Perfusion CT investigation of chronic internal carotid artery occlusion: comparison with SPECT

This study investigated the usefulness of perfusion computed tomography (CT) for the evaluation of patients with chronic internal carotid artery (ICA) occlusion by comparing the findings with those of iodine-123 iodoamphetamine ([(123)I]IMP) single photon emission computed tomography (SPECT). Twenty five patients with chronic ICA occlusion were investigated on the same day by perfusion CT to measure the cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transient time (MTT), and [(123)I]IMP SPECT to measure the regional CBF, significant correlations were observed between regional CBF measured by SPECT and CBF measured by perfusion CT (r = 0.659, R(2) = 0.434, p < 0.001), regional CBF and CBV (r = -0.406, R(2) = 0.165, p < 0.001) and regional CBF and MTT (r = -0.592, R(2) = 0.350, p < 0.001). Significant correlations were also observed between CBF and CBV (r = -0.153, R(2) = 0.023, p < 0.001), CBF and MTT (r = -0.580, R(2) = 0.337, p < 0.001) and MTT and CBV (r = 0.763, R(2) = 0.582, p < 0.001). Perfusion CT is useful to evaluate the hemodynamic state of patients with chronic major cerebral artery occlusive disorders.     

Fifty percent reduced-dose cerebral CT perfusion imaging of Alzheimer's disease: regional blood flow abnormalities

To evaluate the value of 50% reduced-dose cerebral computed tomography (CT)perfusion imaging (CTPI) to show the perfusion abnormalities in Alzheimer's disease (AD), as an attempt to develop a new imaging protocol with lower radiation dose to track the correlation of AD with regional blood flow abnormalities. A total of 52 patients with AD were assigned to the AD group and 28 healthy volunteers served as the control group. All participants were given a 50% reduced-dose cerebral CTPI (current was reduced from 160 to 80 mA) test by a multislice spiral CT scanner. Perfusion parameters of the bilateral frontal cortex, temporal cortex, hippocampus, and basal ganglia were measured, including the cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP). Both the CBV and CBF values of the measured regions were significantly higher in the healthy control group than in the AD group (P < .05), while the MTT and TTP values of these cerebral areas were significantly lower in the healthy control group than in the AD group (P < .05). Four perfusion parameters, namely the MTT of the left frontal cortex, right temporal cortex, right basal ganglia, and right hippocampus, had the greatest sensitivity and a striking correlation with the incidence of AD. The blood flow per unit of time in the regions of interest was significantly lower in the AD group, which provides new evidence for the existence of microcirculation disturbance and ischemia in AD. The 50% reduced-dose cerebral CTPI scan is valuable to show the regional perfusion abnormalities in the patients with AD.     

症状性大脑中动脉狭窄率与组织灌注的相关性

目的 应用单一症状性M1段狭窄模型定量分析症状性大脑中动脉狭窄率与组织灌注的相关性.方法 从连续203例症状性颅内动脉狭窄选择性支架成形术患者中严格筛选所有单一M1段狭窄患者.所有患者均进行头颅CT、CT灌注(CTP)和DSA检查.根据CTP检查结果,测量两侧从前往后包括额叶、前分水岭、岛盖、颞叶、后分水岭和枕叶的各脑区CTP各参数.CTP参数包括平均通过时间(MTT)、脑血流量(CBF)和脑血容量(CBV).以健侧作为正常对照,计算患侧各脑区CTP参数相对值和判定患侧各脑区CTP各参数变化.根据DSA造影结果,肓法手工测量M1段狭窄率和判断侧支代偿动脉来源及侧支血流分级.对M1段狭窄率与患侧各脑区CTP各参数绝对值、相对值进行相关性分析.结果 20例患者入组,患侧M1段狭窄率平均为70.5%±10.6%(53%～91%).以对侧为对照,患侧额叶MTT正常,CBF正常,CBV升高;前分水岭MTT延长,CBF正常,CBV升高;岛盖MTT延长,CBF正常,CBV升高;颞叶MTT延长,CBF正常,CBV正常;后分水岭MTT延长,CBF下降,CBV正常;枕叶MTT正常,CBF正常,CBV正常.狭窄M1段供血相关脑区,从前往后各脑区血流灌注逐渐减低;而后分水岭是惟一处于血流失代偿期的脑区.所有患者DSA显示侧支代偿均主要来自大脑前动脉软脑膜支.M1段狭窄率与后分水岭区相对CBV正相关(r=0.66,P=0.002);与其余各脑区各CTP灌注参数均没有相关性.结论 症状性大脑中动脉狭窄患侧各脑区组织灌注水平受侧支代偿动脉的影响有明显空间分布效应;M1段狭窄率与血流失代偿期脑区相对CBV呈正相关,与血流代偿期脑区组织灌注没有相关性.

