3.0T MRI T_2~* mapping评估儿童血友病性关节病膝关节软骨的价值

目的探讨磁共振T_2~* mapping成像技术在儿童血友病性关节病(hemophilic arthropathy, HA)膝关节软骨损伤的诊断价值。方法采用西门子Skyra 3.0T MRI对19例HA患儿组、15例正常组儿童膝关节行MRI扫描,行T_2~* mapping序列扫描,并测量T_2~*值。比较患儿组T_2~* mapping、T_1WI-SE、T_2WI-TSE-FS序列所测量的关节内含铁血黄素沉积。T_2~* mapping序列扫描后在工作站分别测量膝关节研究髌骨、股骨远端内侧髁(承重区、后部非承重区)、股骨远端外侧髁(承重区、前后部非承重区)、胫骨内、外侧平台面8处软骨T_2~* mapping成像的T_2~*值,比较两组膝关节T_2~*值的差异。另对关节内含铁血黄素在T_2~* mapping、T_1WI-SE、T_2WI-TSE-FS三个序列中分别测量最大截面,比较这三个序列在评估血友病性关节病含铁血黄素沉积显示结果的差异,P0.05具有统计学意义。结果血友病性关节病患者膝关节髌骨软骨平均T_2~*值(31.6±12.5)ms,股骨远端内侧髁承重区、后部非承重区软骨平均T_2~*值分别为(29.4±10.0)ms、(34.1±9.7)ms,股骨远端外侧髁承重区、前部、后部非承重区软骨平均T_2~*值分别为(33.7±9.8)ms、(35.6±12.2)ms、(37.2±11.2)ms,内、外侧胫骨平台面软骨平均T_2~*值(30.2±7.9)ms、(28.0±8.7)ms。股骨外侧髁、股骨内侧髁后部非承重区、胫骨平台内外侧与健康组T_2~*平均值比较,差异具有统计学意义(P0.05)。股骨内侧髁承重区、髌骨软骨与健康组T_2~*平均值比较无统计学意义(P0.05)。T_2~* mapping、T_1WI-SE、T_2WI-TSE-FS三个序列最大截面显示含铁血黄素沉积分别是(142.0±137.9)mm~2、(114.8±111.4)mm~2、(115.6±115.3)mm~2,差异不具有统计学意义。结论磁共振T_2~* mapping序列通过T_2~*值的测量,能定量的反应膝关节血友病性关节病早期的损伤、变性。     

膝关节软骨磁共振T2弛豫时间测定在早期骨关节炎中的应用价值

目的:探讨关节软骨磁共振T2弛豫时间定量分析在早期膝关节骨关节炎(OA)中的应用价值。方法:运用T2mapping成像测量正常组(n=12)和平片没有阳性发现的早期OA组(n=15)膝关节胫骨内侧髁、外侧髁,股骨内侧髁、外侧髁和髌骨5处软骨的T2值,并进行统计学分析。结果:正常组膝关节软骨T2值33.8~35.6ms,早期OA组膝关节软骨T2值40.3~42.7ms。病例组膝关节各处软骨的T2值差异有显著性意义(P<0.01)。结论:T2弛豫时间定量分析可以发现没有形态学变化的OA关节软骨内成分变化,在早期OA诊断中有较高的应用价值。     

膝关节骨关节炎软骨磁共振T2-mapping成像与X线分级的对照研究

目的:测量不同程度膝关节骨关节炎(OA)患者和正常关节软骨的T2弛豫时间并比较其差异性,探讨磁共振T2-mapping成像在OA中的应用价值.方法:48例受检者共66个膝关节分为正常组(n=15)、轻度OA组(n=19)和重度OA组(n=14).采用4回波SE序列扫描形成T2-mapping,分别测量胫骨内侧髁、外侧髁,股骨内侧髁、外侧髁和髌骨这5处软骨的T2值并对各组间的差异进行统计学分析.结果:正常组5个部位膝关节软骨T2均值为(34.8±1.9) ms～(36.7±1.4) ms;轻度和重度OA组5个部位膝关节软骨的T2均值分别为(42.2±2.3) ms～(44.7±3.5) ms和(44.5±3.0) ms～(46.0±4.0) ms.所有OA患者膝关节周围各处软骨T2弛豫时间均比正常组显著增高(P《0.01),但轻度OA组与重度OA组之间差异没有显著性(P》0.05).结论:膝关节OA患者关节软骨的T2弛豫时间比正常者明显增加,磁共振T2-mapping成像在早期OA的诊断和监测方面具有很高的临床应用价值.     

