经关节镜证实的正常髌软骨T2值空间分布特征

目的 明确关节镜证实的正常髌软骨T2值的区域差异性及场强对软骨T2值的影响.资料与方法 43例(1.5T MR)和31例(3.0T MR)经关节镜证实的无髌软骨病变患者行髌骨轴位T2-mapping成像.将髌软骨分为上、中、下部,每部又分为内、外侧区,分别测量T2值,比较各处软骨T2值的差异,以及场强对软骨T2值的影响.结果 在1.5T和3.0T MR上,髌软骨内侧、外侧、总体(包括内外侧)T2值差异无统计学意义(P＞0.05);上、中、下各部软骨T2值差异无统计学意义(P＞0.05);在髌软骨最厚层面上,软骨浅、中、深3层T2值差异有统计学意义(P＜0.001),且软骨T2值从软骨表面到软骨下骨有逐渐减小趋势.正常髌软骨在1.5T与3.0TMR上软骨T2值随场强增加而减小(P＜0.001).结论 正常髌软骨T2值在内外侧和上、中、下部位之间无显著差异,髌软骨T2值从软骨表面到软骨下骨不断减小.随着MR场强的增高,软骨T2值下降.     

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。     

1.5T MR研究健康人膝关节软骨T_2值空间分布

目的 研究健康成人膝关节软骨T2弛豫时间(T2值)空间分布.方法 1.5T场强下对21名健康男性(年龄24～39岁,平均30岁±4岁)行膝关节矢状位多回波多层面SE序列扫描,使用Profile软件测量股骨非承重软骨的前部、股骨承重软骨、胫骨承重软骨、髌软骨的T2弛豫时间(即T2值),采用方差分析检验各部位软骨深层和浅层T2值、承重软骨和非承重软骨的T2值空间分布的差异.结果 健康人膝关节软骨T2值空间分布呈浅凹形曲线,即近软骨下骨质T2值较高,随后T2值从软骨深层到浅层逐渐增高,并且各层T2值存在差异(F=70.892,P＜0.05).髌软骨T2值空间分布变化最大,股胫关节承重软骨和股骨前部非承重软骨T2值的空间分布变化较平缓.髌软骨深层T2值[(26.56±4.4) ms]明显低于所有软骨深层T2值(P=0.001).股骨外髁承重软骨浅层T2值[(35.2±6.31) ms]明显低于髌软骨[(40.78±3.56) ms]和股骨非承重软骨前部[(42.31±2.4) ms](P=0.002,P=0.000).胫骨外髁承重部软骨浅层T2值[37.11±6.6) ms]明显低于股骨非承重前部(P=0.000).结论 1.5T 场强下健康人膝关节软骨T2值具有特定空间分布,对量化研究退行性骨关节炎和其他关节病变具有参考价值.     

磁共振成像研究膝股骨髁软骨T2值空间分布

目的 研究健康成人和早期骨性关节炎(osteoarthritis,OA)病人膝关节股骨内外髁软骨横向弛豫时间(T2值)空间分布.方法 采用Siemens 3.0T磁共振,正常组(20例;年龄25~38岁,平均28.7岁±4.5岁)25个膝关节和早期OA病人组(27例;年龄40~78岁,平均54.2岁±11岁)31个膝关节,应用T2图成像观察和测量2组股骨内外侧髁非负重区与负重区软骨T2值,并进行统计学分析.结果 正常组与早期OA组股骨髁负重区软骨平均T2值[(51.1±4.3) ms,(58.9±4.0) ms]明显高于各自非负重区[(47.2±3.8) ms,(53.5±4.1) ms],差异有统计学意义(F值分别为22.151和54.670,P值均<0.05);正常组股骨髁各区软骨浅层T2值明显高于深层,差异有统计学意义(F值分别为27.960、12.972、12.718、7.837,P值均<0.05);早期OA组股骨内外髁非负重区软骨浅层T2值明显高于深层(F值分别为6.062和10.436,P值均<0.05),负重区软骨浅层与深层比较差异无统计学意义(F值分别为1.208和1.472,P值均>0.05).结论 健康成人和早期OA病人膝关节股骨内外髁软骨T2值具有特定空间分布特点,对量化监测早期OA软骨病变具有参考价值.负重对软骨T2值空间分布有一定影响.     

