应用ARFI技术评估肝脏纤维化和肝占位患者术前肝储备功能

目的:探讨声脉冲辐射力弹性成像(ARFI)技术评估肝脏纤维化和肝占位患者肝脏储备功能的临床应用价值.方法:选取肝占位患者112例(肝占位组),健康志愿者34例(对照组),采用ARFI技术测量患者肝实质硬度(LS)值;采用吲哚氰绿(ICG)排泄实验记录ICG 15分钟滞留率(ICG-15R)和ICG血浆清除速率(ICG-K);采用Metavir分期对肝纤维化进行病理分期.LS值与肝纤维化分期、ICG-15R、ICG-K的相关性采用Pearson相关分析;比较肝脏占位组与对照组、手术治疗与非手术治疗患者及肝纤维化各病理分期之间的LS值并进行统计学分析;以肝纤维化病理分期为标准,采用受试者工作特性(ROC)曲线计算LS值对肝占位患者肝纤维化分期的诊断效能.结果:LS值与肝脏病理分期呈显著正相关(r=0.823,P＜0.001),并且LS值在评估不同分期纤维化时均有较高的特异度和敏感度;LS值与ICG-15R呈显著正相关(r=0.716,P＜0.001),与ICG-K呈显著负相关(r=-0.717,P＜0.001).肝占位组LS值为(1.78±0.48) m/s,对照组LS值为(1.19±0.11) m/s,差异有统计学意义(P＜0.001).非手术患者LS值为(2.49±0.27)m/s,手术患者LS值为(1.49±0.37) m/s,差异有统计学意义(P＜0.001).纤维化各病理分期之间的LS值差异有统计学意义(H=83.226,P＜0.001).结论:ARFI技术通过测量LS值能对肝纤维化进行量化分析,同时可有效评估肝占位患者的肝脏储备功能,为临床提供一种简单、无创的肝纤维化程度和术前肝储备功能的评估手段.     

声辐射力脉冲成像技术对肝纤维化分级的应用价值

目的探讨声辐射力脉冲成像技术(ARFI)对慢性乙型肝炎病毒引起的肝纤维化的诊断价值。方法对239例经肝穿刺活检病理检查、26例临床确诊的乙肝肝硬化患者(列为F4级),应用ARFI技术测定肝脏剪切波速,检测肝纤维化程度,根据病理S0～S4分期,将患者分为F0～F4级。比较ARFI与血清肝纤维化标志物对肝纤维化程度的诊断价值,建立本地区的最佳界限值。设立50例正常对照组。结果 239例肝活检患者中病理诊断为S0～S4期的病例数分别为58例、48例、54例、59例和20例,ARFI平均值分别为(1.17±0.25)m/s、(1.39±0.36)m/s、(1.91±0.49)m/s、(2.66±0.51)m/s、(2.75±0.41)m/s。265例中,F0期与F1期,F3期与F4期的ARFI值之间差异无统计学意义。F0期与F2期、F3期、F4期之间,F1期与F2期、F3期、F4期之间,F2期与F3期、F4期之间差异有统计学意义(P<0.05)。ARFI分级结果与肝纤维化病理分期的相关性高于血清肝纤维化标志物,肝剪切波速中值数2.7是ARFI检查肝纤维化与肝硬化的交界点。结论 ARFI技术可较客观的评价肝纤维化分级,为临床提供一种无创评价肝纤维化程度的检查方法。     

肝纤维化磁共振ADC值与病理学分期的相关性研究

目的 探讨磁共振ADC值、肝纤维化血清学指标与肝纤维化病理分期之间的相关性.方法 检测41例慢性肝病患者磁共振ADC值和肝纤维化血清学4项指标,包括透明质酸(HA)、Ⅳ型胶原(C-Ⅳ)、层粘连蛋白(LN)和Ⅲ型前胶原(PCⅢ),并与肝穿刺的病理纤维化分期结果进行相关性分析.结果 b=400 s/mm2时,S0～1期、S2～3期及S4期ADC值分别为(1661.5±94.4)、(1522.7±83.4)、(1408.3±110.3)×10-6 mm2/s;b=600 s/mm2时3组ADC值为(1448.3±75.1)、(1349.7±55.9)、(1222.6±79.9) ×10-6mm2/s;b=800 s/mm2时3组ADC值为(1361.4±48.1)、(1285.0±46.5)、(1214.3±50.2)×10-6mm2/s.随肝纤维化分期进展ADC值递减,差异均具有统计学意义(P＜0.01),且ADC值与肝纤维化分期之间具有很好的负相关性,以b=600 s/mm2时相关关系最密切(r=-0.786).肝纤维化血清学4项指标与ADC值之间存在不同程度的负相关性.结论 ADC值可以定量肝纤维化的严重程度,与血清学指标共同反映肝纤维化的特征性病理表现.     

