本文来源于公众号“神经病学医学网”、“医学影像学英语”
Ischemic Stroke (PartⅠ)
Case-01
Clinical Information
A 68-year-old male presents to the casualty with left hemiparesis.
患者男，68岁，因左侧偏瘫至急诊科就诊。
Images
Interpratations
Emergency nonenhanced brain CT (A) demonstrates an ill-defined, slight hypodense area in right fronto-parietal lobes, associated with a subtle loss of gray-white differentiation (asterisk), but with no evidence of mass effect. A hyperdense middle cerebral artery (MCA) sign is detected on 1-mm-thick images (B, thick-arrow), indicating acute thrombus in the vessel. These two findings are strongly suggestive of an acute ischemic cerebral infarction in the right MCA territory.
急诊颅脑CT平扫示右侧额、顶叶边界模糊的稍低密度区，对应灰白质分界欠清，未见明确的占位效应。层厚1 mm图像可见大脑中动脉高密度征，提示血管内急性血栓形成。这两个表现强烈提示右侧大脑中动脉供血区的急性缺血性脑梗死。
Images of cerebral CTA
Interpretations
Cranial CT angiography (CTA) that performed 2 days after onset confirms the findings of the plain CT scan. Maximum intensity projection (C) and 3-D volume rendering (D) show occluded M1 segment of the right MCA (thick-arrow). That is exactly the site of bright MCA sign shown on figure B. Enhanced axial CT (E) following CTA shows a well-defined area of hypodensity in the right MCA territory associated with effacement of the cortical sulci (thin-arrow).
发病两天后的颅脑CT血管造影(CTA)证实了CT平扫的诊断。最大密度投影和三维容积重建显示右侧大脑中动脉M1段闭塞，与图B所示的大脑中动脉高密度征位置一致。CTA检查获得的增强后轴位CT图像显示右侧大脑中动脉供血区边界清楚的低密度区，对应脑沟消失。
Diagnosis
Acute ischemic cerebral infarction in the right MCA territory secondary to right MCA occlusion.
继发于右侧大脑中动脉闭塞的右侧大脑中动脉供血区急性缺血性脑梗死。
Case-02
Clinical Information
A 45-year-old female who has a history of breast malignancy, presents with sudden onset of aphasia and right hemiparesis.
患者女，45岁，既往乳腺恶性肿瘤病史，突发失语和右侧偏瘫。
Images
Interpretations
On non-contrast brain MRI, an area of diffusion restriction, involving the left frontal and temporal lobes (thick-arrow), presents as hyperintensity on DWI (A) and hypointensity on ADC images (B). And subtle low signal on T1WI(C) and high signal on T2WI (D) are also presented, accompanying swollen gyri and effaced sulci. These appearances are in keeping with acute ischemic infarction in the left middle cerebral artery territory.
颅脑MRI平扫示左侧额叶和颞叶脑组织扩散受限区，于DWI呈高信号，ADC图呈低信号；相应区域T1WI呈稍低信号，T2WI呈高信号，伴发脑回肿胀、脑沟消失。这些表现符合左侧大脑中动脉供血区急性缺血性脑梗死。
Diagnosis
Acute left frontal and temporal ischemic infarction.