显示正常人膝关节软骨分层的最佳MRI序列

目的:显示正常人膝关节软骨分层的最佳MRI序列,为关节病变的早期诊断提供技术支持.方法:选择无膝关节症状的志愿者140例,分别采用SE-T1WI、脂肪抑制二维快速小角度激发(FS -2D-FLASH)和脂肪抑制三维稳态旋进快速成像(FS-3D-FISP)三个扫描序列,行膝关节矢状面扫描.分析显示软骨分层的最佳MRI序列.结果:FLASH序列显示结果为140例中有129例显示膝关节软骨分3层,9例无分层,2例可见分5层,显示分层例数多,分层清楚,扫描时间较短;SE序列140例中有101例显示膝关节软骨分3层,39例无分层,未见分5层者,显示分层例数较少;FISP序列140例中有133例显示膝关节软骨分3层,5例无分层,2例分5层,显示分层例数多,但分层模糊,扫描时间长.结论:FS-FLASH-2D序列是显示膝关节软骨分层的最佳序列.     

正常人膝关节软骨MRI显示的分层现象分析

目的观察正常人膝关节软骨的MRI分层现象。方法选择无膝关节症状而以其他部位病变就诊的患者140名,分为7个年龄组,每个年龄组男女各10名。用1.5T超导型磁共振机,行膝关节矢状面扫描。采用FLASH-FS-T1WI、SE-T1WI和3D-FISP-FS-T2WI3个扫描序列,FLASH和SE序列扫描层厚3mm,FISP序列层厚1.5mm。观察软骨在膝关节不同部位的分层表现。结果在MRI上膝关节软骨可见分层表现,大部分分为3层(约92.1%),少数无分层(约6.4%),有2例分5层(约1.5%)。在FLASH和FISP序列,膝关节软骨可显示5层、3层和1层,分5层者信号强度从表面向深层依次为高信号、中等信号、高信号、中等信号和高信号,分3层者信号强度从表面向深层依次为高信号、中等信号和高信号,无分层者为均匀高信号。SE序列膝关节软骨可显示3层或1层,分3层者从表面向深层信号强度依次为中等信号、低信号、中等信号,无分层者为均匀中等信号。结论MRI上正常人膝关节软骨大部分分为3层,少数无分层,个别分为5层。     

MRI测量正常人膝关节软骨厚度

目的　探讨MRI测量膝关节软骨厚度的方法以及软骨密度与年龄、性别、身高和体重的关系 ,研究正常人膝关节软骨的分布特征 ,为关节病变的早期诊断提供影像学基础。方法　正常膝关节 14 0例 ,分为 7个年龄组 ,用FLASH -FS -T1WI和 3D -FISP -FS -T2 WI序列行矢状面扫描。分别选取胫骨内、外髁正中矢状面图像作为测量层面 ,每个膝关节选取 12个测量点 ,测量软骨厚度规定为从软骨表面至“潮线”处。结果　膝关节软骨的分布是不均匀的 ,在不同区域厚度不同 ,股骨侧软骨平均厚度大于胫骨侧 ,分别为 3 .0 1mm和 2 .70mm。男性软骨平均厚度大于女性 ,分别为 ( 2 .90± 0 .75 )mm和 ( 2 .5 7± 0 .5 6)mm。 15岁以下年龄组平均软骨厚度明显 >16岁以上各年龄组 ,16岁以上各年龄组软骨厚度近似。身高低于 15 0cm时 ,身高越高软骨越薄 ,身高高于15 0cm与软骨厚度无明显关系。体重在 40kg以下时 ,体重越重软骨越薄 ,体重在 40kg以上时与软骨厚度无明显关系。 结论　正常人膝关节不同区域软骨厚度不同。男性软骨厚度大于女性。 16岁以后软骨厚度与年龄、身高和体重均不相关 ,15岁以前与年龄、身高和体重呈负相关可能仅代表了发育过程的变化     

