同相位与反相位梯度回波T_1WI在肝脏的应用价值

目的　评估同相位与反相位梯度回波T1WI在肝脏应用的价值 ,尤其是评估其对肝内脂肪变的检测能力。方法　 76例病人采用屏气同相位与反相位T1W梯度回波序列对肝脏扫描。将76例病人分成 3组分析 :(1)肝内无占位病变组 ,8例 ;(2 )肝癌组 ,34例 ;(3)血管瘤或囊肿组 ,共 34例。对 2种序列的图像进行了定量分析。结果　 76例中发现 14例肝脂肪变 ,6 2例无脂肪变。在 14例肝脂肪变中 ,反相位MRI还显示了 4例低信号肿块周边环状高信号带 ,其中 3例肝癌 ,1例血管瘤。在肝脂肪变的反相位上显示肝与脾和病灶信噪比或对比信噪比值较同相位低 ,但肝与脾和病灶间信噪比 (SNR)或对比信噪比 (CNR)在同相位与反相位上均无显著性差异 (P >0 .0 5 )。结论　同相位与反相位对显示肝脏病变和对脂肪成分的诊断是有价值的。两者互补 ,缺一不可。为避免肝脏病变在T1WI上的误诊或漏诊 ,建议常规行同相位与反相位T1W扫描     

同相位与反相位梯度回波T1WI在肝脏的应用价值

目的 评估同相位与反相位梯度回波Ｔ１ＷＩ在肝脏应用的价值,尤其是评估其对肝内脂肪变的检测能力。方法 ７６例病人采用屏气同相位与反相位Ｔ１Ｗ梯度回波序列对脏脏针７６例病人分成３组分析：（１）肝内无占位病变组,８例;（２）肝癌组,３４例;（３）血管瘤或囊肿组,共３４例,对２ 序列的 定量分析。结果 ７６例中发现１４例肝脂肪变,６２例无脂肪变。在１４例肝脂肪变中,反相位ＭＲＩ还显示了４例低信号肿块周边     

ADC值与MR T_1WI最大强化值相关性分析评估肝癌的临床随访价值

目的定量分析原发性及继发性肝癌肿瘤组织的表观扩散系数(ADC)值,探讨MR扩散加权成像(DWI)在临床上评估肝癌患者的治疗疗效及预后的能力。资料与方法对53例肝癌患者行MR DWI、常规平扫T1WI、T2WI和T1WI钆对比剂增强扫描,系统化分析并观察病灶内部存活的肿瘤组织与肿瘤液化坏死组织成分的DWI与增强图像上的信号特征,测量各组信号强度值,并计算出各组ADC值与对应的MR T1WI增强扫描最大强化值,进行统计学相关性分析。结果 MR DWI像上肝癌病灶内残存或复发的肿瘤组织表现为稍高信号,增强扫描显示明显正性强化;液化坏死部分表现为明亮高信号,增强扫描无明显强化;ADC图上肿瘤组织为稍高于正常肝实质的高信号,肿瘤坏死组织部分为低信号;均数ADC值分别为:b=500 s/mm2时,肝癌肿瘤组织约为(1.15±0.43)×10-3mm2/s,肿瘤坏死囊变组织约为(1.88±0.43)×10-3 mm2/s,正常肝实质约为(1.31±0.16)×10-3 mm2/s;b=800 s/mm2时,肝癌肿瘤组织约为(1.02±0.37)×10-3mm2/s,肿瘤坏死组织约为(1.71±0.32)×10-3mm2/s...     

梯度回波反相位T1WI对口腔颌面部疾病的诊断价值

目的探讨梯度回波反相位T1WI(GRE-OP-T1WI)对口腔颌面部疾病的诊断价值. 资料与方法对10名健康志愿者(对照组)绘制GRE-T1WI的回波时间-信号强度(TE-SI)曲线以确定0.5T场强中GRE-OP-T1WI的最小TE值,然后对23例口腔颌面部疾病患者(研究组)进行GRE-OP-T1WI与常规MRI序列对病灶显示程度的比较研究. 结果 0.5T MR仪实际最小TEOP值为21ms; 平扫和增强GRE-OP-T1WI与T2WI、平扫和增强T1WI相比能显著提高病灶显示程度. 结论 GRE-OP-T1WI可以抑制少量脂肪,对口腔颌面部疾病的诊断是常规MRI序列的有效补充,尤其对中、低场MR设备具有极大的应用价值.     

