The study of 201Tl, 123I-IMP-SPECT before and after radiation therapy of brain tumor

201Tl, 123I-IMP-SPECT were performed in 17 patients with brain tumors before and after radiation therapy, compared with X-CT. 15 of 17 patients showed enhanced areas on X-CT and higher accumulations on 201Tl-SPECT in the same lesions before radiation therapy. There was significant correlation between enhanced lesions on X-CT and lesions of higher accumulation on 201Tl-SPECT before and after radiation therapy. But, the patients with residual enhanced lesions on X-CT did not always show higher accumulation on 201Tl-SPECT after radiation therapy. And, 2 patients with radiation injury after radiation therapy for brain tumor did not show higher accumulation on 201Tl-SPECT, though one patient showed enhanced lesion on X-CT. 201Tl-SPECT was expected to evaluate viability of brain tumor. 123I-IMP-SPECT was useful to recognize the site of higher 201Tl accumulation and evaluate blood flow around brain tumor. It is concluded that 201Tl, 123I-IMP-SPECT is useful for the evaluation of treatment effect of brain tumor and for the differentiation of cerebral radiation injury from recurrent tumor.     

Magnetic resonance imaging of the solitary hepatic mass: Direct correlation with pathology and computed tomography

Magnetic resonance images (MRI) of the liver were obtained using a combination of short time inversion recovery (STIR) and spin echo (SE) sequences. These were correlated with comparable tissue slices generated from resected specimens obtained at partial hepatectomy. All 10 cases appeared to have solitary masses on contrast enhanced computed tomography (CT). Histological examination revealed five primary tumours (two hepatocellular carcinomas, two haemangiomas and one cholangiocarcinoma) and five metastatic tumours. The STIR images demonstrated a high signal intensity in all areas of viable tumour involvement and reduced signal intensity in regions of confluent necrosis with superimposed haemorrhage or calcification. This sequence also demonstrated additional areas of high signal intensity adjacent to several lesions which were not visible on CT. Microscopy of these regions in the specimens demonstrated no tumour involvement or steatosis and their precise cause remains obscure. All the lesions demonstrated on the CT images were visible on MRI and no additional lesions were discovered on detailed microscopical examination of the specimens. Delineation of the extent of the cholangiocarcinoma was a problem with both techniques. MRI showed no major advantage over CT except for a higher contrast of the lesion compared with normal liver and also a better delineation of the tumour mass.     

不典型神经鞘瘤的影像学诊断

目的 探讨不典型神经鞘瘤的临床影像学表现特点。方法 回顾分析44例经病理学诊断的不典型神经鞘瘤的CT和MRI表现。结果 CT表现为类圆形或分叶状低密度或等低混杂密度灶,绝大多数（38/40）边界清楚,其中实性肿瘤17例,囊实性病灶19例,单纯囊性病灶4例。CT增强扫描肿瘤实质呈渐进性不均匀强化。囊性病灶内存在强化程度不一的结节灶可能是囊实性神经鞘瘤较为特征性的表现。实性病灶呈＂同心圆样＂强化可能是实性神经鞘瘤比较有价值的征象。MRI上肿瘤实质部分呈稍长T1稍长T2信号,囊性部分呈长T1长T2信号,病灶周围可见水肿信号;＂靶征＂是特征性的MRI表现。结论 不典型神经鞘瘤可发生在身体任何部位,熟悉其影像学特点对诊断很有帮助。     

Role of MR in characterizing expansive lesions of the adrenal gland]

Five patients with adrenal tumors (20 metastases, 12 adenomas, 8 myelolipomas, 6 primary tumors, 4 pheochromocytomas, and 1 hyperplasia) were studied by means of MRI with SE sequences. Twenty of them underwent dynamic study with GE sequences after i.v. injection of paramagnetic contrast media. Sixteen of 20 metastases exhibited low signal intensity on T1 and high signal on T2. One patient had low signal on both T1 and T2. Two lesions in patients with melanoma showed high signal in T1; in 1 case, the lesion exhibited a hemorrhagic area. Signal from adenomas was low in T1- and T2-weighted pulse sequences in 10/12 patients, while in the extant 2 cases signal was higher in T2. Myelolipomas had hyperintense signal on T1-weighted images in 5 cases and isointense signal with the renal cortex in the extant 3 cases. Pheochromocytomas and primary tumors appeared hypointense on T1 and hyperintense on T2. In 3 CT questionable cases, MRI showed the adrenal origin of the lesion. Dynamic study with GE sequences after Gd-DTPA injection showed low enhancement and fast washout in adenomas, while malignant lesions had higher enhancement and slower washout. In our study, MRI allowed to correctly characterize 11/12 adenomas, with only 1 false negative in a metastatic lesion.     

