3D-SPACE序列在面神经内耳道段成像中的初步研究

目的探讨可变翻转角的三维快速自旋回波序列(3D-SPACE)在面神经内耳道段成像中的应用价值。方法使用1.5T磁共振,对16例志愿者行颅底3D-SPACE横断位扫描,并重建面神经长轴位和斜矢状位图像,观察各方向上面神经的图像质量。结果 16例共32侧面神经内耳道段及其周围血管均清晰显示,显示率100%;面神经及周围血管在图像上显示为低信号,脑脊液显示为高信号,脂肪显示为中等信号。图像锐利,对比良好,空间分辨率高。结论 3D-SPACE序列能清晰显示面神经内耳道段,可作为面神经MRI的常规序列。     

虚拟内镜技术在分流失败脑积水中的诊治价值

目的 探讨虚拟内镜技术在分流失败的脑积水中的诊疗价值.方法 对2012年2月至2014年11月解放军总医院连续收治的76例,在其他医院分流失败的脑积水患者行三维快速自旋回波(3D-SPACE)序列扫描,根据3D-SPACE序列的DICOM数据采用3D-Slicer软件在个人电脑上进行三维重建虚拟内镜,依二者结果决定手术策略,评价虚拟内镜技术提供的信息对治疗策略的影响和临床价值.结果 在3D-SPACE基础上三维重建后的虚拟内镜图像对判断之前分流手术失败的原因和显示中脑导水管及室间孔梗阻有较大帮助.最终,共56例(73.7％)无需分流管而通过神经内镜治疗获得了脑积水的治愈.结论 虚拟内镜技术比常规磁共振影像能够提供更多的术前解剖影像信息,在分流失败的脑积水中有较好协助诊断价值,对决定手术策略亦能提供非常有价值的帮助.     

Depicting the semicircular canals with inner‐ear MRI: A comparison of the SPACE and TrueFISP sequences

Purpose:

To assess the ability of magnetic resonance imaging (MRI) to depict the semicircular canals of the inner ear by comparing results from the sampling perfection with application‐optimized contrasts by using different flip angle evolutions (SPACE) sequence with those from the true free induction with steady precession (TrueFISP) sequence.

Materials and Methods:

A 1.5‐T MRI system was used to perform an in vivo study of 10 healthy volunteers and 17 patients. A three‐point visual score was employed for assessing the depiction of the semicircular canals and facial and vestibulocochlear nerves and the contrast‐to‐noise ratio (CNR) was computed for the vestibule and pons on images with the SPACE and TrueFIPS sequences.

Results:

There were no susceptibility artifact‐related filling defects with the SPACE sequence. However, the TrueFISP sequence showed filling defects for at least one semicircular canal on both sides in seven cases for healthy subjects and in 10 cases for patients. The CNR with the SPACE sequence was significantly higher than with the TrueFISP sequence (P < 0.05). There was no statistically significant difference in depicting the facial and the vestibulocochlear nerves (P = 0.32).

Conclusion:

For the depiction of the semicircular canal, the SPACE sequence is superior to the TrueFISP sequence. J. Magn. Reson. Imaging 2013;37:652–659. © 2012 Wiley Periodicals, Inc.     

Assessment of Changes in the Cesarean Scar and Uterus Between One and Two Years after Cesarean Section Using 3D T2w SPACE MRI

ObjectiveTo evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution, three dimensional T2-weighted sampling perfection with application optimized contrast using different flip angle evolutions Magnetic Resonance Imaging (3DT2w SPACE MRI).MethodsThis prospective study was performed to investigate morphological changes in the cesarean scars and uterus from one to two years after cesarean section using high-resolution, 3D T2w SPACE MRI. The healthy volunteers having no childbearing history were recruited as the controls. All data were measured by two experienced radiologists. All data with normal distribution between the one-year and two-year groups were compared using a paired-sample t test or independent t test.ResultsFinally, 46 women took a pelvic MR examination one year after cesarean section, and a subset of 15 completed the same examination again after two years of cesarean section. Both the uterine length and the anterior wall thickness after two years of cesarean section (5.75 ± 0.46 and 1.45 ± 0.35 cm) were significantly greater than those measured at one year (5.33 ± 0.59 and 1.25 ± 0.27 cm) (t = -2.363 and -2.175, P= 0.033 and 0.048). No significant difference was shown in myometrial thickness two years after cesarean section (1.45 ± 0.35 cm) with respect to the control group (1.58 ± 0.21 cm, P = 0.170). Nine women who underwent MRI twice were considered to have scar diverticula one year after cesarean section, and still had diverticula two years after cesarean section. The thickness, height, and width of the uterine scar showed no significant change from one to two years (all P > 0.05).Conclusions3D T2w SPACE MRI provides overall morphologic details and shows dynamic changes in the scar and the uterus between one and two years after cesarean section. Scar morphology after cesarean section reached relatively stable one year after cesarean section, and uterine morphology was closer to normal two years after cesarean section.     

Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen’s kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.     

High-spatial-resolution three-dimensional MR cholangiography using a high-sampling-efficiency technique (SPACE) at 3T: comparison with the conventional constant flip angle sequence in healthy volunteers

PURPOSE: To evaluate the image quality of high-spatial-resolution three-dimensional magnetic resonance cholangiography (MRC) with a high-sampling-efficiency technique (sampling perfection with application optimized contrasts using different flip angle evolutions [SPACE]) in comparison with a conventional constant flip angle (FA) sequence at 3T. MATERIALS AND METHODS: Eighteen volunteers were examined on a 3T MR unit using MRC imaging performed with three different free-breathing three-dimensional T2-weighted turbo spin-echo (TSE) sequences: 1) SPACE (spatial resolution, 1.1x1.0x0.84 mm), 2) constant FA (1.1x1.0x0.84 mm), and 3) SPACE at a higher resolution (SPACE HR; 1.0x0.9x0.644 mm). A five-point scale was used to compare overall image quality and visualization of the third branches of the bile duct (B2, B6, and B8). Depictions of cystic duct insertion and the highest order of bile duct visible were also compared. RESULTS: MRC with SPACE and SPACE HR sequences produced significantly better overall image quality than the constant FA sequence. In all analyses of duct visibility, SPACE and SPACE HR sequences showed higher scores than the constant FA sequence. CONCLUSION: High-resolution three-dimensional MRC with SPACE at 3T allows high-quality imaging of the biliary tract, and has the ability to depict nondilated intrahepatic bile ducts (IHBD) in healthy volunteers.     

黑血SPACE序列与MRCP、T2-HASTE在婴幼儿胆道成像中的对比应用

目的探讨磁共振黑血SPACE序列与MRCP、T2-HASTE在婴幼儿胆道成像中的对比应用价值。方法运用Siemens 3.0 T超导磁共振扫描仪对30例对照组患儿和12例罹患胆道疾病的婴幼儿进行全腹部常规MRI序列(包括T2-HASTE)以及黑血SPACE序列、MRCP检查,比较黑血SPACE序列与MRCP、T2-HASTE图像对正常胆道结构及病灶的显示能力。结果(1)对照组图像分析:黑血SPACE和MRCP对胆囊管、左右肝管及肝内二级胆管的显示能力较T2-HASTE好,且黑血SPACE序列显示门静脉的能力优于MRCP和T2-HASTE,但黑血SPACE与MRCP在显示胆道结构的能力方面差异无统计学意义。(2)病例组图像分析:黑血SPACE序列在清晰显示胆总管扩张的同时较MRCP拥有更好的组织对比度;黑血SPACE序列较MRCP、T2-HASTE更清晰的显示胆道闭锁患儿肝门区及门静脉周围的异常信号影(纤维斑块),并了解毗邻门静脉的走行及轮廓;黑血SPACE序列在显示微小胆管结石时优于T2-HASTE。结论黑血SPACE序列基本具备MRCP和T2-HASTE序列两者的优势,在观察婴幼儿胆道结构形态、轮廓及边缘的同时了解毗邻肝组织、血管(门静脉)的情况,且成像时间相对较短,但其运用于部分婴幼儿胆道成像时存在较多的运动伪影及肠气干扰,目前将其作为婴幼儿胆道成像的一种补充检查手段,针对不同疾病利用其不同优势,为胆道疾病的影像诊断提供更多助益。     

An anatomical study of normal meniscal roots with isotropic 3D MRI at 3T

Objectives

To clarify the morphological features of normal meniscal roots on magnetic resonance (MR) imaging with an isotropic 3D proton density-weighted (PDW) sequence.

Materials

3D PDW MR was performed in sixty-two patients at 3 T before knee arthroscopy. MR images of 34 normal medial menisci and 33 intact lateral menisci confirmed by arthroscopy were retrospectively evaluated. MR signals, insertion sites, dimensions and courses of four meniscal roots were recorded.

Results

The anterior root of medial meniscus (ARMM) was typically hypointense, while the posterior root of medial meniscus (PRMM) and the anterior root of lateral meniscus (ARLM) were prone to be hyperintense or showing a comblike signal, and the posterior root of lateral meniscus (PRLM) was usually hypointense or comblike on PDW MR images. ARMM and PRLM had more complex and diverse insertion patterns than ARLM and PRMM. There were significant statistical differences of the lengths, widths, heights and course angles among four meniscal roots (all P < 0.001).

Conclusions

The signal intensity of each meniscal root can be hypointense, hyperintense, or comblike on 3D PDW MR images. ARMM and PRLM have more complex and diverse insertion patterns than ARLM and PRMM. The dimensions and courses of four meniscal roots all differ.