3.0T磁共振扩散张量成像诊断前列腺外周带癌的初步研究

目的应用3.0 T磁共振成像系统探讨扩散张量成像(DTI)诊断前列腺外周带癌的价值。资料与方法搜集在3.0 T MR行前列腺检查并经穿刺活检证实的33例前列腺病变患者资料。扫描序列包括矢、冠、轴位TSET2WI序列及轴位单次激发平面回波成像(SS-EPI)DTI序列,b值采用0和700 s/mm2。扫描图像由两名放射学家进行评估,将前列腺外周带分为六个区域(每侧外周带分为尖部、中部和基底部三部分),根据穿刺结果将每个区域定为癌区或非癌区,测量前列腺外周带癌区和非癌区的表观扩散系数(ADC)值和各向异性分数(FA)值。采用t检验比较两者的ADC和FA值,并对DTI参数建立Logistic回归模型,对ADC、FA值和DTI参数行受试者工作特征(ROC)曲线分析以确定它们区分前列腺外周带癌区和非癌区的效能。结果前列腺外周带癌区及外周带非癌区的ADC值分别为(1.02±0.16)×10-3mm2/s和(1.22±0.14)×10-3mm2/s;FA值分别为0.38±0.09和0.31±0.06,两者差异均具有统计学意义(P<0.0001,P<0.0001)。ADC值、FA值及DTI区分前列腺外周带癌区和非癌区的ROC曲线下面积分别为0.84、0.76和0.86。DTI曲线下面积显著高于FA值(P=0.0009),但DTI和ADC曲线下面积无显著差异(P=0.1595)。结论 DTI有助于诊断前列腺外周带癌。     

磁共振扩散峰度成像与T2 mapping成像对颈椎间盘退变的诊断价值

目的 探讨扩散峰度成像（DKI）、T₂ mapping成像定量参数对颈椎间盘退变程度的应用。方法 对临床因颈痛就诊的80例颈椎间盘退变患者行颈椎T₂WI、DKI及T₂ mapping定量成像扫描,按照Miyazaki分级进行颈椎间盘退变程度分类,对颈椎髓核的DKI定量参数值平均扩散系数（MD）、平均扩散峰度（MK）及T₂ mapping参数T₂值与Miyazaki分级、被检者性别和椎间盘形态的关系进行分析。结果 MD值与Miyazaki分级呈显著负相关（r=-0.850,P<0.01）,MK值与Miyazaki分级呈显著正相关（r=0.785,P<0.01）,T₂值与Miyazaki分级呈显著负相关（r=-0.851,P<0.01）。C_6/7节段T₂值（56.51±24.58）高于C_2/3（50.43±18.13）、C_3/4（49.96±17.51）、...     

ADC及FA值对腰椎间盘退变程度的评估价值

目的：探讨表观扩散系数（ADC）及各向异性分数（FA）定量评估腰椎间盘退变程度的价值。方法：收集腰椎MRI检查资料完整的患者84例,其中44例临床诊断为腰椎间盘退行性疾病,另40例腰椎间盘正常;84例均行常规MRI、矢状位DWI及DTI。测量各椎间盘的修正Pfirrmann分级、ADC值和FA值,行修正Pfirrmann分级评级：正常（1～2级）、轻度退变（3～4级）、重度退变（5～8级）,分析不同退变分级椎间盘与ADC值、FA值的相关性,并比较ADC值与FA值的诊断价值。结果：ADC值、FA值与修正Pfirrmann分级均具有相关性,且ADC值与修正Pfirrmann分级的相关性强于FA值;正常椎间盘与退变椎间盘平均ADC值及FA值比较,差异均具有统计学意义（均P<0.05）。结论：ADC、FA值能够为腰椎间盘退变的早期诊断和其退变程度的定量评估提供参考,且ADC值比FA值诊断价值更高。     

磁共振扩散张量成像在诊断脑膜瘤及星形细胞瘤中的应用

磁共振扩散张量成像（diffusion tensor imaging,DTI）是在扩散加权成像（diffusion-weighted imaging, DWI）基础上发展起来的一种水成像新技术,是通过测定表观扩散系数（apparent diffusion coefficient, ADC）和各向异性分数（fractional anisotropy, FA）来量化组织内水分子的扩散速度和方向,反映脑白质纤维束病理状态及其与邻近肿瘤关系,进而鉴别肿瘤良恶性,为临床制定手术方案和预后评估提供有价值的信息。     