脊髓内海绵状血管瘤的MR影像诊断

目的 探讨脊髓内海绵状血管瘤的MR影像表现特点.资料与方法 经临床证实的11例脊髓内海绵状血管瘤,其中7例经病理证实,男4例,女7例,年龄9～62岁.主要临床表现有反复发作性背部疼痛、肢体疼痛、感觉、运动障碍.MR扫描行矢状位T_1WI、T_2WI,横轴位T_2WI,冠状位T_1WI,增强扫描6例.结果 9例病灶为单发,2例为2个病灶,病灶位于颈段脊髓内8个、胸段脊髓内5个.11个病灶呈类圆形、卵圆形,2个病灶呈梭形.病灶均呈稍长T_1、长T_2信号,其中1个卵圆形病灶、2个梭形病灶内见点条状稍短T_1、短T_2信号分隔,周边均绕以形态不一的短T_2信号环,1个病灶周围有稍长T_1、长T_2信号水肿.6例增强检查,2例病灶未见明显强化,4例病灶显示轻中度不均匀强化.结论 脊髓内海绵状血管瘤MR表现形式具有一定特征性,对提高该病诊断准确率具有价值.     

预饱和脂肪抑制技术在乳腺MRI检查中的临床应用

目的 探讨预饱和脂肪抑制技术在乳腺MRI检查中的临床应用价值。资料与方法 对58例乳腺疾病患者进行常规MRI平扫、脂肪抑制MRI平扫和脂肪抑制动态增强MRI扫描，对比分析SE TlWI、FSE T2WI、脂肪抑制SE T1WI、脂肪抑制FSE T2WI和脂肪抑制SE T1WI增强扫描5种图像对病变的检出情况及病变形态和内部信号的显示效果。结果 (1)对病变的检出，脂肪抑制增强扫描明显优于平扫各图像，检出率达100％，平扫各图像对病变的检出无显著性差别，其中以脂肪抑制T2WI为最好，检出率为93．1％，脂肪抑制T1WI最差，检出率为85．06％；(2)在病变形态的显示上，虽然脂肪抑制T2WI效果较好，但与常规T2WI相比并无显著性差别，而脂肪抑制的增强扫描则明显优于平扫各图像；(3)在病变内部信号的显示方面，脂肪抑制的平扫(包括T1WI、T2WI)明显优于常规平扫，而脂肪抑制的增强扫描明显优于平扫各图像。结论 乳腺MRI平扫中脂肪抑制的应用对病变的检出及内部信号的显示具明显优势，以脂肪抑制T2WI效果更好；在脂肪抑制基础上进行动态增强扫描不仅对病变强化的形态学特征显示良好，明显提高病变的检出率，而且能准确判断病变强化程度，观察病变血流灌注的动态变化过程．明显提高了MRI对乳腺疾病诊断的准确性，因此预饱和脂肪抑制技术在乳腺MRI增强扫描中的应用具有重要价值。     