60d头低位卧床对人体膝关节软骨磁共振T_2值的影响

目的基于MRT2map技术研究60d模拟失重条件对人体膝关节软骨T2值的影响。方法7名健康男性头低位-6°卧床60d,应用1.5T磁共振扫描仪进行卧床前后膝关节矢状位多回波多层面序列扫描,使用profile软件测量实验前后膝关节非承重、承重软骨,髌软骨的T2弛豫时间,采用配对t检验比较实验前后软骨T2值改变。结果卧床实验前后软骨T2值具有相同的空间分布形态。60d模拟失重条件下胫骨内外侧髁承重软骨、股骨非承重软骨卧床后软骨深部T2值有降低趋势,近表面T2值有升高趋势,但是只在胫骨外侧髁承重软骨距骨软骨下骨质0.3处、胫骨内侧髁承重软骨距骨软骨下骨质0.0,0.1处、股骨非承重软骨距骨软骨下骨质0.0处T2值降低有统计学差异(P0.05);而胫骨内侧髁承重软骨距骨软骨下骨质0.4,0.5处T2值升高有统计学差异(P0.05)。其余各处软骨实验前后T2值未见统计学差异。结论-6°头低位卧床60d前后膝关节软骨T2值空间分布相似,胫骨内外髁承重软骨、股骨非承重软骨深部T2值发生改变,但总体来看头低位卧床对膝关节软骨T2特性影响较小。     

3.0T磁共振3D-FS-SPGR序列对膝关节软骨损伤的评价

目的 分析评价3.0T磁共振3D-FS-SPGR序列对膝关节软骨损伤的诊断价值.方法 对将要进行关节镜检查的35个膝关节进行磁共振多序列、多方位成像,其中包括矢状位3D-FS-SPGR序列及矢状位、冠状位、轴位FS-FSE-T2WI序列.在MRI上对股骨内外侧髁、胫骨内外侧平台、股骨滑车及髌骨6个关节面关节软骨(共210处)进行评价.将3D-FS-SPGR序列及FS-FSE-T2WI序列上软骨损伤分级与关节镜分级进行比较.结果 3D-FS-SPGR序列对软骨损伤显示的敏感度为97.50%,特异度为97.69%,Kappa值为0.798 ;FS-FSE-T2WI序列的敏感度 为90.00%,特异度为94.61%,Kappa值为0.714.结论 3D-FS-SPGR序列显示膝关节软骨损伤优于FS-FSE-T2WI序列;3D-FS-SPGR序列是目前诊断膝关节软骨损伤的最佳序列之一.     

正常青少年膝关节软骨的低场MRI表现

目的：探讨正常青少年膝关节软骨的MRI表现。方法：使用GE 0．2T低场磁共振成像机，采用膝关节线圈，对膝关节行矢状面扫描，应用序列为梯度回波序列T2WI、自旋回波T1WI、自旋回波T2WI、脂肪抑制序列、质子密度序列。翻转角200。扫描野16cm。层厚4mm，间隔1mm。结果：膝关节矢状位MRI梯度回波序列T2WI。和质子密度序列中，股骨髁与胫骨平台的骺软骨MRI能显示出3层不同的信号强度。结论：MRI能准确地显示膝关节软骨的层次结构，为临床诊断膝关节疾病提供参考依据。     

MR 3D SPGR、3D FIESTA和2D SE/FSE序列对外伤性膝关节软骨损伤的分级诊断研究

目的 回顾性研究外伤性膝关节关节软骨的损伤发生率及程度,比较三维扰相梯度回波序列(3DSPGR)、三维稳态采集快速成像序列(3D FIESTA)和膝关节常规检查序列(2D SE/FSE)在诊断外伤性膝关节软骨损伤中的准确性.资料与方法 45例患者的46个外伤膝关节,行手术治疗前均进行了多序列的MRI,包括膝关节常规MRI(SE T1WI,FSE PD/T2WI),3D SPGR和3D FIESTA序列.运用改良的Noyes分类系统来评价膝关节软骨面的损伤等级,每个膝关节的关节面包括:股骨外侧髁(LFC)、股骨内侧髁(MFC)、胫骨外侧平台(LTP)、胫骨内侧平台(MTP)、股骨滑车(Trochlea)和髌骨(Patella).以手术结果为"金标准",比较各序列发现软骨损伤的敏感性、特异性、准确性、阳性及阴性预测值.用Wilson评分法计算敏感性和特异性的95%可信区间,用McNemar统计法的双尾精确表来比较不同MRI序列对软骨分级诊断的显著性差异.结果 根据手术结果,软骨形态改变的发生率为43%(118/276),软骨缺损的发生率为23%(63/276).各个关节面软骨损伤的发生率无明显差异.MR图像(3D SPGR、3D FIESTA、3D SPGR结合常规MRI)表现与手术结果的完全一致率分别为53%、60%和85%,之间差异无统计学意义.但是3D SPGR结合常规MRI序列评价软骨损伤的敏感性、特异性、阳性预测值和阴性预测值均为最高,分别为73%、98%、95%和90%.结论 3D SPGR和3D FIESTA序列在诊断膝关节软骨病变时无明显差异.3D SPGR结合常规MRI序列,不仅可以在合理的扫描时间内提高诊断软骨病变的准确性,而且还可对膝关节的其他组织结构做出全面的评价.     

