磁共振扩散加权成像对前列腺癌的诊断价值

目的:评价MR扩散加权成像对前列腺癌的诊断价值。方法:搜集有手术或穿刺病理结果的前列腺疾病患者15例,其中前列腺癌10例,前列腺炎5例。所有病例均行MR常规T1WI、T2WI及DWI扫描。回顾性分析各组病例的MR常规表现及DWI表现。结果:在MR扩散加权图像上,8例前列腺癌表现为外周带内局限性显著高信号,其余病变在扩散加权成像上为低信号或等信号。结论:MR扩散加权成像对前列腺癌有重要的鉴别诊断价值。     

颅内表皮样囊肿的CT、MRI及DWI诊断

目的:通过分析55例颅内表皮样囊肿CT、MRI和DWI表现,探讨表皮样囊肿的影像学诊断和鉴别诊断。方法:对55例经手术病理证实的颅内表皮样囊肿的CT、MRI及DWI表现进行回顾性分析。男33例,女22例。全部病例均行MR平扫检查,其中26例行MR增强扫描,18例行扩散加权成像,26例行CT平扫检查,5例行CT增强扫描。结果:表皮样囊肿位于脑外29例,脑实质23例,脑室3例。CT平扫24例呈低密度,2例密度稍高于脑实质。51例类似脑脊液信号,1例呈短T1短T2信号,2例呈短T1长T2信号,1例T1WI大部分呈等信号,少部分为低信号,T2WI呈低信号。2例囊壁似有轻微强化。DWI上囊肿均表现为高信号,且ADC值高于脑实质。结论:形态不规则、类似脑脊液信号、DWI呈高信号、不强化是表皮样囊肿的影像学表现特点,不典型表皮样囊肿可呈其它密度和信号变化,可根据不强化和DWI呈高信号与其它类似病变鉴别。     

颅内表皮样囊肿和蛛网膜囊肿的DWI鉴别诊断

目的:探讨磁共振扩散加权成像(DWI)对颅内表皮样囊肿和蛛网膜囊肿的鉴别诊断价值。方法:对20例颅内表皮样囊肿和15例颅内蛛网膜囊肿患者进行常规MRI及DWI检查,并获得表观扩散系数(ADC)图,分别测量病变区、健侧脑组织及健侧侧脑室内脑脊液的ADC值并进行统计学分析。结果:表皮样囊肿和蛛网膜囊肿在T1WI和T2WI上呈相同的信号改变;在DWI上表皮样囊肿呈高信号,而蛛网膜囊肿呈低信号;表皮样囊肿的ADC值[(10.197±0.329)×10-4mm2/s]明显低于蛛网膜囊肿[(30.098±1.510)×10-4mm2/s],差异有显著性意义(P<0.05)。结论:DWI对于表皮样囊肿与蛛网膜囊肿的鉴别诊断具有重要价值。     

磁共振扩散加权成像在颅内表皮样囊肿中的诊断价值

目的：探讨磁共振扩散加权成像（DWI）在颅内表皮样囊肿中的诊断价值。方法：收集颅内表皮样囊肿病例16例，均行常规MRI和DWI检查，分析表皮样囊肿在T2WI、T1WI、增强扫描和DWI上的影像表现。结果：16例均呈长T2长T1信号，其中2例伴短T2间隔信号，增强扫描14例无强化，2例呈包膜和间隔强化。16例DWI上均呈明显高信号。结论：磁共振DWI在颅内表皮样囊肿中具有重要的诊断价值，可作为常规MRI的重要补充检查方法。     

颅内表皮样囊肿MRI诊断的序列选择及应用价值

目的探讨MR各种扫描序列对颅内表皮样囊肿的诊断价值。资料与方法49例经手术及病理证实的颅内表皮样囊肿,均行T1WI、T2WI、液体衰减反转恢复序列(FLAIR)、扩散加权成像(DWI)及增强扫描。9例T1WI呈高信号者加扫脂肪抑制像。结果49例肿瘤中不规则形36例,圆形或类椭圆形13例。在T2WI上,38例呈高信号,另11例为高信号中夹杂斑片状等信号;肿瘤在T1WI上信号多变,其中40例为低信号,余9例为高低混杂信号(6例)或高信号(3例),经脂肪抑制后,其中3例部分高信号衰减;FLAIR为中等及低混杂信号;所有患者DWI均为高信号;增强后34例无强化,15例边缘弧线形强化。结论颅内表皮样囊肿在MR各序列上均有特征性表现。DWI扫描有助于鉴别诊断。MRI多方位、多序列扫描的综合应用,能术前准确诊断,使选择最佳手术方式和入路成为可能。     