Abstract：

Objective To quantitatively analyze the correlation between stenosis ratio and cerebral perfusion in patients with solely symptomatic M1 stenosis of middle cerebral artery.Methods All the patients with solely symptomatic M1 stenosis of middle cerebral artery were selected to this study from consecutive 203 patients with elective stenting of symptomatic intracranial artery stenosis.Brain CT, CT perfusion (CTP) and DSA examinations were performed in all cases.The CTP parameters of mean transit time (MTT), cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured in regions of interest (ROIs) including bilateral frontal lobe, anterior watershed, opercula of the insula (including parsopercluaris and part of insula), temporal lobe, posterior watershed and occipital lobe.Compared with the unaffected side as control, the change of CTP and their relative CTP parameters in these ROIs at affected side were analyzed.Based on DSA data, the ratio of M1 stenosis was measured manually and blindly, the source of collateral branch of compensative artery was estimated and the blood flow was graded.Correlation between the ratio of M1 stenosis and the CTP parameters including the absolute and the relative values was investigated.Results Twenty patients were selected into this study; their average M1 stenosis ration of the affected side was 70.5% ± 10.6% (53% to 91%).Compared with the unaffected side, MTT and CBF were no significant change but CBV increased in the affected frontal lobe; MTT prolonged, CBF was normal and CBV increased in the affected anterior watershed and opercula of the insula; MTT prolonged, CBF and CBV had no significant difference in the affected temporal lobe; MTT prolonged, CBF decreased and CBV had no significant difference in the affected posterior watershed; MTT, CBF and CBV were normal in occipital lobe.Tissue perfusion gradually decreased from the front to the backward in all the M1 stenosis affected cerebral regions and the posterior watershed area was the only region at hemodynamic failure stage.Leptomeningeal vessels of the anterior cerebral artery were the major sources of compensative arteries shown in the DSA in all cases.The ratio of M1 stenosis was positively correlated (r =0.66, P =0.002) with the rCBV in posterior watershed and there is no significant correlation between the ratio and any other CTP parameters in any regions.Conclusions Associated with distribution of collateral compensative artery,tissue perfusion showed obvious spatial distribution at different level in different cerebral region.M1 stenosis ratio is positively correlated with rCBV in hemodynamic failure regions, and there is no correlation with tissue perfusion in hemodynamic compromise regions.     

多层螺旋CT灌注成像对星形细胞肿瘤分级的准确性评价

目的 评价多层螺旋CT灌注成像(CTP)参数对星形细胞肿瘤分级的敏感性和特异性.方法 对第三军医大学第三附属医院野战外科研究所收治的53例脑肿瘤患者进行CTP检查,经手术和病理学证实为星形细胞肿瘤的30例患者纳入研究对象.CTP采用GE LightSpeed 64层螺旋CT机行灌注扫描,在AW4.2P后处理工作站对原始数据进行后处理,测定肿瘤最大灌注区和对侧正常组织的脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)及毛细血管表面通透性(PS).手术获取脑肿瘤标本进行组织病理学检查.结果 星形细胞肿瘤高级别组CBF、CBV和PS值均明显高于低级别组,差异有统计学意义(P<0.05),MTT值比较差异无统计学意义(P>0.05).受试者工作特征曲线(ROC曲线)分析表明,CBF、CBV和PS值对鉴别高、低级别星形细胞肿瘤的ROC曲线下面积分别为0.914、0.876和0.914,而MTT无鉴别作用,其ROC曲线下面积为0.455.采用CBF=62.635 mL/(100 g·min),CBV=4.310 mL/100 g和PS=5.925 mL/(100 g·min)作为分界点鉴别高、低级别星形细胞肿瘤的敏感性均为84.2%,特异性分别是81.8%、81.8%和91.9%.结论 多层螺旋CTP参数CBF、CBV及PS值对鉴别高、低级别星形细胞肿瘤具有较高敏感性和特异性.     

