脑转移瘤在低场MRI的诊断及鉴别诊断|脑梗和脑转移瘤MRI

　　[摘要]目的探讨脑转移瘤在低场MR的表现,以提高诊断及鉴别诊断水平。方法 回顾性分析经手术病理或临床证实的47例脑转移瘤的MR平扫及增强扫描图像表现。结果脑转移瘤幕上37例,幕下6例,幕上、幕下同时发生4例;多发脑转移瘤41例、单发脑转移瘤6例;瘤周无水肿3例、轻度水肿8例、中度水肿11例、重度水肿25例;增强扫描共发现158个瘤灶,T1WI 低信号112个、等信号32个、混杂信号14个,T2WI 高信号115个、混杂信号39个、等信号4个;T1WI强化,斑片强化23个、环形强化61个、结节强化63个、不规则强化11个。结论MRI平扫及增强扫描对脑转移瘤的诊断及鉴别诊断具有重要价值。
　　[关键词]磁共振成像;脑转移瘤;诊断及鉴别诊断
　　[中图分类号]R445.2 [文献标识码]A [文章编号] 1005-0515(2010)-8-225-01
　　
　　Diagnosis and Differential Diagnosis of low-field MRI in Brain Metastasis
　　Zhou Wei-qiang Lin Fa-hon
　　(Department of CT and MRI , the third Hospital of Zigong City)
　　[Abstract]Objective To study the MRI characteristics of brain metastasis, and to improve the diagnostic accuracy of brain metastasis. Methods To collect 47 cases of brain metastases diagnosed by clinical and surgical pathology, and to retrospectively analyse their MRI characteristics.. Results37 cases were Supratentorial metastasis , 6 cases were infratentorial metastasis,4 cases were Supratentorial and infratentorial metastasis; 41 cases were multiple brain metastasis,6 cases were Single brain metastases ; 3 cases were without hydropsia, 3 cases were with mild hydropsia, 11 cases were with moderate hydropsia, 25cases were with strong hydropsia;Enhancement scanning found 158 focus,T1WI:low signal were 112, equisignal were 32, mixsignal were 14; T2WI: high signalwere 115, mixsignal were 39, equisignal were 4;T1WI intensification: patch intensification were 23, ring-shaped intensification were 61, nodus intensification were 63, irregular intensification were 11. ConclusionMRI scanning and enhancement scanning arevaluable in the diagnosis and differential diagnosis of brain metastasis.
　　[Keywords]MRI; Brain metastasis; diagnosis and differential diagnosis
　　
　　恶性肿瘤发生颅内转移颇为常见,其中以脑转移最多。今年来随着低场MRI在基层医院的广泛应用,小的转移灶可被早期发现,有效的提高了脑转移瘤的检出率及诊断率。本文对本院2006-2009年间47例经手术病理或临床证实的脑转移瘤进行回顾性分析,探讨脑转移瘤在低场MRI的表现,以提高脑转移瘤的诊断及鉴别诊断水平。
　　1资料与方法
　　1.1一般资料 47例中,男30例,女17例,年龄34-71岁,平均年龄53.4岁;临床以头昏、头痛等颅内高压症状首发者34例,有视力障碍、语言及运动功能障碍13例;其中肺癌转移29例,乳腺癌10例,甲状腺癌4例,鼻咽癌2例,未找到原发癌2例。
　　1.2检查方法采用安科公司 OPEN MARK 0.2TMRI扫描仪,头线圈,自旋回波序列,常规进行横断位、冠状位T2WI、T1WI扫描,扫描条件T2WI TR/TE 4000/130ms;T1WI 350/16ms;强化扫描做横断位、冠状位T1WI层面与平扫同层面对照,造影剂选用Gd-DTPA,剂量为0.2mmol/kg,行手背静脉推注。
　　2结果
　　2.1瘤灶部位及形态特点幕上37例,幕下6例,幕上、下同时发生4例;发生于脑皮髓交界处43例,脑髓质4例;病灶多为圆形、椭圆形、环行、结节状。
　　2.2病灶数目和大小 本组47例共发现158个瘤灶,其中多发41例,单发6例;瘤灶直径3cm的49个。
　　2.3平扫继强化信号特征 平扫158个瘤灶中,在T1WI上112个病灶呈低信号,32个病灶呈等信号,14个病灶呈混杂信号;在T2WI上115个病灶呈高信号,39个呈混杂高信号,4个呈等信号。增强扫描158个病灶均呈不同程度的强化,表现为斑片状强化23个,环行强化61个,结节状强化63个,不规则状强化11个。其中23个病灶平扫T1WI和T2WI均未发现,后增强扫描发现。
　　3讨论
　　3.1脑转移瘤一般特征脑转移瘤占颅内肿瘤20%-40%左右,其中肺癌转移占40%-60%[2]。脑转移瘤多数为多发病灶,占50-70%;少数为单发病灶,占30%-50%[3]。脑转移瘤好发于40-60岁。
　　3.2脑转移瘤MRI的鉴别诊断典型的脑转移瘤,并且有原发肿瘤病史的诊断并不困难,但不典型脑转移瘤需与脑脓肿、胶质瘤、髓母细胞瘤等相鉴别:①与脑脓肿鉴别:脑脓肿也好发于皮髓交界区,环行强化,但脑脓肿环行强化壁多较薄且均匀一致,内外壁均较光滑,无强化壁结节,鉴别困难的可结合临床感染病史,抗炎治疗有效等相鉴别。②与胶质瘤鉴别:胶质瘤患者发病年龄多较年轻,病灶多位于大脑髓质内,边界不清,呈不均匀或花环状强化,瘤体相对较大,水肿较轻。③与髓母细胞瘤鉴别:髓母细胞瘤多呈圆形,好发于小脑蚓部,突向四脑室,致脑室系统阻塞性积水,坏死、囊变、出血等非常少见。
　　4结论
　　典型的脑转移瘤在MRI上有特征性的表现,诊断并不困难,但有时不能区别瘤灶和瘤周水肿,采取MRI平扫加增强扫描能发现平扫未能显示的病灶并区分瘤灶和瘤周水肿,结合临床病史,有效的提高脑转移瘤的敏感性及准确率,对脑转移瘤的诊断及鉴别诊断具有重要价值。因此对有原发肿瘤,临床有症状并高度怀疑有脑转移瘤的,常规头颅MRI平扫加增强扫描具有重要的临床意义。
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