（5）神经系统疾病影像学.ppt

1、Imaging of the Central Nervous System,The modality of choice Cerebrovascular diseases Intracranial Tumors Spine & spinal cord,Contents,Routine x-ray examination (X-ray) Angiography Computed Tomography (CT) Myelography & CT myelography Magnetic Resonance Imaging (MRI) Neurosonography,The modality of

2、choice,脑窗、骨窗、软组织窗 平扫 vs. 增强 二维 vs. 三维 CT值 CTA、CT灌注,CT,脑窗vs.骨窗vs.软组织窗,76,2D vs. 3D,平扫vs.增强,CT value of normal cerebral tissues (Hu),Normal CT,Normal CT Older person,CTA,CT灌注,CBF CBV MTT,Myelography CT myelography In most situation, myelography is substituted by MRI.,Myelography,T1WI vs. T2WI vs. T2fl

3、air 平扫 vs. 增强 二维 vs. 三维 MRA,MRI,MR signal of normal brain,T1WI,T2WI,T2flair,No C,+C,21,MR Angiography,62,Cerebral Vascular Diseases,Ischemic/infarction 80% intracerebral Hemorrhage 15% subarachnoid hemorrhage 5% Occlusion of vein & Dural Sinuses 1%,Pathogenesis of stroke,The goals of diagnostic imag

4、ing the location and extent of the disease process the underlying pathogenesis with identification of treatable disease or processes detection of hemorrhage or other coexisting processes monitoring the response to therapy,Acute cerebrovascular diseases,infarction,Ischemic infarction Border zone infa

5、rction Lacunar infarction hemorrhagic infarction,Ischemic infarction,急性期/亚急性期/慢性期 CT MRI,MRI,DWI显示大脑后、大脑前、大脑中动脉梗死,看一看，发现什么了？,DWI非常清楚的显示了梗死的部位 所以DWI序列又称为中风序列,在左侧首先一个DWI显示一个不可逆的坏死 中间图像显示灌注不足的范围更大 右侧是弥散-灌注的结合像 蓝色显示缺血半影区，这些组织是可以通过治疗获得恢复的,Diffusion in yellow. Perfusion in red. Mismatch in blue is penumbr

6、a.,Perforating arteries Small ( 1.5cm), multiple 15%-25% of total stroke Location：the basal ganglia, deep white-matter differentiation：enlargement of peri-vascular space, focal demyelination of white matter,Lacunar infarction,41,42,43,DWI,Etiologies hypertension，atherosclerosis Rare etiologies AVM，r

7、upture of aneurysm，vasculitis，hemorrhage of neoplasm Location the basal ganglia,bHemorrhage,CT value of normal cerebral brain(Hu),Whole blood(15g/dl) 52 Hu Plasma 25Hu Red cells of 100% 82Hu clotted blood 50-80Hu,51,MR evolvement of intracranial hematoma,57,Etiologies：may be classified as congenital

8、 (berry aneurysm), arteriosclerotic, mycotic, traumatic, neoplastic, and dissecting Location: predominantly in or near the circle of Willis Methods of examination：DSA, CTA, MRA,Vascular malformation Aneurysm,63,64,Plain CT scans: patchy areas of increased densities interspersed with areas of low den

9、sity; Calcifications within the densities;local atrophy. Contrast enhanced CT will show serpiginous dilated afferent and efferent vessels, as well as enhancement of the nidus of the AVM. MRI: the AVM nidus as an area of serpiginous signal-flow voids, intermixed with areas of heterogeneous hyperinten

10、sity. DSA: the arterial feeders + draining veins+ the nidus.,Vascular malformation AVM,69,70,The epidural space is a potential one between the periosteum and the bone. This potential space is bound down by the suture margins. Typical CT appearances: a biconvex, high-density mass calvarium fracture m

11、ass effect the hematoma do not run across skull suture.,Epidural Hematoma,76,77,peripheral crescentic collections of blood-density material lying between the inner table of the skull and the cerebral hemisphere not across the midline more common than epidural hematoma,Subdural Hematoma,Bleeding into

12、 the subarachnoid space results from disruption of veins and arteries in the pia or arachnoidal meninges Usually due to head trauma & small aneurysm rupture,Subarachnoid Hemorrhage,Methods of examination Radiological appearances of intra-axial & extra-axial tumors,Intracranial Tumors,a. low-density

13、(fat, water-containing) b. High-density (parenchyma of tumor, hemorrhage, calcification) c. mixed-density (low-density tumor secondary to hemorrhage and calcification or tumor in the posterior fossa ),density,T1: low SI high SI mixed SI,T2: high SI high or low SI mixed SI,signal,Mass effect displace

14、ment of meddle-line， The deviation of choroid calcification, compression of the lateral ventricles Blocking the circulation of CSF causing obstructive hydrocephalus (dilation of ventricles) Perifocal tumor Edema mainly distributing in white matter,After injection of contrast, any alteration of SI or

15、 density can be called as enhancement while comparing plain scan with enhanced imaging. It will benefit the identification of lesions & display of normal structure.,Contrast enhancement,subfalcine herniation Transtentorial herniation Herniation of sphenoid wings Tonsillar herniation,Brain herniation

16、,93,94,95,96,97,98,99,103,T2,T1,Brain Abscess,CT features: Most abscesses occur near the corticomedullary junction. Acute-stage: low density, ill-defined margin, no enhanced lesion. The second week: the abscess is clearly seen as a well-defined lesion by CT and MR. A contrast-enhanced study may reve

17、al a 3- to 6-mm enhancing capsule with surrounding edema. The stage of abscess formation：ring-enhanced, with smooth inner wall , with significant mass effect.,112,脑脓肿,胶质母细胞瘤,Spine & spinal cord,How to identify an intramedullary, extradural, & extramedullary intradural mass. How to select examination

18、 methods,Key points,117,119,120,Intramedullary tumors: Ependymoma & Astrocytoma Extramedullary/intradural tumors: Meningioma & Neurinoma Extradural tumors: Metastasis , lymphoma & Neurinoma,Spinal cord tumor,127,脑梗死的影像表现 脑血肿的演变 脑肿瘤的影像表现要点 胶质母细胞瘤和脑脓肿的鉴别 椎管内肿瘤的定位,137,对于一个怀疑脑卒中的患者，首选影像学检查方法是什么，为什么？ 一个急性脑卒中的患者8小时，左侧肢体中枢性瘫，右侧中枢性面瘫，CT 报告：右侧颞叶脑梗塞。请问梗塞的诊断有问题吗？需要进一步检查吗？WHY? 一个身体健康20岁男性，晨起发现双下肢瘫，大小便失禁，请问首选影像学检查方法是什么，为什么？,谢 谢,