Hemodynamics in the cerebral cortex and basal ganglia--observation on normal volunteers and patients with lacunes using PET]

We examined ten healthy volunteers using positron emission tomography (PET) in order to elucidate regional changes and correlations in the cerebral circulation and oxygen metabolism. We also studied eight lacunar stroke patients so as to disclose the influences of vascular risk factors and aging on the cerebral blood flow and metabolism. We can conclude from our result as follows: 1. Cerebral blood volume (CBV) was minimum in the basal ganglia and cerebral blood flow (CBF)/CBV ratio was higher than that of cerebral cortex in healthy volunteers; 2. CBF of gray matter in healthy volunteers correlated with CBV and cerebral metabolic rate of oxygen where oxygen extraction fraction inversely correlated with CBF, CBV, and CBF/CBV; and 3. the basal ganglia CBF/CBV ratio in lacunar stroke patients was lower than that of healthy volunteers. These findings suggested that the perfusion pressure in the basal ganglia was so high in the normal condition that the angionecrosis or occlusion in the perforating arteries would be induced, especially in the aged and hypertensive patients.     

Cerebral hemodynamics in CADASIL before and after acetazolamide challenge assessed with MRI bolus tracking

BACKGROUND: White matter lesions in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) are underlaid by severe ultrastructural changes of the arteriolar wall. Although chronic ischemia is presumed to cause the tissue lesions, the pattern of perfusion abnormalities and hemodynamic reserve in CADASIL, particularly within the white matter, remains unknown. METHODS: We used the MRI bolus tracking method in 15 symptomatic patients with CADASIL (5 with dementia) and 10 age-matched control subjects before and 20 minutes after the intravenous injection of acetazolamide (ACZ, 17 mg/kg). Cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT) were calculated both in the cortex and in the white matter according to the singular value decomposition technique. Perfusion parameters were obtained in regions of hyperintensities and within the normal-appearing white matter as observed on T2-weighted images. Analysis was performed with both absolute and relative (region/whole brain) values. RESULTS: A significant reduction in absolute and relative CBF and CBV was found within areas of T2 hyperintensities in white matter in the absence of significant variations of MTT. This reduction was more severe in demented than in nondemented patients. No significant change in absolute CBF and CBV values was observed in the cortex of patients with CADASIL. A decrease in relative CBF and CBV values was detected in the occipital cortex. After ACZ administration, CBF and CBV increased significantly in both the cortex and white matter of affected subjects, but the increase in absolute CBF was lower within areas of increased signal on T2-weighted images in patients than in the white matter of control subjects. CONCLUSIONS: In CADASIL, both basal perfusion and hemodynamic reserve are decreased in areas of T2 hyperintensities in the white matter. This hypoperfusion appears to be related to the clinical severity. The significant effect of ACZ on CBF and CBV suggests that cerebral perfusion might be increased using pharmacological vasodilation in CADASIL.     

Perfusion computed tomography: prediction of final infarct extent and stroke outcome

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) has not been previously applied to perfusion CT (CTP). Five raters assigned ASPECTS to baseline noncontrast CT (NCCT), CT angiography source images (CTA-SI), CTP source images (CTP-SI), and CTP maps of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) from 37 consecutive patients with less than 6-hour anterior circulation ischemic stroke. Major reperfusion was identified on follow-up imaging. Mean baseline ASPECTS was compared with follow-up imaging ASPECTS. Rates of favorable outcome were compared for dichotomized baseline ASPECTS. In patients with major reperfusion, mean CBV and CTP-SI ASPECTS closely predicted final infarct ASPECTS. In patients without major reperfusion, mean CBF and MTT ASPECTS best predicted final infarct ASPECTS. There were significant increases in rates of favorable outcome for CTP-SI and CBV ASPECTS of greater than 6, versus less than or equal to 6, but not for other baseline CT modalities. ASPECTS applied to CTP is more accurate at identifying the extent of reversible and irreversible ischemia and at predicting final clinical outcome than NCCTor CTA-SI.     