侧脑室表皮样囊肿的磁共振影像表现及其扫描技术分析

目的回顾性分析侧脑室表皮样囊肿的磁共振成像(MRI)表现,探讨磁共振(MR)扫描技术在侧脑室表皮样囊肿诊断中的价值。方法分析12例手术病理证实为侧脑室表皮样囊肿的MR影像表现及术前做MR常规平扫、增强扫描和T2FLAIR以及磁共振弥散加权成像(DWI)资料。结果 11例T1WI呈低信号,1例T1WI呈高信号,脂肪抑制像未能抑制。12例T2WI呈高信号,稍高于脑脊液。10例T2FLAIR囊内见不同数量的絮状稍高信号影,其中有2例仅在边缘出现少量絮状等高信号影。DWI均表现为明显高信号,信号不均匀。增强多无强化或或囊壁轻度强化,其中2例发生恶性变者局部囊壁呈结节状及花环状明显强化。结论侧脑室表皮样囊肿MR表现具有一定的特征性,对本病的诊断与鉴别诊断具有价值。侧脑室表皮样囊肿病灶检出方面,DWI均优于MRI平扫以及T2FLAIR,是首选扫描技术。     

磁共振扩散加权成像对于颅内表皮样囊肿的诊断价值

目的:探讨磁共振扩散加权成像(DWI)对于颅内表皮样囊肿的诊断价值。方法:回顾性分析11例经手术病理证实的颅内表皮样囊肿术前常规MRI和DWI的信号特征。结果:11例均为单发;7例表现为囊状均匀性长T1长T2信号,4例病灶信号不均匀,以长T1长T2信号为主,其内混杂少许等T1等T2信号;5例行增强扫描均未见异常强化;所有病灶在DWI上均表现为明显高信号,边界清楚,ADC图表现为中等信号。结论:DWI对于颅内表皮样囊肿的诊断及鉴别诊断具有重要价值,应作为首选检查与常规扫描同时应用。     

颅内不典型表皮样囊肿MR表现和病理对照分析

目的 探讨颅内不典型表皮样囊肿的MR表现及其与病理所见的关系.方法 回顾性分析7例颅内不典型表皮样囊肿的MR表现,并与手术病理所见对照.全部病例均行MR平扫检查,2例行MR增强扫描,1例行CT扫描.结果 4例表皮样囊肿位于小脑半球实质,2例位于大脑半球实质,1例位于小脑周围.T1WI 6例表皮样囊肿呈高信号,1例呈等信号,T2WI 5例呈很低信号,2例呈高信号.增强扫描囊肿不强化.病理检查镜下可见囊肿内大量蛋白物质.结论 颅内表皮样囊肿呈短T1和等T1信号主要与囊肿内存在大量蛋白物质有关,需要与颅内短T1信号的病变鉴别.     

弥散MRI诊断颅内表皮样囊肿的价值

目的:探讨磁共振弥散加权成像(DWI)及表观弥散系数(ADC)图诊断颅内表皮样囊肿的价值.材料和方法:分析19例表皮样囊肿常规MRI和DWI的信号特征,定量测定表皮样囊肿、正常脑实质和脑脊液的ADC值.结果:17例表皮样囊肿T1WI、T2WI呈等或稍高于脑脊液信号,2例T1WI呈高低混杂信号.肿瘤边缘弧线形增强或不增强.19例肿瘤DWI呈明显高于脑实质和脑脊液信号,肿瘤较脑脊液的平均ADC值显著减低,较脑实质的平均ADC值显著增高.结论:DWI优于常规MRI发现颅内表皮样囊肿,DWI上表皮样囊肿的高信号可能是肿瘤组织的T2余辉效应所致.     

