Brain perfusion is abnormal in cocaine-dependent polydrug users: a study using technetium-99m-HMPAO and ASPECT

Cocaine abuse is widespread and has been associated with serious neurovascular complications. We studied a group of cocaine-dependent polydrug users with 99mTc-HMPAO and high-resolution SPECT and compared their perfusion pattern to cerebral perfusion in a group of older control subjects. Sixteen of 18 cocaine-dependent polydrug users had abnormal perfusion characterized primarily as small focal defects involving inferoparietal, temporal, and anterofrontal cortex and basal ganglia. Psychometric testing was abnormal in all 18 cocaine-dependent subjects. No relation was found between the severity of SPECT abnormalities and mode of administration or frequency or length of cocaine use. All 15 older normal subjects had normal cerebral perfusion. While the focal perfusion abnormalities to the cortex and basal ganglia could be explained by the profound vasoconstrictor effects of cocaine, the combinational use of multiple substances including cannabis and alcohol may play a contributory role. This study documents the high incidence of functional brain abnormalities in cocaine-dependent chronic polydrug users without corresponding abnormalities on imaging studies of cerebral anatomy and morphology.     

Functional imaging of brain maturation in humans using iodine-123 iodoamphetamine and SPECT

The application of regional cerebral blood flow (rCBF) study by means of lipophilic radiotracers and single photon emission computed (SPECT) devices in very young infants is hampered by the considerable changes of rCBF pattern as a result of the cerebral maturation process. In an attempt to determine the normal evolution of [123I]IMP SPECT pattern as a function of age, we retrospectively selected the studies of 30 babies with normal clinical examination, EEG and CT or ultrasound scans at time of SPECT. There was a marked predominance of the thalamic perfusion over cortical areas until the end of the second month. The distribution of regional cortical activity followed a strict sequence. The perfusion of both parietal and occipital areas was well-visualized around the 40th week of gestational age and thereafter rapidly rose, always, however, with a slight predominance of the parietal activity. At the opposite, frontal activity which remained scarcely recognizable up to the second month tremendously rose to present the adult-like pattern at the beginning of the second year. The rCBF changes described above are well in agreement with the behavioral evolution occurring during prime infancy.     

Use of magnetic resonance imaging to identify changes in cerebral blood flow in epilepsia partialis continua

The use of a phase mapping technique for detection of brain perfusion is described. The method was used in a patient with epilepsia partialis continua and displayed an area of abnormal perfusion in the frontal lobe during the ictal phase. Following improved treatment the perfusion pattern was near normal 12 weeks later.     

Technetium-99m HM-PAO-SPECT study of regional cerebral perfusion in early Alzheimer's disease

Regional cerebral perfusion was evaluated by single photon emission computed tomography (SPECT) using technetium-99m hexamethylpropyleneamine oxime ([99mTc]HM-PAO) in sixteen patients with Alzheimer's disease (AD) in early clinical phase and in 16 healthy elderly controls. In all patients transmission computed tomography (TCT) and/or magnetic resonance imaging (MRI) did not show focal brain abnormalities. Relative to normal subjects, AD patients showed significant reductions in cortical/cerebellar activity ratio: cortical perfusion was globally depressed with the largest reductions in frontal and posterior temporo-parietal cortices. Asymmetries of relative perfusion between cerebral hemispheres were also demonstrated when language was affected or visuospatial functions were unevenly impaired. In patients with early AD, SPECT provides functional information to be compared with clinical and psychometric data.     

The relationship between magnetic resonance diffusion imaging and autoradiographic markers of cerebral blood flow and hypoxia in an animal stroke model.