声脉冲辐射力成像技术联合肝纤维化指标评估肝硬化程度的诊断价值

目的:探讨声脉冲辐射力成像技术(ARFI)联合肝纤维化指标评估肝硬化程度的诊断价值.方法:选取本院90例肝硬化患者作为观察组,按照Child-Pugh(CP)评分对患者肝硬化程度进行分级;选取45例健康体检者作为对照组.检测所有研究对象的肝纤维化4项指标:透明质酸(HA)、层黏蛋白(LN)、Ⅲ型前胶原(PCⅢ)、Ⅳ型胶原(Ⅳ-C),并行ARFI技术检测,测得肝实质硬度值(LS).观察不同CP评分分级的LS值与肝纤维化4项指标(HA、LN、PCⅢ、Ⅳ-C),采用受试者操作特征(ROC)曲线分析LS值与血清肝纤维化4项指标单用或联用对肝硬化的诊断价值.结果:观察组CP评分A、B、C三级患者的LS值和血清肝纤维化4项指标水平均明显高于对照组,且C级＞B级＞A级,差异均具有统计学意义(P＜0.05).CP评分与LS值、HA、LN、PCⅢ、Ⅳ-C均呈正相关(r=0.782,P＜0.01;r=0.147,P＜0.05;r=0.485,P＜0.01;r=0.421,P＜0.01;r=0.262,P＜0.05).ROC曲线显示:不同CP等级的LS值的AUC均高于血清肝纤维化4项指标;而LS值与血清肝纤维化4项指标联用对不同CP等级肝硬化诊断的AUC、敏感性及特异性均高于其单用.结论:ARFI检测的LS值联合血清肝纤维化4项指标对肝硬化程度的诊断效能较高,具有重要的临床应用价值.     

DWI及声辐射力脉冲成像在肝纤维化诊断中的价值

目的对比DWI和声辐射力脉冲成像(acoustic radiation force impulse imaging,ARFI)对肝纤维化的诊断价值。方法对50例肝纤维化患者(观察组)及16例健康志愿者(正常对照组)行DWI(b=0、600s/mm 2)扫描,并测量ADC值;2组同时行ARFI检查,检测指标为低频剪切波传播速度(shear wave velocity,SWV)。分析并对比不同组间ADC值和SWV的变化规律。结果SWV波速随肝脏纤维化分期(从S0~S4期)升高而递增,而ADC值则呈降低趋势(P<0.05)。肝纤维化各组与正常对照组间比较差异均有统计学意义,肝纤维化各组组间比较差异均有统计学意义。结论在肝纤维化定量中,ARFI和DWI均具备一定的检测能力。在诊断肝纤维化敏感度方面,ARFI高于DWI;而在特异度方面,DWI优于ARFI,两者皆可检测重度肝纤维化及肝硬化。     

