臂丛神经损伤的MR诊断

以外伤最为常见的多种疾病均可累及臂丛神经,导致患者出现肢体功能障碍,甚至于终身残疾。仅凭临床表现和神经电生理检查,难以准确、直观地定位定性诊断臂丛神经病变[1]。显微外科日益成熟,使臂丛神经的修复成为可能。对臂丛神经病变的定位定性诊断和损伤程度判定成为临床急需解决的问题。MR作为首选检查方法,常规扫描很难完整、清楚地显示臂丛神经结构[2],磁共振神经成像(magnetic resonance neurography, MRN)使MR对周围神经成像进入了一个新的时代[3]。笔者在3.0T超高场 MR扫描仪上采用 MRN 技术对怀疑臂丛神经损伤患者进行扫描,现报告如下。     

高分辨率磁共振周围神经成像在臂丛神经损伤中的应用

目的 探讨高分辨率磁共振神经成像技术对臂丛神经显示的可行性及其对臂丛神经损伤的临床应用价值.方法 对20名志愿者及30例外伤后有臂丛神经损伤表现的患者行颈段常规扫描序列、高分辨周围神经成像序列(3D-STIR序列)扫描成像,并将图像传至工作站进行三维后处理.评价磁共振神经成像技术对正常臂丛解剖细节及外伤后臂丛神经损伤征象的显示效果.结果 高分辨磁共振周围神经成像技术可清楚明确的显示所有志愿者臂丛神经的相关解剖细节情况;3D-STIR序列增强扫描能明显改善背景抑制效果,可清楚显示外伤累及臂丛神经所致各种征象.结论 高分辨磁共振周围神经成像技术能清晰、直观显示臂丛神经及其损伤后表现,可为临床提供一种新型的无创性臂丛神经影像检查手段.     

胸廓出口综合征的3T MR神经成像——纤维带形成下臂丛的可见病变

正摘要目的研究臂丛靶向MR神经成像(MRN)能否显示纤维带压迫臂丛并直接检出丛状神经束膜的损伤。方法30例临床拟诊为真神经性胸廓出口综合征(TOS)或非特异     

3.0T MRI在臂丛神经疾病诊断中的价值

目的:探讨3.0T MRI对臂丛神经疾病的临床应用价值。方法:使用GE signa HDx 3.0T超导磁共振仪,GEADW 4.3工作站进行图像后处理,磁共振脉冲序列:常规序列、三维超快速稳态进动成像序列(3D-FIESTA-c)及短时反转恢复脉冲序列(STIR),对20例临床怀疑臂丛神经受累的患者行磁共振检查。将所得数据进行图像后处理,分析臂丛神经疾病的影像学特点及MRI对臂丛病变的诊断价值。结果:20例怀疑臂丛神经受累的患者中,创伤性臂丛神经损伤13例,其主要征象包括:正常神经根消失或离断、连续性中断,创伤性脊膜囊肿、"黑线征",神经根袖形态失常;神经根增粗。7例非创伤性病变,分别为1例神经纤维瘤病(Ⅱ型),2例臂丛神经鞘瘤,1例神经纤维瘤,1例脊膜瘤,1例囊肿,1例神经根鞘囊肿,STIR序列能够清晰显示病变的位置及与神经的关系。结论:磁共振可以清晰地显示臂丛神经的节前纤维、节后纤维的解剖结构,并对累及臂丛神经的疾病作出比较准确的诊断,是诊断臂丛神经疾病的一种无创、有效的影像学检查方法。     

在扩散加权MR神经成像中利用单向动态探查梯度场显示骶丛

<正>背景在扩散加权(DW)磁共振神经成像(MRN)中,利用单向动态探查梯度场(MPGs)显示骶丛。方法对比单向MPGs与三向和六向MPGs。结果与结论在DW MRN中,利用单向MPGs显     

MR神经成像在非产科损伤性儿童臂丛神经疾病中的应用

目的许多研究已经详细阐述了MR神经成像(MRN)在评估创伤性臂丛神经疾病中的应用,其中大部分涉及的是成人创伤性丛状神经疾病或产科臂丛神经麻痹(OBPP)方面的MRI表现。因此,作者认为有必要对非产科损伤性臂丛神经麻痹的MRN表现进行研究,以便于了解此类病人的损伤分布和严重程度。方法本研究为2015年4月—2016年6月期间进行的单中心前瞻性研究。本研究纳入了所有因臂丛神经病变到医院就诊且无产科外伤史的儿童。结果在MRN中,在3个水平寻找损伤征象:神经根、神经干和脊髓。有22例病人(88%)在神经根水平发现损伤,20例病人(80%)在神经干水平发现损伤,22例病人(88%)在脊髓水平发现损伤。结论对患有非产科性损伤性臂丛神经病的儿童进行这项研究得出了一些有意思的结论,其中包括当儿童神经丛受损时,损伤常较为严重且多水平发生,且有很大可能伴神经根损伤。     

