成人大脑中央沟在冠状面MRI上的定位

目的：探索大脑中央沟在冠状面MRI上的准确定位。方法：随机选用成年男性头部标本30例、活体健康成年男性6例,以经连合间线中点的垂线为基线,获得4mm层厚的颅脑MR冠状面图像;将头部标本开颅取脑,重要脑回着不同颜色,切制与MR扫描一致的脑断层标本。将脑断层标本与颅脑MRI相对照,统计有关结构的出现率,以确定中央沟在冠状面MRI上的定位。结果：在中央沟首次出现的断面上,背仙是丘脑的出现率左侧为93%、右侧97%,锥体束的出现率左侧为20%、右侧13%;在胼胝体压部后缘断面上,中央沟几近消失,大脑外侧面中央沟出现率两侧均为33%。结论：中央沟首次出现在背侧丘脑显现而锥体束尚未出现的1-2个断面上;在锥体束出现的断面上,外侧沟上方可以3大髓突辨认额上回、中央前回和中央后回,中央前、后回之间为中央沟;至胼胝体压部后缘断面,中央沟大多消失。     

MR灌注成像在结直肠癌中的应用现状

MR灌注成像在结直肠癌诊治中的应用越来越广泛,其对该病的诊断、治疗方案的制订以及提高5年生存率方面均有重要意义。由于MR灌注成像可无创性地评估肿瘤的微循环情况,其在结直肠癌术前诊断分期、术前放化疗效果预测与监测、术后随访等多方面的研究报道日渐增多,但相关研究所使用的成像方法及评价参数各异,所得结论亦不相同。就MR灌注成像在结直肠癌中的应用现状和研究趋势予以综述,以期为今后的研究提供参考。     

MR仿真结肠镜诊断结直肠癌的价值

 目的 评价MR仿真结肠镜对结直肠癌的显示能力和临床应用价值.方法 手术病理证实的结直肠癌患者35例行MRVC.肠道准备后,经肛管注入结肠1:100的钆喷酸葡胺水溶液约1 300～1 800 ml,被检查者取俯卧位和仰卧位进行以下扫描:(1)True-FISP序列扫描;(2)3D-FLASH序列扫描;(3)若发现病变,可加扫常规二维FLASH /TSE脉冲序列.将3D-FLASH容积扫描数据传输到工作站进行仿真内窥镜(MRVE)、容积再现的半透明(MR-VRSV)、多平面重建(MPR)等后处理.比较其MRVC和电子光学结肠镜,分析以下3方面征象:(1)肿瘤检出率;(2)肿瘤环肠周程度;(3)肿瘤分型.结果 MRVC检出37/38个恶性病变(97.4%),电子光学结肠镜检出34/38个恶性病变(89.5%)(χ2=0.856,P=0.355).MRVC不仅对结直肠癌环肠周程度和分型的显示与电子光学结肠镜及手术病理结果具有良好的一致性,还能更好的显示结直肠癌的周围侵犯及远处转移情况.结论 MRVC可清楚显示结直肠癌病灶,明确其数目、环肠周程度和分型,有助于确定肿瘤分期和制定治疗方案,有具有较高的临床应用价值.     

膝关节前交叉韧带MR扫描方式的研究

目的：探讨前交叉韧带MRI最佳的扫描方式,提高前交叉韧带MR图像的显示程度。方法：回顾性分析100例前交叉韧带MRI图像。每住受检者都按两种不同扫描方式进行扫描,第一组：斜矢状面以轴面定位像进行扫描;第二组：斜矢状面在第一组定位方式基础上,再在冠状面上按前交叉韧带走行倾斜角度进行扫描,观察两组前交叉韧带MR图像的显示情况,将所得前交叉韧带图像分为可全程显示、可分段显示、不显示三种,最后将统计出的数据进行分析。结果：第一种扫描方式全程显示70例（70／100）、分段显示25例（25／100）、不显示5例（5／100）;第二种扫描方式全程显示95例（95／100）、分段显示5例（5／100）、不显示0例（0／100）。结论：两种扫描方式前交叉韧带的显示程度差异有显著性意义（P〈0．01）,第二种扫描方式对前交叉韧带的显示情况良好,是一种较为理想的扫描方式,能显著提高前交叉韧带的显示率。     