背部弹力纤维瘤的超声、CT和MRI诊断及病理表现

目的探讨背部弹力纤维瘤的超声、CT和MRI表现及其诊断价值。资料与方法收集经手术病理证实的21例背部弹力纤维瘤患者的资料,测量肿块大小、分析影像学特征,比较肿块、前锯肌及周围脂肪的CT平扫及增强CT值,评价超声及CT对病灶显示的一致性。结果①所有病灶均位于前锯肌、背阔肌内侧,表现为扁丘状或梭形软组织肿块。②影像学表现:超声表现为肿块边界不清,以中强回声为主,可见条索状高低回声,所有病灶均未探及血流信号;CT平扫示病灶密度稍低于或接近邻近肌肉组织,肿块边缘不清,其内可见条纹状脂肪密度,增强扫描呈轻度强化或无强化;MRI示病灶T1WI呈中等信号为主的肌纤组织与高信号脂肪组织交替排列,T2WI呈稍低信号,其内夹杂条纹状高信号,后者在脂肪抑制序列呈低信号,增强扫描呈轻度强化。③单、双侧发病率及左、右侧病灶大小比较,差异均有统计学意义(P<0.05);超声和CT对病灶的显示一致性较好(Kappa=1.000,P=0.000)。结论背部弹力纤维瘤具有典型的发病部位及影像学特征,仔细观察可做出明确诊断。     

Multi-contrast,isotropic, single-slab 3D MR imaging in multiple sclerosis

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion-recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting multiple sclerosis (MS) brain lesions compared to 2D T2-weighted spin-echo (T2SE). All single-slab 3D sequences and 2D-T2SE were acquired in 16 MS patients and 9 age-matched healthy controls. Lesions were scored independently by two raters and characterized anatomically. Two-tailed Bonferroni-corrected Student's t-tests were used to detect differences in lesion detection between the various sequences per anatomical area after log-transformation. In general, signal and contrast properties of the 3D sequences enabled improved detection of MS brain lesions compared to 2D-T2SE. Specifically, 3D-DIR showed the highest detection of intracortical and mixed WM-GM lesions, whereas 3D-FLAIR showed the highest total number of WM lesions. Both 3D-DIR and 3D-FLAIR showed the highest number of infratentorial lesions. 3D-T2 and 3D-MPRAGE did not improve lesion detection compared to 2D-T2SE. Multi-contrast, isotropic, single-slab 3D MRI allowed an improved detection of both GM and WM lesions compared to 2D-T2SE. A selection of single-slab 3D contrasts, for example, 3D-FLAIR and 3D-DIR, could replace 2D sequences in the radiological practice.     

肝脏血管平滑肌脂肪瘤的CT及MRI征象分析

目的 分析13例肝脏血管平滑肌脂肪瘤（AML）的CT及MRI表现,进一步提高诊断准确性。方法 所有病例均经手术病理证实。12例经CT检查,其中6例做过MRI检查,仅1例只做MRI检查。平扫后行增强动脉期和门脉期扫描,5例做了延迟期扫描。MRI检查行SE T1WI、快速自旋回波（FSE）T2WI和快速多层面干扰梯度回波（FMPSPGR）序列横断面动态多期增强扫描。结果 CT平扫11个病灶为低密度,1个为略高密度。动脉期所有病灶均有强化表现,8个病灶见到中心血管影。门脉期8个病灶有持续强化,有6个病灶见到中心血管影。MR T1WI上5个病灶为混杂信号,T2WI上所有病灶均为高信号,但信号强度各不相同。MR增强动脉期6个病灶有强化,1个病灶强化不明显。门脉期4个病灶有持续强化,3个为低信号。MR增强扫描中也有4个病灶显示中心血管影。结论 CT和MRI检查均可显示AML的特征,特别是病灶中脂肪成分和血管影高度提示AML的诊断。MR SE序列加脂肪抑制显示脂肪成分比CT更加敏感。CT和MR动态增强多期扫描可充分反映AML的强化特征,有助于提高AML的诊断准确性。     

(1)H MRI of pneumococcal pneumonia in a murine model

PURPOSE: To detect and quantify pulmonary lesions due to pneumococcal pneumonia in a murine model by (1)H MRI. MATERIALS AND METHODS: Pneumonia was induced in mice (N = 5) by intranasal administration of about 1 x 10(6) colony-forming units (CFU) of Streptococcus pneumonie. A group of noninfected animals (N = 5) was used as a control group. MRI was performed, 48 hours after infection induction, at 4.7 T. ECG-gated gradient-echo (GRE) sequences with TE = 5 msec were used. After MRI examination, the animals were sacrificed for histological examination. RESULTS: Lungs appeared at MRI as regions with signal intensity (SI) at the level of the noise. Lesions appeared as hyperintense regions over the background and were localized mainly in the apical part of the lungs, in the medial and peribronchial regions. The anatomical localization of the lesions was confirmed by histology. The total lesion volume quantified by MRI data correlated with the total lesion volume quantified by histology. CONCLUSION: This work shows that standard (1)H MRI allows detection and quantification of lesions due to pneumococcal pneumonia in mice.     

