320排CT在短暂性脑缺血发作中的应用价值初探

目的 初步探讨320排容积CT在短暂性脑缺血性发作(TIA)的应用价值. 方法 在11例TLA患者发作间隙期应用320排容积CT进行一站式CT扫描,收集患者的头颅平扫、CT血管造影(CTA)及全脑灌注的信息,对影像资料进行综合分析.观察TIA患者的脑血管及其组织单元的病变情况. 结果 11例患者头颅CT平扫均未发现明确的责任病灶,3例行MRI无阳性发现;CTA结果显示,10例患者责任病灶区域内脑血管网明显稀疏,8例发现有相对应的血管明显变细,2例血管栓塞同时存在代偿血管形成.11例全脑灌注图像显示与临床症状相对应的灌注区达峰时间、平均通过时间延迟,5例脑血流量下降,3例脑血容量轻度增加. 结论 320排容积CT灌注成像可以通过一次对比剂注射,获得常规CT扫描、全脑灌注、CTA的数据,实现对缺血性脑血管病的全面评估.

Abstract：

Objective To explore the application value of 320-slice volume CT in detecting the cerebral transient ischemic attack (TIA). Methods One-stop CT scan was performed at intermission of onset on 11 patients with cerebral TIA; the data of plain CT scans, CT angiography (CTA) and whole brain perfusion on these patients were collected. Analysis by synthesis was performed on these imaging data. Results No lesions responsible for the attack were found in the brains of 11 patients with TIA under plain CT scan; 3 of them performed MRI did not have positive results. CTA indicated that the vascular networks in 10 patients were obviously sparse in the region of lesions responsible for the attack;the corresponding vessels in 8 of them became thin; both vascular thrombosis and compensatory angiogenesis occurred in 2 patients. The cerebral perfusion indicated that perfusion areas corresponding to clinical symptoms displayed delayed mean transit time and time to peak level in these 11 patients.Decreased regional cerebral blood flow was noted in 5 patients and regional cerebral volume increased mildly in 3 patients. Conclusion The 320-slice-volume CT perfusion imaging can obtain the information about whole brain perfusion, routine CT scan and CTA by injecting a kind of contrast medicament for only one time, thus can assess the ischemic cerebrovascular disease comprehensively.     

高血压性脑出血局部组织血流量变化的CT灌注研究

目的 利用CT灌注成像的方法探讨高血压脑出血血肿周围及其远隔区域脑血流变化情况。方法 对20例高血压脑出血患者行治疗后2周颅脑CT灌注扫描及计算机辅助系统制作颅脑CT灌注参数图,对血肿周围局部脑血流量（regional cerebral blood flow,rCBF）、局部脑血容量（regional cerebralblood volume,rCBV）和对比剂平均通过时间（mean transit time,MTT）脑血流动力学参数进行定量测量,并与正常侧对应参照点进行比较。结果 血肿周围存在不同程度低灌注,血肿边缘区rCBF、rCBV显著低于血肿外层区,血肿边缘区MTT较血肿外层区明显延长（P <0.05）,血肿边缘区及外层区rCBF、rCBV、MTT较相应镜像点均有统计学差异（P <0.05）。结论 血肿周围局部脑血流显著降低,CT灌注成像可显示血肿周围异常的脑血流动力学变化, 可为脑出血临床救治提供有价值信息。     

多模式CT对卒中患者血脑屏障完整性和侧支循环的评估价值

多模式计算机断层扫描（computed tomography,CT）对急性缺血性卒中患者的重要性逐 渐引起临床医生的重视,在脑缺血超急性期,CT平扫可对脑出血或其他脑部疾病进行鉴别,CT血管 造影可评估血管梗死部位和侧支循环状态,CT灌注成像可以通过毛细血管的实际灌注情况来评估 脑组织的活力,并通过计算血脑屏障的表面通透性（permeability surface,PS）判断血脑屏障的完整 性,进一步指导临床医生溶栓及血管性治疗方案的制定,也可以预测卒中后患者发生出血转化的风 险。临床诊疗过程中,结合多模式CT提供的信息,可对急性缺血性卒中患者出现出血转化和临床预后 进行全面评估。     

The role of SPECT brain imaging in assessing psychopathology in the medically ill.