急性左侧额颞叶缺血性脑梗死。
Key Vocabularies and Phrases
· ischemic stroke 缺血性卒中
· casualty 意外事故；伤亡人员；急诊室（同emergency room）
· hemiparesis 轻偏瘫（paresis 轻瘫；不全麻痹）
· hyperdense 高密度（反hypodense/ hypoattenuation/ low attenuation，CT常用）
· hyperintense 高信号（hypointense低信号，isointensity 等信号，MRI常用）
· blurring of grey-white matter junction 灰白质交界区不清（程度轻）
· loss of grey-white matter differentiation 灰白质分界消失（程度重）
· hyperdense middle cerebral artery sign 大脑中动脉高密度征
· acute ischemic cerebral infarction 急性缺血性脑梗死
· cortical sulci 脑沟（脑沟也可直接用sulci或cerebral sulci; cortex 皮质、皮层）
· secondary to 继发于（类似result from，均为报告常用语）
· diffusion restriction 扩散受限
· diffusion-weighted imaging 扩散加权成像（DWI）
· apparent diffusion coefficient 表观扩散系数（ADC)
· swollen gyri 脑回肿胀（gyrus 脑回单数；gyri脑回复数）
· effaced sulci 脑沟消失（effaced 明显受压的、消失的，名词effacement）
· in keeping with/ corresponding to/ consistent with/ compatible with （报告常用语）与…相符、符合…
· middle cerebral artery territory大脑中动脉供血区（vascular territory 供血区）
· atherosclerotic plaques动脉粥样硬化斑块
· blood clots 血栓（同thrombus）
· thrombolysis 溶栓；溶栓治疗
Notes
Ischemic stroke results from a sudden interruption of the blood flow reaching parts of the brain due to intracranial artery embolism or thrombosis, and leads to deprivation of oxygen and glucose in the supplied vascular territory.
缺血性卒中是由颅内动脉栓塞或血栓形成导致该部分脑组织血流突然中断，引起相应供血区脑组织氧和葡萄糖供应不足所致。
Atherosclerosis is a major cause of intracranial artery stenosis and potential obstruction. The arteries most likely to be affected are the internal carotid artery (ICA), the middle cerebral artery (MCA), the vertebral arteries (VA), and the basilar artery (BA).
动脉粥样硬化是导致颅内动脉狭窄和潜在阻塞的主要原因，最易受累的动脉有颈内动脉(ICA)、大脑中动脉(MCA)、椎动脉(VA)和基底动脉(BA)。
There are three ways in which intracranial artery atherosclerotic plaques can result in a stroke:
1) Plaque can grow larger and larger, markedly reducing blood flow, and can eventually occlude the artery.
2) Plaque can roughen and deform the artery wall, causing blood clots formation and blocking blood flow.
3) Plaque can rupture and break away, traveling downstream and blocking smaller arteries.
颅内动脉粥样硬化斑块导致卒中的方式有三种：
1）斑块逐渐增大，血流量显著减少，最终阻塞动脉。
2）斑块使动脉壁变得粗糙和变形，导致血栓形成，阻塞血流。
3）斑块破裂、脱落，移至下游并阻塞小动脉。
CT of the brain remains the mainstay of imaging in the setting of an acute stroke. Acute infarctions may be difficult to identify on non-contrast head CT scans. But CT is effective to exclude:
1) Intracranial hemorrhage;
2) Other intracranial pathologies that may mimic a stroke, such as tumor.
颅脑CT仍是急性卒中主要的影像检查方法。急性期脑梗死在颅脑CT平扫上可能较难识别，但其可以有效地排除：
1）颅内出血；
2）其他类似卒中表现的颅内病变，如肿瘤。
Sometimes, subtle CT changes can be detected in large area acute cerebral infarctions:
1) Early parenchymal signs: blurring of the grey-white matter junction or loss of gray-white matter differentiation in the affected regions; deep grey matter structures particularly the lentiform nucleus and caudate nucleus should also be noted.
2) Hyperdense cerebral artery sign: bright change of main intracranial vessels (such as MCA, BA), appeared as hyperdense strips (parallel to scanning plane) or dots (vertical to scanning plane), representing the intravascular thromboembolism.
有时，大面积急性脑梗死可出现轻微的CT改变：
1) 早期实质征象：受累区域灰白质交界区模糊或灰白质分界消失；同时需注意观察深部灰质结构，特别是豆状核和尾状核。
2) 大脑动脉高密度征：颅内较大血管(如大脑中动脉、基底动脉)的密度增高，呈条状(平行于扫描平面)或点状(垂直于扫描平面) 高密度，代表血管内血栓栓塞（急性血栓形成）。
MRI has significantly higher sensitivity and specificity than CT in the diagnosis of acute cerebral infarction in the first few hours after onset by diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC). However, the majority of imaging of acute strokes is performed with non-contrast CT, mainly due to that MRI acquisition is relatively time consuming and lack of compatible resuscitation equipment.