磁共振T2弛豫时间和ADC评估腰椎间盘退变的对比研究

目的:探讨MRI定量测量T2弛豫时间和表观扩散系数(ADC)对腰椎间盘退变的诊断价值和临床意义.方法:46例无症状青年志愿者行腰椎常规MRI、T2-mapping和DWI检查.由两位医师分别对椎间盘进行Pfirrmann分级,并间隔一周2次测量髓核的T2值和ADC值.结果:同一观察者或不同观察者间测量的T2值和ADC值的一致性均较好(ICC=0.86～0.93,P＜0.01).髓核T2值及ADC值均与Pfirrmann分级呈负相关,但以T2值相关性更佳(rT2 =-0.70,P＜0.01;rADc=-0.60,P＜0.01).髓核T2值和ADC值在不同Pfirrmann分级之间的差异均有统计学意义(F=60.6和72.3,P＜0.01);各级间两两比较,T2值的差异均有统计学意义(P＜0.05).但ADC值在Pfirrmann Ⅰ级与Ⅱ级间的差异无统计学意义(P＞0.05).T2值和ADC值鉴别Ⅰ级与Ⅱ级、Ⅱ级与Ⅲ级、Ⅲ级与Ⅳ级椎间盘的ROC曲线下面积分别为0.86、0.92和0.80(P均＜0.01);0.69(P＜0.01)、0.90(P＜0.01)和0.74(P＜0.05).结论:T2值和ADC值均能定量评估腰椎间盘退变,二者相互结合能更全面地观察椎间盘早期退变的特征.     

磁共振T2-mapping及T2*-mapping对兔腰椎间盘退变的定量研究

目的:探讨T2-mapping及T2*-mapping成像对椎间盘退变的诊断价值.方法:将30只新西兰大白兔随机分为正常对照组(15只)和糖尿病模型组(15只),两组中按时间(1月、3月、6月)随机各均分为3组.按分组时间对实验兔脊柱行T2 WI、T2-SPAIR、T2-mapping和T2*-mapping序列矢状面...     

3.0T MR T2 mapping在腰椎间盘退变中的初步研究

目的：运用3.0T MR T2 mapping 成像技术定量研究椎间盘退变及生物力学与腰椎间盘退变的关系。方法分析34例下腰痛(LBP)及(或)坐骨神经痛患者腰椎间盘 T2值与 Pfirrmann 分级、椎间盘部位、年龄的相关性及加压前后腰椎间盘 T2值。结果髓核 T2值与 Pfirrmann 分级、椎间盘部位、年龄存在相关性。结论(1)T2 mapping 可以对椎间盘退变作无创性定量检测;(2)体外压力负荷变化可影响椎间盘 T2值。     

臂丛神经MR成像:3.0 T MR DTI相关测量与纤维示踪技术的精确性及可重复性

目的对无臂丛神经病理改变的志愿者进行3.0 T MRI检查,评估DTI相关测量与纤维示踪技术(FT)的组内与组间可重复性。方法本研究经机构伦理委员会批准并获得     

Thoracic and lumbar spinal cord diffusion tensor imaging in dogs

Purpose:

To analyze four clinically applicable diffusion tensor imaging (DTI) protocols (two each in the transverse and sagittal planes) in the normal dog.

Materials and Methods:

Seven healthy Dachshund dogs were scanned with four DTI protocols. Within each plane, identical spatial resolution was used while the number of diffusion‐encoding directions and averages varied. Agreement of measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) was analyzed with Bland–Altman methods, subjective image quality within each plane was compared, and FA and ADC were explored as a function of anatomic location.

Results:

There was good agreement in FA and ADC values within each plane. FA had the smallest bias and most precision. No difference was detected in subjective image quality within each plane. FA and ADC were slightly higher cranial to the lumbar intumescence compared to within it.

Conclusion:

DTI is a promising tool in the assessment of spinal cord injury (SCI) in the study of dogs with intervertebral disk herniation as a preclinical model of human SCI. J. Magn. Reson. Imaging 2013;37:632–641. © 2013 Wiley Periodicals, Inc.     

DTI在腰椎间盘退行性改变中的应用初探

目的:探讨扩散张量成像(DTI)定量指标ADC及FA值与腰椎间盘退行性改变Pfirrmann分级的相关性.方法:将105例腰腿痛患者纳入研究,所有患者行椎间盘常规MRI及矢状面DTI扫描,根据T2 WI上椎间盘的特点对525个腰椎椎间盘进行Pfirrmann(Pm)分级,观察邻近终板的退变情况,测量椎间盘髓核区的ADC值及FA值并比较各级椎间盘之间的差异,采用Spearman等级相关检验分析ADC和FA值与Pm分级的相关性,并计算2个指标对椎间盘退变(PmⅣ～Ⅴ级)的诊断效能.结果:105例共525个腰椎椎间盘中PmⅠ～Ⅴ级分别有41、112、164、141和67个.经方差分析,Pm Ⅰ和Ⅱ级椎间盘间ADC值、PmⅣ及Ⅴ级椎间盘间ADC值和FA值的差异无统计学意义(P＞0.05),其余各分级之间2个指标的差异有统计学意义(P＜0.05).经ROC分析,ADC值及FA值对PmⅣ、Ⅴ级椎间盘的诊断效能分别为0.846和0.932,两者间差异有统计学意义(P＜0.05).Spearman秩相关分析显示,椎间盘退变Pm分级与ADC值呈负相关(rs=-0.66,P＜0.05),与FA值呈正相关(rs=0.805,P＜0.05).结论:DTI作为定量MRI的一种特殊检查技术,其测量参数与Pfirrmann分级之间具有很好的相关性,可作为一种无创性的检查方法应用于椎间盘退变的研究.     