不同b值DWI对大鼠肝纤维化、肝硬化病理分级的意义

目的:探讨1.5 T MRI不同b值DWI下的ADC值、e ADC值与大鼠肝纤维化、肝硬化分级的相关性。方法:清洁级SD大鼠100只,雄性,体质量180~200 g。将大鼠随机分为实验组84只,对照组16只,实验组采用硫代乙酰胺(TAA)腹腔定点注射,对照组同期腹腔注射同剂量生理盐水。常规MRI检查后,DWI采用FSE-EPI,按b=300、600 s/mm2分为2组,生成ADC图及e ADC图,并测量相应ADC及e ADC值;根据病理结果将肝损伤分为肝纤维化0期(对照组)、肝纤维化I~Ⅱ期(早期)、肝纤维化Ⅲ~Ⅳ期(晚期)、肝硬化结节期。结果:共59只(实验组47只,对照组12只)大鼠成功行DWI检查。1b=300 s/mm2时,实验组ADC值均低于对照组,对照组与实验组各期之间及肝硬化结节期与其余各组之间差异均有统计学意义(均P0.05);e ADC值均高于对照组,肝硬化结节期与其余各组间差异均有统计学意义(均P0.05),对照组与肝纤维化晚期组之间差异有统计学意义(P0.05)。b=600 s/mm2时,实验组ADC值均低于对照组,肝硬化结节期与其余各组间差异有统计学意义(均P0.05),对照组与肝纤维化晚期组之间差异有统计学意义(P0.05);肝硬化结节组e ADC值与各组两两比较差异均有统计学意义(P0.05)。2ADC值与SD大鼠肝纤维化、肝硬化病理分级之间呈负相关,b=300 s/mm2时,r=-0.463(P0.05);b=600 s/mm2时,r=-0.606(P0.05)。e ADC值与SD大鼠肝纤维化、肝硬化病理分级之间呈正相关,b=300 s/mm2时,r=0.504(P0.05);b=600 s/mm2时,r=0.435(P0.05)。结论:ADC值和e ADC值能对肝纤维化、肝硬化进行分级,且有一定的相关性。b=600 s/mm2时,ADC值与肝纤维化、肝硬化分级之间相关性最好。     

3.0 T MR标准化表观扩散系数值评价肝纤维化程度的研究

目的 探讨标准化ADC值对肝纤维化程度定量分析的能力.方法 采用3.0 TMRDWI检查回顾性分析10名健康志愿者(对照组)和43例经肝脏穿刺活检病理证实为肝功能代偿期的肝病患者(慢性肝病组)资料,慢性肝病组患者进行肝纤维化分期(S分期).测量不同肝纤维化分期下肝脏ADC值、脾脏ADC值、肾皮质ADC值、脾脏标准化ADC值(S-ADC)及肾脏标准化ADC值(R-ADC).采用非参数Spearman检验分析S分期与ADC值之间的相关性;采用单因素方差分析比较各期ADC值间的差异,采用Logistic回归分析评价ADC值预测纤维化程度的能力,选择约登指数最大作为截断点,计算曲线下面积(AUC)、敏感度及特异度.结果 10名对照组志愿者均为SO期.慢性肝病组SO、S1、S2、S3、S4期分别有2、5、9、12和15例.S0～S4期肝脏ADC值分别为(1.37±0.13) ×10-3、(1.33±0.16)×10-3、(1.17±0.16) ×10 -3、(1.23 ±0.14)×10-3和(1.12 ±0.11)×10-3 mm2/s,S-ADC分别为1.86 ±0.18、1.68 ±0.12、1.34 ±0.14、1.48 ±0.15和1.34 ±0.10,R-ADC分别为0.71 ±0.08、0.68 0.12、0.61 ±0.09、0.64±0.11和0.60±0.08,差异均有统计学意义(F值分别为6.48、18.70和3.04,P＜0.05).S-ADC、肝脏ADC值和R-ADC均与肝纤维化分期呈负相关性(r值分别为-0.71、-0.51和-0.41,P值均＜0.01),但S-ADC与肝纤维化分期的相关性高于肝脏ADC值和R-ADC.对于预测≥S2期、≥S3期及s4期纤维化,S-ADC的效果均优于肝脏ADC值、R-ADC,约登指数分别为0.91、0.58和0.59.结论 S-ADC在评价肝纤维化方面优于肝脏ADC值及R-ADC,具有良好的诊断准确性.     