膝关节前交叉韧带前内侧束和后外侧束的MR成像研究

目的 提高对膝关节前交叉韧带前内侧束和后外侧束的影像认识,并探讨其3.0T MR的理想常规成像显示平面.方法 回顾性分析149例正常膝关节的3.0TMR图像,采用x2分割法分析前交叉韧带、前内侧束和后外侧束双束结构及双束上、中、下各段在MR矢状面、冠状面、横断面各成像平面显示率的差异.结果 前交叉韧带前内侧束和后外侧束双束结构显示率,横断面(115/149,77.2％)与冠状面(103/149,69.1％)比较,×2=2.4606,P＞0.0125;横断面、冠状面分别与矢状面(21/149,14.1％)比较,x2值分别为119.5138、92.8695,P值均＜0.0125.前内侧束和后外侧束双束上段显示率,横断面( 104/149,69.8％)与冠状面(7/149,4.7％)、矢状面(0/149,0)及冠状面与矢状面分别比较,x2值分别为135.0813、159.7526、7.1684,P值均＜0.0125.前内侧束和后外侧束双束中段显示率,横断面(108/149,72.5％)与冠状面(94/149,63.1％)比较,x2=3.0120,P＞0.0125;横断面、冠状面分别与矢状面( 10/149,6.7％)比较,x2值分别为134.7454、104.2173,P值均＜0.0125.前内侧束和后外侧束双束下段显示率,横断面(103/149,69.1％)与冠状面(110/149,73.8％)比较,x2=0.8065,P＞0.0125;横断面、冠状面分别与矢状面(18/149,12.1％)比较,x2值分别为100.5300、115.9132,P值均＜0.0125.前交叉韧带双束各段在MRI各序列上均呈低信号,形态、走行正常.结论 3.0TMR常规扫描平面能够在一定程度上显示前交叉韧带的双束结构,横断面和冠状面是较为理想的显像平面.     

7T MR辅助猴丘脑定位注射的研究

目的 探讨7T MR辅助猴脑内丘脑定位注射的价值.方法 对20只猴子的双侧丘脑均进行定位穿刺,8只猴子根据恒河猴脑部定位图谱将穿刺针插到预定为丘脑的位置,术后2 d行MR扫描验证穿刺的位置并做病理检查证实.通过穿刺针的位置对定位方法进行改进后,剩余12只猴子按改进的定位方法进行穿刺,术后2 d做MR扫描验证穿刺的结果并对其进行病理证实.结果 改进定位方法前后各有1只猴子因为麻醉状态不稳定而缺失MR扫描结果,改进定位方法前11次准确定位于丘脑(78.6%),改进定位方法后21次准确定位于丘脑(95.5%).MR所得结果与病理证实结果一致(88.9%).结论 高分辨能力的7T MR可以改进猴脑内精细解剖和功能结构定位的方法.     

三维MR影像对前交叉韧带损伤诊断价值的研究

目的 比较常规2D及3D超长回波链采集FSE序列(3D Cube T2WI) MRI对前交叉韧带(ACL)损伤的诊断价值.方法 40例膝关节外伤患者先后行常规2D MR及3D Cube T2WI MR检查并分别作出ACL损伤的诊断,包括ACL完整、部分撕裂及完全撕裂.以关节镜检查结果作为ACL损伤的金标准.应用ROC法计算2种影像检查对ACL部分撕裂及完全撕裂诊断的曲线下面积(AUC)值并应用Hanley&McNeil检验比较两者在统计学上的差异.结果 40例经关节镜证实的膝关节损伤患者中,ACL完整者16例,双束完全撕裂为12例,部分撕裂者为12例.对ACL完全撕裂,2D MR的AUC值为0.839,3D Cube的AUC值为0.923,两者差异无统计学意义(Z=1.245,P=0.213);而对于ACL部分撕裂,2D MR的AUC值为0.643,3D Cube的AUC值为0.881,两者差异有统计学意义(Z =2.384,P=0.017).结论 常规2D MR及3D Cube MR对ACL完全断裂诊断效力无差异,3D Cube MR对于ACL部分损伤诊断效力优于常规2D MR.     

利手和非利手随意运动的全脑功能磁共振成像

目的 利用全脑功能磁共振成像(fMRI)技术，探讨参与利手和非利手简单随意运动的关键脑结构。方法 采用Siemens公司Sonata 1．5T磁共振成像系统，对7名健康右利手志愿者的利手或非利手食指按键运动进行了全脑扫描。数据经头动矫正、空间标准化、空间平滑等预处理后，通过互相关分析分别获得利手和非利手运动的脑激活统计参数图。结果 利手运动主要激活对侧初级运动区(MI)、双侧辅助运动区(SMA)、双侧运动二区(MII)和同侧小脑，而非利手运动除以上区域外还激活了对侧前运动区(PMC)，而且SMA和MII的激活体积大于利手运动。结论 全脑fMRI研究表明，随意运动依赖于大脑皮质和小脑等许多脑结构的参与.与利手运动相比，非利手运动更依赖于SMA和PMC等高级运动控制区.     

Chromomycosis presenting as soft-tissue mass: report of a case with MRI features

Chromomycosis is primarily a skin disease that superficially presents as slowly growing, verrucous lesions, often warty or cauliflower-like in appearance. It may occasionally create a flat, plaque-like lesion in the skin but deep-seated tumorous presentation has not previously been reported. As the lesion is limited to the cutaneous and superficial subcutaneous tissues, hitherto reported cases have been described from the view point of dermatology and, so, without MRI study. We report a patient with pathologically proven chromomycosis that produced a subcutaneous mass in the dorsum of the hand with an emphasis on MRI features.     