Cerebral single photon emission computed tomography (SPECT), a method of functional brain imaging, measures cerebral blood flow and metabolism. This paper describes the imaging procedure and several cases where cerebral SPECT was of use in the differential diagnosis of medically ill patients who also presented with psychopathology. SPECT patterns in cerebrovascular disease, dementia, focal epilepsy, and AIDS are at present the best described and seem to be the most specific. Often changes in regional cerebral blood flow are seen before structural changes become apparent on CT or MRI. Cerebral SPECT can add valuable diagnostic information in assessing psychopathology in the medically ill and can often lead to changes in treatment.     

CT perfusion cerebral blood flow imaging in neurological critical care

Computed tomography (CT) perfusion imaging is a technique for the measurement of cerebral blood flow, cerebral blood volume, and time-to-peak or mean transit time. The technique involves the administration of a single-bolus dose of iodinated contrast material, followed by spiral CT imaging during the passage of the contrast bolus through the cerebral vasculature. CT perfusion is a fast and inexpensive brain imaging modality for use in the management of patients with various neurological disorders, ranging from acute stroke to subarachnoid hemorrhage. This article reviews the technique of CT perfusion and presents several illustrative cases in which this imaging modality was used effectively in the critical care of patients with neurological disorders.     

Evaluation of brain death by computed tomography

The absence of cerebral circulation and electrocerebral silence have served as an accurate index of irreversible brain death. It is proposed that computed tomography (CT) findings be evaluated as confirmatory criteria of brain death. To this end, CT evaluation of 14 patients satisfying the conventional criteria of brain death was performed. A.CT finding of severe compression or disappearance of the ventricular system, or so-called "brain tamponade", was seen in 7 (50%) of the 14 patients. Enhanced contrast CT, especially dynamic CT, usually distinctly reveals the cerebral vessels whenever the cerebral blood flow is preserved; conversely, the lack of enhanced brain structures, even comparing attenuation values, indicates the absence of cerebral blood flow. In 7 (70%) of 10 patients, however, there was enhanced contrast of vascular brain structures, especially the circle of Willis, major cerebral arteries, choroid plexuses, and venous sinuses. It is suggested that this result is due to the improvement of demonstrability by CT. The usefulness of CT in the confirmation of brain death lies in visualization of the pathological changes associated with a dead brain, such as "brain tamponade", and the lack of enhanced contrast indicating the absence of cerebral blood flow. The latter point is still problematic as angiography revealed an extremely low cerebral blood flow in a few cases of "dead brain" patients. It is recommended that cerebral blood flow in brain death be evaluated by dynamic CT scanning and correlated with other methods of cerebral blood flow determination (e.g., intravenous digital subtraction angiography).     

Imaging viable brain tissue with CT scan during acute stroke

Viability of the cerebral parenchyma is dependent on cerebral blood flow (CBF). The assessment of cerebral perfusion in patients with acute stroke, in a clinically relevant time frame, could be of utmost importance for patient selection before thrombolytic therapy. In individual patients, quantitative mapping of CBF to indicate the severity and potential reversibility of neuronal damage can be used to predict which brain tissue will be salvaged with reperfusion or die without it (penumbra), as well as which brain tissue is already infarcted. Recent investigations of perfusion CT have shown major advances in the assessment of acute stroke patients. Perfusion CT offers a number of practical advantages over other cerebral perfusion imaging methods as it can be performed immediately after unenhanced CT, and used, in general, to exclude cerebral haemorrhage. It is fast (typical procedure time <5 min) and does not require specialized computer hardware. The accuracy of cerebral perfusion maps has been demonstrated for normal and decreased CBF value by comparison with xenon CT used as a gold standard. Perfusion CT infarct and penumbra maps provide a potential recuperation ratio (PRR) (or Lausanne Stroke Index), defined as PRR = penumbra/ (penumbra + infarct). This index is correlated with the improvement of the National Institutes of Health Stroke Scale (NIHSS) in case of arterial recanalization. Also, the size of the ischaemic area (infarct + penumbra) is correlated with the NIHSS score on hospital admission. Further studies may demonstrate the use of perfusion CT for the assessment of penumbra dynamics in function-specific brain areas. Perfusion CT is now ready to be used in clinical trials as a decision-making tool to tailor more precisely the thrombolytic therapy to the individual patient.     