多层螺旋CT肝脏灌注成像评价慢性肝纤维化、肝硬化的价值

目的 探讨MSCT灌注参数评价慢性肝纤维化、肝硬化的价值.方法 对经肝穿刺病理活检确诊的轻度肝纤维化(肝纤维化分期为S1、S2期)31例,重度肝纤维化(肝纤维化分期为S3、S4期)和(或)早期肝硬化34例,具有典型临床症状和影像表现的晚期肝硬化42例以及对照组30例行16层螺旋CT肝脏灌注扫描,取得不同病变阶段肝实质的灌注参数,包括肝动脉灌注量(HAP)、门静脉灌注量(PVP)、全肝总灌注量(TLP)、肝动脉灌注指数(HPI)及达峰时间(TTP)5个指标,并与病理分期作对照研究.各组肝脏不同CT灌注参数值的比较采用方差分析;各灌注参数值与肝纤维化严重程度的相关性采用秩相关分析;采用多因素分析(Logistic回归)探讨肝脏灌注参数值中对肝纤维化病理分期影响最大的指标.结果 对照组、S1、S2期组、S3、S4期组及肝硬化组的HAP值分别为(28.9±8.6)、(24.6±2.4)、(29.2±2.3)和(38.9±7.0)ml·100 ml-1·min-1,表现为先下降后增高,各组间差异有统计学意义(F =40.26,P＜0.01);上述各组PVP分别为(111.3±18.1)、(92.9±5.3)、(73.0±9.0)和(54.1 ±13.8)ml·100 ml-1·min-1,TLP分别为(140.2 ±25.9)、(117.1±4.5)、(102.3±8.7)和(93.0±ll.8)ml.100 ml-1·min-1,差异均有统计学意义(F值分别为136.79、67.40,P值均＜0.01);各组的HPI分别为(20.4±2.6)％、(21.0±2.1)％、(28.5±3.1)％和(42.6±1 1.1)％,TTP分别为(123.7±22.2)、(137.1 ±27.1)、(145.0±28.6)和(166.5 ±25.1)s,差异亦均有统计学意义(F值分别为93.05、17.37,P值均＜0.01).PVP、TLP与肝纤维化严重程度呈显著负相关,r值分别为-0.920和-0.846,P值均＜0.01;HAP、HPI、TTP则与肝纤维化程度呈正相关关系,r值分别为0.611、0.882和0.545,P值均＜0.01.在肝脏CT灌注扫描的参数值中,PVP的标准化回归系数最大(-8.798).ROC曲线判断得到的最佳临界点PVP =84.76 ml· 100 ml-1· min1作为重度肝纤维化S3、S4期和(或)早期肝硬化的诊断阈值,其敏感度和特异度分别为0.890、0.950,准确度达0.931.结论MSCT灌注参数能反映肝纤维化、肝硬化的血流动力学改变;CT灌注成像有助于鉴别重度肝纤维化和(或)早期肝硬化及晚期肝硬化.     

磁共振灌注成像在鼠肝纤维化、肝硬化病理分级中的价值

目的:分析大鼠肝纤维化、肝硬化磁共振灌注成像(MR-PWI)参数特征,评价PWI对肝纤维化、肝硬化病理分级的价值.方法:清洁级SD大鼠100只,体重约150～200 g,雄性.将大鼠随机分为2组,对照组(n=16),实验组(n=84);实验组腹腔定点注射硫代乙酰胺(TAA),对照组同期腹腔注射相同剂量生理盐水.建模成功后实验组和对照组分批次进行肝脏常规磁共振扫描及PWI扫描.依据病理结果将肝脏损伤分为5组:肝纤维化0期(对照组)、肝纤维化Ⅰ期(S1),肝纤维化Ⅱ期(S2),肝纤维化Ⅲ期(S3),肝硬化结节期(S4),然后分析灌注参数与病理分级的相关性.结果:共69只大鼠(实验组57只,对照组12只)成功获取PWI图像并进行灌注参数测量,成功率69％(69/100).各期门静脉诸灌注参数之间差异有统计学意义(P＜0.05),各期肝实质诸灌注参数之间差异有统计学意义(P＜0.001).门静脉TTP及WOR与肝纤维化分级之间存在相关性(r=0.420、-0.464,P＜0.001).肝实质TTP及WIR与肝纤维化分级之间存在相关性(r=0.424、-0.488,P＜0.001).结论:MR-PWI参数与大鼠肝纤维化、肝硬化的分级有一定相关性.MR-PWI对评价肝纤维化分期具有一定的临床价值.     

