梗阻性脑积水的弥散加权成像及弥散张量成像研究

目的探讨磁共振弥散加权成像(DWI)与弥散张量成像(DTI)对梗阻性脑积水的诊断价值。方法 25例梗阻性脑积水患者和30例志愿者均行3.0T磁共振常规序列以及DWI和DTI扫描,重建出ADC图、MD图、FA图、RA图、VR图及AI图,并对各参数图进行测量和记录,所得数据进行统计学分析。结果 30例志愿者及25例梗阻性脑积水患者分别测量双侧侧脑室周围脑白质、胼胝体膝部及压部区域的ADC、MD、FA、RA、VR及AI进行测量,ADC图中胼胝体膝部两组ADC值差异具有统计学意义(P<0.05),双侧侧脑室外侧脑白质两组所测得MD、FA、VR、AI值均有统计学意义(P<0.05),两组胼胝体压部RA值有统计学差异(P<0.05),两组间胼胝体膝部所有测得DTI各参数值均无统计学差异(P>0.05)。结论 DWI和DTI在脑积水的诊断中具有重要的诊断价值。     

Diagnostic performance of conventional diffusion weighted imaging and diffusion tensor imaging for the liver fibrosis and inflammation

Objective

To evaluate the diagnostic accuracy of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation.

Materials and methods

Thirty-seven patients with histologic diagnosis of chronic viral hepatitis and 34 healthy volunteers were included in this prospective study. All patients and healthy volunteers were examined by 3 T MRI. CDI and DTI were performed using a breath-hold single-shot echo-planar spin echo sequence with b factors of 0 and 1000 s/mm². ADCs were obtained with CDI and DTI. Histopathologically, fibrosis of the liver parenchyma was classified with the use of a 5-point scale (0–4) and inflammation was classified with use of a 4-point scale (0–3) in accordance with the METAVIR score. Quantitatively, signal intensity and the ADCs of the liver parenchyma were compared between patients stratified by fibrosis stage and inflammation grade.

Results

With a b factor of 1000 s/mm², the signal intensity of the cirrhotic livers was significantly higher than those of the normal volunteers. In addition, ADCs reconstructed from CDI and DTI of the patients were significantly lower than those of the normal volunteers. Liver ADC values inversely correlated with fibrosis and inflammation but there was only statistically significant for inflammatory grading. CDI performed better than DTI for the diagnosis of fibrosis and inflammation.

Conclusion

ADC values measured with CDI and DTI may help in the detection of liver fibrosis. They may also give contributory to the inflammatory grading, particularly in distinguishing high from low grade.     

毛细胞型星形细胞瘤影像学诊断现状

本文对毛细胞型星形细胞瘤的临床表现、病理表现、影像学诊断、鉴别诊断的进展进行了介绍,着重介绍毛细胞型星形细胞瘤MR影像学诊断现状以及黏液性毛细胞型星形细胞瘤的特殊影像学表现。     

儿童脑多形性黄色星形细胞瘤的MRI分析

目的 :分析儿童期脑多形性黄色星形细胞瘤 (PXA)的MRI表现。方法 :对经手术病理证实的 7例儿童期脑PXA的MRI资料进行回顾性分析 ,研究肿瘤的部位、形态和信号特征。结果 :7例肿瘤均呈囊实性 ,位于脑表浅部位 ,3例边界清楚 ,4例边界欠清楚。肿瘤实质与脑灰质比较在T1WI呈低信号 ,在T2 WI呈混合性高信号 ,增强后肿瘤实性部分和壁结节明显强化 ,3例囊性伴壁结节的肿瘤中 2例囊壁有强化 ,1例无强化。结论 :儿童期脑PXA多起源于脑表浅部位 ,颞叶为最常见部位 ,肿瘤常呈囊实性 ,增强后肿瘤实性部分和壁结节明显强化。     