磁共振T2-mapping成像对早期膝关节软骨损伤的诊断价值研究

目的：测量不同程度膝关节骨关节炎（osteoarthritis,OA）患者和正常对照组关节软骨的T2弛豫时间并比较其差异性,评价磁共振T2-mapping成像在早期膝关节软骨损伤中的应用价值。方法：采用GE signa 3.0T磁共振扫描系统T2-mapping成像测量OA组（n=78）和正常组（n=32）膝关节股骨内侧髁、外侧髁,胫骨内侧髁、外侧髁4处软骨的T2值,并进行统计学分析。结果：正常组、轻度OA组、重度OA组平均T2值分别为（38.36±2.45）ms（、49.28±4.24）ms、（53.12±5.36）ms,病例组与对照组关节软骨表面T2值有差异且具显著性统计学意义（P〈0.05）,轻度OA组和重度OA组之间差别无统计学意义（P〉0.05）。结论：T2-mapping成像可以发现没有形态学改变的关节软骨内组织成分的变化,对早期膝关节软骨损伤的诊断和监测具有很高的临床应用价值。     

急性创伤性髌骨外侧脱位后内侧髌股韧带和股骨外侧髁关节软骨损伤的MRI分析

目的探讨急性创伤性髌骨外侧脱位后内侧髌股韧带(MPFL)和股骨外侧髁关节软骨损伤的MRI特点。方法回顾性分析51例经临床证实的急性创伤性髌骨外侧脱位患者的MRI资料。51例病例均行常规MRI矢状面、冠状面和横断面T1WI、T2WI、脂肪抑制FSE双回波序列扫描,并与手术结果相对照。结果急性创伤性髌骨外侧脱位后,MPFL损伤发生率为100%,其中完全性MPFL撕裂31例,部分性MPFL撕裂20例,股骨侧撕裂30例,髌骨侧撕裂19例,体部撕裂2例,MRI诊断MPFL部分性撕裂的敏感性、特异性和准确性分别为85%、93.5%和90.2%,MRI诊断完全MPFL撕裂的敏感性、特异性和准确性分别为93.5%、85%和90.2%。股骨外侧髁关节软骨损伤17例,发生率为33.3%,其中13例位于股骨外侧髁承重面关节软骨,1例位于股骨滑车,3例股骨滑车和股骨外侧髁承重面关节软骨均受累;17例股骨外侧髁关节软骨损伤病例中,16例(94.1%)关节软骨损伤位于股骨外侧髁骨挫伤的偏后部分,1例(5.9%)位于骨挫伤的中间部分;MPFL髌骨侧损伤病例中,57.9%(11/19)伴发股骨外侧髁关节软骨损伤,MPFL股骨侧损伤病例中,20%(6/30)伴发股骨外侧髁关节软骨损伤,二组数据比较,差异具有显著统计学意义(χ2=5.80,P=0.016)。MPFL完全撕裂、部分撕裂病例中,股骨外侧髁骨软骨骨折发生率分别为19.4%(6/31)、0%(0/20),二者比较,差异具有显著统计学意义(χ2=4.39,P=0.036)。结论急性创伤性髌骨外侧脱位后,MPFL股骨侧最易损伤,其次为髌骨侧,MRI诊断MPFL损伤准确性高;急性创伤性髌骨外侧脱位后股骨外侧髁关节软骨损伤比较常见,MPFL髌骨侧损伤病例易于伴发股骨外侧髁关节软骨损伤,而MPFL完全撕裂较部分撕裂更易伴发股骨外侧髁骨软骨骨折;股骨外侧髁关节软骨损伤多位于股骨外侧髁承重关节面处,绝大多数位于股骨外侧髁骨挫伤的偏后部分。     

