前列腺的MRI

本文着重论述正常前列腺及各种前列腺疾病的 MRI 所见。使用 SE 法摄取 T_1加权像和 T_2加权像,选择能够表现正常解剖组织或病变的断层像,检查时多用横断面。T_2加权像中前列腺显示和肌肉相似的低信号,能明确前列腺的形状、大小及其与周     

脑无症状性脱髓鞘病变MRI及其病因分析(附52例报告)

对52例颅脑MRI显示脱髓鞘病变的患者进行了影像学特征及病因分析,结果表明本组患者脑部双侧脑室周围白质在MRI的T_2加权像上显示条索状或斑片状的不规则高信号影;T_1加权像相应显示低或等信号影,而临床表现无特异性症状。病因是多数病例(40例)可能继发于脑缺血或多发性脑梗塞后的皮质下白质脑病,少数病例(12例)不能排除原发性脱髓鞘病变如MS的诊断。     

鼻咽癌放疗前后转移淋巴结的MRI分析

28例鼻咽癌在放疗前和放疗后一个月内作了MRI检查，放疗前触诊和MRI分别检出36和60枚阳性淋巴结，其差别主要是MRI能发现咽后和都分上颈深区淋巴结并能准确地测量出淋巴结的大小；转移淋巴结在T_1像上表现为与肌肉一致的等信号，T_2像上为类似于脂肪组织的不均匀性高信号，Gd-DTPA增强后出现明显的不均匀强化现象，与鼻咽部原发病灶有类似表现。放疗后MRI图像上有83％的颈淋巴结信号强度基本正常，而鼻咽部信号强度正常者占64％，MRI检查的结果使得对鼻咽癌患者颈淋巴结转移的随访更有针对性。     

不同部位诊断的实际·高中低磁场各自的有用性及限度:肾、肾上腺(泌尿器官)低磁场的临床

作者使用0.22T东芝制MRT22A机,二维富立叶变换法成象,矩阵256×256。脉冲序列用SE法,摄T_1加权象用SE(500/30或40)、质子加权象用SE(2000/30或40)、T_2加权象用SE(2000/60或80)。正常肾皮质的T_1加权象呈中等信号强度,而髓质为低信号强度,故可作出两者的区分。在T_2加权像上,皮及髓质的信号皆较肝脏者高,故难作出区分。肾被膜虽不能显示,但肾筋膜则呈线状低信号区。肾盂、肾盏中的尿液使T_1、T_2增长,故T_1加权象及T_2加权像分别呈低及高信号区,血     

脂肪抑制T2加权成像与增强磁共振成像在鼻咽癌颈部淋巴结转移的应用价值

目的总结鼻咽癌颈部淋巴结转移的磁共振成像(MRI)表现,比较脂肪抑制技术T2加权成像(T2WI)与增强扫描MRI在鼻咽癌颈部淋巴结转移的作用。方法收集210例鼻咽癌颈部淋巴结转移脂肪抑制T2WI与增强扫描MRI资料,比较2种检查序列对鼻咽癌淋巴结转移分区、数量的判断。结果鼻咽癌颈部转移淋巴结分布自上向下发展,短时反转恢复序列(STIR)T2WI在分区及范围上具有优势,增强扫描MRI在淋巴结数量检出率上高于STIR T2WI。结论使用STIR T2WI结合增强MRI有利于鼻咽癌颈部淋巴结转移灶的显示。     

类似灰结节肿瘤的颅内梅毒树胶肿

作者报道了1例经临床诊断且累及灰结节的神经梅毒的MR和CT征象。37岁,持续头痛3个月,伴轻微运动失调,颈部淋巴结肿大,结膜炎,性欲减退。CT扫描显示鞍上强化团块影,MRI显示灰结节处一直径为7 mm的肿块,T_1加权和双自旋回波象上肿块与大脑皮层等信号,在Magnevist增强的T_1加权象上呈显著强化。经化验检查,确立神经性梅毒诊断。给予青霉素G10天后症状改善,3个月后复查神经学检查正常,复查MRI灰结节肿块显著缩小。作者指出,症状性神经性梅毒分实质型和脑膜血管型,但混合型更常见。脑膜血管型神经性     

