 [0.90–5.14]. Adults with accelerated or typical KOA demonstrate heterogeneity in spatial distribution of cartilage thinning and thickening. These results provide preliminary evidence of a different spatial pattern of cartilage change between individuals who will develop accelerated versus typical KOA. These data suggest there may be different mechanisms driving the early structural disease progression between accelerated versus typical KOA. Clin. Anat. 32:369–378, 2019. © 2018 Wiley Periodicals, Inc.     

Thickening of the knee joint cartilage in elite weightlifters as a potential adaptation mechanism

Thickening and increase of area of cartilage have been proposed as two alternative mechanisms of cartilage functional adaptation. The latter has been reported in endurance sportsmen. In weightlifters, extreme strain applied to the articular surfaces can result in other forms of adaptation. The aim of this research is to determine whether cartilage thickness is greater in elite weightlifters than in physically inactive men. Weightlifters (13) and 20 controls [age and body mass index (BMI) matched] underwent knee Magnetic Resonance Imaging (MRI). A single sagittal slice of the knee was taken and cartilage thickness was measured in five and six regions of the medial and lateral femoral condyles, respectively. The analyzed segments represented weight‐bearing and nonweight‐bearing regions. The tibia cartilage in the weight‐bearing area was also measured. The time of training onset and its duration in the weightlifter group were recorded. The cartilage was found to be significantly thicker in weightlifters in most of the analyzed regions. The distribution of cartilage thickness on the medial and lateral femoral condyles was similar in both groups. The duration of training was not associated with cartilage thickness, but the time of training onset correlated inversely with cartilage thickness. It is possible that in high‐strain sports, joint cartilage can undergo functional adaptation by thickening. Thus, mechanical loading history could exert a postnatal influence on cartilage morphology. Clin. Anat. 27:920–928, 2014. © 2014 Wiley Periodicals, Inc.     

基于同轴相衬成像方法的人体膝关节软骨可视化

目的同轴相位衬度成像对软组织具有高衬度和高分辨率的特性。利用该成像技术,通过纹理特征参数提取进行定量分析,可为骨性关节炎的早期诊断提供可行性的依据。方法研究样本来自人工关节置换手术患者的膝关节软骨。样本分为正常组与早期骨性关节炎(osteoarthritis,OA)组,每组18例膝关节软骨组织。利用同轴相衬成像(in-line phase contrast imaging,IL-PCI)技术,观察两组软骨组织的纹理差异,并运用行程长度矩阵与分形维数方法提取纹理特征参数长行程加重(long run emphasis,LRE)、短行程加重(short run emphasis,SRE)、程分数(run percentage,RP)、灰度级的非均匀性(gray level non-uniformity,GLN)、行程长度的非均匀性(run length non-uniformity,RLN)以及分形维数。通过独立样本t检验方法比较上述参数,量化分析正常与病变软骨组织纹理差异。结果利用IL-PCI技术可以清晰观察到正常与早期OA软骨中微结构的变化。通过纹理参数提取比较两组的软骨纹理特征,结果表明正常组的LRE明显高于早期OA组(P<0.01),而早期OA组的GLN、RLN远高于正常组(P<0.01),正常组的分形维数小于早期OA组(P<0.01)。结论同轴相衬技术可为骨性关节炎的早期诊断提供定量分析手段。     

The effects of joint immobilization on articular cartilage of the knee in previously exercised rats

Studies have determined the effects of joint immobilization on the articular cartilage of sedentary animals, but we are not aware of any studies reporting the effects of joint immobilization in previously trained animals. The objective of the present study was to determine whether exercise could prevent degeneration of the articular cartilage that accompanies joint immobilization. We used light microscopy to study the thickness, cell density, nuclear size, and collagen density of articular cartilage of the femoral condyle of Wistar rats subjected to aerobic physical activity on an adapted treadmill five times per week. Four groups of Wistar rats were used: a control group (C), an immobilized group (I), an exercised group (E), and an exercised and then immobilized group (EI). The right knee joints from rats in groups I and EI were immobilized at 90 °C of flexion using a plastic cast for 8 weeks. Cartilage thickness decreased significantly in group I (mean, 120.14 ± 15.6 μm, P < 0.05), but not in group EI (mean, 174 ± 2.25), and increased significantly in group E (mean, 289.49 ± 9.15) compared with group C (mean, 239.20 ± 6.25). The same results were obtained for cell density, nuclear size, and collagen density (in all cases, P < 0.05). We concluded that exercise can prevent degenerative changes in femoral articular cartilage caused by immobilization of the knee joint.     

Measurement of knee cartilage thickness using MRI: a reproducibility study in a meniscectomized guinea pig model of osteoarthritis

The in vivo precision (reproducibility) of quantitative MRI is of particular importance in osteoarthritis (OA) progression of small magnitude and response to therapy. In this study, three-dimensional high-resolution MRI performed at 7 T was used to assess the short-term reproducibility of measurements of mean tibial cartilage thickness in a meniscectomized guinea pig model of OA. MR image acquisition was repeated five times in nine controls (SHAM) and 10 osteoarthritic animals 3 months after meniscectomy (MNX), in vivo. The animals were then killed for histomorphometric assessment and correlation with the MRI-based measurements. Medial tibial cartilage thickness was measured on MR images using semi-automatic dedicated 3D software developed in-house. The reproducibility of measurements of cartilage thickness was assessed by five repeated MRI examinations with a short recovery delay between examinations (48 h). The computed coefficients of variation were 8.9% for the SHAM group and 8.2% for the MNX group. The coefficients of variation were compatible with expected thickness variations between normal and pathological animals. A positive agreement and significant partial correlation (Spearman r' = 0.74; P < 0.01) between the MRI and histomorphometric data was established. Three-dimensional high-resolution MRI is a promising non-invasive research tool for in vivo follow-up. This modality could be used for staging and monitoring therapy response in small-animal models of OA.     