磁共振体素内不相干运动成像诊断肝纤维化的初步研究

＿目的：采用磁共振体素内不相干运动（IVIM）扩散成像,获得正常志愿者和不同病理分期肝纤维化患者肝脏的磁共振IVIM扩散成像相关信号值（D、f、D*）,为临床评估肝纤维化提供一种无创、安全和简便的检测方法。方法：对39例不同病理分期的肝纤维化患者（S1期15例,S2期10例,S3及 S4期14例）及19例健康志愿者进行肝脏磁共振IVIM扩散成像。取多b值（10,20,40,60,80,100,150,200,400,800s／mm2）,经过分析和公式 SI（b）＝ SI0[（1－f）· exp（－b·D）＋f·exp（－b·D*）]非线性回归计算获得D、f、D*值,采用统计学分析正常肝脏和纤维化肝脏之间、肝纤维化不同病理分期之间肝脏的D、f、D*值差异。结果：肝纤维化组和健康组的肝脏磁共振体素内不连贯运动成像扫描参数D、f、D*值分别是0．940±0．129和1．089±0．127（10－3mm2／s,P＜0．001）,0．126±0．026和0．163±0．018（P＜0．001）,9．616±1．747和12．715±2．335（10－3mm2／s,P＜0．001）。结果显示肝纤维化患者的D、f、D*值均显著减低。随着肝纤维化程度的进展,f、D*值持续下降,差异具有统意义（P≤0．001）。结论：磁共振IVIM扩散成像研究发现纤维化肝脏D、f、D*值降低,f值与D*值的降低与肝纤维化程度相关,为评价肝纤维化的严重程度提供了依据。     

Detection of Small Hypervascular Hepatocellular Carcinomas in Cirrhotic Patients: Comparison of Superparamagnetic Iron Oxide-Enhanced MR Imaging with Dual-Phase Spiral CT

Objective

To compare the performance of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging at 1.5T and dual-phase spiral computed tomography (CT) for the depiction of small hypervascular hepatocellular carcinomas (HCCs).

Materials and Methods

Forty-three patients with 70 small nodular HCCs (5-20 mm; mean, 13.7 mm) were examined. Diagnosis was based on the results of surgical biopsy in 22 patients and by the combined assessment of MR imaging, lipiodol CT, alpha feto-protein levels, and angiographic findings in 21. MR imaging consisted of respiratory-triggered turbo spin-echo T2-weighted imaging, T1-weighted fast low-angle shot, and T2*-weighted fast imaging with steady-state precession imaging before and after SPIO enhancement. CT imaging was performed with 5-mm collimation and 1:1.4 pitch, and began 30 and 65 secs after the injection of 150 mL of contrast medium at a rate of 3 mL/sec. Two blinded observers reviewed all images independently on a segment-by-segment basis. Diagnostic accuracy was evaluated using receiver operating characteristics (ROC) analysis.

Results

The mean areas (Az) under the ROC curves were 0.85 for SPIO-enhanced MR imaging and 0.79 for dual-phase spiral CT (p < .05). The mean sensitivity of SPIO-enhanced MR imaging was significantly higher than that of CT (p < .05), i.e. 70.6% for MR imaging and 58.1% for CT. MR imaging had higher false-positive rates than dual-phase spiral CT, but the difference was not statistically significant (3.7% vs 3.3%) (p > .05).

Conclusion

SPIO-enhanced MR imaging is more sensitive than dual-phase spiral CT for the depiction of small hypervascular hepatocellular carcinomas.     

Early-stage focal nodular hyperplasia: US/CT/MR features correlated with histology

Two cases of local nodular hyperplasia (FNH), in which ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MR) studies detected an atypical hemorrhagic pattern associated with an intrahepatic arterio venous malformation (AVM) around the growths, are presented. In both cases, histology demonstrated a very early regenerative stage — without central scar or fibrosis — and necrotichemorrhagic areas within the lesions. In these cases, the analysis of radiological findings, surgical specimens and histology seemed to confirm the pathogenetic hypothesis suggested by Wanless [1]: in normal liver parenchyma, a blood steal phenomenon due to congenital or acquired intrahepatic AVM — arterio portal or porto systemic shunt — could cause ischemic damaged, appering as a hemorrhagic necrotic area, the extent of which depends on the degree of residual portal supply (maintained in Case 1, and markedly reduced in Case 2 due to arterio portal shunting). The subsequent phase of repair could activate the regenerative-hyperplastic process, evolving into final fibrosis, which represents the mature pattern of FHN. Correspondence to: R. Golfieri     

