大鼠肝细胞癌MR信号特征及相关病理基础

目的探讨肝癌演进过程中的MR信号特征及其相关病理基础.方法诱导法建立大鼠肝癌模型,于不同时相行MRI检查,对病灶行病理分级,并定量分析脂肪、糖原含量.结果51个病灶T2WI均呈高信号,T1WI分别呈高(10/51)、等(9/5D)低(32/51)信号.T1WI高信号以16～18周多见,等信号20～21周多见,低信号22～25周多见.T1WI高信号组癌组织脂肪含量明显高于癌周组织及低信号癌组织(P＜0.01).结论肝细胞癌演进过程中TIWI信号呈由高到低的趋势;T1WI信号与癌组织病理分级和脂肪含量有关.     

磁化传递对比磁共振成像在诱发性大鼠肝硬化肝癌中的初步应用研究

目的 初步探讨磁化传递对比（MTC）磁共振成像（MRI）技术在诱发性大鼠肝硬化肝癌中的作用。方法二乙基亚硝胺溶液诱发的大鼠肝硬化肝癌模型16只，结合病理检查发现〉5．0cm的癌结节66个，对照组为10只正常Wister大鼠。所有大鼠均行附加MT脉冲前后MRI扫描，序列包括SE序列T1WI、FSE序列T2WI。测量MR图像上正常肝组织、硬化肝脏及肝癌组织附加MT脉冲前后的的信号强度，计算信噪比（SNR）、对比噪声比（CNR）及磁化传递率（MTR）。结果SE序列T1WI上，附加MT脉冲后正常肝实质信号强度降低，SNR低于无MT脉冲图像（P=0．002）；肝硬化组织附加MT后信号强度显著下降，SNR明显低于无MT时（P=0．000）；肝癌附加MT后SNR两者无显著差异（P-0．334），CNR较附加MT前降低但无统计学差异（P-0．158）。FSE序列T2WI上，正常肝实质附加MT后信号强度降低，SNR低于无MT脉冲时（P=0．021）；肝硬化附加MT后SNR显著低于无MT时（P=0．000）；肝癌附加MT脉冲前后信号强度无明显变化，SNR无统计学差异（P=0．549），CNR较附加MT前增高，但两者间无显著差异（P=0．205）。SE序列T1WI上，肝硬化MTR显著高于正常肝实质及肝癌（P=0．001）；正常肝实质与肝癌MTR类似（P=0．788）。FSE序列T2WI上，硬化肝组织的MTR较正常肝实质及肝癌明显增高（P=0．002；P=0．000）；正常肝实质与肝癌的MTR无统计学差异（P=0．352）。结论FSE序列T2WI附加MT脉冲图像上肝硬化组织信号降低，而肝癌信号强度变化不明显，对比度提高。有利于肝硬化背景上肝癌病灶的检出和显示。     

肝细胞癌的MRI诊断

目的：提高MRI对肝细胞癌的诊断与鉴别诊断能力。通过分析MRI征象，建立肝细胞癌的MRI信号变化模式。材料与方法：28例肝细胞癌患者均接受MRI检查。男24例，女4例，年龄32～80岁，平均52岁。检查使用0．5T超导型MR成像系统。常规SE序列T1W成像．TSE序列T2W双回波成像。采用双盲法作前瞻性回顾分析。结果：MRI能清楚显示肝细胞癌的部位，大小、形态、数目，与周围组织关系及继发改变。其MR信号变化具有一定特征性，即T1WI多呈低信号强度，T2WI第一回波（PDWI）呈稍高信号强度或等信号强度，T2WI第二回波多呈不均质性稍高信号强度。结论：根据MRI表现，尤其是信号变化特征，对肝细胞癌能作出定性诊断。并建议把SE序列T1WI，TSE序列T2WI双回波成像技术作为肝细胞癌的常规和首选检查方法。     

碘油在磁共振上信号特点的探讨

目的探讨碘油在磁共振上信号特点。方法收集2例肝癌插管化疗栓塞（TACE）患者，于0．5T的MR仪行常规腹部磁共振检查，包括SE序列T1WI、T2WI。制备样品：碘油样品取作肝栓塞剂的碘化油，并各取12ml的蒸馏水、泛影葡胺、碘海醇、碘（分析纯）、大豆色拉油、菜子油、血清置试管内作为对照。将试管顺序排列，于0．5T的MR仪进行多参数扫描；同时，将各制备品试管置于随机选取的常规扫描者体侧，获得试管与身体组织共同扫描图象，计算SNR值进行对比。结果在不同的磁场强度中碘油产生的信号强度不同，但可以通过调整扫描参数使信号强度趋于一致。碘油在体外SE序列T1WI上呈高信号，T2WI上低信号。体内成像的表现与周围环境的信号对比有关，在与正常肝脏对比中均为低信号。碘在MRI各个序列上均不成像，并且影响其他物质的碘油的信号强度低于油脂的信号强度。自旋回波长TR多回波的图像上信号强度SNR，TE30=6．3、TE60=2．8，TE90=1．6。结论可以用在自旋回波长TR多回波的图像来区分碘油，判断碘油的沉积情况，同时显示残存肿瘤的信号。     