Evaluation of cerebral hemodynamics with perfusion CT]

We report on the evaluation of cerebral ischemic lesions with perfusion CT. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) of 52 patients mostly with ischemic cerebrovascular disease were analysed using the box-modulation transfer function method with 30 ml of contrast medium intravenously injected at 5 ml/sec. CBF, CBV and MTT of the middle cerebral artery (MCA) territory were 43.5 +/- 4.6 ml/100 g/min, 1.9 +/- 0.2 ml/100 g and 2.9 +/- 0.6 seconds at the unaffected side, and 37.7 +/- 7.3 ml/100 g/min, 2.1 +/- 0.3 ml/100 g, 3.7 +/- 0.9 seconds at the lesion side with stenosis or occlusion in the main MCA trunks or internal carotid artery, respectively. A statistically significant difference was shown in CBF and MTT values. Furthermore, there was a close correlation in CBF values of MCA territories between Xe-CT and perfusion CT (r = 0.645, n = 76, p < 0.0001). MTT showed a positive correlation with CBV in those subjects when MTT was below 4.1 seconds (r = 0.526, p < 0.0001, n = 83). MTT also showed a negative correlation with CBF in those patients when MTT indicated more than 4.1 seconds (r = 0.818, p < 0.001, n = 21). These results suggest that the progression of cerebral ischemia may be classified in 4 stages using perfusion CT. The stages are as follows: stage 0; normal CBF without prolonged MTT and increased CBV, stage 1; relatively increased CBV, stage 2; significantly prolonged MTT, and stage 3; significantly decreased CBF with prolonged MTT.     

Postictal deficit mimicking stroke: role of perfusion CT

OBJECTIVES: To demonstrate the use of perfusion CT in patients presenting with a suspected diagnosis of stroke to avoid the administration of inappropriate thrombolytic therapy in stroke-mimicking conditions such as status epilepticus. MATERIAL AND METHODS: We reviewed the imaging studies of four patients presenting with symptoms suggestive of stroke, but finally diagnosed with status epilepticus. Imaging was by a 16-section multidetector CT scanner using a protocol consisting of non-contrast CT, CT angiography and perfusion CT. Color-coded maps allowed calculation of the CBV (cerebral blood volume), CBF (cerebral blood flow) and MTT (mean transit time). RESULTS: In all four cases, perfusion CT revealed increases in CBF and CBV as well as a decreased MTT, consistent with hyperperfusion linked to status epilepticus with focal deficit-in contrast to the hypoperfusion observed in stroke patients. CONCLUSION: The use of perfusion CT accurately detected hyperperfusion in status epilepticus presenting as stroke. In such cases, perfusion CT imaging avoided the administration of potentially harmful thrombolytic therapy to patients experiencing seizures due to different underlying etiologies.     

Changes in cerebral hemodynamics after carotid stenting: evaluation with CT perfusion studies

PURPOSE: To determine changes in cerebral perfusion parameters, based on CT perfusion imaging, in patients after unilateral transluminal angioplasty and stent placement. MATERIAL AND METHODS: 74 patients with symptomatic high - grade internal carotid artery stenosis (>70%) were studied with CT perfusion imaging before and - on average - 70 hours and 172 days after carotid stent placement. There were 50 patients with unilateral carotid artery stenosis and 24 with stenosis and accompanying contralateral internal carotid artery occlusion. CT examination was performed using a multidetector helical CT scanner (Light Speed Ultra Advantage, GE Healthcare, USA). Maps showing the absolute values of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were generated. RESULTS: In a group with unilateral carotid artery stenosis perfusion deficits were present in 84% of patients, ipsilaterally to stenosis. MTT elongation was noted (6.2-6.8s) together with decreased values of CBF (40-46ml/100g/min) and slightly increased CBV (3.2ml/100g). In this group, 3 days after stenting, 30% of patients had perfusion deficits, and after 6 months only 6%. In a group with carotid artery stenosis and contralateral artery occlusion severe perfusion deficits were noted in both hemispheres and they were present in 100% of patients. 6 months after stenting hypoperfusion was observed only in 17% of patients. CONCLUSIONS: Brain perfusion deficits, observed in a majority of patients with carotid artery stenosis tend to improve considerably after carotid artery stenting, in long - term follow up.     

Visualization of ischaemic penumbra using a computed tomography perfusion method

A computed tomography (CT) perfusion imaging and a diffusion/perfusion magnetic resonance imaging (MRI) were performed in a 51-year-old man at 15 and 15.5 h of onset of left middle cerebral artery infarction, respectively. The established infarct, as revealed by the diffusion-weighted MRI, had low values of cerebral blood flow (CBF) and cerebral blood volume (CBV) on the CT perfusion study. The ischaemic penumbra, as reflected by the perfusion-diffusion mismatch on MRI, had reduced CBF, prolonged mean transit time (MTT) and compensated CBV. Spontaneous bleeding occurred in the medial part of the left lentiform nucleus, immediately following decompressive craniectomy. CT measurements of CBF, CBV and MTT may visualize the ischaemic penumbra and explain the site of bleeding after surgical decompression.     