低场MR扰相梯度回波T_2*WI在颈椎病诊断中的价值

目的：探讨低场强扰相梯度回波（SPGR）T2＊WI序列在颈椎病分型诊断中的应用价值。方法：74例临床怀疑为颈椎病的患者,均采用FSE T2WI（常规组）和SPGR T2＊WI序列（改良组）行MRI扫描,两组的影像资料分别由2位高年资放射科医师独立进行分析,结果与临床及／或手术结果进行对照分析。结果：74例中最终确诊为颈椎病65例,阴性9例。其中经临床证实35例、手术证实30例。FSE T2WI序列正确诊断颈椎病48例,误诊7例,漏诊17例;SPGR T2＊WI诊断颈椎病65例,结果均与临床及／或手术结果相符。改良组诊断准确性明显高于常规组（P〈0．05）。结论：低场强SPGR T2＊WI序列对颈椎病具有较高诊断价值,可以取代FSE T2WI序列。     

MR梯度回波T2^＊WI检出脑微出血

目的：MR梯度回波T2^＊WI可检出无症状性脑微出血,本研究旨在探讨脑微出血的发生率、部位以及与高血压、脑卒中、脑室周围白质高信号的相关性。方法：在1年时间内共有375例患者在常规MRI／序列的基础上加扫T2^＊加权序列,排除了存在脑血管畸形出血、颅内占位、外伤、手术史等病例,共有324例进行分析处理。结果：脑微出血37例,总的发生率为11．4％,尤其位于基底节／放射冠（n=22）、丘脑（n=15）、小脑（n=14）和脑叶区域（n=15）,脑微出血主要见于存在脑中风史病例,与年龄、高血压、脑白质疏松症（脑室周围白质高信号）存在相关性（P〈0．001）。在2年多的影像学随访过程中,共发现2例（5．4％）出现新鲜脑出血。结论：MR T2^＊加权像可用于检出脑微出血,其发生提示存在脑微小血管病变,存在继发出血的可能性,建议对于60岁以上的老年人尤其是存在脑中风的病例,MR T2^＊加权应作为常规扫描序列。     

利用自旋回波平面成像T_2加权序列提高肝脏实性病变的检出率

目的　评价自旋回波平面成像 (SE EPI)T2 W序列对肝脏实性病变的检出能力。方法74例病人 (2 0 2个病灶 )接受肝脏 3种SE EPIT2 W序列磁共振扫描 ,评价其图像信噪比 (SNR)、肝脾对比噪声比 (L SCNR)、病灶对比噪声比 (CNR)及病变检出率 ,并与真实稳态进动快速成像 (true FISP)、快速自旋回波 (TSE)及半傅立叶采集单次激发快速自旋回波 (HASTE)等屏气T2 W序列相比较。结果SE EPI的SNR高于TSE (P <0 0 5 ) ,与true FISP相近 (P >0 0 5 ) ,但低于HASTE(P <0 0 1)。SE EPI序列的L SCNR及实性病变的CNR均显著高于true FISP、HASTE及TSE(P <0 0 1)。对于囊性病变 ,各序列间的检出率无明显差异 (P >0 0 5 )。各序列均检出所有直径大于 5cm的实性病变。直径 2～ 5cm的实性病变 ,SE EPI序列的检出率略高于true FISP、HASTE及TSE ,但无显著性差异 (P >0 0 5 )。直径小于 2cm的实性病灶 ,SE EPI序列的检出率 (93 9% )明显高于true FISP(5 7 6 % )、HASTE(71 2 % )及TSE(6 8 2 % ) (P <0 0 1)。结论　与其他屏气T2 W序列相比 ,SE EPIT2 WI有较高的病灶对比 ,能提高肝脏实性病变的检出率     

不同MR扫描序列在SPIO增强大鼠肝癌模型的对比研究

目的：比较多种扫描序列超顺磁氧化铁（SPIO）增强扫描对显示大鼠肝癌病灶的能力，找出最佳扫描方案。TSE T2WI、SE双回波的T2WI＋PDWI、GRE T1WI、T2^＊WI，分析增强前后大鼠肝癌病灶的强化特征，并进行病理学检查对照分析。结果：注射SPIO对比剂后，所有扫描序列均显示肝脏的信号强度较增强前有不同程度的下降，肝癌病灶CNR均分别高于平扫。增强后GRE T2^＊WI中病灶的CNR明显高于其它序列，但增强后TSE T2WI和常规SE T2WI在显示病变的SNR、CNR方面没有显著性差异。结论：SPIO增强后检测肝癌病灶的各种序列中，以GRE T2^*WI最为敏感，其次是双回波的T2WI＋PDWI序列。     