肝硬化的MRI诊断及临床评价

目的 研究肝硬化及其并发症的MRI表现、诊断及其临床价值。方法 收集108例临床综合诊断为肝硬化病例的MRI资料，其中合并有原发肝细胞癌32例（小肝癌6例），20例行Gd-DTPA动态增强扫描。结果 肝硬化及其并发症MRI表现：（1）肝内弥漫性结节，按结节大小分为小结节、大小结节混合和大结节型。结节呈T1WI等或略高、T2WI低信号影。（2）肝脏增大或缩小，肝表面凹凸不平，各叶比例失调。（3）脾脏肿大、脾静脉扩张、胃冠状静脉或／和脾门静脉曲张，T1WI及T2WI均呈迂曲扩张的流空无信号影。（4）肝细胞癌，呈T1WI低、等或略高，T2WI高信号影。小肝癌在Gd-DTPA动态增强扫描中具有“快进快出”特征性强化形式。（5）腹水、呈T1WI明显低、T2WI明显高信号影。结论 MRI是诊断肝硬化及其并发症的可靠检查方法，Gd-DTPA动态增强扫描对小肝癌诊断有重要意义。     

臂丛神经MRI正常表现及检查方案

目的分析正常臂丛神经在MRI不同成像序列中的表现,确定臂丛神经损伤时最佳MRI检查方案。方法20名正常志愿者行常规及MR新技术检查。观察各序列中臂丛神经的表现及显示情况。结果常规T1WI、T2WI臂丛神经呈等信号,STIR上呈高信号。冠状面T1WI、T2WI及STIR图像对比噪声比分别为：4.96±0.31、6.07±0.18、23.09±1.20,STIR图像对比噪声比明显高于常规组（P=0.000）;对节后段C5,6神经根及上干的显示评分STIR序列明显高于常规序列。3D-FIESTA-c序列清晰显示椎管内神经前后根,为脑脊液高信号环绕下的等信号丝状结构。3D-FSPGR图像可清晰显示臂丛与邻近组织结构的关系。结论联合常规及MRI新技术,可全面、清晰地显示臂丛神经,作为臂丛神经的常规检查方案。     

膝关节周围隐匿性骨折MRI诊断的价值

目的:探讨膝关节周围隐匿性骨折MRI诊断的临床价值.方法:对30例有明确外伤史,临床症状明显但平片检查阴性患者行MRI检查,其中男19例,女11例.使用Philips Intera Achieva超导高场MRI系统,场强1.5 T.采用常规SE序列T1WI成像(TR、TE=700、20)、快速SE序列T2WI成像(TR、TE=4 700/100)和脂肪抑制序列.结果:30例患者共有40处骨髓信号异常,30处为T1WI低信号、T2WI高信号,10处为T1WI低信号、T2WI混杂信号.脂肪抑制序列均为明显高或混杂偏高信号.结论:MRI是早期诊断隐匿性骨折的理想方法,T2WI脂肪抑制序列最为准确和敏感.     

梯度回波同、反相位T1WI在不典型脂肪肝的应用价值

目的:探讨MR梯度回波同相位与反相位T1WI在不典型脂肪肝诊断中的应用价值。材料与方法:前瞻随访性研究24例不典型脂肪肝患者的常规MR成像及MR梯度回波同相位与反相位T1WI,直接观察肝脏脂肪变性灶在MRI常规序列及SPGR T1WI同相位与反相位像上的信号变化,并计算梯度回波同相位与反相位T1WI上肝脏脂肪变性灶与脾脏的信号强度比(SIR),应用小样本配对t检验作统计学差异分析。结果:弥漫性脂肪肝伴正常肝岛8例,肝内局灶性脂肪浸润16例,肝脂肪变性灶在SE T1WI及FSE T2WI上为均等或稍高信号,正常肝岛呈相对低信号。在SPGR T1WI同相位与反相位像上,肝脂肪变性灶信号分别为等或稍高信号及低信号,脂肪变性灶与脾脏的信号强度比值分别为1.37±0.13和0.92±0.13,有明显统计学差异(t=-13.187,P=0.000)。结论:MR梯度回波同相位与反相位T1WI能对脂肪肝进行简单而敏感的定性检出,在US或CT表现不典型脂肪肝的诊断上具有重要价值。     