腰椎间盘退行性变的MR扩散张量成像初步研究

目的 运用DTI初步探讨无创评价活体椎间盘纤维环退变.方法 选择2010年9月至2011年3月腰椎门诊就诊行腰椎MR检查患者,排除脊柱畸形、肿瘤及相关手术患者,共纳入研究对象88例,年龄16 ～63岁,平均(37±13)岁.对研究对象进行快速自旋回波及平面回波成像.剔除磁敏感重的图像,共获得428个椎间盘,测量其平均扩散系数(MD)、各向异性分数(FA)并获得其纤维环成像图,根据纤维环示踪图(FT)图形态学改变,对纤维环进行分型并测量其MD和FA,并进行比较.数据资料为非正态分布,以四分位间距及中位数表示.采用SPSS11.0软件包,x2检验进行统计学分析.结果 运用纤维环示踪技术每个椎间盘均可得到纤维环成像图,且不同Pfirrmann级别其纤维环类型不同,纤维环分型与Pfirrmann分级密切相关:规则型FT图135个,其中PfirrmannⅡ级(92个)比例最高,占68.15％;杂乱型纤维环FT图195个,以PfirrmannⅢ(93个)、Ⅳ级(30个)为主,占63.07％;团块型纤维环FT因98个,以PfirrmannⅣ(39个)、Ⅴ级(43个)为主,占83.68％,差异具有统计学意义(Mantel-Haenszel x2检验,x2=183.90,P＜0.01).完整型FA值为0.32(0.29 ～0.35),MD值为12.40(11.50 ～13.20)×10-10 mm2/s;杂乱型FA值为0.35(0.33 ～0.38),MD值为11.10(9.92 ～ 12.00)×10 10mm2/s;团块型FA值为0.54(0.46～0.62),MD值为6.30(5.03～7.72)×10-10mm2/s.纤维环结构越杂乱,其MD值越低,FA值越高,差异具有统计学意义(Kruskal-Wallis秩和检验,x2值分别为219.74、243.88,P值均＜0.01).结论 DTI可无创性评估活体椎间盘结构变化,MD值及FA值有助于评价椎间盘退变程度.     

腰椎失稳致大鼠椎间盘蜕变的组织学和影像学观察

目的:建立大鼠椎间盘蜕变的动物模型,并对其组织学和影像学改变进行观察。方法:采用SD大鼠30只,手术对照组15只,手术模型组15只。后正中切口,剥离骶棘肌并向两侧分开,显露L1~6棘突,切除,暴露双侧椎板、关节突,咬除L1~6的小关节的外1/2部分,切断椎板间韧带;对照组仅行皮肤切开。X线检查大鼠腰椎的影像学改变,收集大鼠腰椎间盘组织,行HE染色观察组织学的表现。结果:手术模型组于术后3个月时出现椎间隙的楔形改变,于术后6个月时出现终板软骨的钙化和椎间隙的狭窄,术后9个月时则更为明显,同手术对照组相比有显著性差异(P<0.05);组织学改变于术后3个月时即可见髓核的皱缩,终板的轻度钙化,纤维环的排列不规则,术后6个月和9个月时可见髓核的纤维化,终板钙化明显纤维环板层状结构消失。结论:腰椎失稳可以引起大鼠的椎间盘的蜕变,为不直接损伤椎间盘组织建立椎间盘蜕变动物模型的好方法。     

Quantitative T2 evaluation at 3.0T compared to morphological grading of the lumbar intervertebral disc: a standardized evaluation approach in patients with low back pain

Background

The purpose of our investigation was to compare quantitative T2 relaxation time measurement evaluation of lumbar intervertebral discs with morphological grading in young to middle-aged patients with low back pain, using a standardized region-of-interest evaluation approach.

Patients and methods

Three hundred thirty lumbar discs from 66 patients (mean age, 39 years) with low back pain were examined on a 3.0 T MR unit. Sagittal T1-FSE, sagittal, coronal, and axial T2-weighted FSE for morphological MRI, as well as a multi-echo spin-echo sequence for T2 mapping, were performed. Morphologically, all discs were classified according to Pfirrmann et al. Equally sized rectangular regions of interest (ROIs) for the annulus fibrosus were selected anteriorly and posteriorly in the outermost 20% of the disc. The space between was defined as the nucleus pulposus. To assess the reproducibility of this evaluation, inter- and intraobserver statistics were performed.