结核性脊椎炎的MRI

作者用MRI检查8例结核性脊椎炎,3例化脓性脊椎炎,15例转移癌。作者见到,活动性的病变部位的椎体及间盘与正常椎体及间盘比较T_1加权象呈低信号,T_2加权象呈高信号。非活动性的病椎及未消失的病变间盘T_1、T_2加权象与正常椎体及其间盘大致为等信号。T_1加权象可清楚显示脊髓压迫的有无及程度。脓液等炎性物质的压迫,还是驼背所致的骨性压迫等原因,MRI均可判断。关于椎旁脓肿,横断面,冠状面,矢状面MRI均可显示。T_2加权象显示高信号,T_1加权象有显示低信号的倾向。CT和平片能看到脓肿的钙化,MRI显示困难。     

骨盆肿块的US和MRI

作者用MRI观察了20例应用US不能确定的盆腔肿块。MR的指征包括区分子宫肌瘤和附件肿块,确定US显示为单纯囊肿内存在的血液和证实US疑为良性囊性畸胎瘤。20例中13例US不能区分子宫和附件肿瘤。据报道US诊断子宫平滑肌瘤的阳性率是65～93%,但偶有偏心性位于浆膜下及带蒂的肌瘤难以确定,此时MR能提供有关肿瘤位置的更精确资料。作者的检查结果9例确为肌瘤,MR的特点是T_2加权象显示一较低的平滑肌瘤信号,与子宫肌瘤的较高信号有很明显的差别,(变性肌瘤间信号较高)T_1加权成象能分出子宫与附件间的脂肪。作者报导大的浆膜下肌瘤通常围绕一子宫肌肉,(最少一部份)T_2加权显示为较低或不均匀的     

MRI在肝脏占位性病变诊断中的应用

目的:探讨MRI在肝脏占位病变诊断中的应用价值。材料与方法:对98例肝肿瘤患者的MRI影像分析了图像质量、病灶显示清晰度及病变信号特征。全部病例均用1.0T超导磁共振机检查,采用自旋回波(SE)及快速自旋回波(TSE)序列摄取横轴位T_1及T_2加权像。36例患者接受了Gd-DTPA增强,其中12例进行了动态增强检查。结果:图像优良者89％,较差者占11％。MRI能显示的最小病灶为0.5～1.4cm。转移瘤均呈不同程度的长T_1、长T_2信号,信号不均匀,无包膜。肝细胞癌呈不均匀长T_2信号,T_1加权像上7例呈等信号或轻度高信号,其余呈轻度低信号。5例可清晰显示包膜,3例可见门静脉内瘤栓形成。海绵状血管瘤呈均匀性长T_1低信号、长T_2显著高信号,轮廓清晰,边缘光整或呈分叶状。结论:MRI对肝占位病变的诊断敏感度高,特异性好,对发现病变及定性、定量诊断均具有重要价值,值得广泛应用。     

小脑梗塞的影像诊断

小脑梗塞发病率低,作者应用CT、MRI及血管造影对18例小脑梗塞作了对照研究。1.分布:位于小脑后下动脉9例,小脑上动脉8例,小脑前下动脉1例,其中1例于小脑上动脉及小脑后下动脉可见2个梗塞灶。2.CT所见:发病24小时内行CT检查3例,无异常所见。24小时后～7日内检查8例,可见异常低密度区。7日后检查12例,1例未发现小脑下动脉梗塞灶、11例可见异常低密度区。3.MRI所见:发病后2小时行MRI检查1例,T_2加权像未见异常信号。24小时MRI检查2例及5日、9日、10日行MRI检查3例,T_1加权像呈等信号,T_2加权像呈高信号。发病后7日行MRIⅠ检查1例、1个月3例及1个月以上6例,T_1加权     