臂丛神经损伤的影像诊断进展

【摘要】 臂丛神经解剖复杂,而臂丛神经损伤的患者在临床上却日益增多。既往临床上对臂丛神经损伤的诊断主要根据病史、查体和肌电图检查等,近年来影像技术迅速发展（如超声及MRI）,尤其磁共振神经成像在臂丛神经方面的运用取得了较好的效果,能够安全、清晰地显示臂丛神经损伤,为臂丛神经损伤的诊断、分型及治疗提供有力依据。本文主要对臂丛神经损伤的影像诊断进展进行综述。     

臂丛神经节前损伤的影像学研究进展

臂丛神经损伤是周围神经损伤中最复杂、最严重的一种,致残率较高,现已成为临床上的常见病.主要分为节前和节后损伤2大类型,两者手术方法及预后完全不同.节前损伤是指椎管内颈神经前后根丝状结构处断裂,损伤后不能自行恢复,亦不能外科手术修复.臂丛神经前后根在神经节后融合成单一的神经根,被覆神经外膜,此处的损伤称为节后损伤.节后损伤除完全撕脱外,保守及手术治疗预后尚可.因此,术前准确判定臂丛神经损伤的部位及程度对临床具有重要的指导意义[1],其中影像检查可作为术前诊断的一种良好方法,可用于臂丛神经损伤的原因调查[2-3].     

优化MRI重T23D-SPACE-STIR序列在臂丛神经扫描中的临床应用价值

【摘要】目的：探讨优化MRI重T2 3D-SPACE-STIR序列在臂丛神经显示方面的可行性及临床应用价值。方法:回顾性分析行磁共振臂丛神经扫描的50例患者的临床及影像资料，所有患者均行常规臂丛神经平扫（方法A）、增强扫描（方法B）及优化MRI重T2 3D-SPACE-STIR序列（方法C）扫描。比较三种成像方法的图像质量、图像背景抑制、信噪比(SNR)、对比噪声比(CNR)和臂丛神经锁骨上、下段的显示率，并进行统计学分析。结果:三种成像方法的图像质量评分分别为3.51±0.42、3.76±0.47、3.75±0.43，方法B和C明显优于方法A，差异有统计学意义（方法A与C比较P=0.024，方法A与B比较P=0.043），但B与C之间差异无统计学意义。方法B的背景抑制效果最佳，三种成像方法两两之间差异均有统计学意义(方法A与B比较P=0.000，方法A与C比较P=0.024，方法B与C比较P=0.010)。方法A与C之间的SNR和CNR差异均有统计学意义（P值均=0.000）。三种成像方法对锁骨上段的显示率分别为66.0%、88.0%、84.0%，方法A与C之间差异有统计学意义(P=0.035)，方法B与C之间差异无统计学意义(P=0.727)；三种成像方法对锁骨下段的显示率分别为52.0%、80.0%、74.0%，方法A与C之间差异有统计学意义(P=0.027)，方法B与C之间差异无统计学意义(P=0.607)。结论:优化MRI重T2 3D-SPACE-STIR序列与常规增强扫描在臂丛神经的显示上无明显差异，且均优于常规臂丛神经平扫。优化MRI重T2 3D-SPACE-STIR序列不需要注射对比剂，对不适合使用对比剂的患者具有较高的临床应用价值。     

MRI检查在周围神经病变中的应用

周围神经病变是指各种损伤因素造成外周神经损伤引起相应支配区感觉及运动功能障碍。对于如何精确判断周围神经损伤的部位及程度,是临床亟待解决的难题。磁共振成像技术因其较高的组织分辨率、无辐射、可重复操作等优势,其在临床各个领域都有较普遍的应用。随着神经磁共振成像(magnetic resonance neurography, MRN)技术的不断成熟及完善,MRI在周围神经损伤中的应用越来越广泛。本文主要探讨周围神经病变的因素以及MRI各种成像技术在周围神经病变中的应用。     

Gd-EOB-DTPA增强3.0T MR成像:注射对比剂后10min和20min获得的肝实质期影像对于检测结直肠癌肝转移的定量及定性对照

目的定性和定量比较注射Gd-EOB-DTPA 10min和20min后3.0TMR设备上所获得的影像用于检测结直肠癌肝转移的区别。方法共48例病人(男26例,女22例;平均64岁)进行了Gd-EOB-DTPA增强MR检查,经组织病理     