急性脑梗死的320排动态容积CT脑灌注成像研究

目的研究320排动态容积CT全脑灌注成像(CTP)在脑梗死患者中的价值。方法对2014-01—2016-01驻马店市中心医院收治的33例脑梗死患者采取CT全脑灌注成像检查,测量梗死核心区、缺血半暗带(IP)与健侧镜像区的脑血流量(CBF)、脑血容量(CBV)、达峰时间(TTP)及平均通过时间(MTT)值,计算梗死核心区及IP的相对脑血流量(rCBF)、相对脑血容量(rCBV)、相对达峰时间(rTTP)、相对平均通过时间(rMTT),并进行对比分析。结果 33例患者中,头颅平扫发现9例早期脑梗死征象,其余24例未发现异常。33例患者行CTP成像均发现异常灌注区,其中25例存在IP;与健侧镜像区对比,CBV无显著差异(P0.05),而TTP、MTT值明显延长,CBF显著降低,差异有统计学意义(P0.05);与梗死核心区对比,CBF、CBV升高,TTP缩短,MTT延长,差异均有统计学意义(P0.05)。IP区与梗死核心区rCBF、rCBV、rTTP、rMTT对比,差异有统计学意义(P0.05)。10例超急性期(发病6h以内)、15例急性期(发病6~72h)中11例、8例亚急性期(发病72h~14d)中4例存在IP。缺血半暗带分期:Ⅰ2期6例,Ⅱ1期12例,Ⅱ2期7例。结论 320排动态容积CT全脑灌注成像可通过注射一次对比剂获得常规CT、CTP、CTA数据,对脑梗死患者的病变部位、范围及有无IP等提供明确的影像学依据,且可对IP进行分期,为临床实现对患者的个体化治疗提供了可能,且显著降低了患者所受的辐射剂量,安全性高。     

Carbon disulfide vasculopathy: a small vessel disease

We present the clinical manifestations of 4 male patients with acute stroke-like symptoms and polyneuropathy after long-term exposure to carbon disulfide (CS2) in a viscose rayon plant. The ages of onset of polyneuropathy ranged from 42 to 45 years with a duration of CS2 exposure between 6 and 21 years. The ages of onset of stroke were from 42 to 48 years. The risk factors for stroke including heart disease and diabetes were denied, except for smoking in 4, hyperlipidemia in 2 and hypertension in 1. At the initial visit in 1992, only 2 patients developed sudden onset of hemiparesis suggesting a lacunar stroke before the diagnosis of CS2 intoxication. Brain computed tomography (CT) scans showed low-density lesions in the basal ganglia in 2 patients, cortical atrophy in 1 and normal in 1. Brain magnetic resonance image (MRI) study disclosed multiple lesions in the corona radiata and basal ganglia on T(2)-weighted images in 3 patients and cortical atrophy in 1. After the diagnosis, they left their jobs for a CS2-free environment, and improvement of the working conditions was noted. During 5 years follow-up period, another 2 patients also developed an acute episode of stroke with hemiparesis. Brain CT and/or MRI follow-up studies in these 2 patients revealed new lesions in the basal ganglia and corona radiata. Intriguingly, a patient with previous stroke also developed new lesions in the bilateral thalami and brainstem. Carotid Doppler scan, transcranial Doppler scan and/or cerebral angiography did not show any prominent stenosis or occlusion in the major intracranial large arteries. We conclude that encephalopathy may occur in patients after long-term CS2 exposure, probably due to impaired cerebral perfusion. The lesions tend to occur in the basal ganglia, corona radiata and even brainstem, particularly involving the small-sized vessels. In addition, the cerebral lesions may progress even after cessation of CS2 exposure. Therefore, we suggest that CS2 exposure may be a risk factor for stroke.     