对发病几个小时内的急性脑梗死，MRI借助弥散加权成像(DWI)和表观弥散系数(ADC)能够获得较CT更敏感和特异的诊断。然而，大多数急性卒中影像检查仍选择平扫CT，主要由于磁共振检查耗时过长且缺乏合适的复苏设施。
Ischemic Stroke (PartⅡ)
Case-03
Clinical Information
A 67-year-old diabetic female with acute onset of dizziness, left ptosis and right facial palsy two weeks ago.
患者女，67岁，糖尿病病史，两周前突发头晕、左上睑下垂和右面神经麻痹。
Images
Interpratations
Brain MRI demonstrates a T1WI hypointense (A) and T2WI hyperintense (B) focus in the left side of the pons (arrow), with high signal intensity on both DWI (C) and ADC (D) (due to T2 shine through effect, not caused by restricted diffusion), representing a subacute ischemic stroke.
颅脑MRI：脑桥左侧见一T1WI低信号、T2WI高信号病灶，在DWI和ADC图上均呈高信号（DWI高信号由T2透射效应所致，而不是由于扩散受限引起），代表亚急性缺血性卒中。
Diagnosis
Subacute left pontine ischemic infarction.
脑桥左侧亚急性缺血性脑梗死。
Case-04
Clinical Information
A 61-year-old male, who has a history of hypertension, diabetes and previous ischemic stroke, presents with a right hemiplegia.
患者男，61岁，因右侧偏瘫就诊，既往高血压、糖尿病和缺血性卒中病史。
Image of brain CT
Interpretations
Brain CT scan without contrast (A) reveals ill-defined low attenuations (thick-arrow) in the left corona radiata and basal ganglia with density slightly lower than white matter, indicating recent ischemic cerebral infarction. There is also a well-defined hypodense focal (thin-arrow) seen in the right corona radiata and basal ganglia with a density mimicking cerebrospinal fluid and slightly negative mass effect, compatible with an encephalomalacia.
颅脑CT平扫：左侧放射冠及基底节区见多发边界不清低密度影，密度略低于白质，提示近期发生的缺血性脑梗死。右侧放射冠和基底节区可见一边界清楚的低密度灶，密度与脑脊液相似，有轻微的负占位效应，符合脑软化灶。
Images of brain MRI
Interpretations
Nonenhanced brain MRI demonstrates that lesions on left side (thick-arrow) exhibit hyperintense T2WI signal (B) and slight hypointense T1WI signal (C), as well as diffusion restriction demonstrated by increased DWI signal (D) and reduced ADC values (E). These correlate well with acute ischemic cerebral infarcts. The signal intensity of right-side lesion (thin-arrow) predominantly resemble the signal of CSF, except a rim area with slightly increased signals on T1WI, DWI and ADC map (high signals on both DWI and ADC are not appearances of restricted diffusion). These characteristics are indicative of encephalomalacia (chronic infarction) with adjacent gliosis.
颅脑MRI平扫示左侧病灶呈T2WI高信号和T1WI稍低信号，DWI呈高信号和ADC图呈低信号，提示扩散受限，这些信号特征符合急性缺血性脑梗死表现。右侧病灶的信号强度与脑脊液信号相似，但病灶边缘见环形T1WI、DWI和ADC略高信号（DWI、ADC均为高信号不是扩散受限的表现），这些特征提示脑软化(慢性期脑梗死)伴邻近胶质增生。
Images of cerebral CTA
Interpretations
The cerebral CT angiography is done after MRI scanning. Thin-MIP reconstructions demonstrate high grade (>70%) luminal stenoses (thick-arrow) in M3 segment of the right MCA (F) and M2 segment of the left MCA (G), that most probably caused by noncalcified atherosclerotic plaques.
MRI扫描后行颅脑CTA检查。薄层最大密度投影重建显示右侧大脑中动脉M3段和左侧大脑中动脉M2段管腔均呈重度狭窄(＞70%)，这很可能是非钙化性动脉粥样硬化斑块所致。
Diagnosis
1) Multiple ischemic strokes at different stages, most likely result from atherosclerotic occlusion of deep perforating arteries;
2) Multiple atherosclerotic stenosis of bilateral MCA.