This study examined the relationship between magnetic resonance diffusion imaging and autoradiographic markers of cerebral blood flow (99mTc-hexamethylpropylene amine oxime) and cerebral hypoxia (125I-iodoazomycin arabinoside) in a rat model of stroke. Middle cerebral artery occlusion in the rat was performed using an intraluminal suture approach. Diffusion, hypoxia, and blood flow maps were acquired 2 hr following occlusion, and were compared with T2 images and histology at 7 hr. Two hours following middle cerebral artery occlusion the lesion distributions from the diffusion maps and hypoxic autoradiographs were similar. The blood flow threshold for increased uptake of the hypoxic marker was approximately 34 +/- 7% of the normal flow. The combination of diffusion or hypoxic images with perfusion maps allowed differentiation between four regions: 1) normal tissue; 2) a region of decreased perfusion but normal diffusion and normal uptake of hypoxic marker; 3) a region of decreased perfusion, decreased diffusion and increased uptake of hypoxic marker; 4) a region of decreased perfusion, decreased diffusion and low uptake of hypoxic marker. The areas for increased uptake of hypoxic marker and decreased diffusion are equivalent, indicating similar blood flow thresholds. Regions of oligaemic misery perfusion, ischaemic misery perfusion and lesion core may be delineated with the combination of diffusion or hypoxic images and perfusion maps.     

Perfusion abnormality of the caudate nucleus in patients with paroxysmal kinesigenic choreoathetosis

Purpose Previous cerebral blood flow and glucose metabolism studies suggest that the basal ganglia or thalamus is involved in the pathogenesis of paroxysmal kinesigenic choreoathetosis (PKC). However, the underlying cerebral abnormalities in idiopathic PKC have not been elucidated. To localise cerebral perfusion abnormalities in PKC, we performed interictal brain perfusion ^99mTc-ethylcysteinate dimer (ECD) single-photon emission computed tomography (SPECT) in PKC patients and in normal controls.Methods Sixteen patients with idiopathic PKC and 18 age- and sex-matched normal controls were included. The patients were de novo diagnosed as having PKC, or had not taken medication for at least 3 months; none of them had structural abnormalities on MRI. Patients had a history of PKC attacks of a duration not exceeding 5 min and starting either on one side or on both sides of the body. These attacks were always induced by a sudden initiation of voluntary movement. PKC attacks were recorded in a hospital after being induced by neurology staff in 13 of the 16 patients. Interictal brain perfusion ^99mTc-ECD SPECT was performed in all 16 patients and 18 normal controls. Differences between the cerebral perfusion in the PKC group and the normal control group were tested by statistical parametric mapping. Students t test was used for inter-group comparisons.Results Compared with normal controls, patients with idiopathic PKC showed interictal hypoperfusion in the posterior regions of the bilateral caudate nuclei (false discovery rate-corrected P<0.001 with a small volume correction).Conclusion This study showed that cerebral perfusion abnormality of bilateral caudate nuclei is present in idiopathic PKC.     

Experience with 123I-iomazenil SPECT in acute cerebral infarction

Neuronal cells are susceptible to cerebral ischaemia. As gamma-aminobutyric acid(A) (GABA(A)) receptors are specific for neurones, functional receptor imaging using I-iomazenil (IMZ), a ligand to the GABA benzodiazepine receptor, has been proposed as an imaging modality for the assessment of neuronal integrity. However, there is only limited experience with IMZ in patients with acute cerebral infarction. Therefore, the aim of this study was to evaluate IMZ single photon emission computed tomography (SPECT) in patients with acute cerebral ischaemia. IMZ SPECT was performed in 21 patients with acute cerebral infarction 7-10 days after stroke onset. Eleven patients underwent systemic thrombolysis within 6 h after symptom onset (group 1), whereas 10 patients were treated conservatively (group 2). IMZ (150-200 MBq) was injected intravenously and imaging was performed using a dedicated four-head SPECT camera at 5 min (perfusion) and 90 min (receptor distribution) post-injection, with an acquisition time of 50 min each. Images were analysed by visual inspection. Four patients showed normal IMZ distribution, and 17 patients showed abnormalities of IMZ uptake on both early and late images. In six patients with regional uptake deficits, a crossed cerebellar diaschisis was observed on early images. Cerebellar inhomogeneity of tracer uptake was absent at the time of late images in all six patients. In eight patients, areas of hypoperfusion corresponded exactly to the regions of receptor deficiency (match). In five patients, preserved neuronal integrity was present in hypoperfused areas (mismatch). In four patients, normally or even hyperperfused areas exhibited regional receptor deficiency (inverse mismatch). In conclusion, IMZ SPECT demonstrated differences between regional perfusion and receptor distribution in about one-half of patients 7-10 days after acute cerebral ischaemia. Interesting patterns between the early phase (perfusion) and the late phase (receptor distribution) were found. These patterns are indicative of the heterogeneous development of cerebral ischaemia where, even days after stroke onset, areas of hypoperfusion but preserved neuronal integrity may be present. However, the evaluation of the potential clinical and therapeutic impact of individual IMZ distribution patterns requires further investigation.     

