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传统的卒中治疗方法是在患者的临床表现和医生的经验指导下治疗急性卒中。这个方法导致对那些虽然出现急性缺血性卒中,但起初症状轻微的患者不能得到适当的治疗。这种治疗的结果是永久性的神经功能缺失,如果在起病早期可以准确诊断,这种情况是可以避免的。氙增强CT(Xenon-enhancedCT)是一个令人兴奋的技术进步,它可以帮助确定脑血流(cer-ebralbloodfluid,CBF)缺失的部位并提供更准确的诊断。氙增强CT的应用可以提高对急性缺血性卒中患者病情程度的评价,并给予相应的治疗。本文的目的是对氙增强CT的临床应用做一综述。一、脑血流解剖和生理四个主要的血管向大脑提供CBF两个颈内动脉和两个椎动脉。两个颈内动脉提供血液到前循环。颈动脉起源于主动脉弓,首先形成颈总动脉,然后在下颌水平分叉形成颈内动脉(ICA)和颈外动脉(ECA)。ECA供应头皮、硬脑膜和颅外表面组织。ICA从颈动脉分又处上升在颞骨岩部硬脑膜之间进入颅内。然后ICA分出大脑中动脉(MCA)、大脑前动脉(ACA)、前交通动脉和后交通动脉。这些大的前部血管供应大脑半球并控制认知、记忆、运动、感觉和语言。椎动脉起源于锁骨下动脉并在颈1、颈2到颈7上升通过横突孔到颅。然后椎动脉通过枕骨大孔进入颅腔。三个重要的动脉(小脑后下动脉(PICA)、脊髓前动脉和脊髓后动脉)在椎动脉汇合成基底动脉前发出,在脑桥延髓连接处连接,在中脑基底动脉分成两个大脑后动脉。后循环的大血管供应脑干、枕叶、小脑、丘脑、颈部脊髓。脑血流输送葡萄糖和氧到神经元以便维持细胞的生理功能。脑吸收全身总血量的10%的葡萄糖和35-45%氧。CBF的正常值时45-55ml/100g脑组织/min。大脑不同区域代谢率和需要血液的量不同。脑灰质需要较多血流供应,范围从50到80ml/100g/min,而自质仅有10-30ml/100g/min。脑膜与白质和灰质的平均血流相等,因此脑血流的平均值近似于50ml/100g/min。脑脊液(CSF)和血管平滑肌的附近的细胞外液的PH值是脑血管张力的主要决定因素。PH值正常值时在7.35-7.45之间。PH值从6.7到7.8变化尚不足以影响CBF。然而,氢离子(H+)和碳酸氢盐(HCO3-)的浓度改变与二氧化碳(CO2)的浓度变化有关从而影响CBF。研究者证实CO2每升高1mmHg,VBF升高3-5%。动脉CO2升高,血管平滑肌松弛,允许血管扩张并提高CBF。
The traditional method of stroke treatment is to treat an acute stroke under the guidance of the patient’s clinical performance and medical experience. This approach led to those who initially developed mild symptoms of stroke but did not receive proper treatment. The result of this treatment is a permanent loss of neurological function, which can be avoided if the diagnosis is accurate early in the disease. Xenon-enhanced CT is an exciting technological advance that can help identify areas with missing cer-ebral blood flow (CBF) and provide more accurate diagnoses. The application of xenon enhanced CT can improve the evaluation of the severity of patients with acute ischemic stroke, and give the appropriate treatment. The purpose of this paper is to review the clinical application of xenon enhanced CT. First, cerebral blood flow anatomy and physiology The four major blood vessels to the brain to provide two internal carotid artery CBF and two vertebral arteries. Two internal carotid arteries provide blood to the anterior circulation. Carotid artery originated in the aortic arch, the common carotid artery is formed first, then the internal carotid artery (ICA) and the external carotid artery (ECA) are bifurcated horizontally in the mandible. ECA supplies scalp, dura and extracranial surface tissue. ICA from the carotid artery points up again in the temporal bone rock dural into the intracranial. The ICA then separates the middle cerebral artery (MCA), the anterior cerebral artery (ACA), the anterior communicating artery and the posterior communicating artery. These large anterior vessels supply the hemispheres and control cognitive, memory, motor, sensory, and speech. Vertebral artery originated in the subclavian artery and neck 1, neck 2 to neck 7 rose through the transverse foramen to the skull. Then the vertebral artery into the cranial cavity through the foramen magnum. Three important arteries (posterior inferior cerebellar artery (PICA), anterior spinal cord arteries and posterior spinal cord arteries) are issued before the vertebral arteries merge into the basilar artery, connected at the medullary pontine junction, and divide into basilar artery in the midbrain into two posterior cerebral arteries . Circulating blood vessels supply the brain stem, occipital lobe, cerebellum, thalamus, cervical spinal cord. Cerebral blood flow delivers glucose and oxygen to the neurons in order to maintain the physiological function of the cells. The brain absorbs 10% of the total body weight of glucose and 35-45% oxygen. Normal CBF 45-55ml / 100g brain tissue / min. Different regions of the brain metabolic rate and the amount of blood required. Cerebral gray matter requires more blood flow, ranging from 50 to 80 ml / 100 g / min, whereas only 10-30 ml / 100 g / min. The mean blood flow in the meninges is the same as that in white matter and gray matter, so the mean value of cerebral blood flow approximates 50ml / 100g / min. The pH of extracellular fluid near the cerebrospinal fluid (CSF) and vascular smooth muscle is the major determinant of cerebrovascular tone. PH value of 7.35-7.45 between normal. Changes in pH from 6.7 to 7.8 are not enough to affect CBF. However, changes in the concentration of hydrogen ions (H +) and bicarbonate (HCO3-) are related to changes in the concentration of carbon dioxide (CO2) and thus CBF. The researchers confirmed that for every 1 mmHg increase in CO2, VBF increased 3-5%. Arterial CO2 increases, vascular smooth muscle relaxation, allowing blood vessels to dilate and improve CBF.