青少年急性单纯膝关节软骨骨折的MRI表现

目的分析青少年急性单纯膝关节软骨骨折的MRI表现，以提高对MRI表现的认识。方法回顾性分析经关节镜手术证实的26例27处急性单纯膝关节软骨骨折的MRI表现，重点观察软骨、软骨下低信号线和软骨下骨髓的改变。26例均采用矢状面和冠状面扫描，矢状面应用快速小角度激发成像序列T1WI加脂肪抑制（FLASH-FS-T1WI）、SE-T1WI和三维稳态进动快速成像序列T2WI加脂肪抑制（FISP-3D-FS-T2WI）序列，冠状面应用多回波数据结合成像序列T2WI（ME-T2WI）和SE—T1WI，有5例还加扫了横轴面ME-T2WI。结果26例27处软骨骨折中髌骨8处，股骨内髁7处，股骨外髁11处，胫骨平台1处。单纯软骨骨折有3种类型，软骨全层缺损（7处，其中髌骨3处、股骨内髁2处、股骨外髁1处、胫骨平台外后髁1处）、裂隙状软骨骨折（3处，其中股骨内髁2处、股骨外髁1处）、软骨部分缺损（17处，其中髌骨5处、股骨内髁3处、股骨外髁9处）。关节镜手术发现2l例有关节内软骨游离体，而MRI仅发现3例。全部患者软骨骨折附近均有骨髓挫伤，软骨下低信号线形态、信号均正常。结论膝关节股骨和胫骨平台软骨骨折采用矢状面FLASH-FS-T1WI、SE-T，WI和FISP-3D-FS-T2WI序列及冠状面ME．T2WI、SE-T1WI，髌骨软骨骨折加扫横轴面ME-T2WI序列可显示急性单纯膝关节软骨骨折的部位、范围和类型，是软骨骨折最好的无创性检查方法。     

Stabilization of echo amplitudes in FSE sequences

The classical CPMG sequence and its extension as an imaging sequence, fast spin echo (FSE, based on RARE), suffer from signal magnitude variations in the early echoes when the re-focusing pulses are not set exactly to 180°. It has been suggested that by varying the value of the nutation angle of each refocusing pulse the signal magnitude could be made constant. This article describes an algorithm permitting the generation of sequences of nutation angles yielding series of echsoes with constant signal magnitudes. This result is then usesd to design selective pulses for the FSE imaging technique.     

Phase errors in multi-shot echo planar imaging

Field inhomogeneity related phase errors in multi-shot echo planar imaging (EPI) are directly visualized and analyzed in the spatial frequency domain data or ‘k-space’. The echo time shift (ETS) technique incrementally moves the position of the echo train and improves the phase error function by redistributing phase discontinuities away from the center of k-space.     

Musculoskeletal MR imaging: turbo (fast) spin-echo versus conventional spin-echo and gradient-echo imaging at 0.5 tesla

The value of T2-weighted fast spin-echo imaging of the musculoskeletal system was assessed in 22 patients with various neoplastic, inflammatory, and traumatic disorders. Images were acquired with high echo number (i.e., echo train length) fast spin-echo (FSE; TR 2000 ms, effective TE 100 ms, echo number 13, lineark-space ordering), conventional spin-echo (SE; TR 2000 ms, TE 100 ms) and gradient-echo (GRE) sequences (TR 600 ms, TE 34 ms, flip angle 25°). Signal intensities, signal-to-noise ratios, contrast, contrast-to-noise ratios, lesion conspicuousness, detail perceptibility, and sensitivity towards image artifacts were compared. The high signal intensity of fat on FSE images resulted in a slightly inferior lesion-to-fat contrast on FSE images. However, on the basis of lesion conspicuity, FSE is able to replace time-consuming conventional T2-weighted SE imaging in musculoskeletal MRI. In contrast, GRE images frequently showed superior lesion conspicuity. One minor disadvantage of FSE in our study was the frequent deterioration of image quality by blurring, black band, and rippling artifacts. Some of these artifacts, however, can be prevented using short echo trains and/or short echo spacings.     

Steady state of echo-shifted sequences with radiofrequency phase cycling.