DSCTA联合早期疗效的评价CTPI对颅内外动脉吻合术后

目的联合应用数字减影CT血管造影(DSCTA)和CT灌注成像(CTPI)对颅内外动脉吻合术(EIAB)后早期疗效进行评价。方法因脑血管疾病经受了EIAB的患者18例,其中9例行术后DSCTA检查,13例行手术前后CTPI检查,其中4例同时接受手术前后CTPI检查和术后DSCTA检查。结果 CTPI显示8例术后脑血供明显改善,表现为原异常灌注区域范围减小,部分吻合血管周围脑组织呈过度灌注状态,脑血容量、脑血流量明显增加,平均通过时间明显缩短(P0.05);3例术后脑血供无明显变化;2例脑血供减少。术后DSCTA显示搭桥血管通畅7条,闭塞3条。DSCTA可清楚显示旁路血管全程及吻合口的部位、大小或宽度。多平面重组(MPR)和去骨结构容积再现重建均可清楚显示搭桥血管及吻合口,但MRP更有助于测量吻合口的宽度。结论联合应用DSCTA和CTPI成像技术可对EIAB后早期疗效进行无创性定量评估,具有良好的临床应用前景。     

Tomographic cerebral blood flow scanning in diagnosis of psychiatric disorders

The paper summarises the role of tomographic cerebral blood flow SPECT scanning in psychiatric diagnostics, its' physical and radiopharmaceutical basis, pathological physiology of cerebrovascular circulation in psychiatric disorders and interpretation of cerebral blood flow scanning results by the clinician. Cerebral blood flow scanning is, to some extent, a functional equivalent of CT/MRI scanning. In psychiatry cerebral blood flow SPECT scanning's basic application is the differentiation of dementia and cognitive impairment, in particular Alzheimer's disease, frontotemporal lobar degeneration and multi-infarct dementia. The other indications for brain SPECT scanning involve the organic brain lesions and medico-legal diagnostics, including the sequelae of cranio-cerebral trauma. Contraindications and economical aspects are underlined.     

Uncoupling of blood flow and oxygen metabolism in the cerebellum in type 3 Gaucher disease

Cerebral blood flow and oxygen metabolism were measured in a fourteen-year-old girl with type 3 Gaucher disease by using positron emission tomography (PET). Cranial CT and MRI showed only mild brain atrophy. PET demonstrated uncoupling of cerebral blood flow and oxygen metabolism, that is, a mild increase of cerebral blood flow and a reduction of oxygen extraction fraction and cerebral metabolic rate of oxygen only in the cerebellum. Although the mechanism is unknown, the above finding may reflect the underlying pathogenesis of the disorder. PET seems to be more sensitive than CT and MRI in detecting some functional abnormalities in the affected structures. However, further investigations must be done before concluding that this finding is unique to type 3 Gaucher disease.     

头颅移动CT灌注扫描对重型颅脑损伤患者的临床价值

目的 探讨移动CT灌注扫描（CTP）在重型颅脑损伤（TBI）患者中的临床应用价值。方法 2015年4~9月我院神经外科重症监护室收住重型TBI患者26例,受伤24 h之内同时进行头颅CT平扫（CT1）和移动CTP,并在5 d后复查头颅CT平扫（CT5）。CTP提供脑血流量（CBF）影像、脑血容量（CBV）影像及平均转运时间（MTT）影像;将CTP影像、CT1及CT5进行比较。结果 CTP平均在伤后（15.6±4）h进行。16例（61.5%）患者CTP影像显示灌注改变区域大于CT1显示的病灶区域,其中7例（27%）患者低灌注程度达到缺血水平。3例（11.5%）患者通过CTP扫描发现严重的脑灌注不足,尽管在CT5上并没有明显的缺血梗死表现,根据CTP结果,改变此3例患者的治疗方案,最终只有1例发生严重脑梗死,另外2例恢复良好。与CT1相比,CTP与CT5结果具有更好的一致性。结论 头颅移动CTP可以在创伤后早期对重型TBI患者的脑血流灌注情况作出较为准确的评估,为临床干预提供有力依据。     