正常人胫股关节软骨T2及T2*弛豫值的比较研究

目的:探讨正常志愿者膝关节软骨的T2及T2*弛豫值范围、影响因素及其内在相关程度。方法:将63名健康人胫股关节按照年龄分为青少年组(<35岁)18人、中年组(36~55岁)28人和老年组(56~78岁)17人,计算体重指数(BMI)并行T2图、T2*图成像,按照全器官磁共振成像评分(WORMS)规定的软骨分区法测量胫股关节软骨10个感兴趣区的T2、T2*弛豫率并取平均值,然后进行统计学分析。结果:健康人胫股关节软骨T2、T2*值分别为(42.98±4.19)ms、(19.75±2.43)ms。左右膝胫股关节T2、T2*值分别为(43.60±4.08 ms,42.37±4.26 ms)、(19.29±2.48 ms,20.21±2.37 ms),经检验两者均无明显统计学差异(P>0.05)。女性及男性胫股关节软骨T2、T2*值分别为(44.28±5.14 ms,41.86±4.09 ms)、(19.36±2.48 ms、20.09±2.42 ms),亦无明显统计学差异(P>0.05)。青少年组、中年组及老年组胫股关节软骨的T2、T2*值分别为(37.45±1.76 ms,41.29±2.13 ms,44.98±4.73 ms)、(17.95±1.58 ms,20.76±1.52 ms,22.30±2.08 ms),三组间有明显统计学差异(P<0.01)。青少年组、中年组及老年组三组内T2、T2*值均呈显著相关(P<0.05,Pearson相关系数分别为0.61、0.63、0.55)。结论:正常人胫股关节软骨T2及T2*弛豫值研究可以为关节软骨早期病变的诊断提供相似的参考价值,定量测定T2*值有望替代传统的T2值用于研究软骨形态学改变之前软骨内生化成分的变化。     

MR T2图评价膝关节软骨的初步探讨

目的 探讨MR T2图(T2 mapping)评价膝关节软骨生物组织构成变化的应用价值.方法 对20名健康志愿者运动前后双膝关节、19例骨性关节炎(OA)患者的患膝行矢状面SE序列8回波扫描.测量关节软骨各感兴趣区的T2值,比较志愿者运动前后及运动前浅、深层,以及志愿者与OA患者之间T2值的差异.原始图像经后处理后获得相应的T2图.运动前后T2值的比较采用配对t检验,运动前浅、深层及志愿者与OA患者间T2值的比较采用独立样本t检验.结果 志愿者运动前膝关节胫骨面软骨浅、深层的T2值分别为(48.8±6.3)ms、(44.3±5.7)ms;运动后分别为(43.4±5.0)ms、(40.3±6.1)ms,运动前后差异有统计学意义(t值分别为6.004和5.037,P值均<0.05);运动前胫骨面软骨浅、深层T2值差异有统计学意义(t=3.148,P<0.01).运动前股骨面软骨浅、深层的T2值分别为(52.1±5.7)ms、(47.7±5.3)ms;运动后分别为(47.2±4.5)ms、(43.6±4.1)ms;运动前后差异有统计学意义(t值分别为6.169和5.957,P值均<0.05);运动前股骨面软骨浅、深层T2值差异有统计学意义(t=3.384,P<0.01).相应的T2图显示了T2值变化的空间分布趋势.OA患者膝关节胫骨面关节软骨T2值为(56.0±9.1)ms,较志愿者要高,两组间比较差异有统计学意义(t=-3.446,P<0.01).结论 MR T2图可用于评价运动前后、OA时关节软骨生物组织构成的变化,对关节软骨退变诊断具有一定的临床指导价值.     

正常人膝关节软骨MR成像和软骨重建

目的　研究正常人膝关节软骨的MR成像和软骨三维重建方法 ,为临床诊治关节软骨病变提供科学依据。材料与方法　使用Philips 1.0T磁共振成像仪对 2 0例志愿者行软骨序列扫描 ,然后进行三维软骨重建。 结果　软骨序列及软骨重建技术可以清晰显示软骨的结构 ,关节软骨在SE序列上显示为 3层结构 ,在SPIR/ 3D/FFE/T1WI上最多显示为 4层结构 ,重建后的软骨像具有立体直观的效果 ,并具有良好的空间分辨率。结论　软骨MR成像和软骨重建能清晰显示膝关节的软骨结构 ,可为临床对骨关节病变的诊断和治疗提供帮助。     

Comparison of T2 Relaxation Values in Subtalar Cartilage between Patients with Lateral Instability of the Ankle Joint and Healthy Volunteers

Purpose

To evaluate the difference between T2 relaxation values of the subtalar cartilage in lateral ankle instability patients and healthy volunteers.