MRI diagnosis and follow-up of subcutaneous fat necrosis

The purpose of this report is to present the MRI features of subcutaneous fat necrosis (SFN) and the natural history of this process. We have seen 12 patients with SFN, one case of which was confirmed histopathologically. In six patients, a follow-up MRI study was performed. MRI findings were very similar in all of the cases: small, linear, and spiculated lesions with one or two components: a globular area yielding high signal intensity on T1-weighted images, intermediate to high signal intensity on fast SE T2-weighted images and focal signal void on short-inversion -time inversion recovery (STIR) sequence, corresponding to an area of fat necrosis; and a laminar starred component, with low signal intensity on T1 and fast SE T2-weighted images and high signal intensity on the STIR sequence, corresponding to reactive fibrous tissue. The follow-up MRI study of six patients showed either disappearance (n = 2) or decrease in size (n = 3) of the globular component; in one patient, no change was observed. A less prominent decrease of the laminar component also was seen in five patients. One patient did not present any change in this laminar component. The most characteristic MRI findings of this lesion are the high signal intensity areas on T1-weighted images, their small size (<3 cm), their linear spiculated shape with both laminar and globular components, and no contrast enhancement after injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection. We believe that the location, size, morphology, and MRI signal intensity of SFN may allow its differentiation from other types of soft tissue lesions.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.

Abstract：

Objective To explore the imaing features of hemangioma in the long bone and improve the diagnostic level of this disease. Methods The X-ray(14 cases), CT(9 cases) and MRI(6 cases)findings of 18 patientswith histologically proven hemangioma in the long bone after surgery were retrospectively reviewed. Results Ten tumors occurred in medullary cavity or bone end(medullary type),6 on the surface of bone (periosteal type) and 3 in cortex (intracortical type). X-ray findings: among 8 cases of medullary type, 3 showed honeycomb appearance, 3 lytic areas with sclerotic borders, one purely osteolyticchanges, and 1 frosted glass; 3 cases of periosteal type showed sclerosis and thickening of the underlying cortex; 3 cases of intracortical type showed well-defined osteolytic foci. CT findings: among 6 cases of medullary type, 5 appeared as expansile lytic lesion with uneven selerotic rim (3 cases)orhoneycomb appearance (2 cases), 1 cribriform appearance in the cortical bone, 2 periostealnew bone formation in vertical radiation pattern; 1 ground-glass appearance; among 2 cases of periosteal typeone showed regular cortical thickening, and the other irregular periosteal proliferation with marrowing of medullarycavity; 1 case of intracorticaltype showed density similar to that of soft tissue, with cortical thickening and expansion . MRI findings: 2 apeared as well-defined lesions with low signal intensity on T1WI and high signal intensity on T2WI; 1 appeared as ill-defined lesion with low to intermediate signal intensity on T1 WI and T2 WI. One showed breakthrogh of cortex and formation of soft tissue mass with low signal intensity on T1 WI and high signal on T2WI. Two showed thickening of periosteumwith intermediate signal intensity in one of them and very low signal intensity in the other. Two showed abnormal signal intensity in surrounding muscles, which was high on T2 WI and intermediate on T1 WI. Conclusions The soap-bubble or honeycomb appearance is the typical radiographic finding of hemangioma in long bone. CT and MRI can provide useful information for the diagnosis of hemangioma in long bone.     