扩散加权成像在卵巢表皮样囊肿中的诊断应用简

目的：探讨磁共振扩散加权像（DWI）及表观扩散系数对卵巢表皮样囊肿的诊断价值。方法回顾性分析11例经手术病理证实的卵巢表皮样囊肿患者磁共振常规及扩散加权成像,选取感兴趣区,测量表观扩散系数进行分析。结果磁共振平扫11例T1WI呈低信号,T2WI为高信号,DWI呈高信号,表观扩散系数（ADC）值降低,ADC值范围为（0．632~1．082）×10-3 mm2/s。结论通过对卵巢表皮样囊肿磁共振表现的分析,提示扩散加权成像对卵巢表皮样囊肿诊断有一定特异性。     

Intracranial epidermoid cysts: diffusion-weighted, FLAIR and conventional MR findings

PURPOSE: To compare diffusion-weighted echo-planar imaging (DW) with spin-echo (SE), and fluid-attenuated inversion recovery (FLAIR) sequences in the evaluation of epidermoid cysts (ECs), and to evaluate T2 shine-through effect. MATERIALS AND METHODS: Fifteen patients were imaged prospectively in two different 1.5 T magnetic resonance (MR) units with standard head coils with SE, FLAIR and DW echo planar imaging sequences. The qualitative and quantitative assessments were performed by two radiologists in consensus. Apparent diffusion coefficient (ADC) values were obtained from all ECs. Exponential DW images are obtained in 11 cases to eliminate T2 shine-through effects. The results are analyzed with variance analysis (ANOVA) and Bonferroni t method. RESULTS: FLAIR sequence was superior to T1- and T2-weighted sequences in showing ECs. In 13 cases, the borders of the lesions could be delineated from the surrounding structures with only DW imaging where ECs were markedly hyperintense. The ADC values of ECs are significantly lower than CSF (P < 0.001), and significantly higher than deep white matter (P < 0.01). On exponential DW images, ECs had similar intensity with brain parenchyma showing that the real cause of the hyperintensity of the lesions on trace images is the enhanced T2 effect of the tissue. CONCLUSION: FLAIR sequence is superior to the conventional MR sequences in demonstrating the ECs and DW imaging is superior to other MR sequences in delineating the borders of the ECs. Exponential DW images had shown that the hyperintensity in the trace images are caused by increased T2 effect of the lesion rather than the decrease in ADC values.     

Evaluation of complex cystic masses of the brain: value of steady-state free-precession MR imaging.

OBJECTIVE. This study evaluated the effectiveness of steady-state free-precession (SSFP) MR imaging of complex cystic masses of the brain compared with that of conventional T1- and T2-weighted spin-echo imaging. Our hypothesis is that SSFP MR images provide better characterization of these masses and facilitate more appropriate preoperative diagnoses and planning. SUBJECT AND METHODS. Axial T1-weighted and SSFP MR images and specimens for pathologic examination were obtained in seven consecutive patients, 9-81 years old, with cystic mass lesions of the brain and neurologic symptoms and signs directly related to the masses. Axial contrast-enhanced T1-weighted images were obtained in six patients, surgical exploration was done in five patients, and stereotaxic biopsy was done in two. After examination of the routine spin-echo and SSFP images, the usefulness of SSFP images was determined by how well they facilitated correct preoperative diagnosis. RESULTS. On SSFP MR images, the solid or inhomogeneous components of a cystic mass had extremely low signals in contrast to the high signal of surrounding fluid. On routine spin-echo images, however, the signals of these components were masked by the signal of the surrounding fluid. SSFP MR images helped markedly in diagnosis of hemorrhagic, epidermoid, and arachnoid cysts. In cases of enhancing brain tumors, SSFP MR images provided the same information that contrast-enhanced images did. Overall, when SSFP MR imaging was used, more information about the texture and constituents of the cystic mass was obtained, and a more useful diagnosis was made. CONCLUSION. Initial results show that SSFP MR imaging is a more useful technique than conventional spin-echo imaging for characterizing complex cystic masses of the brain. SSFP MR imaging (1) allows distinction of edema from tumor, (2) helps establish where biopsy has the best chance of providing tissue that will show pathologic changes, and (3) helps distinguish simple cysts from tumors, tumor-cyst, or multicompartmental cyst and may be particularly helpful in detecting the contents of hemorrhagic cysts.     

Diffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors

This study demonstrates the use of diffusion-weighted MR imaging in improving the specificity of the diagnosis of extraaxial brain tumors. Three surgically proved lesions (one arachnoid cyst and two epidermoid tumors) and two nonsurgically proved lesions (arachnoid and ependymal cysts) were evaluated with T1- and T2-weighted spin-echo studies followed by intravoxel incoherent motion (IVIM) MR imaging. The IVIM images of the lesions were displayed as an apparent diffusion coefficient (ADC) image obtained at 0.65 G/cm (maximum gradient b value = 100 sec/mm2) and compared with external oil and water phantoms. The ADC of arachnoid cysts was similar to stationary water whereas the ADC of epidermoid tumors was similar to brain parenchyma, indicating the solid nature and the slower diffusion rate of the epidermoid tumors. Cisternal CSF demonstrated uniformly high ADC, primarily because of bulk flow, which enhanced image contrast. Improved delineation of postsurgical changes was also possible. Our preliminary results show that diffusion-weighted MR imaging can be useful in distinguishing between arachnoid cysts and epidermoid tumors.     

Diffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors

This study demonstrates the use of diffusion-weighted MR imaging in improving the specificity of the diagnosis of extraaxial brain tumors. Three surgically proved lesions (one arachnoid cyst and two epidermoid tumors) and two nonsurgically proved lesions (arachnoid and ependymal cysts) were evaluated with T1- and T2-weighted spin-echo studies followed by intravoxel incoherent motion (IVIM) MR imaging. The IVIM images of the lesions were displayed as an apparent diffusion coefficient (ADC) image obtained at 0.65 G/cm (maximum gradient b value = 100 sec/mm2) and compared with external oil and water phantoms. The ADC of arachnoid cysts was similar to stationary water whereas the ADC of epidermoid tumors was similar to brain parenchyma, indicating the solid nature and the slower diffusion rate of the epidermoid tumors. Cisternal CSF demonstrated uniformly high ADC, primarily because of bulk flow, which enhanced image contrast. Improved delineation of postsurgical changes was also possible. Our preliminary results show that diffusion-weighted MR imaging can be useful in distinguishing between arachnoid cysts and epidermoid tumors.     

卵巢内膜异位性囊肿的MRI诊断

目的：评价MRI诊断卵巢内膜异位性囊肿的价值。材料和方法：记录14例患者的25个痛灶MRI形态及信号变化特点，并与手术病理结果相对照．结果：发现当囊肿在T1WI上呈均匀高信号，T2 WI上部分区域出现中等至低信号暗影，或T1 WI病灶由多个全为高信号的囊腔组成时，不管其T2 WI上的信号强度如何．基本可确诊为卵巢内膜异位性囊肿．当囊肿在T1WI和T2WI上呈高信号．或囊肿与邻近器官有粘连，囊腔周围有纤维被膜包绕，在T1WL及T2WI上形成-低信号带影时．应高度怀疑之。结论：MRI对内膜异位性囊肿诊断的敏感性及准确性分别可选96%和93%．     

MR imaging of epidermoid cysts

Nine patients with epidermoid cysts, five of them pathologically proved, were evaluated with MR imaging. Six patients also had CT. The cases were reviewed to evaluate the MR appearance of epidermoid cysts and to compare the MR findings with those of CT. The epidermoid cysts demonstrated low-signal intensity on T1-weighted MR images and hyperintensity on T2-weighted images. In five cases the cysts appeared heterogeneously iso- to hyperintense on the intermediate echo, and were surrounded by a thin rim of high signal intensity, which we believe was caused by encased CSF. The CT scans showed the cysts as low-density, well-demarcated lesions that do not enhance after infusion with contrast material. We conclude that MR is superior to CT in the evaluation of epidermoid cysts and is particularly useful in surgical planning.     

Use of diffusion-weighted MR imaging in differential diagnosis between intracerebral necrotic tumors and cerebral abscesses.