Results

The Pfirrmann scoring of 330 discs showed the following results: grade I: six discs (1.8%); grade II: 189 (57.3%); grade III: 96 (29.1%); grade IV: 38 (11.5%); and grade V: one (0.3%). The mean T2 values (in milliseconds) for the anterior and the posterior annulus, and the nucleus pulposus for the respective Pfirrmann groups were: I: 57/30/239; II: 44/67/129; III: 42/51/82; and IV: 42/44/56. The nucleus pulposus T2 values showed a stepwise decrease from Pfirrmann grade I to IV. The posterior annulus showed the highest T2 values in Pfirrmann group II, while the anterior annulus showed relatively constant T2 values in all Pfirrmann groups. The inter- and intraobserver analysis yielded intraclass correlation coefficients (ICC) for average measures in a range from 0.82 (anterior annulus) to 0.99 (nucleus).

Conclusions

Our standardized method of region-specific quantitative T2 relaxation time evaluation seems to be able to characterize different degrees of disc degeneration quantitatively. The reproducibility of our ROI measurements is sufficient to encourage the use of this method in future investigations, particularly for longitudinal studies.     

Predicting survival in glioblastomas using diffusion tensor imaging metrics

Purpose

To retrospectively correlate various diffusion tensor imaging (DTI) metrics in patients with glioblastoma multiforme (GBM) with patient survival analysis and also degree of tumor proliferation index determined histologically.

Materials and Methods

Thirty‐four patients with histologically confirmed treatment naive GBMs underwent DTI on a 3.0 Tesla (T) scanner. Region‐of‐interest was placed on the whole lesion including the enhancing as well as nonenhancing component of the lesion to determine the various DTI metrics. Kaplan‐Meier estimates and Cox proportional hazards regression methods were used to assess the relationship of DTI metrics (minimum and mean values) and Ki‐67 with progression free survival (PFS). To study the relationship between DTI metrics and Ki‐67, Pearson's correlation coefficient was computed.

Results

Univariate analysis showed that patients with fractional anisotropy (FA)_mean ≤ 0.2, apparent diffusion coefficient (ADC)_min ≤ 0.6, planar anisotropy (CP)_min ≤ 0.002, spherical anisotropy (CS)_mean > 0.68 and Ki‐67 > 0.3 had lower PFS rate. The multivariate analysis demonstrated that only CP_min was the best predictor of survival in these patients, after adjusting for age, Karnofsky performance scale and extent of resection. No significant correlation between DTI metrics and Ki‐67 were observed.

Conclusion

DTI metrics can be used as a sensitive and early indicator for PFS in patients with glioblastomas. This could be useful for treatment planning as high‐grade gliomas with lower ADC_min, FA_mean, CP_min, and higher CS_mean values may be treated more aggressively. J. Magn. Reson. Imaging 2010;32:788–795. © 2010 Wiley‐Liss, Inc.     

Clinical applications of diffusion tensor imaging

Directionally-ordered cellular structures that impede water motion, such as cell membranes and myelin, result in water mobility that is also directionally-dependent. Diffusion tensor imaging characterizes this directional nature of water motion and thereby provides structural information that cannot be obtained by standard anatomic imaging. Quantitative apparent diffusion coefficients and fractional anisotropy have emerged from being primarily research tools to methods enabling valuable clinical applications. This review describes the clinical utility of diffusion tensor imaging, including the basic principles of the technique, acquisition, data analysis, and the major clinical applications.     

In vivo diffusion tensor imaging of the human prostate.

This study demonstrates the feasibility of in vivo prostate diffusion tensor imaging (DTI) in human subjects. We implemented an EPI-based diffusion-weighted (DW) sequence with seven-direction diffusion gradient sensitization, and acquired DT images from six subjects using cardiac gating with a phased-array prostate surface coil operating in a linear mode. We calculated two indices to quantify diffusion anisotropy. The direction of the eigenvector corresponding to the leading eigenvalue was displayed by means of a color-coding scheme. The average diffusion values of the prostate peripheral zone (PZ) and central gland (CG) were 1.95 +/- 0.08 x 10(-3) mm2 s and 1.53 +/- 0.34 x 10(-3) mm2 s, respectively. The average fractional anisotropy (FA) values for the PZ and CG were 0.46 +/- 0.04 and 0.40 +/- 0.08, respectively. The diffusion ellipsoid in prostate tissue was anisotropic and approximated a prolate model, as shown in the color maps of the anisotropy. Consistent with the tissue architecture, the prostate fiber orientations were predominantly in the superior-inferior (SI) direction for both the PZ and CG. This study shows the feasibility of in vivo DTI and establishes normative DT values for six subjects.