MRI扩散加权成像对乳腺良恶性病变的诊断

目的:探讨磁共振扩散加权成像(DWI)对乳腺良恶性疾病的诊断价值。方法:回顾性分析40例经病理确诊的乳腺疾病,其中良性病变22个,恶性病变18个;均行DWI检查,测定病灶区表观扩散系数(ADC值),与正常组织进行比较,计算相对表观扩散系数(rADC值),应用SPSS 16.0软件比较其平均值,并以病理结果为金标准,作ROC曲线,求其最佳诊断阈值。结果:良性病变及恶性病变的ADC值分别为(1.55±0.35)×10-3和1.00±0.18)×10-3 mm2/s,其rADC值分别为(0.82±0.19)和(0.52±0.08)。良恶性病变组间均有统计学差异,以ADC值及rADC值为诊断标准作受试者工作特征曲线(ROC曲线),其中ADC值的曲线下面积(AUC)为(0.927±0.04),rADC值的AUC为(0.965±0.03),诊断阈值分别为1.17×10-3 mm2/s、0.66,相应敏感度及特异度分别为(90.9%、88.9%)和(95.5%、94.4%),rADC值的AUC、敏感度及特异度均高于ADC值。结论:DWI对乳腺良恶性病变的的诊断具有重要作用,其中rADC值有更好诊断效能。     

A case report of pilocytic astrocytoma mimicking meningioma on imaging

Pilocytic astrocytoma (PA) is categorized as grade I gliomas with a good prognosis. Although PA mostly occurs in the cerebellum, it also can occur in the orbital and mostly presents as a cystic tumor with a mural nodule. PA often presents in the second decade of life, with 75% occurring under the age of 20 years. This case report describes a 10-year-old boy presented a left eye tumor for over 3 years. MRI examination showed unrestricted intraconal lesions in the optic nerve, visible from the optic canal to the anterior with well-defined borders. The excised tumor specimen depicted a nodular tumor tissue, measuring 35 × 28 × 20 mm, weighing 11 grams, solid with gray and white. The microscopic examination showed a classical biphasic pattern including combinations of loose glial tissue and compact pyloid tissue. Hispathology result revealed a pilocytic astrocytoma.     

Comparison of acquired diffusion weighted imaging and computed diffusion weighted imaging for detection of hepatic metastases

Objective

To compare the accuracy of acquired diffusion weighted imaging (DWI) (b = 1000 s/mm²) with that of computed DWI (b = 1000 s/mm²) for the detection of hepatic metastases.

Methods

Two hundred and sixty patients underwent abdominal magnetic resonance imaging (MRI) at 3.0 T for the evaluation of hepatic metastasis, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI, DWI with b-values of 0, 500, 1000 s/mm², and three-dimensional dynamic contrast-enhanced MRI with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), and 190 patients were included in the final study. Computed DWI (=1000 s/mm²) was synthesized from lower b-values (b = 0 and 500 s/mm²). Two groups were assigned and compared: group A (acquired DWI) and group B (computed DWI). Diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis.

Results

A total of 76 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B (Observer 1; 0.919–0.915, Observer 2; 0.926–0.901), but there were no significant differences (observer 1, P = 0.500; observer 2, P = 0.190). There were 5 metastases visualized in group A, but these were difficult to detect in group B. However, there were 2 metastases that were better visualized in group B than in group A.

Conclusion

There were no significant differences between acquired DWI and computed DWI in the detection of hepatic metastasis.     

MR DWI对急性胰腺炎的诊断价值

目的 探讨MR扩散加权成像(DWI)对急性胰腺炎(AP)的诊断价值.方法 回顾性分析50例AP及75例正常胰腺的MR资料,计算DWI序列b=800 s/mm2图像上胰腺与肝脏的信号强度比(SIR),测量胰腺的表观扩散系数(ADC),分别比较2组的SIR及ADC,并根据受试者工作特征(ROC)曲线确定最佳诊断阈值,评价SIR、ADC与MRI常规序列的诊断效能.结果 与正常胰腺相比,AP组SIR显著升高(2.06±0.48 vs 1.24±0.27,t=12.2,P<0.0001),ADC显著降低[(991±133)μm2/s vs(1153±149)μm2/s,t=-6.2,P<0.0001].最佳诊断阈值分别为SIR>1.51、ADC≤1039μm2/s.SIR的敏感度(92.0%)高于ADC(72.0%)及MRI常规序列(74.0%),SIR(88.0%)及MRI常规序列(93.3%)的特异度高于ADC(77.3%).结论 AP时水分子扩散受限,SIR诊断效能优于ADC及MRI常规序列,有利于AP的检出.     