DWI评估宫颈癌盆腔淋巴结转移的应用价值

目的探讨扩散加权成像(DWI)对于鉴别宫颈癌转移与非转移淋巴结的诊断价值。资料与方法 36例宫颈癌初诊患者于治疗前行常规MRI及DWI检查,观察并比较宫颈癌转移淋巴结与非转移淋巴结常规MRI及表观扩散系数(ADC)图表现,测量各淋巴结的长径(L)、短径(S)、T2信号强度、平均ADC值和最小ADC值,利用受试者工作特征(ROC)曲线下面积(Az)评价上述各项指标鉴别宫颈癌转移与非转移淋巴结的诊断效能。结果转移淋巴结短径和长径的平均秩次均大于非转移淋巴结,且两者差异具有统计学意义(均为P=0.000),而转移淋巴结与非转移淋巴结的L/S、S/L以及T2信号强度差异均无统计学意义(P=0.261;P=0.157;P=0.166);转移淋巴结的平均ADC值和最小ADC值均低于非转移淋巴结,且差异均具有统计学意义(均为P=0.000);短径、长径、平均ADC值和最小ADC值对鉴别宫颈癌转移与非转移淋巴结均有诊断意义(Az>0.5),其中最小ADC值的诊断效能最高,选取最小ADC阈值为0.983×10-3mm2/s时,其敏感性和特异性分别为94.6%和91.8%。结论 DWI有助于宫颈癌转移和非转移淋巴结的检出,最小A...     

儿童眼眶转移性神经母细胞瘤和绿色瘤的特征性MR表现

目的 分析儿童眼眶转移性神经母细胞瘤和绿色瘤的特征性MR表现。资料与方法 回顾性分析经手术病理证实的9例儿童眼眶转移性神经母细胞瘤和5例绿色瘤的CT和MRI表现。所有病例均行CT平扫以及MRI平扫和增强扫描。结果 14例CT表现均为眼眶不规则肿块和邻近的眶壁溶骨性骨质破坏,7例骨质破坏区邻近的颅内可见扁平不规则肿块。2例转移性神经母细胞瘤表现为眼眶肌锥外间隙肿块内有与眶外壁垂直的针状高密度影。14例MRI表现为眼眶肌锥外间隙略长T1、略长T2信号不规则软组织影,7例骨质破坏区邻近的颅内硬膜外间隙可见略长T1、略长T2信号扁平不规则肿块,增强后明显强化。14例双侧眶骨及蝶骨大翼,9例斜坡和双侧岩尖及2例双侧颞骨鳞部骨髓腔脂肪高信号影被略长T1、略长T2信号影取代,采用脂肪抑制的增强T1WI显示均有强化,强化程度与眼眶内肿块相似。结论 儿童眼眶转移性神经母细胞瘤和绿色瘤的眶壁和颅面骨MR表现具有特征,有助于诊断和鉴别诊断。     

原发性肛管直肠恶性黑色素瘤影像学诊断(5例报告及文献复习)

目的探讨原发性肛管直肠恶性黑色素瘤(AMM)的CT和MRI诊断价值。方法回顾性分析经组织病理学证实的AMM5例,其中男2例,女3例。4例行CT检查,1例行MRI检查。结果AMM表现明显蕈伞型肿块充满肠腔不伴肠梗阻(n=4),肠壁明显增厚(n=1);2例伴肠周脂肪浸润,其中1例延伸至骶前间隙;4例伴淋巴结转移,其中1例淋巴结直径>3cm。CT平扫示肿块呈稍低密度影,轻度强化1例、中度强化3例;AMM及其转移灶在MRIT1WI均呈高信号,T2WI为低信号。抑脂T1WI能更好地显示病灶范围及转移灶。结论肛门直肠部AMM可表现为腔内较大蕈伞型肿块,虽充满肠腔,但不伴肠梗阻,同时具较大淋巴结转移及明显肠周脂肪浸润。MRI对鉴别黑色素性AMM有提示价值。     

淋巴结炎性增生和肿瘤转移动物模型的建立及其MRI初步研究

目的 :探讨建立淋巴结炎性增生和肿瘤转移模型的方法及其MRI表现。材料和方法 :18只新西兰白兔随机等分成 3组。实验组分别经股四头肌注射VX2癌细胞、经股四头肌和胁腹注射蛋黄乳胶 ,对照组不作处理。 1周后开始在不同时间行MRI平扫。病理取材 ,HE染色、光镜下观察。结果 :淋巴结炎性增生和VX2癌转移的模型成功建立。炎性增生淋巴结和VX2转移淋巴结的大小无明显差异 ,二者MRI表现均为T1WI等信号、T2WI高信号 ,且信号强度无明显差异。结论 :上述方法制作的动物模型可为医学影像学研究提供可靠的动物模型 ,MRI平扫不能区分炎性增生淋巴结和VX2转移淋巴结。     

Magnetic resonance imaging, chest radiography, computed tomography and ultrasonography in malignant lymphoma