Due to a delayed echo-formation, echo-shifted gradient echo sequences (ES-GRE) allow for an enhanced T(2)*-weighting at short repetition times. While they are in use with and without RF spoiling, analytical solutions are only known for the latter. The signal formation in the former could only be assessed in approximative form, so far. In this article an exact analytical solution is presented for TR-periodic ES-GRE sequences with RF phase cycling. Besides providing a better numerical performance, it should be useful for systematic sequence development. The relation to recent approximative solutions is discussed.     

On the calculation and interpretation of signal intensity in echo-shifted sequences.

Echo-shifted sequences have been shown to be useful in applications where strong T*2-weighting and short repetition times are wanted, such as BOLD-contrast fMRI, MR thermometry, and perfusion studies. However, a full understanding of signal formation with such methods, which is mandatory to optimize sequence parameters for particular applications, has still not been achieved. Here, two methods are proposed to calculate the steady-state signal intensity in coherent TR-periodic and TR-shifted gradient-echo sequences. The integration method, which consists of averaging the steady-state magnetization over all isochromats in a voxel, is shown to be a particularly efficient way of obtaining the analytical expression of the measurable signal. The partition method, based on a physical decomposition of the steady-state magnetization into a sum of contributions from past excitation pulses, reveals that the net transverse magnetization results from a destructive interference between the wanted component and a series of stimulated echoes. The analysis includes off-resonance effects and is illustrated by phantom measurements. Relationships with previous publications on this subject are discussed.     

Multisection T1-weighted hybrid-rare: A pulse sequence for MR imaging of the entire liver during suspended respiration

It is shown that the maximum average-data-collection-speed (ADCS) of multisection 2D hybrid-RARE sequences is independent of TR and TE_eff, and a monotonically increasing function of echo-train-length (ETL). This result was used in the design of an optimized T₁-weighted hybrid-RARE sequence that produces 20 images of the abdomen in 31 s divided into four breath-hold periods. The resulting ADCS is 58 lines in k-space per second. Twenty-four subjects (2 healthy volunteers and 22 patients) were imaged with a protocol that also included: (a) breath-hold T₁-weighted FLASH which acquires data at 34 lines in k-space per second (49 s scan time), and (b) T₁-weighted conventional spin-echo (9:44 minutes scan time) with respiratory compensation. The experiments show that this T₁-weighted-hybrid-RARE sequence has: (1) a level of T₁ weighting that is comparable with the conventional sequences, (2) very low vulnerability to susceptibility artifacts, (3) high data acquisition efficiency, and (4) higher SNR than T₁-weighted-FLASH. In conclusion, the T₁-weighted-hybrid-RARE sequence described herein is an efficacious and reproducible technique for rapid imaging of the upper abdomen during suspended respiration.     

Single-shot T2(*) measurement to establish optimum echo time for fMRI: studies of the visual, motor, and auditory cortices at 3.0 T.

The signal change in fMRI is dependent on the echo time and the rate of decay of transverse magnetization. The latter factor may vary across regions of the brain as a result of variations in field homogeneity. Previous measurements of the signal change with echo time have generally employed relatively slow multi-echo techniques, which may be sensitive to movement and habituation effects. Here a fast T(2)(*) measurement technique, involving the generation of six low-resolution echo planar images from a single FID, is described, and its use in the evaluation of the optimum echo time for visual, motor, and auditory fMRI experiments at 3.0 T is outlined.     

磁共振胆管胰管成像的临床应用研究

目的：探讨快速自旋回波（ＦＳＥ）及单次激发快速自旋回波（ＳＳＦＳＥ）对磁共振胆胰管成像（ＭＲＣＰ）的临床应用价值。材料与方法：分析应用ＦＳＥ对３５例胆道系统病变及正常志愿者的ＭＲＣＰ检查，其中２１例行ＳＳＦＳＥ并与ＦＳＥ行对照观察：结果：仅用ＦＳＥ行ＭＲＣＰ的１４例中，９例扩张的胆管经后处理显示清楚，３例显示胰管，５例无扩张的胆道显示不满意。同时用ＦＳＥ和ＳＳＦＳＥ扫描２１例，对胆管梗阻部位和扩张胆管的显示无显著差异；ＳＳＦＳＥ对无扩张胆、胰管的显示分别是７４．４％、５２．４％，显著高于ＦＳＥ的１６．６％、０．９％，对胆囊显示二者相似。结论：梗阻性胆胰管扩张者，ＦＳＥ和ＳＳＦＳＥ均可得到满意结果，而正常无扩张胆胰管的显示，ＳＳＦＳＥ较ＦＳＥ好