Focal epilepsies: HM-PAO SPECT compared with CT, MR, and EEG

Regional cerebral blood flow (rCBF) was evaluated quantitatively by 99mTc hexamethyl propyleneamine oxime and single photon emission CT (SPECT) during the interictal phase in 52 patients with focal epilepsy. The results were compared with those obtained by electroencephalography (EEG), CT, and magnetic resonance (MR) imaging. Twenty-four of the 52 patients had one area of local hypoperfusion whereas 7 patients showed an area of local hyperperfusion. In 20 of the 52 patients, both reduced and elevated rCBF values were found. One patient had a normal perfusion pattern. The SPECT findings correlated well with the foci shown by EEG, both with regard to the sides affected and the locations of the regions of altered perfusion. The MR images showed focal lesions in only approximately one-half of the patients examined, and CT in even fewer.     

PC机辅助MR脑灌注成像初步研究

目的:研究PC机辅助MR脑灌注成像软件,探讨其临床应用价值。方法:在PC机上使用MR脑灌注成像软件,对5例健康人和18例脑缺血患者的灌注图像进行后处理,计算出有关脑灌注参数图,包括相对脑血流量(rrCBF)图、相对脑血容量(rrCBV)图、局部灌注达峰时间(TTP)图和团注平均通过时间(bMTT)图。结果:应用MR脑灌注成像软件可以在PC机上实现灌注图像的后处理,脑灌注参数图能够为脑缺血患者提供有价值的脑血液动力学信息,显示灌注异常的范围。结论:PC机辅助MR脑灌注成像软件简单易行,可显示常规MR无法显示的血流动力学异常,对临床和科研具有重要价值。     

潘生丁与乙酰唑胺负荷脑血流灌注显像的对比研究

目的 探讨潘生丁负荷脑血流灌注显像的可行性。方法 8例健康志愿者和23例患者于1周内先后进行静息、乙酰唑胺及潘生丁负荷脑血流灌注显像。自身比较静息，负荷状态下的脑血流灌注情况。结果健康志愿者的脑血流灌注双侧对称。患者组中8例正常；1例患者静息态脑局部血流灌注低下，潘生丁和乙酰唑胺负荷态正常；余14例静息态局部脑血流灌注低下或正常，应用潘生丁，乙酰唑胺后局部脑血流量更低或出现低灌注区。两药显示低血流储备区的能力无明显差异。结论 潘生丁可以替代乙酰唑胺实施负荷脑血流灌注显像。     

CTP联合CTA对慢性脑缺血患者血流动力学的评价

目的：利用CT灌注（CTP）和CT血管成像（CTA）探讨慢性脑缺血患者脑血流动力学变化及其与脑供血动脉狭窄、血管性认知功能障碍之间的关系。方法：对55例临床拟诊为慢性脑缺血的患者行常规头颅CT平扫、CTP及CTA检查,应用简易智能状态检查（MMSE）量表评定受试者的智能状态。结果：根据平均通过时间（MTT）、达峰时间（TTP）图灌注延迟范围将灌注表现分为3型：Ⅰ型为大脑中动脉和/或大脑前动脉供血区广泛性低灌注22例;Ⅱ型为分水岭区局限性低灌注21例;Ⅲ型为灌注正常12例。颈内动脉（ICA）或大脑中动脉（MCA）的重度狭窄或闭塞所致脑灌注异常（Ⅰ、Ⅱ型）明显高于轻中度狭窄者（χ^2=29.49,P〈0.01）,Ⅲ型未见ICA或MCA的重度狭窄或闭塞。ICA或MCA狭窄程度与脑灌注异常之间呈正相关（Spearman′sr=0.74,P〈0.01）。脑灌注Ⅰ、Ⅱ型患者MMSE评分均低于正常值（P〈0.01）,且以Ⅰ型为著（P〈0.01）,Ⅲ型MMSE评分正常。结论：慢性脑缺血患者脑血流低灌注与ICA或MCA狭窄程度密切相关,在血管性认知功能障碍的发病机制中起着重要作用。     

Cerebral hemodynamics on MR perfusion images before and after bypass surgery in patients with giant intracranial aneurysms.