MRI 对陈旧与新鲜椎体骨折的鉴别诊断价值

目的:探讨MRI对陈旧与新鲜椎体骨折的鉴别诊断价值。方法:45例(62个椎体)椎体骨折患者于外伤后1 d内行MRI检查,并分别于3、6、9个月行MRI随访复查。结果:62个椎体骨折中,54个椎体为新鲜骨折,SE序列T1WI上呈低信号或低信号中混有少许高信号,FSE序列T2WI呈高信号,STIR序列上呈更亮的高信号;随访3~9个月,3个月时有8个椎体T1WI、T2WI信号基本恢复正常,STIR序列仍呈高信号;6个月时有31个椎体T1WI、T2WI信号基本恢复正常,其中有19个椎体STIR序列仍呈高信号;9个月时54个椎体T1WI、T2WI、STIR序列均恢复正常信号。8个椎体为陈旧性骨折,在T1WI、、T2WI、STIR序列上与正常椎体信号相近。结论:MRI对鉴别陈旧与新鲜椎体骨折敏感,尤其是STIR序列更具鉴别诊断价值。     

MRI评价兔VX2肝癌射频消融后改变:与病理对照

目的 观察兔VX2肝癌射频消融(RFA)后的MRI动态变化,并与病理所见相对照,探讨MRI评价肝癌RFA疗效的价值.方法 采用生理盐水与VX2瘤块混悬液注射法复制肝肿瘤动物模型24只.开腹直视下对24只兔肝癌进行RFA,并将其随机分为4组,分别于术后即刻、术后1周、2周和4周进行MR平扫及增强扫描检查;之后处死实验兔,进行大体病理和光镜检查.结果 MRI表现为病灶T1WI中央低信号,外周高信号,T2WI中央高信号,外周低信号,增强扫描病灶外周环形强化,中央无强化.光镜下消融灶呈凝固性坏死,术后即刻组外周见少许中性粒细胞、巨噬细胞浸润,肝窦扩张充血;术后1周组外周见炎性细胞浸润及少许纤维肉芽组织增生;MRI表现为病灶T1WI呈稍低信号,T2WI呈稍高信号,增强扫描病灶周边呈环状强化,中央无强化.术后2周组外周见淋巴细胞、浆细胞、多核巨细胞浸润及梭形纤维组织增生;MRI表现为病灶T1WI稍低信号,T2WI混杂信号影,向外为等低信号包膜,增强扫描病灶周边环状强化,中央无强化.术后4周组外周见大量纤维肉芽组织增生;MRI表现为病灶T1WI低信号,T2WI由内向外呈低信号-稍高信号-线状高信号环,增强扫描病灶周边环状强化,中央无强化.本组实验中17只实验兔病理学发现有肿瘤残留,MRI表现为T1WI稍低信号,T2WI高信号,增强扫描呈结节状或厚度不均的环状强化.结论 MRI可全面评价RFA后病灶的变化,及时发现肝癌残存与复发.     

肝细胞癌高强度聚焦超声治疗后近期MR成像观察

目的分析原发性肝细胞癌高强度聚焦超声(high intensity focused ultrasound,HIFU)治疗后的MRI表现.方法21例经病理或临床诊断的原发性肝细胞癌患者在HIFU治疗前、后行腹部的轴位T1WI,轴位T2WI,冠状位SPIR,以及GD-DTPA增强后T1WI的轴位、FFE序列的冠状位扫描.在MRI图像上观察肿瘤在HIFU治疗前、后的大小及信号改变.结果HIFU治疗29个癌灶,其中24个缩小(82.76%),5个增大(17.24%);在T1WI增强上26个(89.66%)出现无信号增强区,12个癌灶无增强区周围见环状强化,7个强化环内见低信号环(T1WI、T2WI、SPIR).无强化区大多在T1WI表现为低信号或高信号,T2WI为低、等信号或高信号,SPIR序列为低、等信号或高信号,FE序列为低信号.结论HIFU治疗后,肝癌瘤灶内可出现多种MR信号改变,MR成像应成为肝癌HIFU治疗效果评估的一种无创而有效的方法.     