MR T_1WI抑脂及MR胰胆管造影术用于梗阻性黄疸的诊断

目的：探讨Ｔ１ＷＩ抑脂技术（ＦＴ１ＷＩ）和ＭＲ胰胆管造影术（ＭＲＣＰ）对梗阻性黄疸的诊断价值。方法：回顾４７例不同病因所致梗阻性黄疸的ＭＲＩ征象。应用ＧＥＳｉｇｎａ１．５Ｔ超导ＭＲ机,除常规的Ｔ１ＷＩ、Ｔ２ＷＩ序列外,还采用ＦＴ１ＷＩ和ＦＭＰＳＰＧＲ造影增强及ＭＲＣＰ技术。结果：恶性病变均可见大小不等的肿块,ＦＴ１ＷＩ序列对肿块的显示最清楚,为明显的低信号。良性病变均无肿块。ＭＲＣＰ可以明确梗阻的部位及阻塞端的形态。结论：根据ＭＲＣＰ所示胆道梗阻的部位和形态,结合轴位各序列,尤其是ＦＴ１ＷＩ显示的病灶特点,能更加准确地诊断梗阻性黄疸的病因。     

高场强原发性肝癌MR表现及分析

目的：分析高场强下原发性肝癌的MRI表现。方法：收集经手术或尸检病理证实的原发性肝癌MR资料43例，其中巨块型肝癌32例，其中伴子灶3例，结节型5例，小肝癌6例。设备为GE1．5T超导signa advantage MR。应用SET1WI，FSEPDWI，T2WI进行轴位扫描，所有病均行增强扫描。结果：肝癌在T1WI呈高、等、低信号，在T2WI呈高信号，部分肿瘤内部信号不均，肝癌的强化程度主要取决于肿瘤血供的多少，肝癌的包膜由纤维组织构成，表现为低信号环，无包膜的肿瘤门静脉侵犯发生率高，肿瘤的信号及包膜与其病理分级有一定的相关性。结论：MRI对反映原发性肝癌的病理特征有其独特的优越性。     

不同MR成像方式对肝细胞癌射频消融术后的评估

以射频消融为主的肝细胞癌消融治疗已经广泛应用于临床,但治疗后肿瘤残存和复发是影响疗效的主要问题,所以消融后的评估显得尤为重要.MRI具有多参数、多序列、任意平面成像及多种功能成像方式,使其对肿瘤消融术后的评估更具优势.因此,本文就MRI常规平扫、MRI增强、DWI、DKI、PWI及MRS在肝细胞癌射频消融术后评估中的应...     

Added diagnostic value of T2-weighted MR imaging to gadolinium-enhanced three-dimensional dynamic MR imaging for the detection of small hepatocellular carcinomas

Purpose

To assess the added value of T2-weighted MRI to gadolinium-enhanced dynamic MRI for detection of HCCs.

Materials and methods

Two readers retrospectively analyzed MRIs of 115 patients with 131 HCCs (size; 0.6–2.0 cm) that had been diagnosed by histology (n = 41) or imaging findings (n = 90). Two separate blind image analyses of the gadolinium set and the combined T2-weighted imaging and gadolinium sets were performed. Diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method with four-point scale. Sensitivity and positive predictive value were also calculated.

Results

For both observers, the Az values and sensitivities with the combined T2-weighed imaging and gadolinium set (mean Az 0.806, sensitivity 84.7) were significantly higher than those with the gadolinium set (mean Az 0.660, sensitivity 59.9) (p < 0.05). The addition of T2-weighted imaging led to a change in diagnosis for 27 lesions by both observers, which at gadolinium set were assigned a confidence level of 1 or 2 but at additional reading of T2-weighted imaging were assigned a confidence level of 3 or 4. For the positive predictive values, each image set showed a similar value for each observer.

Conclusion

The addition of T2-weighted imaging to gadolinium-enhanced 3D dynamic imaging could be helpful in the detection of HCC by increasing reader confidence for HCCs with equivocal findings on gadolinium-enhanced MRIs.     

Signal intensity of the normal pontine tegmentum on T2-weighted MR imaging

On T2-weighted MR images, the pontine tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the pontine tegmentum normally differs from that of the pontine base. We evaluated the signal intensity of the pontine tegmentum and pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the tegmentum to the base. The CNR was significantly higher for the tegmentum than the base at each level of the pons (P<0.0001), and the signal intensity ratio of the tegmentum to the base in the upper pons was significantly higher in children than in adults (P<0.005). On T2-weighted images, a high signal intensity of the pontine tegmentum is frequently seen in neurologically healthy subjects. This finding should not be considered abnormal, particularly in children.     

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。     

Hepatocellular carcinoma with marginal superparamagnetic iron oxide uptake on T2*-weighted magnetic resonance imaging: histopathologic correlation

Purpose

To evaluate the characteristics of hepatocellular carcinomas (HCCs) with marginal superparamagnetic iron oxide (SPIO) uptake on T2*-weighted MRI.

Materials and methods

The study group consisted of 73 patients with 83 surgically resected HCCs. Preoperative SPIO-enhanced MRI studies were retrospectively reviewed. Marginal SPIO uptake was considered positive if a rim-like or band-like low intensity area was present on SPIO-enhanced T2*-weighted images. The prevalence of marginal SPIO uptake was evaluated. Pathological specimens with hematoxylin and eosin staining and immunohistochemical staining of CD68 were reviewed in HCCs with marginal SPIO uptake and 33 HCCs without marginal SPIO uptake (control group).