多形性黄色星形细胞瘤的CT、MRI诊断

目的：探讨多形性黄色星形细胞瘤的CT、MRI表现特征。方法：回顾分析10例经手术、病理证实的多形性黄色星形细胞瘤的CT、MR表现特点。其中男6例,女4例,年龄13～50岁,平均28岁。8例行MR平扫及增强扫描,2例行CT平扫及增强扫描。结果：病变好发于脑实质表浅部位,多位于颞叶,单发。7例表现为囊性病变伴有结节,3例为囊实性病变。增强扫描7例囊性结节病变,壁结节均明显强化,4例囊壁无强化,3例囊壁轻度强化;3例囊实性病变呈不均匀强化。结论：多形性黄色星形细胞瘤具有一定的CT、MR表现特征,充分认识这些影像特征有助于提高诊断的准确性。     

多b值DWI对术前幕上胶质瘤分级的应用研究

目的：探讨何种 b 值扩散加权成像(DWI)对胶质瘤术前分级更有价值。方法回顾性分析经手术病理证实的38例胶质瘤(高级别24例、低级别14例)患者的 MRI 资料,均行常规 MRI 检查和3种 b 值的 DWI 检查(b=1000 s/mm2、2000 s/mm2、3000 s/mm2),分析 DWI 上肿瘤的信号特征,测量肿瘤最小表观扩散系数(ADC)值。对不同 b 值的肿瘤最小 ADC 值绘制受试者工作特征曲线(ROC),选取最佳诊断阈值,采用χ2检验分析不同序列的敏感性、特异性的差异。结果 b= 3000 s/mm2 DWI 图像上,91.6%(22/24)高级别胶质瘤呈高信号,85.7%(12/14)低级别胶质瘤呈低信号,以高信号作为诊断高级别胶质瘤的标准,诊断高级别和低级别胶质瘤的敏感性及特异性最高(91.6%和100%)。在 b 值相同时高级别胶质瘤的最小 ADC 值低于低级别胶质瘤,差异有统计学意义(P<0.05);3种 b 值鉴别高级别和低级别胶质瘤敏感性的差异有统计学意义(P<0.05),当以 ADC 3000<0.74×10-3 mm2/s 作为鉴别高级别胶质瘤的敏感性和特异性最高,分别为100%和87.3%。结论高 b 值 DWI 比常规 b 值 DWI 更能准确反映胶质瘤分级,应用 b=3000 s/mm2 DWI 肿瘤最小 ADC 值为胶质瘤术前更准确分级提供量化指标。     

DWI联合M RCP 在鉴别诊断壶腹周围病变良恶性中的价值

目的：探讨扩散加权成像（diffusion weighted imaging ,DWI）联合MRCP序列在鉴别导致胆管狭窄的壶腹周围病变的良恶性的应用价值。方法回顾性分析自2012年11月～2013年11月在我院怀疑壶腹部胆管狭窄,行常规MRI、MRCP及DWI检查的69例患者。经手术或ERCP活检病理证实,良性病变43例,恶性病变26例。由两名放射科资深医师首先参照常规MRI ,在MRCP和DWI图像基础上分别进行诊断,然后结合两者对壶腹周围病变进行再次评估,分别统计其恶性的可能性。两位资深医师的结果分别通过ROC曲线进行分析。结果2位医师分别通过M RCP和DWI对壶腹周围病变良恶性诊断的敏感度、特异度和准确度进行计算,M RCP分别为55．6％,86．9％,71．3％;53．5％,87．5％,70．9％;DWI分别为87．5％,62．5％,74．9％;89．4％,61．3％;76．3％。MRCP联合DWI图像后对病变诊断的准确度均得到提升,分别提高到81．2％和82．7％。结论 M RCP联合DWI可以提高对引起壶腹部胆管狭窄疾病的良恶性诊断的准确度。     