Hepatic angiomyolipoma: MRI findings

Objective: To analyze the variable appearances of hepatic angiomyolipoma (AML) on the magnetic resonance imaging (MRI), and to improve the diagnostic accuracy of AML with MRI. Methods and materials: Twelve cases were proved by surgical pathology. MRI with SE T₁WI, FSE T₂WI and FMPSPGR axial dynamic multi-phase contrast scanning were performed in all cases. Results: Eight of ten lesions showed inhomogeneous hyperintense on SE T₁WI and the part of hyperintensity turned to hypointensity with the application of fat suppression technique. The other four lesions were hypointense. Flow void signal could be seen in four lesions. Ten lesions were various hyperintensity from slight hyperintensity to strong hyperintensity on FSE T₂WI. One lesion appeared as isointensity and the other one was hypointensity on heavy T₂WI with fat suppression technique because of containing most of fat. Vessels within the lesions appeared as curved linear or tubular hyperintensity resulting from slow blood flow also could be seen in four lesions. On dynamic contrast-enhanced arterial phase scanning, all of 12 lesions had enhancement. Central vessels could be shown within six lesions. On portal venous phase scanning, four lesions were hypointensity, the other eight lesions remained enhancement. The vessels within the lesions were still shown in seven lesions. Discussion and conclusion: MRI SE sequence with fat suppression technique combined with dynamic contrast-enhanced scanning could demonstrate the features of hepatic AML, such as fat components, marked inhomogeneous early and prolonged enhancement, especially the central vessels within the lesions suggested strongly the diagnosis of AML. MRI is helpful to improve the diagnostic accuracy. For atypical cases, it should be carefully differentiated from other hypervascular lesions like HCC, FNH, HCA and hemangioma.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.     

长骨血管瘤的影像诊断

目的 分析长骨血管瘤的影像特征,旨在提高其诊断水平.方法 回顾性分析经手术病理证实的18例长骨血管瘤患者的X线平片(14例)、CT(9例)及MRI(6例).结果 18例长骨血管瘤中髓型10例、骨膜型5例、皮质内型3例.X线表现:髓型8例,其中3例表现为典型的蜂窝状,3例为溶骨性病灶周围骨质硬化明显,单纯溶骨、毛玻璃样密度各1例;骨膜型3例,表现为骨皮质增厚、硬化;皮质内型3例,表现为边界清晰的溶骨性病灶.CT表现:髓型6例,表现为溶骨膨胀型病灶5例,其中3例可见薄厚不一的硬化边,蜂窝状骨嵴影2例,骨皮质呈筛孔状1例,垂直于骨皮质的放射状骨膜增生2例;毛玻璃样密度1例.2例骨膜型表现为骨皮质均匀增厚1例,不规则骨膜增厚1例,局部髓腔狭窄消失.1例皮质内病变表现为病灶呈均匀软组织密度,局部皮质膨胀、增厚.MRI表现:2例显示髓腔内斑片状T1WI稍低信号,T2WI均呈稍高信号,边界清晰;1例T1WI及T2WI均呈等或稍低信号,病灶与正常组织分界不清;1例显示病灶突破局部骨皮质,肿物向外突出,外突肿物及相连髓腔部分T1WI呈稍低信号,T2WI呈高信号;2例显示骨膜增厚,其中1例呈等信号,1例无信号;2例周围肌肉组织内可见不均匀斑片状长T2信号,T1WI与肌肉组织呈等信号.结论 长骨血管瘤的囊性蜂窝状X线表现较为特征型;CT及MRI有助于长骨血管瘤的诊断.     

Balo同心圆硬化的MRI和功能MRI表现

目的:探讨常规MRI、扩散张量成像和MRS对Balo同心圆硬化(BCS)的诊断价值。方法:分析4例BCS的MRI表现,并与病理结果进行对照,其中行MR扩散张量成像和质子磁共振波谱(1H-MRS)检查各1例。结果:4例中MRI显示13个病灶,3例多发,1例单发。9个病灶呈典型同心圆或洋葱皮样改变,T1WI上呈等信号和低信号交替环,FLAIR序列T2WI上呈等信号和高信号相间,与病理显示的病灶严重脱髓鞘区和髓鞘保留区相间排列的特点一致。1例1H-MRS示病变区NAA降低、Cho升高。1例DWI显示病变不同信号区FA值均低于对侧正常白质,且病变中心区、T1WI和T2WI上显示的等信号带、T2WI上高信号带及病灶周围的FA值存在差异(P<0.05)。纤维束扩散张量成像显示纤维束在病变区部分中断。结论:MRI能反映BCS的病理改变,对BCS活体、无创诊断具有重要意义,DWI和MRS可以作为评价BCS进展、预后和判断疗效的一种成像方法。     