1)多发不同阶段缺血性脑梗死，极可能是深穿支动脉粥样硬化闭塞所致；
2)双侧大脑中动脉多发动脉粥样硬化性狭窄。
Key Vocabularies and Phrases
· subacute ischemic stroke 亚急性缺血性卒中
· diffusion-weighted imaging (DWI) 扩散加权成像
· apparent diffusion coefficient (ADC) 表观扩散系数
· T2 shine through effect T2透射效应
· diffusion restriction 扩散受限
· corona radiata 放射冠
· basal ganglia 基底节
· lentiform nucleus 豆状核
· caudate nucleus 尾状核
· cerebrospinal fluid (CSF) 脑脊液
· encephalomalacia 脑软化症
· negative mass effect 负占位效应
· gliosis 胶质细胞增生（gliocyte 胶质细胞）
· stenosis 狭窄（stenosed狭窄的）
· occlusion 闭塞（occluded 闭塞的）
· deep perforating artery 深穿支动脉
· vasogenic edema 血管性水肿（cellular edema 细胞性水肿）
· noncalcified非钙化性的 (calcified钙化性的，mixed 混合性的)
Notes
Aging (or stage) of ischemic stroke is important in a number of clinical settings. Both CT and MRI can help in determining when a stroke occurred. Based on multiple sequences, especially DWI and ADC, MRI has not only significantly higher sensitivity and specificity in the diagnosis of acute ischemic infarction, but also has high accuracy in the evaluation of subacute or chronic stages.
临床工作中，缺血性卒中的分期非常重要。CT 和 MRI 均有助于确定卒中发生的时间。MRI基于多序列，尤其是 DWI 和ADC，不仅在急性缺血性梗死的诊断中具有更高的敏感性和特异性，其在亚急性期或慢性期的评价中也具有很高的准确性。
1) Acute stage (0-7 days):
① High signal on T2WI after 6 hours, subtle hypointense on T1WI after 16 hours, mass effect maximal after 24 hours, no parenchymal enhancement.
② Marked hyperintensity on DWI and hypointensity on ADC images.
③ Early DWI reversal (rapid reduction of signal intensity) can occur, mostly due to reperfusion related vasogenic edema, but this is probably a 'pseudo-reversal'.
1）急性期（0-7天）：
①6小时后T2WI呈高信号，16小时后T1WI呈轻微低信号，24小时后占位效应明显，无实质强化。
②DWI呈明显高信号，ADC图呈低信号。
③早期扩散加权成像可出现逆转(信号强度迅速降低)，主要是由于再灌注相关的血管源性水肿，但这可能是一种假性逆转。
2) Subacute stage (1-3 weeks):
① Low signal on T1WI, high signal on T2WI, cortical enhancement usually present.
② DWI remains hyperintense due to T2 shine through effect, not caused by restricted diffusion.
③ ADC values start to rise, reach normal parenchymal signal in 2 weeks, and then after appear hyperintense.
2）亚急性期（1-3周）
①T1WI呈低信号，T2WI呈高信号，通常伴发皮层强化。
②扩散加权成像仍为高信号，这是T2透射效应所致，而不是扩散受限所致。
③ADC值开始升高，2周后与正常实质信号相近，之后呈现高信号。
3) Chronic stage (>3 weeks):
① Low signal on T1WI, high signal on T2WI. Mass effect disappears after 1 month.
② Low DWI signal and high ADC signal.
3) 慢性期（>3周）
① T1WI呈低信号，T2WI呈高信号。占位效应1个月后消失。
② DWI呈低信号，ADC图呈高信号。
References
1) https://radiopaedia.org/articles/ischaemic-stroke;
2) Radiographics. 2003 May-Jun; 23(3): 565-92;
3) Radiographics. 2006 Oct; 26 Suppl 1: S75-95;
4) Radiographics. 2012 Sep-Oct; 32(5):1285-97.
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