Results

Ten of 83 (12%) HCCs showed marginal SPIO uptake. All HCCs were hypervascular, and only one nodule showed a nodule-in-nodule appearance on imaging findings. The pathology specimens suggested possible causes of marginal SPIO uptake, including marginal macrophage infiltration in moderately or poorly differentiated HCC (n = 4), residual normal hepatic tissue at the marginal area of confluent multinodular or single nodular with extranodular growth type HCC (n = 3), and a well-differentiated HCC component in nodule-in-nodule type HCC (n = 3). Marginal macrophage infiltration was not seen in the control group.

Conclusion

SPIO-enhanced MRI may be able to demonstrate marginal macrophage infiltration in HCC.     

Dynamic gadopentetate dimeglumine-enhanced MR imaging of hepatocellular carcinoma

Nineteen patients with 28 histologically proven hepatocellular carcinomas (HCCs) were examined using T1- and T2-weighted spin-echo sequences and dynamic gadopentetate dimeglumine-enhanced magnetic resonance imaging (MRI) performed by fast T1-weighted gradient-echo sequence (100/5/80°) which was performed before and repeatedly (12 sets of images) after intravenous bolus injection of gadopentetate dimeglumine (Gd-DTPA) over a period of 10 min. Enhancement of HCC was heterogeneous in 24 lesions (85.7%). Intra-lesional non-enhancing areas were seen in 18 cases (64%). A late-enhancing pseudocapsule was seen in 12 lesions (42.9%). In addition, two groups were distinguished in the examined HCCs: 16 lesions (57.1%) showed stronger enhancement compared to liver parenchyma with maximum positive lesion-to-liver contrast on the 15-s images, while 12 lesions (42.9%) had an enhancement less than normal liver with a maximum negative contrast on the 15-s images. We conclude that the morphologic features most frequently encountered in HCC on dynamic Gd-DTPA-enhanced MRI are inhomogeneity of enhancement, intra-lesional non-enhancing areas, and relatively late enhancement of a pseudocapsule. Taking the degree of enhancement to be representative of the degree of vascularity, we also conclude that HCC can appear either hypervascular or hypovascular in the early phase of the dynamic study. Correspondence to: B. Hamm     

周围型肝内胆管细胞癌的磁共振诊断

目的 :评价磁共振 (MRI)平扫及联合动态增强MRI对周围型肝内胆管细胞癌 (PCC)的诊断价值。方法 :回顾性分析 15例经手术病理证实的周围型肝内胆管细胞癌的MRI平扫及动态增强表现。结果 :全部病灶显示满意。参考平扫胆管扩张情况定性诊断符合率为 3 3 .3 % ,联合动态增强定性符合率提高至 86.7%。结论 :MRI平扫能较好显示病灶和胆管扩张情况 ,平扫联合动态增强检查可提高对PCC的定性符合率。     

局灶性结节增生与肝细胞癌MR扩散加权成像表现特征的比较

目的 探讨肝局灶性结节增生(FNH)和肝细胞癌在MR DWI上的表现特征.方法 同顾性分析2008年8月至2010年11月间,有MR检查资料并经手术病理证实的FNH和小肝癌患者资料,共有24例26个FNH病灶和36例39个小肝癌病灶.行b值=500 s/mm2DWI和常规动态增强扫描,对病灶DWI的信号特点进行记录和分析,对病灶的ADC值,病灶对周围肝实质ADC值比进行测量.对两组病灶信号特点分布行Fisher确切概率法检验,两组病灶ADC值及病灶与周围肝实质ADC值比采用独立样本t检验,并用ROC曲线评价ADC值和病灶与周围肝实质ADC值比对两种病灶的鉴别价值.结果 多数(23/26)FNH病灶在DWI上表现为等或略高信号,多数(25/39)HCC病灶表现为高信号,两者信号特点分布差异有统计学意义(P=0.000).FNH病灶的平均ADC值、病灶与周围肝实质ADC值比分别为(1.76±0.62)×10-3mm2/s和1.06±0.18,均高于HCC的平均值(1.26±0.46)×10-3mm2/s(P=0.001)和0.79±0.12(P=0.000).ADC值和病灶与周围肝实质ADC值比的ROC曲线下面积(Az)分别为0.79±0.05和0.85±0.05,差异无统计学意义(P=0.270);特异度分别为69.23%和97.44%,差异有统计学意义(P=0.001).结论 FNH在DWI上表现为等或略高信号,病灶ADC值和病灶与周围肝实质ADC值比高于HCC,应用ADC参数分析有助于FNH与HCC的鉴别.