短暂性脑缺血发作的动态CT灌注成像与缺血再发作的关系

目的探讨短暂性脑缺血发作(transient ischemic attack,TIA)患者CT灌注成像(CT perfusion,CTP)的变化,为预防TIA再发提供判断依据。方法经临床确诊的TIA患者20例于急性期先行常规16排螺旋CT横断面平扫,然后根据累及的动脉系统,选择感兴趣平面行脑CT灌注扫描,同时行CT血管造影。1个月后复查脑CT灌注。结果20例患者中,在急性期大部分患者患侧局部脑血流(regional cerebral blood flow,rCBF)呈轻到中度异常,患侧局部脑血容量(regional cerebral blood volume,rCBV)呈正常或轻度下降。1个月后复查CT脑灌注结果显示有12例患者未发现异常,8例患者rCBF呈轻到中度下降,患侧rCBV呈正常或轻度下降,随访1年,14例未复发。6例两次CT灌注均有异常者在1年内有5例TIA再发,1例发展为脑梗死。结论对于脑灌注量降低严重而且持续时间长的TIA患者,提示可能出现TIA再发或进展为脑梗死,应及时强化抗缺血治疗。     

The remote effects of brain tumors on cerebral blood flow as measured by single photon emission CT

In order to assess the remote effects of supratentorial brain tumors, the cerebellar blood flow and cerebral blood flow of the symmetrical regions in the contralateral cerebral hemispheres were measured by single photon emission CT. Forty four patients with supratentorial brain tumors, such as gliomas, meningiomas and germ cell tumors etc., were included in this study. Contralateral cerebellar hypoperfusion (CCH) was exhibited in 51%, 18 of 35 unilateral brain tumors. Regarding tumor location, CCH was more correlated with frontoparietal lesions. The mean values of contralateral delta Cerebellar blood flows (delta CBFs) were lower than those of ipsilateral delta CeBFs, and also statistically, bilateral delta CeBFs significantly decreased. The greater the volume of lesions including peritumoral edemas, the lower the delta CeBF became. Among the 9 cases with obstructive hydrocephalus, the preoperative delta CeBFs which had decreased significantly, returned to normal postoperatively. Statistically, it seemed that there was no transcallosal suppression caused by unilateral brain tumors. However the delta rCBF of the mirror foci in postoperative patients decreased significantly. In conclusion, the remote effects on the cerebral blood flow, which are common in strokes cases, were demonstrated in many cases of supratentorial brain tumors and the occurrence of CCH was closely related to the frontoparietal lesion including the tumor and peritumoral edema. Also the mechanism of CCH was discussed with preference for a transneural suppression.     

Neuroimaging studies of delirium: a systematic review

OBJECTIVE: Neuroimaging offers clear potential in developing a better understanding of the pathophysiology of delirium. We performed a systematic review of structural and functional neuroimaging findings in delirium. The aims were to categorize and summarize the existing literature, and to determine whether this literature provides conclusive information on structural or functional brain predictors, correlates, or consequences of delirium. METHODS: Studies were identified by comprehensive textword and MeSH-based electronic searches of MEDLINE, EMBASE, and Evidence-Based Medicine reviews, combining multiple terms for neuroimaging, brain structure, and delirium. RESULTS: Twelve studies met the inclusion criteria. There were a total of 194 patients with delirium and 570 controls. Patient age, population, comorbidities, and identified precipitating factors were heterogeneous. Of the 10 structural studies, 3 studies used computed tomography (CT), 3 studies used magnetic resonance imaging (MRI), and 4 studies used a mixture of CT and MRI. One functional study used xenon CT, and the other used single photon emission computed tomography. There was a wide range of measurement techniques and timing of scans. Some studies found associations between delirium and cortical atrophy, and between ventricular enlargement and white matter lesion burden, but many studies did not control for potential confounders. Only two small studies of cerebral blood flow were identified, with both suggesting that there may be reduced regional cerebral blood flow, but the data were limited and somewhat inconsistent. CONCLUSIONS: The small sample sizes and other limitations of the studies identified in this review preclude drawing any clear conclusions regarding neuroimaging findings in delirium, but these studies suggest multiple avenues for future research.     

