Magnetic resonance imaging of anterior cruciate ligament tears: reevaluation of quantitative parameters and imaging findings including a simplified method for measuring the anterior cruciate ligament angle

We evaluated the diagnostic utility of magnetic resonance imaging (MRI) for predicting anterior cruciate ligament (ACL) tears using both quantitative parameters and nonquantitative imaging findings. MRI examinations were retrospectively evaluated in a group of patients with arthroscopically confirmed complete ACL tear and in a control group with arthroscopically confirmed intact ACL. We evaluated multiple MRI features to compare their sensitivity and specificity for detecting ACL tears. Particular emphasis is put on the evaluation of three different quantitative parameters, including a simplified method for measuring the ACL angle. With a threshold value of 45° the ACL angle reached a sensitivity and specificity of 100% for detecting ACL tears. With a threshold value of 0° the Blumensaat angle had a sensitivity of 90% and a specificity of 98%. Finally, a threshold value of 115° gave the posterior cruciate ligament angle a sensitivity of 70% and a specificity of 82%. Discontinuity was found to be the most useful of the ACL abnormalities. Of the secondary findings anterior tibial displacement was the best predictor of ligamentous injury. However, ACL abnormalities and secondary findings, alone or combined, failed to surpass the diagnostic value of the ACL angle for predicting ACL tears. Quantitative parameters are thus good predictors of ACL tears and may increase the overall sensitivity and specificity of MRI. The ACL angle may be confidently measured in a single MRI section and can be considered to be the most reliable quantitative parameter for detecting ACL tears.     

Magnetic resonance imaging and histopathology of cerebral gliomas

Summary The correlation of magnetic resonance imaging (MRI) with histopathological findings was analysed in 26 patients with untreated cerebral gliomas. In low-grade gliomas, T2-weighted images demonstrated relatively homogeneous high-intensity lesions involving both the grey and the white matter. In high-grade gliomas, especially grade IV, T2-weighted images demonstrated prominent heterogeneity in signal intensity, which consisted of a hyperintense core, less hyperintense or normal intensity rim and surrounding finger-like areas of high intensity. Marked and irregular contrast enhancement was evident in all but one case of these high-grade gliomas in which gadolinium-DTPA was used. Histological examination revealed tumour cells extending as far as the borders of the high-intensity areas shown on T2-weighted images in both high-and low-grade gliomas, but in 5 of 8 low-grade and 4 of 18 high-grade gliomas, isolated tumour cells extended beyond the hyperintense areas shown on T2-weighted images.     

The distal femoral and proximal tibial growth plates: MR imaging,three-dimensional modeling and estimation of area and volume

Objective To explore how the size of the growth plate changes with age using three-dimensional (3D) models of the distal femoral and proximal tibial growth plates in pediatric patients.Design and patients We retrospectively created 3D models of the normal unaffected distal femoral (n=20) and proximal tibial (n=10) growth plates in 14 patients (9 males, 5 females) age range 3.8–15.6 years who were referred for evaluation of premature partial closure of the growth plate or hyaline cartilage abnormality. All patients had one or more 3D fat-suppressed spoiled GRASS sequence from which models were made of normal growth plates. Total projected area was estimated from standardized maximum intensity projection (MIP) views, and volume was computed from the entire model. We also included the total projected area of the distal femur (n=7) or proximal tibia (n=8) in 11 patients (8 males, 3 females, 5–13 years) who had previously been evaluated for bone bridging.Results The 3D femoral and tibial growth plate anatomy was displayed. Femoral growth plate area varied from 804 mm² to 3,463 mm². Femoral physeal cartilage volume varied from 2.1 cm³ to 12.6 cm³. Tibial growth plate area varied from 736 mm² to 3,026 mm². Tibial physeal cartilage volume varied from 1.9 cm³ to 13.2 cm³. The growth plate area values appear to increase linearly with increasing age.Conclusions The distal femoral and proximal tibial physeal plates have complex anatomy. Both area and volume of the growth plates appeared to follow a linear increase with age and reached a plateau in adolescence, although there was some scatter. Area appears to have less measurement variability than volume, and may be a more reliable predictor of growth plate tissue quantity.     