全身扩散加权成像在恶性淋巴瘤诊断中的价值

目的：评价全身磁共振扩散加权成像（WB-DWI）在恶性淋巴瘤诊断及疗效评价中的作用。方法：回顾性分析47例经病理证实的恶性淋巴瘤患者WB-DWI表现;另选10例健康志愿者进行比较。8例霍奇金淋巴瘤（HD）患者,其中5例治疗前、后均行WB-DWI检查,3例为治疗后患者;39例非霍奇金淋巴瘤（NHL）患者,治疗前行WB-DWI检查19例,治疗前、后均行WB-DWI检查11例,仅治疗后检查9例。在ADC图上分别测量恶性淋巴瘤患者和健康志愿者淋巴结的ADC值,16例复查患者在初次检查相一致部位再次测量淋巴结的ADC值,并进行前后比较,同时与健康志愿者进行比较。结果：全身MR-DWI对淋巴瘤的显示较敏感,MR-DWI共检出大于1cm淋巴结372处。35例治疗前恶性淋巴瘤患者平均ADC值为（0.86±0.21）×10^-3mm^2/s,28例治疗后复查患者平均ADC值为（1.22±0.31）×10^-3mm^2/s,治疗前、后平均ADC值的差异具有统计学意义（P〈0.05）;10例健康志愿者颈部淋巴结平均ADC值为（1.29±0.12）×10^-3mm^2/s,与30例治疗前淋巴瘤患者ADC值比较,差异具有统计学意义,与28例治疗后患者ADC值比较,差异无统计学意义（P〉0.05）。结论：WB-DWI和ADC值的测量在恶性淋巴瘤的临床诊断、分期及疗效监测的评价方面是一种快速和行之有效的技术,具有一定的临床价值。     

Diagnostic accuracy of diffusion weighted MRI in cervical lymphadenopathy cases correlated with pathology results

Introduction

Diffusion weighted magnetic resonance imaging (DW MRI) is an imaging technique showing molecular diffusion. Cell size, density and integrity influence the signal intensity seen on diffusion-weighted images. This technique is a helpful complementary tool to distinguish tumoral from non tumoral tissue.The aim of this prospective study is to define the diagnostic accuracy of DWI to differentiate benign from malignant cervical lymph nodes.

Patients and methods

Twenty six patients who presented with 32 nodes were included in this study, 9 males (35.6%) and 17 females (65.4%). Their age ranged from: 6 to 76 years, mean age 45 ± 18.8 years referred to the radiology department of NCI, complaining of neck swelling, ultrasound showed cervical nodes.

Results

According to histopathological analysis we divided the examined lymph nodes (n = 32) into 2 categories: malignant lymph nodes 75% (n = 24) benign lymph nodes 25% (n = 8). DWI and ADC (apparent diffusion coefficient) values revealed 27 malignant lesions (84%), 5 benign (16%). The accuracy of the DWMRI was 89%. A significant difference between benign and malignant cervical nodes on DWI and on ADC maps is reported.The results obtained were 24 true positive, 3 false positive, 5 true negative. No false negative cases were identified, yielding a sensitivity of 100%, specificity of 62.5%, NPV = 100% and PPV = 89%. The difference between the mean ADC values between benign and malignant lesions was statistically significant (P < 0.0001).

Conclusion

MR diffusion imaging could be an important supportive tool in differentiation between benign and malignant lymph nodes, can to a lesser extent differentiate between the types of malignant lymphadenopathy and can be used as an indicator for improvement and recurrence post chemo and radiotherapy.     

鞍区毛细胞星形细胞瘤影像学表现及病理对照分析

目的：探讨鞍区毛细胞型星形细胞瘤的影像学特征并与病理结果进行对照分析。方法：回顾性分析10例经手术及病理证实的鞍区毛细胞型星形细胞瘤的CT、MRI特征并与病理改变进行对照。结果：10例中实性肿瘤2例,囊实性8例。主要CT表现为不均匀稍高密度,1例边缘见钙化灶。主要MRI表现为TzwI上呈不均匀高信号,T1wI上呈低信号,增强扫描示肿瘤呈明显不均匀强化,其内可见多发小囊状或裂隙样不强化区。10例视交叉显示不清,3例肿瘤包绕大脑中动脉,1例伴有软脑膜播散。结论：鞍区毛细胞型星形细胞瘤多为囊实性且多具有向周围组织侵袭及软脑膜播散的表现,其影像学表现有一定的特征性。     