Magnetic resonance imaging (MRI) was compared with chest radiography, computed tomography (CT) and ultrasonography (US) for demonstration of spleen and liver engagement and enlarged lymph nodes in patients with malignant lymphoma. The investigation comprised 24 patients with Hodgkin's disease (HD) and 39 with non-Hodgkin lymphoma (NHL). MRI demonstrated enlarged lymph nodes, distinctly separated from vessels, fat, muscle, liver and occasionally also pancreas without any contrast medium. The distinction between lymph nodes and spleen was, however, poor in the images. In the mediastinum, MRI was superior to chest radiography and had an accuracy similar to that of CT. In the abdomen and the pelvis MRI had slight advantages over CT in detection of enlarged lymph nodes. Compared with US the MRI results were similar in the abdomen and somewhat better in the pelvis. MRI and US were better than CT in revealing HD infiltrates in the spleen. Infiltration of NHL in the spleen was slightly better disclosed at US than at CT and MRI; most of the NHL infiltration, confirmed at histopathology, could, however, not be revealed with any of the modalities, except when the size of the spleen was considered. Regions in the spleen, displayed with low image intensity in the T2 weighted image, were most likely due to increased amount of fibrotic tissue in the lymphomatous lesions. Good demonstration of lymph nodes and lymphomatous lesions in the spleen with MRI required two sequences; one with short TR and TE (T1 weighted image) and one with long TR and TE (T2 weighted image).     

MR studies of extension and spread pattern of nasopharyngeal carcinoma

Seven patients with T2-T4 nasopharyngeal carcinoma were examined by MRI on a 0.5T superconducting system. The obtained MRI images were reviewed focusing on the signal intensity (SI) of tumors, and the extension of tumors into the related spaces from the pharyngeal mucosal space (PMS). Consequently, the SI of tumors demonstrated low on T1 weighted images and high on T2 weighted images. The parapharyngeal space was the first space where the tumors extended from the pharyngeal mucosa. The parapharyngeal space was an intermediate point of extension to the masticator space (MS), the carotid space (CS), the retropharyngeal space (RPS), and the prevertebral space (PVS). The PVS involvement by tumors was not a direct extension from the PMS, because the posterior portion of pharyngobasilar fascia worked as a barrier on MR. Therefore, the longus capitus muscle in the prevertebral space was considered to be involved via the parapharyngeal space (PPS). The masticator space involvement was indicated by slightly high SI of pterygoid muscle on T2 weighted images, and also the effacement of the PPS fat and parapharyngeal venous plexus were considered as a sign of involvement into the masticator space. The retropharyngeal lateral lymph node (Rouviere) metastases were recognized by MR. These metastasized lymph nodes were low on T1 weighted images and high on T2 weighted images.     

Nodal metastases of nasopharyngeal carcinoma: patterns of disease on MRI and FDG PET

The patterns of nodal spread of nasopharyngeal carcinoma (NPC) have an important influence on treatment planning, but have not yet been fully addressed. We prospectively used MRI and FDG PET to document the patterns of nodal spread in NPC. One hundred and one patients with newly diagnosed NPC were studied with MRI and FDG PET. On MRI, nodes were considered as metastatic according to criteria regarding size, the presence of nodal necrosis, and extracapsular spread. FDG PET images were interpreted visually, and nodes were considered metastatic if they showed prominent FDG uptake against the background. Nodal metastases were found in 89 of our 101 patients. Analysis of the distributions of nodal metastases in these 89 patients showed that retropharyngeal nodes were less frequently involved than cervical nodes (82.0% vs 95.5%). The vast majority of cervical nodal metastases were to the internal jugular chain, including nodes at levels II, III, and IV, with decreasing incidences of 95.5%, 60.7%, and 34.8%, respectively. Level V nodal involvement was found in 27% of patients. Supraclavicular fossa nodal metastases were not uncommon and occurred in 22.5% of patients. Skip metastases in the lower-level nodes or supraclavicular fossa nodes occurred in 7.9% of patients. Mediastinal and abdominal metastatic adenopathy was present in 4.5% and 3.4% of patients, respectively, and was associated with advanced nodal metastasis in the supraclavicular fossa. Level VI (2.2%), level VII (1.1%), submandibular (2.2%), and parotid (3.4%) nodal metastases were uncommon and were always associated with advanced ipsilateral nodal metastases of the neck. We conclude that the combined use of FDG PET and MRI can comprehensively depict the pattern of nodal metastasis in NPC patients. Nodal metastases principally affected level II nodes, from which lymphatic spread extended down in an orderly manner to involve level III, level IV, and the supraclavicular fossa nodes, or extended posteriorly to involve level V nodes. The frequency of skip metastases was 7.9%. Distant spread to mediastinal or abdominal nodes was found in 3–5% of patients, usually in association with supraclavicular nodal metastases.     