Posterior cranial fossa dimensions in the Chiari I malformation: Relation to pathogenesis and clinical presentation

Summary Skull dimensions were measured on lateral skull radiographs in 33 adult patients with MRI-verified Chiari I malformations and in 40 controls. The posterior cranial fossa was significantly smaller and shallower in patients than in controls. In the patients, there was a positive correlation between posterior fossa size and the degree of the cerebellar ectopia, which might indicate that a posterior cranial fossa which was originally too small had been expanded by the herniation of hindbrain structures at an early stage. Pyramidal signs and cerebellar symptoms and signs, which may be due to compression of neural structures, were associated with a large degree of ectopia and a relatively large posterior cranial fossa. Syringomyelia and headache, which may be due to the valve action of the herniated cerebellar tissue, were not associated with a particularly large posterior fossa or herniation. No special clinical presentation was associated with a very small posterior cranial fossa, which may indicate that a small posterior cranial fossa per se has little or no clinical significance, although it may be the primary developmental anomaly.     

轻微型肝性脑病BOLD-fMRI研究进展

轻微型肝性脑病作为肝性脑病的早期阶段,临床症状不明显,表现缺乏特异性,目前诊断困难。近年来血氧水平依赖功能磁共振成像(BOLD-fMRI)新技术逐渐运用于肝性脑病的研究,通过探测不同状态下各脑功能区神经元的活动,不仅可以定位异常活动脑功能区,还可以发现脑功能区连接作用改变。尤其是BOLD-fMRI联合其他MR技术的应用,对于轻微型肝性脑病的病理基础和发病机制的研究,实现了从微观到宏观、从结构到功能的全面探讨,能对其早期诊断治疗提供更有价值的依据。     

3.0 T高分辨率自由呼吸导航全心冠状动脉成像初步研究

目的前瞻性评价3．0T高分辨率自由呼吸导航全心冠状动脉成像的临床应用价值。资料与方法68例临床疑为冠心病的患者接受了3．0TMRA全心冠状动脉检查,采用向量心电门控（VCG）和自由呼吸导航技术,自由呼吸状态下成像。后处理使用3D容积再现（VR）技术和“肥皂泡（Soap-Bubble）”曲面重组技术进行全心冠状动脉重建,分析冠状动脉的走行、狭窄的原因及程度,并与其中26例同期开展了冠状动脉血管造影的患者进行了对比,分析3,0T全心冠状动脉MRA评估冠状动脉狭窄的临床意义。结果68例受检者中,64例获得了满意的检查结果（94％）。发现先天性冠状动脉变异1例,冠状动脉壁斑块形成49例,敏感性为87％,特异性为73％,阳性预测值为81％,阴性预测值为80％。所有病例的检查时间少于30min。3DVR全心冠状动脉重建能完整地再现冠状动脉树,观察冠状动脉的走行,发现冠状动脉先天性变异、主干局部变细以及中断等;“Soap—Bubble”则能够分别测量冠状动脉每一支狭窄的程度,分析狭窄的原因。结论自由呼吸全心冠状动脉MRA能够成功抑制心肌运动,增强冠状动脉血管与周围组织的对比度,无创性地进行三维冠状动脉成像．初步评价冠状动脉主干近、中段狭窄程度和原因．     