宫颈癌MRI分期与病理对照研究

目的 探讨宫颈癌磁共振成像(MRI)分期与病理分期的相关性.方法 80例经手术或活检病理证实的宫颈癌患者行盆腔MRI检查,MRI的成像序列包括T1加权像、T2加权像、脂肪抑制T2加权像、弥散加权成像,以及钆喷酸葡胺增强T1加权像.观察肿瘤的位置、信号特征及侵犯范围.将MRI所见与病理结果相对比.结果 MRI对宫颈癌分期总的准确率为88.73%.对宫旁侵犯判断的准确率为92.50%,特异度为91.18%,敏感度为100%.MRI与病理诊断的差异主要与宫旁浸润的评价差异有关.结论 MRI在宫颈癌临床分期中具有很高的准确性,是宫颈癌诊断中重要的影像学手段.     

Specificity of SPIO particles for characterization of liver hemangiomas using MRI

We investigated the specificity of superparamagnetic iron oxide (SPIO)â€enhanced T1-weighted spin-echo (SE) magnetic resonance (MR) images for the characterization of liver hemangiomas. When imaging liver hemangiomas, which are the most frequent benign liver tumors, a method with very high specificity is required, which will obviate other studies, follow-up, or invasive diagnostic procedures such as percutaneous biopsy. Eighty-three lesions were examined by MR imaging at 1.5 T before and after intravenous injection of SPIO particles. Lesions were categorized as follows according to the final diagnosis: 37 hemangiomas, nine focal nodular hyperplasias (FNHs), 19 hepatocellular carcinomas (HCCs), and 18 metastases. Their signal intensity values were normalized to muscle and compared. The only lesions showing a significant increase in signal intensity ratio (lesion to muscle) on postcontrast T1-weighted SE images were hemangiomas (p < 0.001). The signal intensity ratio of hemangiomas increased on average by 70%. Based on receiver operating characteristic analysis and using a cutoff level of 50% signal increase, the specificity and sensitivity of SPIO-enhanced MR imaging for the characterization of hemangiomas would be 100% and 70%, respectively. The T1 effect of SPIO particles can help differentiate hemangiomas from other focal liver lesions such as FNHs, HCCs, and metastases and may obviate biopsy. When using SPIO particles for liver imaging, it is useful to add a T1-weighted sequence to T2-weighted images, thereby providing additional information for lesion characterization.     

Magnetic resonance imaging and expression of vascular endothelial growth factor in hepatocellular nodules in cirrhosis and hepatocellular carcinomas

We summarized and discussed our previous research results on correlation between magnetic resonance (MR) imaging findings and vascular endothelial growth factor (VEGF) expression in benign or borderline hepatocellular nodules in cirrhosis, hepatocellular carcinomas (HCCs), and in the surrounding liver. Magnetic resonance images were retrospectively correlated quantitatively and qualitatively with VEGF expression in hepatic nodules and in the surrounding liver. By immunohistochemistry, hepatic nodules with moderate to strong immunoreactivity for VEGF showed higher T1 signal intensity, and those with intense immunoreactivity for VEGF showed higher T2 signal intensity. By Western blotting, HCC-to-liver contrast-to-noise ratio correlated with VEGF indices (VEGFs) of hepatocellular carcinomas inversely on opposed-phase T1-weighted, directly on T2-weighted, and marginally and inversely on gadolinium-enhanced hepatic arterial-phase images. On T2-weighted images, standard-deviation ratio of hepatocellular carcinomas correlated directly with VEGFs of hepatocellular carcinomas. Heterogeneities of hepatocellular carcinomas on MR images correlated directly with VEGFs of HCCs on opposed-phase T1-weighted, T2-weighted, hepatic arterial-phase, and equilibrium-phase images. Our results may reflect that MR signal intensity, hepatic arterial vascularity, and heterogeneity of hepatocellular nodules on MR images are closely related to the intensity of VEGF expression as up-regulated by hyper- or hypoxia in the nodules. Gadolinium-enhanced MR imaging may be useful to monitor ischemic state of hepatocelluar nodules. Although real impacts of our results on radiologic practice have been still debatable, we believe that our results may help future radiologic practice in conjunction with biomolecular or genetic treatments for hepatocellular carcinomas.     