一站式全脑动态容积 CTP-CTA 成像对颅脑损伤后脑血管痉挛的诊断价值

目的 探讨一站式全脑动态容积CT灌注成像(CTP)联合CT血管成像(CTA)成像在颅脑损伤后脑血管痉挛中的应用及临床意义.方法 50例可疑有症状性脑血管痉挛表现的患者接受一站式全脑动态容积成像,CTP检查结果与对侧镜像区进行比较.结果 50例颅脑损伤患者中48例患者CTP存在原脑损伤范围外的低灌注区,同临床症状相符,准确性达96%,同对侧镜像区进行比较,各参数脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)及达峰时间(TTP)差异皆有统计学意义;50例颅脑损伤患者其中42例患者3D-CTA存在颅内大血管痉挛.结论 一站式全脑动态容积CTP-CTA成像技术应用于颅脑损伤后脑血管痉挛,通过CTP显示脑实质低灌注区以判断脑实质微循环血管痉挛的存在,CTA判断脑实质外大血管痉挛的存在,即CTP联合CTA对颅脑损伤后脑血管痉挛的早期诊断、治疗方案的选择、疗效的评估均有重要临床价值.     

320排CT灌注成像对矢状窦旁脑膜瘤诊治的价值

目的探讨矢状窦旁脑膜瘤320排CT灌注成像方法,评估其对该脑膜瘤诊治的价值。方法对38例矢状窦旁脑膜瘤患者术前行320排CT检查,将容积数据导人Toshiba公司的4D-Perfusion专门软件包进行后处理,得出灌注图像及参数,包括脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)和达峰时间(TTP)。结果 38例灌注图像均可以清晰显示肿瘤的大小、轮廓。瘤组织CBF、CBV、TTP分别是(778.1±104.2)ml/100ml·min、(81.7±20.4)ml/100ml、(18.9±1.1)s,均明显高于正常脑组织(P<0.01);瘤组织MTT是(7.4±2.2)s,与正常脑组织无明显差别(P>0.05)。灌注成像与CTA图像融合能清晰显示供血动脉、肿瘤组织、脑组织、引流静脉及与矢状窦的关系。结论 320排CT灌注成像为矢状窦旁脑膜瘤血流灌注的定量研究提供了新的方法,对了解肿瘤内部血流状态及微血管的改变有一定的价值。灌注成像与CTA图像融合对矢状窦旁脑膜瘤手术有指导意义。     

A case of organized chronic subdural hematoma presented with transient neurologic deficits]

A 59-year-old diabetic male presented with transient motor aphasia and monoparesis of the right upper limb. Brain CT scan showed a low density area in the left subdural space with a mild midline shift. Magnetic resonance (MR) T2-weighted and fluid-attenuated inversion recovery (FLAIR) imagings revealed homogenous hyperintensity with a hypointense web-like structure in the subdural hematoma. Cervical MR angiography showed no abnormal lesion at the bifurcation of the bilateral common carotid arteries. Conventional cerebral angiography showed an avascular, crescent, space-occupying mass over the left hemisphere without an etiologic lesion of cerebral ischemia. CT perfusion imagings indicated reduced cerebral blood flow (CBF) and prolonged mean transit time (MTT) in the left middle cerebral artery territory underneath the subdural hematoma. No epileptic discharge was found in electroencephalogram. Operative findings indicated that the hematoma was encapsulated with thickened outer and inner membranes including paste-like materials, and the brain surface was intact. Postoperative CT perfusion imagings revealed normal CBF and MTT. The pathophysiological mechanism which the chronic subdural hematoma produces the transient neurological deficit is still uncertain. The mechanical pressure of the hematoma on the neighboring cerebral vessels may cause impairment of blood flow leading to cerebral ischemia and paralysis of function. Our case indicated the transient neurological deficits attributed to a decreased CBF around the subdural hematoma and a change in pressure exerted by the hematoma during changes of head position and increased blood viscosity.     

Heterogeneity of cortical lesions in multiple sclerosis: an MRI perfusion study

In this study, dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI) was used to quantify the cerebral blood flow (CBF), the cerebral blood volume (CBV), and the mean transit time (MTT) and to analyze the changes in cerebral perfusion associated with the cortical lesions in 44 patients with relapsing-remitting multiple sclerosis. The cortical lesions showed a statistically significant reduction in CBF and CBV compared with the normal-appearing gray matter, whereas there were no significant changes in the MTT. The reduced perfusion suggests a reduction of metabolism because of the loss of cortical neurons. A small population of outliers showing an increased CBF and/or CBV has also been detected. The presence of hyperperfused outliers may imply that perfusion could evolve during inflammation. These findings show that perfusion is altered in cortical lesions and that DSC-MRI can be a useful tool to investigate more deeply the evolution of cortical lesions in multiple sclerosis.     