The differential diagnosis between intracerebral necrotic tumors and cerebral abscesses is frequently impossible with conventional MR imaging. We report two cases of cerebral abscesses that showed high signal on diffusion-weighted echo planar imaging and a strongly reduced apparent diffusion coefficient. This appearance was not present in our cases of necrotic/cystic gliomas (eight cases) and necrotic metastases (two cases). We believe that diffusion-weighted MR imaging may be a diagnostic clue in cases of cerebral "ring-enhancing" masses.     

Spontaneous intracerebral hematoma on diffusion-weighted images: influence of T2-shine-through and T2-blackout effects

BACKGROUND AND PURPOSE: On diffusion-weighted (DW) images, primary hematomas are initially mainly hyperintense, and then hypointense during the first few days after stroke onset. As in other brain disorders, variations in the T2 relaxation time of the hematoma influence the DW imaging signal intensity. Our aim was to evaluate the contribution of the T2 signal intensity and apparent diffusion coefficient (ADC) changes to signal intensity displayed by DW imaging through the course of hematoma. METHODS: The MR images of 33 patients with primary intracranial hemorrhage were retrospectively reviewed. Variations in T2-weighted echo planar images, DW imaging signal intensity, and apparent diffusion coefficient (ADC) ratios (core of hematoma/contralateral hemisphere) were analyzed according to the putative stages of hematoma, as seen on T1- and T2-weighted images. RESULTS: On both T2-weighted echo planar and DW images, the core of the hematomas was hyperintense at the hyperacute (oxyhemoglobin, n = 11) and late subacute stages (extracellular methemoglobin, n = 4), while being hypointense at the acute (deoxyhemoglobin, n = 11) and early subacute stages (extracellular methemoglobin, n = 7). There was a positive correlation between the signal intensity ratio on T2-weighted echo planar and DW images (r = 0.93, P < .05). ADC ratios were significantly decreased in the whole population and in each of the first three stages of hematoma, without any correlation between DW imaging findings and ADC changes (r = 0.09, P = .6). CONCLUSION: Our results confirm that the core of hematomas is hyperintense on DW images with decreased ADC values at the earliest time point, and may thus mimic arterial stroke on DW images. T2 shine-through and T2 blackout effects contribute to the DW imaging findings of hyperintense and hypointense hematomas, respectively, while ADC values are moderately but consistently decreased during the first three stages of hematoma.     

Improved detection of intraventricular cysticercal cysts with the use of three-dimensional constructive interference in steady state MR sequences

BACKGROUND AND PURPOSE: Before the advent of MR imaging, intraventricular cysts were difficult to diagnose noninvasively. Among the invasive procedures used were contrast ventriculography and CT ventriculography. MR imaging, with its multiplanar imaging capabilities, excellent depiction of tissue contrast, and versatile parameters, is an important tool in the assessment of intraventricular cystic lesions. We investigated the role of three-dimensional constructive interference in steady state (3D-CISS) MR sequences in the evaluation of intraventricular cysticercal cysts. METHODS: The study group comprised 11 patients with intraventricular cysticercal cysts. MR studies included spin-echo (SE) T1-weighted, turbo-SE T2-weighted, and 3D-CISS sequences. All images were obtained on a superconducting 1.5-T MR unit. The routine and 3D-CISS sequences were reviewed and interpreted separately by two neuroradiologists. RESULTS: All patients underwent surgery for excision of intraventricular cysticercal cysts. Eight patients had cysts in the fourth ventricle, two in the lateral ventricle, and one in the third ventricle. SE T1-weighted images showed the cystic wall in nine cases, the scolex in four, and the cystic fluid in two. Turbo-SE T2-weighted images showed the cystic wall and scolex in three and four cases, respectively. The routine sequences did not show the scolex, cystic wall, or cystic fluid together in any of the 11 patients. 3D-CISS images showed the scolex in all 11 patients and the cystic wall and cystic fluid in eight patients each. In seven of the 11 patients, 3D-CISS images showed the scolex, cystic wall, and fluid together. CONCLUSION: The 3D-CISS sequence is more sensitive and specific than routine SE sequences in the diagnosis of intraventricular cysticercal cysts.