Evaluation of enzymatic proteoglycan loss and collagen degradation in human articular cartilage using ultrashort echo time-based biomarkers: A feasibility study

The objective of the current study was to investigate the feasibility of quantitative 3D ultrashort echo time (UTE)-based biomarkers in detecting proteoglycan (PG) loss and collagen degradation in human cartilage. A total of 104 cartilage samples were harvested for a trypsin digestion study (n = 44), and a sequential trypsin and collagenase digestion study (n = 60), respectively. Forty-four cartilage samples were randomly divided into a trypsin digestion group (tryp group) and a control group (phosphate-buffered saline [PBS] group) (n = 22 for each group) for the trypsin digestion experiment. The remaining 60 cartilage samples were divided equally into four groups (n = 15 for each group) for sequential trypsin and collagenase digestion, including PBS + Tris (incubated in PBS, then Tris buffer solution), PBS + 30 U col (incubated in PBS, then 30 U/ml collagenase [30 U col] with Tris buffer solution), tryp + 30 U col (incubated in trypsin solution, then 30 U/ml collagenase with Tris buffer solution), and tryp + Tris (incubated in trypsin solution, then Tris buffer solution). The 3D UTE-based MRI biomarkers included T₁, multiecho T₂*, adiabatic T_1ρ (AdiabT_1ρ), magnetization transfer ratio (MTR), and modeling of macromolecular proton fraction (MMF). For each cartilage sample, UTE-based biomarkers (T₁, T₂*, AdiabT_1ρ, MTR, and MMF) and sample weight were evaluated before and after treatment. PG and hydroxyproline assays were performed. Differences between groups and correlations were assessed. All the evaluated biomarkers were able to differentiate between healthy and degenerated cartilage in the trypsin digestion experiment, but only T₁ and AdiabT_1ρ were significantly correlated with the PG concentration in the digestion solution (p = 0.004 and p = 0.0001, respectively). In the sequential digestion experiment, no significant differences were found for T₁ and AdiabT_1ρ values between the PBS + Tris and PBS + 30 U col groups (p = 0.627 and p = 0.877, respectively), but T₁ and AdiabT_1ρ values increased significantly in the tryp + Tris (p = 0.031 and p = 0.024, respectively) and tryp + 30 U col groups (both p < 0.0001). Significant decreases in MMF and MTR were found in the tryp + 30 U col group compared with the PBS + Tris group (p = 0.002 and p = 0.001, respectively). It was concluded that AdiabT_1ρ and T₁ have the potential for detecting PG loss, while MMF and MTR are promising for the detection of collagen degradation in articular cartilage, which could facilitate earlier, noninvasive diagnosis of osteoarthritis.     

正常国人腰段硬膜外脂肪分布及厚度

目的:通过磁共振成像(MRI)探讨正常国人腰段椎管内硬膜外脂肪的分布特征、厚度及其临床应用价值。方法:在MRI正中矢状位观察263例正常国人椎管内硬膜外脂肪的形态及分布特征,测量各节段脂肪厚度并进行统计学分析。结果:腰段硬膜外脂肪在椎管周围分布不等,腹侧成条带状或新月状,背侧脂肪呈节段性梭形分布;椎管内硬膜外背侧脂肪各节段中以第3、4腰椎(L3/4)水平最厚,以第5腰椎、第1骶椎(L5/S1)节段最薄。L5/S1节段平均脂肪厚度小于L4/5节段;第12胸椎、第1腰椎(T12/L1)节段脂肪厚度小于L1/2节段,其他相邻节段脂肪平均厚度比较,差异无统计学意义。结论:正常国人腰骶段椎管内脂肪厚度的正常值范围可以为临床某些椎管疾病提供诊断及治疗依据;L5/S1节段椎管硬膜外背侧脂肪最薄,可以作为腰骶椎分界依据,为腰骶椎变异的患者提供定位依据之一。     

Morphological MRI and T2 mapping of cartilage repair tissue after mosaicplasty with tissue-engineered cartilage in a pig model

The aim of this study was to evaluate the efficacy of mosaicplasty with tissue-engineered cartilage for the treatment of osteochondral defects in a pig model with advanced MR technique. Eight adolescent miniature pigs were used. The right knee underwent mosaicplasty with tissue-engineered cartilage for treatment of focal osteochondral defects, while the left knee was repaired via single mosaicplasty as controls. At 6, 12, 18 and 26 weeks after surgery, repair tissue was evaluated by magnetic resonance imaging （MRI） with the cartilage repair tissue （MOCART） scoring system and T2 mapping. Then, the results of MRI for 26 weeks were compared with findings of macroscopic and histologic studies. The MOCART scores showed that the repaired tissue of the tissue-engineered cartilage group was statistically better than that of controls （P 〈 0.001）. A significant correlation was found between macroscopic and MOCART scores （P 〈 0.001）. Comparable mean T2 values were found between adjacent cartilage and repair tissue in the experimental group （P 〉 0.05）. For zonal T2 value evaluation, there were no significant zonal T2 differences for repair tissue in controls （P 〉 0.05）. For the experimental group, zonal T2 variation was found in repair tissue （P 〈 0.05）. MRI, macroscopy and histology showed better repair results and bony incorporation in mosaicplasty with the tissue-engi- neered cartilage group than those of the single mosaicplasty group. Mosaicplasty with the tissue-engineered cartilage is a promising approach to repair osteochodndral defects. Morphological MRI and T2 mapping provide a non-invasive method for monitoring the maturation and integration of cartilage repair tissue in vivo.