MR microimaging of benign and malignant nodes in the neck

OBJECTIVE: We evaluated the diagnostic criteria of high-resolution MRI in differentiating benign and malignant cervical nodes that were palpable and superficial in the neck. SUBJECTS AND METHODS: We performed MR microimaging on 24 histologically proven metastatic nodes, 14 histologically proven lymphomas, and 35 histologically or clinically proven benign nodes in the necks of 26 patients. The lymph nodes were imaged with T1-weighted spin-echo, fat-suppressed T2-weighted turbo spin-echo, and spin-echo diffusion-weighted echo-planar sequences using a 47-mm microscopy coil. RESULTS: MR microimaging provided high-resolution images of the nodes. Hilar fat was lost in 92%, 79%, and 46% of the metastatic nodes, lymphomas, and benign nodes, respectively. Smooth nodal margins were lost in 58%, 23%, and 9% of metastatic nodes, lymphomas, and benign nodes, respectively. Heterogeneous nodal parenchyma on T1- or fat-suppressed T2-weighted images, or both, was observed in 88%, 29%, and 23% of metastatic nodes, lymphomas, and benign nodes, respectively. The apparent diffusion coefficients were significantly different among these three node groups (p < 0.001), with metastatic nodes being the highest, followed by benign nodes. Logistic regression analyses showed that heterogeneous nodal parenchyma and apparent diffusion coefficient levels were significant in discriminating metastatic nodes, and apparent diffusion coefficient levels in discriminating lymphomas. Combined use of these MR microscopic criteria on nodal architecture and apparent diffusion coefficients yielded 90% accuracy (86% sensitivity, 94% specificity) and 93% accuracy (85% sensitivity, 95% specificity) for discriminating metastatic nodes and lymphomas, respectively. CONCLUSION: The nodal architecture and apparent diffusion coefficient levels on MR microimaging may provide useful information in diagnosing benign and malignant nodes in the neck.     

Discrimination of metastatic cervical lymph nodes with diffusion-weighted MR imaging in patients with head and neck cancer

BACKGROUND AND PURPOSE: Metastasis to the regional cervical lymph nodes may be associated with alterations in water diffusivity and microcirculation of the node. We tested whether diffusion-weighted MR imaging could discriminate metastatic nodes. METHODS: Diffusion-weighted echo-planar and T1- and T2-weighted MR imaging sequences were performed on histologically proved metastatic cervical lymph nodes (25 nodes), benign lymphadenopathy (25 nodes), and nodal lymphomas (five nodes). The apparent diffusion coefficient (ADC) was calculated by using two b factors (500 and 1000 s/mm(2)). RESULTS: The ADC was significantly greater in metastatic lymph nodes (0.410 +/- 0.105 x 10(-3) mm(2)/s, P <.01) than in benign lymphadenopathy (0.302 +/- 0.062 x 10(-3) mm(2)/s). Nodal lymphomas showed even lower levels of the ADC (0.223 +/- 0.056 x 10(-3) mm(2)/s). ADC criteria for metastatic nodes (>/= 0.400 x 10(-3) mm(2)/s) yielded a moderate negative predictive value (71%) and high positive predictive value (93%). Receiver operating characteristic analysis demonstrated that the criteria of abnormal signal intensity on T1- or T2-weighted images (A(z) = 0.8437 +/- 0.0230) and ADC (A(z) = 0.8440 +/- 0.0538) provided similar levels of diagnostic ability in differentiating metastatic nodes. The ADC from metastatic nodes from highly or moderately differentiated cancers (0.440 +/- 0.020 x 10(-3) mm(2)/s, P <.01) was significantly greater than that from poorly differentiated cancers (0.356 +/- 0.042 x 10(-3) mm(2)/s). CONCLUSION: Diffusion-weighted imaging is useful in discriminating metastatic nodes.