应用磁共振软骨T2图成像定量测定退变兔膝关节软骨

目的:探讨T_2图成像技术在检测关节软骨退变早期的应用价值。材料和方法:选用20只新西兰大白兔,随机分为甲、乙、丙、丁四组。甲组左膝关节行常规磁共振成像,扫描结束后即刻处死,取股骨髁软骨行苏木素和伊红染色(HE)、阿利辛兰染色(AB)及蛋白多糖含量测定。乙、丙、丁各组每只兔左膝关节内注射0.2ml(10U)木瓜蛋白酶。乙、丙、丁各组于注射木瓜蛋白酶前及注射后分别于24h、48h、72h先行相同常规磁共振成像及T_2图成像,取感兴趣点,测定关节软骨T_2弛豫时间值并取平均值,对每组数据进行t检验。扫描结束后处死动物,取左膝股骨髁部软骨行大体观察、HE、AB染色及蛋白多糖含量测定。结果:注射木瓜蛋白酶后24h、48h,蛋白多糖含量与甲组比较,统计学均有差异(P=0.048和0.045,P<0.05),注射后72h,统计学没有差异(P=0.455,P>0.05)。T_2图像软骨色阶由注射前的黄红色转为注射后的红色,注射木瓜蛋白酶后24h、48h、72h的T_2弛豫率分别升高了30.14ms,20.92ms和16.17ms。经t检验后,注射后24h与注射前差异具有统计学意义(P= 0.04,P<0.05)。结论:本研究采用的T_2图成像技术能够通过定量检测T_2弛豫时间值反映软骨退变早期软骨内的生化改变。     

关节软骨MR影像表现特点和各种影响因素

目的探讨关节软骨的ＭＲＩ表现特点以及各种因素对软骨层次、厚度和信号强度的影响。方法取１２只新鲜人膝关节标本,行各种位置和序列的ＭＲ成像。标本脱钙、切片、染色后用偏光显微镜观察。结果ＭＲＩ上关节软骨的厚度、层次和信号强度与软骨内纤维排列方向、软骨基质的含量、各区域宽度、容积效应、化学位移、各向异性和成像序列密切相关。结论ＭＲＩ检查判断关节软骨结构需兼顾年龄和其他诸多技术因素     

正常中晚孕胎儿眼球玻璃体信号值随胎龄变化规律的初步探讨

目的 探讨正常中晚孕胎儿眼球玻璃体信号值随胎龄增长变化的一般规律,为临床监测胎儿眼球发育提供参考.方法 回顾性分析2006年7月至2014年2月期间发育正常的中晚孕胎儿共99名(198只眼球)MRI资料;按胎龄大小分成5组,即17 ～21周、22 ～ 26周、27 ～31周、32～36周、37 ～40周.分别测量各胎龄组眼球信号值大小,计数并进行统计学分析.结果 17 ～21、22～ 26、27～31、32～36、37～40周胎龄组胎儿眼球玻璃体信号值分别为600.63±171.77、492.73±214.97、421.43±181.47、388.04±137.11、329.99±119.73.经方差分析显示,胎儿眼球玻璃体信号值随胎龄增长有逐渐减低趋势,组间比较P=0.00,差异有统计学意义.结论 正常中晚孕胎儿眼球玻璃体信号值随胎龄增长有逐渐减低趋势.     

MRI对垂体柄阻断综合征的诊断价值

目的 探讨垂体柄阻断综合征(PSIS)的MRI特点及其临床意义.方法 21例PSIS患者行MR扫描及激素水平检测.所有患者均行液体衰减反转恢复(FLAIR)序列T1WI及快速SE(FSE)序列T2WI,8例加扫FLAIR T1WT脂肪抑制序列,分析垂体柄、垂体前叶形态和垂体后叶信号变化.结果 21例患者的基础生长激素(GH)水平为0.03～1.50μg/L,GH激发试验峰值为0.13～4.14μg/L,均为完全GH缺乏.其中17例为多垂体激素缺乏(CPHD),4例为单一性GH缺乏(IGHD).患者垂体前叶高度为1.0～3.0 mm,平均(1.9±1.2)mm,均有不同程度的缩小.18例在正中矢状面及冠状面上垂体柄均未见明确显示,3例表现为不连续的细线状.所有患者垂体后叶均未见正常高信号,19例表现为垂体后叶高信号异位在第三脑室漏斗隐窝,2例合并有尿崩症的患者表现为垂体后叶高信号消失,也未见异位的高信号.结论 PSIS在MRI上有特征性表现,结合临床激素水平可明确诊断.