非典型多形性黄色星形细胞瘤的MRI及病理表现

目的:探讨分析实质型多形性黄色星形细胞瘤(PXA)的临床、病理及影像学表现特征.方法:回顾性分析经病理证实的23例PXA患者的临床、病理及影像学资料,重点观察、分析11例实质型PXA的病变部位、病灶大小、瘤周水肿、恶变发生率及MRI信号特征.结果:11例实质型PXA患者中,发病平均年龄为(31.0±9.7)岁,9例(81.8％)病程≤1年;病变累及颞叶8例(72％),岛叶3例(27％),囊变发生率为72.7％(8/11);实质型PXA的瘤体体积中位数为7.2 cm3;无水肿或轻度水肿3例(27％),中度水肿7例(64％),实质型PXA恶变发生率为9％(1/11).实质型PXA MRI表现为实性肿块(伴或不伴囊变区),多数形态规则,边界清楚,实质部分T1 WI呈等、低信号,T2 WI呈高信号,瘤周水肿较轻,增强扫描呈明显较均匀或不均匀强化,邻近脑膜一侧强化显著.结论:实质型PXA的病程较短,肿瘤体积较小,恶性程度较低,MRI表现有一定的特征性,手术切除预后较好.     

多形性黄色星形细胞瘤影像学表现与病理学分析

目的探讨多形性黄色星形细胞瘤(PXA)的影像学及病理学表现.方法回顾性分析2003-2011年间共12例经手术病理证实的 PXA 病人组织病理学、免疫组织化学和影像学资料.12例病人均行 MRI 平扫及增强检查,其中5例行 CT 平扫,2例行 CT 平扫和增强扫描.结果12例病人病理组织学均可见不同程度囊变,瘤细胞呈明显多形性,肿瘤中有淋巴组织浸润,少有坏死,核分裂少或无.其中10例表达 CD34.12例病人肿瘤均为单发,位于幕上.MRI 平扫时实性部分 T1WI 呈等信号或稍低信号,T2WI 为等信号或稍高信号;囊性部分 T1WI呈低信号,T2WI 呈高信号.MR 增强扫描时肿瘤实性部分和壁结节明显强化.5例病人进行 CT 平扫,3例表现为低密度囊性病变伴等密度结节,2例呈低密度囊性病变,未见明显结节影;增强扫描可见明显的强化结节.结论 PXA具有一定的影像和病理学特征,综合对比分析可以确定诊断.     

Diagnostic yield of combined magnetic resonance spectroscopy and diffusion weighted imaging in intracranial neoplasms

Purpose

Our intention was to evaluate the role of combined diffusion magnetic resonance imaging and spectroscopy in diagnosis and grading of brain tumors.

Materials and methods

Ninety-three included cases underwent magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of the brain lesion, stereotactic or open biopsies and histopathological examination. MRI protocol included DWI and calculated ADC values. Multivoxel MRS spectroscopic technique (MVS) was used and all MRS metabolic parameters were obtained.

Results

High grade tumors had significantly lower ADC values than low grade tumors (P < 0.001). ADC values were the lowest in lymphoma (0.54 × 10⁻³ mm²/s) and the highest in craniopharyngioma (1.9 × 10⁻³ mm²/s). MRS revealed a statistically significant difference in CHO/NAA and CHO/Cr ratios between low and high grade tumors with P < 0.01 and P < 0.001, respectively. The mI/Cr ratio and presence of lactate, lipid and taurine also aided in differentiation and grading of brain tumors. The overall MRI/MRS sensitivity and specificity were 91%, 90.5%, respectively.

Conclusion

MRS has a robust diagnostic accuracy in cases of well defined high or low grade brain neoplasms. ADC value had the ability to confirm and differentiate low from high grade tumors in many situations where there were diagnostic confusions with MRS due to borderline values.