Heschl gyrus and its included primary auditory cortex: structural MRI studies in healthy and diseased subjects

Despite the fact that the Heschl gyrus (HG) is a crucial brain structure as it contains the primary auditory cortex (PAC), relatively few structural MRI studies have concentrated upon it. We propose that this may be attributed in part to the considerable variability of this structure and, most importantly, to the lack of unified criteria for defining the extent of the PAC along the MRI-determined landmarks of the HG, which ultimately affects the reliability and reproducibility of these studies. This review highlights three aspects: first, the standard and variant anatomy of the HG and PAC with particular focus on MRI definition of these regions; second, the importance of studying the HG and PAC in health and disease using structural MRI; and, third, the problem of MRI localization of the PAC. The scientific community should be aware that the HG and its included PAC are not synonyms. Additionally, owing to the great complexity and variability of these regions, future MRI studies should be cautious when using single brain-based atlas or maps generated by simply averaging across individuals to localize these regions. Instead, and while waiting for future in vivo microstructural localization of the PAC, the use of probabilistic and functional maps is advantageous but not without shortcomings.     

Simultaneous multislice acquisition using rosette trajectories (SMART): A new imaging method for functional MRI

A new acquisition technique for rapid, whole-brain functional MRI is presented. In this technique, several slices are simultaneously acquired using rosette k-space trajectories and a gradient-induced frequency modulation. This modulation together with the spectral properties of the rosette acquisition allow all slices to be reconstructed individually. In functional MRI studies, acquisition rates of 16.7 to 25 images/s were achieved, a threefold improvement over single-slice acquisitions. The raw images showed some increase in noise. However, because this increase is mostly stationary, the functional activation maps showed only a slight increase in noise (8%).     

Partial fourier reconstruction for three-dimensional gradient echo functional MRI: Comparison of phase correction methods

Partial Fourier (PF) methods take advantage of data symmetry to allow for either faster image acquisition or increased image resolution, Faster acquisition and increased spatial resolution are advantageous for fMRl because of increased temporal resolution and/or reduced partial volume effects, respectively. Standard PF methods, which use a phase reference obtained from a low resolution image, are adequate for the reconstruction of time-stationary images acquired using either spin echoes or short TE gradient echoes. In fMRI, however, multiple images are acquired using long TE gradient echoes, which introduces possible phase drifts in the fMRl data and high spatial frequencies in the phase reference. This work investigates several techniques developed to reconstruct fMRl data obtained with PF acquisitions. PF methods that account for both high-frequency spatial variations and time-dependent drifts in the phase reference are discussed and are quantitatively evaluated using receiver operator characteristic curve analysis.     

PET/MRI: Technical Challenges and Recent Advances

Integrated positron emission tomography (PET)/magnetic resonance imaging (MRI), which can provide complementary functional and anatomical information about a specific organ or body system at the molecular level, has become a powerful imaging modality to understand the molecular biology details, disease mechanisms, and pharmacokinetics in animals and humans. Although the first experiment on the PET/MRI was performed in the early 1990s, its clinical application was accomplished in recent years because there were various technical challenges in integrating PET and MRI in a single system with minimum mutual interference between PET and MRI. This paper presents the technical challenges and recent advances in combining PET and MRI along with several approaches for improving PET image quality of the PET/MRI hybrid imaging system.     

Functional MRI of somatosensory activation in rat: Effect of hypercapnic tip-regulation on perfusion- and BOLD-imaging

Functional activation of somatosensory cortex was studied in α-chloralose anesthetized rats by functional magnetic resonance imaging (fMRI), using both perfusion–weighted and T₂*–weighted (blood oxygenation level dependent, BOLD) imaging. The sensitivity of functional activation was altered by ventilating animals for 3 minutes with 6% CO₂. Before hyper–capnic conditioning, electrical stimulation of the left forepaw at a frequency of 3 Hz led to an increase of signal intensity (relative to the unstimulated baseline condition) in the right somatosensory cortex by 6 ± 2% (means ± SD) in T₂*–weighted images and by 45% ± 48% in perfusion–weighted images. After hypercapnic conditioning the signal intensity increase in perfusion–weighted images doubled to 91% ± 62% (P = 0.034), whereas that of T₂*–weighted images only marginally increased to 7 ± 4% (not significant). This different behavior in both imaging modalities is interpreted as evidence for an increased flow response in combination with a higher oxygen extraction. Thus, the fMRI data reflect hypercapniainduced resetting of the functional–metabolic coupling of the tissue during activation.     

Cavernous sinus meningiomas: An MRI study

Summary The authors report their experience in examining cavernous sinus meningiomas with MRI. The advantages of this diagnostic method particularly in comparison with conventional neuroradiological techniques are described.