Materials and Methods

This institutional review board-approved study included 27 preoperative magnetic resonance imaging (MRI) examinations of 26 patients who underwent Broström operations. Data of previously enrolled healthy volunteers (12 volunteers, 13 MRIs) were used as controls. Two radiologists independently measured T2 values in eight posterior subtalar joint cartilage compartments: central calcaneus anterior (CCA) and posterior (CCP), central talus anterior (CTA) and posterior (CTP), lateral calcaneus anterior (LCA) and posterior (LCP), and lateral talus anterior (LTA) and posterior (LTP). Patient and control values were compared using linear regression analysis. Inter- and intraobserver agreement was calculated.

Results

Mean T2 values were significantly higher in the patient group in all measurements of subtalar joint cartilage compartments (p < 0.05) except that in LTP (p = 0.085) measured by reviewer 1. Both inter- and intraobserver agreements were excellent.

Conclusions

The T2 relaxation values of the subtalar cartilage were significantly higher in lateral ankle instability patients compared with those of controls.

Key Points

? Subtalar cartilage T2 values are increased in patients with lateral ankle instability. ? This trend was demonstrated regardless of the presence of talar dome cartilage lesions. ? Inter-and intraobserver agreements were excellent (intraclass coefficient range, 0.765-0.951) in subtalar cartilage T2 mapping.

     

Comparison of the T2 Relaxation Time of the Temporomandibular Joint Articular Disk between Patients with Temporomandibular Disorders and Asymptomatic Volunteers

BACKGROUND AND PURPOSE:T2 relaxation time is a quantitative MR imaging parameter used to detect degenerated cartilage in the knee and lumbar intervertebral disks. We measured the T2 relaxation time of the articular disk of the temporomandibular joint in patients with temporomandibular disorders and asymptomatic volunteers to demonstrate an association between T2 relaxation time and temporomandibular disorder MR imaging findings.MATERIALS AND METHODS:One hundred forty-four patients with temporomandibular disorders and 17 volunteers were enrolled in this study. An 8-echo spin-echo sequence for measuring the T2 relaxation times was performed in the closed mouth position, and the T2 relaxation time of the entire articular disk was measured. Patients were classified according to the articular disk location and function, articular disk configuration, presence of joint effusion, osteoarthritis, and bone marrow abnormalities.RESULTS:The T2 relaxation time of the entire articular disk was 29.3 ± 3.8 ms in the volunteer group and 30.7 ± 5.1 ms in the patient group (P = .177). When subgroups were analyzed, however, the T2 relaxation times of the entire articular disk in the anterior disk displacement without reduction group, the marked or extensive joint effusion group, the osteoarthritis-positive group, and the bone marrow abnormality–positive group were significantly longer than those in the volunteer group (P < .05).CONCLUSIONS:The T2 relaxation times of the articular disk of the temporomandibular joint in patients with progressive temporomandibular disorders were longer than those of healthy volunteers.

Disorders of the temporomandibular joint (TMJ) are characterized by intra-articular positional and/or structural abnormalities.¹ MR imaging is the preferred imaging technique for diagnosing temporomandibular disorders (TMD).² It has been reported that the diagnostic accuracy of MR imaging for the assessment of the articular disk position and articular disk formation is 95% and for the assessment of osseous changes is 93% in postmortem examinations.³ Numerous studies of TMD by using MR imaging have reported qualitative and morphologic evaluations, because the most important subgroup of articular abnormalities in patients with TMD includes different forms of articular disk displacement and deformation of the articular disk, either with normal bony joint components or accompanied by degenerative joint diseases such as osteoarthritis.⁴ Other MR imaging findings of TMD, including joint effusion and bone marrow abnormalities, have also been evaluated qualitatively and morphologically.^5,6The T2 relaxation time is a quantitative MR imaging parameter derived from multiecho spin-echo sequences. Measuring the T2 relaxation times by using MR imaging has been reported to detect degenerated cartilage in the knee and lumbar intervertebral disk.^7–11 The T2 relaxation time of the articular disk of the TMJ in healthy volunteers has been previously described by using a 3T MR imaging system,¹² but the T2 relaxation time of the articular disk of the TMJ in patients with TMD has not been reported, to our knowledge.We hypothesized that the T2 relaxation time of the articular disk of the TMJ correlates with the qualitative and morphologic variations in the pathology of the TMJ. The aims of this study were to measure the T2 relaxation time of the articular disk of the TMJ in patients with TMD and asymptomatic volunteers to demonstrate any association between T2 relaxation time and MR image findings of TMD.     