Clinical experience with the use of xenon-enhanced CT blood flow mapping in cerebral vascular disease

Cerebral blood flow mapping with the xenon-enhanced/CT method has become a useful clinical tool in the management of patients with occlusive cerebral vascular disease. Studies involving 4-5 minutes of inhaling a xenon/oxygen mixture (less than or equal to 35%) can now be performed routinely with acceptable patient tolerance and compliance. Four cases with acute and chronic ischemic injuries are reported here to illustrate the manner in which this method has been used to characterize flow pattern in such patients and the relevance of this flow information to clinical patient management.     

The role of spiral CT for the assessment of the intracranial circulation in suspected brain-death

BACKGROUND AND PURPOSE: The aim of this study was to assess the role of spiral CT for the diagnosis of brain death. METHODS: Over a 12-month period, 15 patients that fulfilled the clinical criteria of brain death were referred from the intensive care unit to evaluate remaining intracranial blood flow by spiral CT. The clinical diagnosis was confirmed by an apnea test in all cases. Two phases of spiral CT were performed at 20 and 60 seconds after the start of contrast media injection. Qualitative analysis included the evaluation of vessel opacification (arteries and veins) by two radiologists in consensus. RESULTS: The cortical segments of the middle cerebral artery (MCA) were assessable in all patients, whereas the internal cerebral veins could not be evaluated in five patients due to artifacts or intracranial hemorrhage. Opacification of the major branches of the circle of Willis was observed in seven cases. Unilateral opacification of cortical branches of the MCA occurred in one. We did not observe bilateral enhancement of cortical MCA branches. The internal cerebral veins did not enhance in brain death. CONCLUSION: The absence of internal cerebral vein opacification and the absence of bilateral enhancement of cortical MCA branches constituted the best criteria of brain death by contrast enhanced spiral CT.     

The Thickness and Texture of Temporal Bone in Brain CT Predict Acoustic Window Failure of Transcranial Doppler

BACKGROUND AND PURPOSE: Although transcranial Doppler (TCD) is useful for evaluation and treatment of ischemic stroke, temporal acoustic window failure (TAWF) limits its application. We performed this study to reveal whether initial brain CT of acute stroke patients predicted TAWF. METHODS: We performed TCD in 92 acute ischemic stroke patients (57 males, aged 38-84 years) with brain CT scans. We measured the thickness (BTW) and evaluated the texture of the temporal bone in acoustic windows shown in the CT scan with the use of picture archiving and communication system. The bone mineral density (BMD) of the vertebral bodies, femurs, and whole body was also measured. RESULTS: Doppler signals were adequately obtained in 121 (65.8%) of the 184 middle cerebral arteries (MCA) from both cerebral hemispheres. BTW and inhomogeneity of temporal bone, besides age, sex, and hypercholesterolemia, was strongly correlated with TAWF. BMD was not directly correlated with TAWF, but inhomogeneous temporal bone was correlated with lower BMD scores. If the brain CT scan showed thick (BTW >or= 2.7 mm) and inhomogeneous temporal bone, the possibility of TAWF was 93.5%, while if brain CT scan showed thin (BTW < 2.7 mm) and homogenous temporal bone, it was only 5.4%. CONCLUSIONS: The texture as well as the thickness of the temporal bone was the most important determinant of TAWF. When acute stroke patients had thin and homogeneous temporal bones in initial brain CT scan, TAWF was very rare, and loss of MCA signals on TCD specifcally indicated the absence of blood flow in MCA.     