肝硬化相关小肝癌的血供特点和MRI表现

目的:通过分析肝硬化相关小肝癌的MRI平扫及增强扫描的信号特点,结合其血供情况,总结小肝癌的MRI特点,提高小肝癌的诊断水平。方法:对经临床和病理证实的48个肝硬化相关小肝癌行MRI平扫及增强扫描,对其影像学资料进行回顾性分析。结果:48个肝硬化相关小肝癌中,T1WI以稍低、低信号(68.8%)为主,T2WI以稍高、高信号(70.8%)为主,其中10例在T1WI同相位呈等或高信号,在T1WI反相位呈等或低信号影;19例可见假包膜。动态增强扫描后,强化方式有5种:无强化、边缘轻度强化、速升速降、缓升速降及速升缓降;以速升速降(35个,72.9%)为主。结论:肝硬化相关小肝癌的血供方式有5种:动脉、门脉血供均减少;动脉、门脉血供正常或略增加;动脉血供增加,门脉血供减少;门脉血供增加;动脉、门脉血供均增加。其中以动脉血供增多、门脉血供减少为主要血供方式,结合MRI信号特点,可提高早期诊断与鉴别诊断水平。     

Selective versus nonselective preparation pulses in two-dimensional MP-RAGE imaging of the liver.

The use of a section-selective preparation pulse in two-dimensional (2D) T1-weighted magnetization-prepared rapid gradient-echo (MP-RAGE) imaging of the liver was investigated. The images were compared with those obtained with a nonselective pulse. The performances of the sequences were evaluated in 11 patients with 12 focal liver lesions, and lesion-liver and lesion-vessel signal difference-to-noise ratios (SD/Ns) were calculated. With the section-selective preparation pulse, small lesions were better differentiated from vessels, and multiple, consecutive images could be obtained at shorter intervals. The mean lesion-liver SD/N was slightly but not significantly greater for images obtained with a selective pulse, while the lesion-vessel SD/N was significantly greater (P less than .01). It is concluded that a section-selective preparation pulse can improve the clinical utility of the 2D MP-RAGE sequence in the evaluation of focal liver disease.     

多排螺旋CT与MRI对乙肝肝硬化背景小肝癌检出的比较研究

目的 比较多排螺旋CT与MRI对乙肝肝硬化背景小肝癌病灶的检出能力.方法 83例乙肝肝硬化患者共91个小肝癌病灶,分为小肝癌(1 ～3 cm)和微小肝癌(≤1 cm)两组,其中小肝癌63个,微小肝癌28个,均行CT(平扫、动脉期、门静脉期、平衡期)与MRI[T2Wl、扩散加权成像(DWI)、梯度回波同相(IN-PHASE)、梯度回波反相(OUT-PHASE)、容积快速三维成像(LAVA)平扫、动脉期、门静脉期及平衡期]两种检查.比较CT与MRI对两者的检出率.结果 (1)63个小肝癌,检出率最高的序列是LAVA动脉期和CT动脉期,检出率最低的序列是CT平扫,CT和MRI共12个期相和序列对小肝癌的检出率总体差异无统计学意义(P=0.213);28个微小肝癌,检出率最高的是LAVA动脉期,最低的是LAVA平衡期,12个期相和序列对微小肝癌的检出率总体差异无统计学意义(P=0.207).(2)CT各期(平扫、动脉期、门静脉期、平衡期)及MRI IN-PHASE、LAVA平扫、LAVA平衡期对小肝癌和微小肝癌的检出率差异有统计学意义(P值分别为:0.020、0.004、0.002、0.004和0.028、0.006、0.000),而MR-T2WI、DWI、OUT-PHASE、LAVA动脉期及LAVA门静脉期对小肝癌和微小肝癌的检出率差异无统计学意义(P值分别为0.249、0.303、0.107、0.251、0.168).(3)CT和MRI对小肝癌、CT和MRI对微小肝癌的检出率差异均无统计学意义(P=1.000、P=0.125).(4)CT与MRI对小肝癌的检出率均高于微小肝癌,CT对小肝癌和微小肝癌的检出率差异有统计学意义(P =0.004),MRI对两者检出率差异无统计学意义(P =0.223).结论 MRI-LAVA动脉期对小肝癌和微小肝癌的检出率最高;MRI相对于CT更有利于微小肝癌病灶的检出.     