T2 Relaxation Time Mapping of the Cartilage Cap of Osteochondromas

Objective

Our aim was to evaluate the cartilage cap of osteochondromas using T2 maps and to compare these values to those of normal patellar cartilage, from age and gender matched controls.

Materials and Methods

This study was approved by the Institutional Review Board and request for informed consent was waived. Eleven children (ages 5-17 years) with osteochondromas underwent MR imaging, which included T2-weighted fat suppressed and T2 relaxation time mapping (echo time = 9-99/repetition time = 1500 msec) sequences. Lesion origins were femur (n = 5), tibia (n = 3), fibula (n = 2), and scapula (n = 1). Signal intensity of the cartilage cap, thickness, mean T2 relaxation times, and T2 spatial variation (mean T2 relaxation times as a function of distance) were evaluated. Findings were compared to those of patellar cartilage from a group of age and gender matched subjects.

Results

The cartilage caps showed a fluid-like high T2 signal, with mean thickness of 4.8 mm. The mean value of mean T2 relaxation times of the osteochondromas was 264.0 ± 80.4 msec (range, 151.0-366.0 msec). Mean T2 relaxation times were significantly longer than the values from patellar cartilage (39.0 msec) (p < 0.0001). These findings were observed with T2 spatial variation plots across the entire distance of the cartilage cap, with the most pronounced difference in the middle section of the cartilage.

Conclusion

Longer T2 relaxation times of the cartilage caps of osteochondromas should be considered as normal, and likely to reflect an increased water content, different microstructure and component.     

肺癌横向弛豫时间的实验研究

通过肺癌Ｔ２值的体内体外测量及比较，探讨了Ｔ２弛豫的机制及影响因素，旨在深化对肺癌ＭＲＩ影像的认识。材料和方法：采集１４个肺癌标本的癌组织、阻塞性病变、淋巴结及正常肺组织等共７６个样体进行体外Ｔ２值及水含量测定，并与标本相应之体内测量值进行比较分析，同时还比较了癌组织与肌肉、脂肪组织的Ｔ２值。所有结果比较均用ｔ检验进行统计学处理。结果：①组织水含量与Ｔ＿２弛豫时间呈正相关，相关系数为０．２１６７。②癌组织与阻塞性病变，正常肺组织及阳性淋巴结之间，阻塞性病变与正常肺组织之间，阳性阴性淋巴结之间之Ｔ２值均差别显著（Ｐ＜０．０５）。肺癌中高分化腺癌之Ｔ＿２值及水含量与其它各种组织类型肺癌差别显著。③体内体外测定之Ｔ２值基本来源于同一样体（Ｐ＞０．０５）。④癌一肌肉及脂肪与肌肉之Ｔ２值差别显著（Ｐ＜０．０１）。结论：组织Ｔ２弛豫时间与其水含量呈正相关，体内体外测定值相关性较好，即体内Ｔ２值测量可靠性较好。肺癌的Ｔ２值与脂肪组织接近，比肌肉组织长。Ｔ２值对鉴别肺癌与其它组织以及肺癌的组织类型有一定价值。     

磁共振T1、T2弛豫率的定量测定在实验性关节软骨退变中的应用研究

目的 通过动物实验,探讨磁共振生理学成像在检测关节软骨退变中的应用价值.材料与方法 20只新西兰大白兔随机分为甲、乙、丙、丁4组.甲组左膝关节行常规磁共振成像后即刻处死,取股骨髁软骨行苏木精和伊红染色(hematoxylin and eosin,HE)、阿利辛兰染色(alcian blue,AB)及蛋白多糖含量测定.乙、丙、丁各组每只兔左膝关节内注射0.2 ml木瓜蛋白酶,于注射前及注射后24、48、72 h先行相同常规磁共振成像及T2图成像(T2mapping),后行磁共振延迟增强软骨成像(delayed gadolinium enhanced MRI of cartilage,dGEMRIC),测定软骨T1、T2弛豫率.扫描结束后取左膝股骨髁部软骨行大体观察、HE、AB染色及蛋白多糖含量测定.结果注射木瓜蛋白酶后24、48 h,蛋白多糖含量与甲组比较,差异均有统计学意义(P=0.048和0.045,P＜0.05),注射后72 h,差异无统计学意义(P=0.455,P＞0.05).经t检验,注射后24、48 h的软骨T1弛豫率与注射前比较差异有统计学意义(P=0.047和0.045,P＜0.05).注射后24 h的软骨T2弛豫率与注射前比较差异有统计学意义(P=0.040,P＜0.05).结论 dGEMRIC、T2 mapping技术能够通过定量检测T1、T2弛豫时间值反映软骨退变早期的生化改变.     