Transcranial Doppler in acute hemispheric brain infarction

We studied cerebrovascular anatomy using intra-arterial digital angiography, and blood flow velocity in the middle cerebral artery (MCA) using transcranial Doppler (TCD) ultrasonography in 42 patients with acute hemispheric ischemic brain infarction. We compared angiography with TCD and the clinical findings within 6 hours of the onset of symptoms. The location and extent of the chronic ischemic brain damage was assessed by CT performed 1 to 3 months after the ictus. Abnormal TCD, as manifested by either an unobtainable MCA flow signal or a significantly depressed MCA flow velocity, was highly associated with proximal MCA occlusions demonstrated by angiography. Abnormal TCD predicted both larger chronic CT lesions and more extensive ischemic change within the MCA territory. These data demonstrate that early TCD conveys useful information concerning cerebral tissue prognosis following hemispheric ischemia.     

Use of various CT imaging methods for diagnosis of acute ischemic cerebrovascular disease

Thirty-four patients with cerebral infarction and 18 patients with transient ischemic attack were examined by multi-slice spiral CT scan, CT perfusion imaging, and CT angiography within 6 hours after onset. By CT perfusion imaging, 29 cases in the cerebral infarction group and 10 cases in the transient ischemic attack group presented with abnormal blood flow perfusion, which corresponded to the clinical symptoms. By CT angiography, various degrees of vascular stenosis could be detected in 41 patients, including 33 in the cerebral infarction group and eight in the transient ischemic attack group. The incidence of intracranial artery stenosis was higher than that of extracranial artery stenosis. The intracranial artery stenosis was located predominantly in the middle cerebral artery and carotid artery siphon, while the extracranial artery stenosis occurred mainly in the bifurcation of the common carotid artery and the opening of the vertebral artery. There were 34 cases (83%) with convict vascular stenosis and perfusion abnormalities, and five cases (45%) with perfusion abnormalities but without convict vascular stenosis. The incidence of cerebral infarction in patients with National Institutes of Health Stroke Scale scores ≥ 5 points during onset was significantly higher than that in patients with National Institutes of Health Stroke Scale scores < 5 points. These experimental findings indicate that the combined application of various CT imaging methods allows early diagnosis of acute ischemic cerebrovascular disease, which can comprehensively analyze the pathogenesis and severity of acute ischemic cerebrovascular disease at the morphological and functional levels.     

Dynamics of cerebral blood flow and metabolism in patients with cranioplasty as evaluated by 133Xe CT and 31P magnetic resonance spectroscopy.

OBJECTIVE--Prolonged improvement in neurological and mental disorders has been seen after only cranioplasty in patients initially treated with external decompression for high intracranial pressure. The objective was to evaluate, using 133Xe CT and 31P magnetic resonance spectroscopy (MRS), how restoring the bone itself can influence cerebral blood flow and cerebral energy metabolism after high intracranial pressure is attenuated. METHODS--Seven patients (45-65 years old) who had undergone external decompression to prevent uncontrollable intracranial hypertension after acute subarachnoid haemorrhage were evaluated. Cerebral blood flow and metabolic changes were evaluated before and after cranioplasty. RESULTS--The ratio of phosphocreatine to inorganic phosphate (PCr/Pi), which is a sensitive index of cerebral energy depletion, was calculated and beta-ATP was measured. The cerebral blood flow value in the thalamus was normalised, from 44 (SD 9) to 56 (SD 8) ml/100 g/min (P < 0.01) and the value in the hemisphere increased from 26 (SD 3) to 29 (SD 4) ml/100 g/min on the side with the bone defect. The PCr/Pi ratio improved greatly from 2.53 (SD 0.45) to 3.01 (SD 0.24) (P < 0.01). On the normal side, the values of cerebral blood flow and PCr/Pi increased significantly (P < 0.01) after cranioplasty, possibly due to transneural suppression. The pH of brain tissue was unchanged bilaterally after cranioplasty. CONCLUSION--Cranioplasty should be carried out as soon as oedema has disappeared, because a bone defect itself may decrease cerebral blood flow and disturb energy metabolism.