Hepatic T2-weighted MRI: A prospective comparison of sequences,including breath-hold,half-Fourier turbo spin echo (HASTE)

The purpose of this study was to quantitatively compare the hepatic contrast characteristics of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences with breath-hold T2-weighted images acquired with half-Fourier turbo spin echo (HASTE). Forty-five patients were examined with a phased-array surface coil. Nineteen patients had focal hepatic lesions, including eight malignant tumors, 10 cavernous hemangiomas, and one hepatic adenoma. Twenty-six patients had no focal hepatic lesions. T2-weighted images with comparable TE were acquired with CSE, FSE, and HASTE pulse sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for liver, spleen, and lesions were measured. FSE demonstrated significantly better quantitative performance than CSE for liver-spleen CNR (P = .0084). No statistically significant difference was demonstrated between FSE and CSE for liver or spleen SNR. FSE demonstrated clear scan time and resolution advantages over CSE. HASTE performed significantly poorer than CSE and FSE for liver-spleen CNR (P < .0001), liver SNR (P = .0002 for CSE and P < .0001 for FSE), and spleen SNR (P < .0001). Optimized FSE images with a short echo train length performed comparably to CSE images of equivalent TE. Liver-lesion CNR was suppressed on HASTE images, suggesting that long echo train length FSE sequences could diminish solid lesion detection compared to CSE and short echo train length FSE.     

肝纤维化指数评价实验兔肝纤维化程度的研究

目的:探讨肝纤维化指数(liver fibrosis index,LF index)评估肝纤维化程度的可行性。方法:54只新西兰兔皮下注射硫代乙酰胺(thioacetamide,TAA)诱导肝纤维化作为模型组,另取8只新西兰兔为正常对照组。每隔2周随机取2~4只实验兔行实时组织超声弹性成像(real-time tissue elastography,RTE)检查,得出LF index。处死实验兔,取肝组织进行肝纤维化病理分组(S0~S4组),并与病理分期进行对照研究。结果:S2、S3、S4组LF index显著高于正常对照组与S1组(P均0.05);S3、S4组LF index显著高于S0组、S2组(P均0.05);LF index随肝纤维化病理分期加重呈增加趋势,二者呈正相关(r=0.718,P0.05)。结论:LF index有望成为无创评估肝纤维化程度的定量指标。     

T2-weighted MR imaging of focal hepatic lesions: Comparison of various RARE and fat-suppressed spin-echo sequences

The authors prospectively compared four T2-weighted magnetic resonance (MR) sequences, including high-resolution 512 × 512 (matrix size) RARE (rapid acquisition with relaxation enhancement), 256 × 256 RARE, 128 × 256 breath-hold RARE, and 192 × 256 fat-suppressed spin-echo (T2FS) sequences, in the evaluation of 16 patients with focal hepatic masses. MR images were evaluated by quantitative lesion-liver signal difference-to-noise ratios (SDNRs) and subjective evaluation of image artifact and image quality. No significant differences were observed between RARE sequences in SDNR values. The T2FS sequence had a significantly higher SDNR than the 512 × 512 RARE sequence (24.6 ± 15.0 vs 14.5 ± 9.7) (P =.008). Image quality was rated highest for the 512 × 512 RARE and T2FS sequences (P =.006). The inherent advantage of high spatial resolution suggests that the 512 × 512 RARE sequence may be of value in detecting hepatic lesions.     

Comparison of breath-hold T1-weighted MR sequences for imaging of the liver

Three rapid T1-weighted gradient-echo techniques for imaging of the liver were compared: fast low-angle shot (FLASH) and section-selective (SSTF) and non-section-selective (NSTF) inversion-recovery TurboFLASH. Ten healthy volunteers were imaged at 1.5 T, with breath-hold images acquired in the transaxial and coronal planes and non-breath-hold images in the transaxial plane. Breath-hold images were evaluated quantitatively and qualitatively, and non–breath-hold images were evaluated qualitatively. FLASH images had significantly higher (P <.001) spleenliver signal difference–to-noise ratios (SD/Ns) than NSTF and SSTF images. Liver signal-to-noise ratios (S/Ns) were significantly higher (P <.001) on FLASH images than on NSTF and SSTF images. With breath hold. FLASH images were rated as having the highest quality in the axial plane, followed by NSTF and SSTF images. In the coronal plane, NSTF images were rated as having the highest quality. For images acquired during patient respiration, NSTF images had the highest quality and showed the least degradation. The results suggest that FLASH images have the highest SD/N and S/N for liver imaging and have the highest quality in the axial plane. In patients who cannot suspend respiration, NSTF images may be least affected by breathing artifact and provide reasonable image quality.