FLASH及FLAIR序列在脑弥漫性轴索损伤中的诊断价值

目的 探讨MR快速小角度激发梯度回波(FLASH)序列及液体衰减反转恢复(FLAIR)序列在脑弥漫性轴索损伤(DAI)中的诊断价值.资料与方法 回顾性分析40例经临床诊断的DAI患者的MR影像资料,所有患者均行T1WI、T2WI、FLAIR及FLASH序列扫描.比较各序列脑内病灶的显示率,分析其信号特征.结果 FLASH序列显示病灶最多、最敏感,病灶主要分布在皮髓交界区、基底节、胼胝体、脑干及小脑等区域,呈散在针尖状、斑点状、结节状、小片状中央显著低信号,周围薄环状高信号,FLAIR序列只有部分病灶显示,为结节状、斑片状高信号,且病灶越小显示越不敏感,常规T2WI较FLAIR序列敏感性差,常规T1WI显示率最低,显示者T2WI为高信号,T1WI为低信号.结论 对DAI病灶检出率FLASH、FLAIR序列较常规T2阢、T1WI高,可为DAI早期诊断、早期治疗提供科学、客观的影像学资料,对临床疑有DAI患者FLASH、FLAIR序列应作为MR检查的常规序列,FLASH序列为首选序列.     

病毒性脑炎的MRI诊断

目的探讨病毒性脑炎MR I表现特点及与急性播散性脑脊髓炎(ADEM)鉴别的可能性。方法分析56例病毒性脑炎及50例ADEM的脑部MR I表现,重点分析病毒性脑炎的脑部MR I表现。结果病毒性脑炎脑内有多发或单发的对称或不对称大片状病灶,主要位于皮层、皮层下及基底节-丘脑区,MR I呈长T1长T2信号,增强扫描27例,显示病灶强化者17例,其中呈大片状或脑回状强化者10例。ADEM则脑内有多发不对称斑点、斑片状病灶,主要位于双侧脑室周围及额颞顶枕叶脑白质区,MR I呈长T1长T2信号,增强扫描20例,显示病灶强化者15例,均为环形或斑点状强化。结论MR I是诊断病毒性脑炎重要的辅助检查方法,可在一定程度上为临床的早期诊断及鉴别诊断提供依据。     

急性实验性变态反应性脑脊髓炎模型的MRI表现及其病理基础

目的 探讨急性实验性变态反应性脑脊髓炎(EAE)模型的MRI表现及其病理基础.方法 用豚鼠全脑脊髓匀浆诱导EAE大鼠模型(6只),观察其体重变化和临床表现,同时设对照组(6只).在EAE大鼠发病后进行MR常规扫描、钆剂增强扫描,并静脉使用超小超顺磁性氧化铁(USPIO),24 h后行USPIO增强扫描,扫描完毕立即处死大鼠取脑,行脑组织切片的HE染色、髓鞘染色和普鲁士蓝染色.观察MRI和病理检查的异常所见,并进行对照.结果EAE大鼠组在诱导后第8～9天开始体重下降,在第10～11天出现临床症状.MR常规扫描未见明确异常,钆剂增强后仅见脑膜弥漫增厚及增强,USPIO增强扫描可见T2WI上延髓实质内大片低信号区,T1WI可见对应部位的高信号.梯度回波T2*WI比T2WI显示在脑干病灶以外的小脑白质内低信号.临床评分高的大鼠其低信号范围也较大.对照组大鼠未见异常.病理检查发现发病大鼠脑白质内散在血管套袖,部分伴相邻区域的脱髓鞘改变.普鲁士蓝染色发现病灶内巨噬细胞胞质内有蓝染颗粒,沉积部位与T2WI上低信号对应.结论USPIO增强MRI可以揭示常规MRI和钆剂增强成像未能显示的急性EAE病变,活体显示EAE病灶内巨噬细胞的分布,具有重要的研究价值和应用前景.     

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。