Expression of vascular endothelial growth factor in hepatocellular carcinoma and the surrounding liver: correlation with MR imaging and angiographically assisted CT

We summarize and discuss our previous research results on the correlation between findings on magnetic resonance (MR) imaging and angiographically assisted computed tomography (CT) and the intensity of vascular endothelial growth factor (VEGF) expression in hepatocellular carcinoma (HCC) and in the surrounding nontumorous liver. MR images (n = 22), CT during arterial portography (n = 20), and CT hepatic arteriography (n = 17) were retrospectively correlated quantitatively and qualitatively with VEGF expression in HCCs and in the surrounding liver assessed by western blotting. HCC-to-liver contrast-to-noise ratio correlated with VEGF expression index (VEGF^IND) values of HCCs inversely on opposed-phase, T1-weighted, spoiled gradient recalled-echo (GRE) images, directly on T2-weighted, fast spin-echo images, and marginally and inversely on gadolinium-enhanced hepatic arterial-phase GRE images. On T2-weighted fast spin-echo images, standard deviation ratio of HCCs correlated directly with VEGF^IND values of HCCs. By CT hepatic arteriography, the contrast-enhancement index of HCCs showed a moderate inverse correlation with VEGF^IND values of HCCs, and the contrast-enhancement index of the liver showed marginal, moderate direct correlation with VEGF^IND values in the liver. Heterogeneities of HCCs on images correlated directly with VEGF^IND values of HCCs on opposed-phase T1-weighted GRE images, T2-weighted fast spin-echo images, hepatic arterial-phase GRE images, equilibrium-phase GRE images, and CT hepatic arteriogram. Our results may reflect that MR signal intensity, hepatic arterial vascularity, and heterogeneity of HCCs on CT or MR images are closely related to the intensity of VEGF expression in HCC as upregulated by hyper- or hypoxia in HCCs. Although the real effects of our results on radiologic practice are debatable at this moment, we believe that our results may help future radiologic practice in conjunction with biomolecular or genetic treatment for HCCs.     

MR imaging of mixed hepatocellular and cholangiocellular carcinoma

Two patients with mixed hepatocellular and cholangiocellular carcinoma underwent partial hepatectomy after magnetic resonance (MR) imaging. Correlation is made with the histopathologic manifestations. In both cases the tumors showed relative low signal intensities on T1-weighted spin-echo (SE) images and high signal intensities on T2-weighted SE images. Dynamic MR imaging showed the enhancement from the periphery of the tumor to the inner area gradually and the enhancement continued into the delayed phase. With both cases fibrosis was marked in the inner area of the tumor compared to the peripheral area. The extent and degree of fibrotic tissue is considered to reflect the enhancement on dynamic MR imaging.     

Well-differentiated hepatocellular carcinoma: findings of US, CT, and MR imaging

Background: To elucidate the imaging characteristics of well-differentiated hepatocellular carcinomas (HCCs) on ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging. Methods: Ultrasonograms, CTs, and MR images of 18 histopathologically proven well-differentiated HCCs in 15 patients were reviewed. The findings of these images were correlated with histopathologic findings. Results: On US, seven tumors were depicted as a hyperechoic area and eight as a hypoechoic area. Three tumors were not visualized. On precontrast CT, four tumors were depicted as a low-density area, but 14 were not visualized. On conventional contrast-enhanced CT, 12 tumors were depicted as a low-density area but six were not visualized. On T1-weighted MR images, 10 tumors had high signal intensity and two had low signal intensity. Six tumors were not visualized. On T2-weighted MR images, five tumors had high signal intensity and two had low signal intensity. Eleven tumors were not visualized. Tumors with fatty change and/or clear cell formation were frequently hyperechoic on US and hyperintense on T1-weighted MR images. Conclusions: Well-differentiated HCCs show different findings on US, CT, and MR imaging. Therefore, reliable diagnosis of well-differentiated HCCs by these imaging techniques may be difficult. Received: 29 April 1998/Revision accepted: 15 July 1998     

前列腺癌和良性前列腺增生的MR影像表现——与组织病理对比研究

目的：了解磁共振成像在前列腺癌和良性前列腺增生诊断与鉴别诊断的价值。方法：本文对２１例有手术病理证实的前列腺癌和良性前列腺增生的病人进行ＭＲ检查，并与组织病理作对比研究。其中６例前列腺癌，２例前列腺肉瘤，１３例良性前列腺增生。采用自旋回波（ＳＥ）Ｔ１和Ｔ２加权像对所有病例进行分析。结果：ＭＲＴ２加权像５２％（１１／２１）的病人显示位于前列腺两侧及后部的边缘带腺体呈高信号，而中央带的腺体呈低信号。７６％（１０／１３）的良性前列腺增生显示为中央带腺体增大呈较低信号强度而两侧高信号的边缘带腺体呈压缩变薄的改变。在前列腺癌和肉瘤中７例表现为ＭＲＴ２加权像一侧或两侧的边缘带高信号消失，且周边不见低信号的纤维包膜。２１例前列腺增生与癌的诊断准确率为８０．９％。此外本文还对肿瘤外侵的估计作了初步探讨。结论：我们认为ＭＲ在前列腺增生和癌的诊断和鉴别诊断上有应用价值。