Comparison of MRI T2 Relaxation Changes of Knee Articular Cartilage before and after Running between Young and Old Amateur Athletes

ObjectiveTo compare changes in T2 relaxation on magnetic resonance (MR) images of knee articular cartilage in younger and older amateur athletes before and after running.ResultsChanges in global cartilage T2 values after running did not differ significantly between the age groups. In terms of the depth variation, relatively higher T2 values in the older group than in the younger group were observed mainly in the superficial layers of the femoral and tibial cartilage (p < 0.05).ConclusionAge-related cartilage changes may occur mainly in the superficial layer of cartilage where collagen matrix degeneration is primarily initiated. However, no trend is observed regarding a global T2 changes between the younger and older age groups in response to exercise.     

无症状志愿者腰椎间盘磁共振定量测量研究

目的 通过测量无症状志愿者的椎间盘MRI横向弛豫时间,为早期判断椎间盘退变提供参考.方法 37名无症状志愿者行腰椎1.5T MRI矢状位T2WI及正中矢状位T2 mapping成像,根据Pfirrmann标准将185个L1～S1椎间盘分级,并测量髓核及纤维环前后缘T2弛豫时间.采用单因素方差分析分别比较各级髓核和纤维环前后缘T2弛豫时间有无显著性差异,并进行年龄与退变分级的Pearson's相关性分析.结果 共计测量185个椎间盘,统计结果示:①无症状志愿者年龄与椎间盘分级呈显著正相关,r＝0.735,P＜0.01;②腰椎间盘各分级髓核平均T2弛豫时间随分级的增高而减小,各分级平均T2弛豫时间统计学均有显著性差异,P值均＜0.05;③腰椎间盘纤维环各分级前后缘平均T2弛豫时间值随分级的增高未见明显变化,各级之间统计学均未见明显显著性差异,P值均＞0.05.结论 无症状志愿者腰椎间盘存在年龄相关性退变,MRI横向弛豫时间测量可以作为一种潜在的无创、早期定量评价年龄与腰椎间盘退变程度的手段.     

Experimental Evaluation of Accelerated T1rho Relaxation Quantification in Human Liver Using Limited Spin-Lock Times

Objective

It was reported lately that to obtain consistent liver T1rho measurement, at 3T MRI using six spin-lock times (SLTs), is feasible. In this study, the feasibility of using three or two SLT points to measure liver T1rho relaxation time was explored.

Materials and Methods

Seventeen healthy volunteers underwent 36 examinations. Three representative axial slices were selected to cut through the upper, middle, and lower liver. A rotary echo spin-lock pulse was implemented in a 2D fast field echo sequence. Spin-lock frequency was 500 Hz and the spin-lock times of 1, 10, 20, 30, 40, and 50 milliseconds (ms) were used for T1rho mapping. T1rho maps were constructed by using all 6 SLT points, three SLT points of 1, 20, and 50 ms, or two SLTs of 1 and 50 ms, respectively. Intra-class correlation coefficient (ICC) and Bland and Altman plot were used to assess the measurement agreement.

Results

Two examinations were excluded, due to motion artifact at the SLT of 50 ms. With the remaining 34 examinations, the ICC for 6-SLT vs. 3-SLT T1rho measurements was 0.922, while the ICC for 6-SLT vs. 2-SLT T1rho measurement was 0.756. The Bland and Altman analysis showed a mean difference of 0.19 (95% limits of agreement: -1.34, 1.73) for 6-SLT vs. 3-SLT T1rho measurement, and the mean difference of 0.89 (95% limits of agreement: -1.67, 3.45) for 6-SLT vs. 2-SLT T1rho measurement. The scan re-scan reproducibility ICC (n = 11 subjects) was 0.755, 0.727, and 0.528 for 6-SLT measurement, 3-SLT measurement, and 2-SLT measurement, respectively.

Conclusion

Adopting 3 SLTs of 1, 20, and 50 ms can be an acceptable alternative for the liver T1rho measurement, while 2 SLTs of 1 and 50 ms do not provide reliable measurement.