Spect measurements of regional cerebral perfusion and carbondioxide reactivity: Correlation with cerebral collaterals in internal carotid artery occlusive disease

Background The aim of the present study was to assess the regional variation in cerebral perfusion, vasomotor reactivity (VMR) and the role of cerebral collaterals in patients with symptomatic internal carotid artery (ICA). Methods Seventeen functionally independent patients (60±9 years, mean±SD) with a unilateral symptomatic internal carotid artery occlusion and a <30% contralateral ICA stenosis were investigated. (99 m) Tc-hexamethyl propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) was performed to study cerebral blood flow in rest and during a CO₂ challenge in the cerebellum, temporal lobe, occipital lobe, basal ganglia, frontal lobe and parietal lobe. Time of flight and phase contrast MRA were used to study collateral flow via circle of Willis. Results In rest, cerebral perfusion on the side ipsilateral to the ICA occlusion was decreased compared with the contralateral side in the basal ganglia (p<0.05), frontal lobe (p<0.01) and parietal lobe (p<0.01). During a CO₂ challenge only the ipsilateral frontal lobe demonstrated a perfusion decrease compared with the contralateral frontal lobe (p<0.05). Furthermore, in patients without collateral flow via the anterior circle of Willis the perfusion of the ipsilateral frontal lobe was significantly decreased (p<0.01) during the CO₂ challenge and crossed cerebellar diaschisis with a decreased perfusion on the contralateral cerebellar hemisphere was detected (p<0.05). No cerebral blood flow (CBF) differences were found for present/absent collateral flow via the posterior communicating artery. Conclusion Regional assessment of cerebral perfusion and VMR with SPECT demonstrated the heterogeneity of cerebral hemodynamics and the importance of collateral flow via the anterior circle of Willis. Received in revised form: 22 November 2005     

VCTDSA联合CT灌注成像对急性缺血性脑卒中影像诊断价值

目的探讨容积CT数字减影血管造影VCTDSA联合CT灌注成像在急性缺血性脑卒中的诊断价值。方法对30例临床诊断为急性缺血性脑卒中的患者于发病后24h内行VCTDSA联合CT灌注成像,观察CT平扫表现及灌注图像、VCTDSA重建图像结果。测定相应区域脑血流量(CBF),脑血容量(CBV),平均通过时间(MTT)和达峰时间(TTP)。结果 25例急性缺血性脑卒中患者头部CT平扫未发现与临床症状相对应的脑缺血区,CT灌注图上可发现与临床症状相对应的脑缺血区。CT灌注成像表现为CBF下降、CBV下降、MTT延长、TTP延长或无TTP出现。VCTDSA可见23例患者相应责任血管的不同程度的狭窄,其余7例患者未检出相应责任血管狭窄。结论 CT灌注成像在急性缺血性脑卒中的早期诊断中有很重要的价值。VCTDSA能发现缺血病变的原因,为临床进一步治疗提供确切依据。     

头颅CT灌注成像在球囊闭塞试验中的辅助作用

目的探讨头颅CT灌注成像（CTP）在球囊闭塞试验（BOT）中的辅助判断作用。方法 20例经DSA确诊的颈内动脉巨大动脉瘤患者,临床判断为BOT阴性的同时行头颅CTP,通过比较双侧半球的脑血流量（CBF）、脑血容量（CBV）及达峰时间（TTP）对脑血流动力学进行评估。结果 20例患者均在BOT过程中完成CTP且无任何脑缺血症状,17例（85.0%）灌注对称,判断为耐受性良好,16例行永久性颈内动脉球囊闭塞术（其中4例联合动脉瘤部分栓塞术）,1例行颈内动脉慢性阻断术;3例（15.0%）灌注不对称,主要为阻断侧TTP延长,CBV正常或轻度升高,而CBF基本正常,即存在早期的脑血流动力学损害,认为其无法耐受颈内动脉的永久闭塞,其中2例行颅内外动脉搭桥联合动脉瘤孤立术,1例行支架辅助的动脉瘤致密栓塞术,载瘤动脉保留完整。所有患者随访15～32个月,均无远期缺血并发症。结论 CTP能检出BOT阴性者潜在的脑血流动力学损害,可以更客观地评估其对颈内动脉永久闭塞的耐受力,是BOT的重要补充。