Gadolinium-enhanced MR imaging, T2-weighted MR imaging, and transurethral ultrasonography

PURPOSE: To assess the value and problems of dynamic gadolinium-enhanced MR imaging, T2-weighted MR imaging, and transurethral ultrasonography(TUUS) in staging of urinary bladder cancer. MATERIALS AND METHODS: Dynamic gadolinium-enhanced MR imaging and FSE T2-weighted MR imaging of 64 patients with urinary bladder cancer who subsequently had surgery were retrospectively reviewed and compared with TUUS findings. RESULTS: Specificity for muscular invasion was 90.5% with TUUS, significantly better than with dynamic MR imaging (64.9%) (p < 0.05). The rates of overestimation of superficial cancer(pT1) with dynamic MRI and T2-weighted MR imaging were 35.1%(13/37) and 24.3%(9/37), respectively. The staging accuracy of invasive cancer(pT2 or over) was 85.2% with dynamic MR imaging, which was better than the rate of 75.0% achieved with T2-weighted MR imaging. CONCLUSION: Although TUUS was a better modality for diagnosing superficial cancer(pT1), dynamic MR imaging was found to be better for diagnosing invasive(pT2 or over) cancer.     

Larynx: MR imaging at 2.35 T

To study the consequences of an improvement in spatial resolution, the authors compared magnetic resonance (MR) images of nine laryngeal specimens with whole-organ histologic slides of the same specimens. Five of the specimens were obtained during laryngectomies performed on patients with high-stage tumors of the larynx. Four specimens were from patients with no known disease. The MR images were obtained on a 2.35-T system with a closely fitting probe head. A conventional spin-echo sequence was used, with T1- and T2-weighted settings. The in-plane resolution obtained was about 0.3 mm. The T2-weighted images generally showed better contrast and allowed identification of the perichondrium. The resolutions used were not much greater than those clinically available. The findings suggest that there will be important advances in clinical MR imaging of the larynx in the near future.     

Proton MR spectroscopy in a 1T open MR imaging system

(1)H-MR spectroscopy is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain lesions and in treatment planning. Claustrophobia and body habitus preclude some patients from routine MR imaging in a closed-bore system. The development of (1)H-MR spectroscopy for use in an open MR imaging system would enable a more complete characterization of brain lesions in these patients.     

Contrast in rapid MR imaging: T1- and T2-weighted imaging

Partial saturation (PS) is an imaging technique that is useful in applications that require rapid image acquisitions (imaging time less than 1 min). Image contrast in PS imaging, as in other magnetic resonance methods, depends on the often conflicting effects of differences in proton density, T1, and T2. Previous analyses of pulse sequence optimization to maximize image contrast have assumed 90 degrees pulses and examined the effects of varying repetition times (TR) and echo times (TE). In this paper we present theoretical calculations and images made with a 0.6 T imager to show that the radiofrequency pulse tip angle alpha, and not the pulse sequence timing parameters, is the most important parameter for producing image contrast. For large tip angles (alpha greater than or equal to 60 degrees), contrast is primarily determined by differences in T1, but for small tip angles (alpha approximately equal to 25 degrees), contrast is primarily due to differences in T2. The T2-weighted images can be produced as quickly as T1-weighted images by using a small pulse angle and a long TE; it is not necessary to use a long TR to reduce the effects of T1 differences. Optimum pulse angles are calculated, and the potential advantages and disadvantages of T2-weighted and T1-weighted PS imaging are discussed.     

Body and cardiovascular MR imaging at 3.0 T

Potential advantages of magnetic resonance (MR) imaging at 3 T include higher signal-to-noise ratios, better image contrast, particularly in gadolinium-enhanced applications, and better spectral separation for spectroscopic applications. In terms of clinical imaging, these advantages can mean higher-spatial-resolution images, faster imaging, and improved MR spectroscopy. However, achieving superior imaging and spectroscopic quality at 3 T can be challenging. This review discusses many of the problems encountered in body and cardiovascular MR imaging at 3 T, such as increased susceptibility, B1 field inhomogeneity, and increased specific absorption rate. The article also considers solutions that are being pursued, such as parallel imaging, variable-rate selective excitation, and variable flip angle sequences. A review of the most commonly used pulse sequences provides practical tips on how these can be optimized for 3-T imaging. In the coming few years, substantial improvements in 3-T technology for clinical imaging and spectroscopy will undoubtedly be seen. An understanding of the basic principles on which these developments are based will help radiologists translate the advances into better imaging studies and, ultimately, better patient care.     

T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Objective

To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods

Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results

SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001).

Conclusion

SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.