BACKGROUND AND PURPOSE: Preoperative assessment of the anatomy and dynamics of cerebral circulation for patients with giant intracranial aneurysm can improve both outcome prediction and therapeutic approach. The aim of our study was to use perfusion MR imaging to evaluate cerebral hemodynamics in such patients before and after extraintracranial high-flow bypass surgery. METHODS: Five patients with a giant aneurysm of the intracranial internal carotid artery underwent MR studies before, 1 week after, and 1 month after high-flow bypass surgery. We performed MR and digital subtraction angiography, and conventional and functional MR sequences (diffusion and perfusion). Surgery consisted of middle cerebral artery (MCA)-internal carotid artery bypass with saphenous vein grafts (n = 4) or MCA-external carotid artery bypass (n = 1). RESULTS: In four patients, MR perfusion study showed impaired hemodynamics in the vascular territory supplied by the MCA of the aneurysm side, characterized by significantly reduced mean cerebral blood flow (CBF), whereas mean transit time (MTT) and regional cerebral blood volume (rCBV) were either preserved, reduced, or increased. After surgery, angiography showed good canalization of the bypass graft. MR perfusion data obtained after surgery showed improved cerebral hemodynamics in all cases, with a return of CBF index (CBFi), MTT, and rCBV to nearly normal values. CONCLUSION: Increased MTT with increased or preserved rCBV can be interpreted as a compensatory vasodilatory response to reduced perfusion pressure, presumably from compression and disturbed flow in the giant aneurysmal sac. When maximal vasodilation has occurred, however, the brain can no longer compensate for diminished perfusion by vasodilation, and rCBV and CBFi diminish. Bypass surgery improves hemodynamics, increasing perfusion pressure and, thus, CBFi. Perfusion MR imaging can be used to evaluate cerebral hemodynamics in patients with intracranial giant aneurysm.     

低温液体灌注产生亚低温的进展

低温对脑损伤的保护作用已被众多动物实验所证实,在临床方面,尤其是发现轻度和中度低温的保护作用之后,应用逐渐增多.近年来,亚低温被用于治疗新生儿缺氧性脑病、心肺复苏后脑保护、脑外伤及脑卒中等领域.目前临床及实验中所应用的低温方式主要为全身亚低温,如降温毯、冰袋等,这些方式降温效率低,不易迅速实现亚低温,而且全身低温可伴有多种并发症,如心律紊乱、凝血功能障碍等.低温液体或自体血液灌注是目前最有效的降温方式,而且局部动脉内灌注低温液体更可以快速实现局部亚低温.介入技术的进步使得快速局部动脉内低温液体灌注成为可能.我们详细回顾相关动物实验及临床应用文献,介绍低温液体灌注产生亚低温的研究进展.     

多相位ASL在颅脑疾病中的初步应用

目的评估多相位ASL在颅脑疾病中的临床应用价值。方法 20例颅内病变患者,其中脑膜瘤8例,胶质瘤2例,胶质母细胞瘤1例,淋巴瘤1例,脑梗死6例,神经源性肿瘤1例,室管膜瘤1例。对患者行3.0MR常规T1WI、T2WI、FLAIR和病变部位8相位ASL扫描。计算第1、5、8相位病变部位相对脑血流量值(rCBF),对病变的灌注情况进行分析。结果出血性脑梗死病例早、中、晚期均表现为高灌注。常规扫描双侧枕叶未发现明显异常病例,ASL显示右侧枕叶出现低灌注。急性或亚急性梗死患者和脑软化患者三期均表现为低灌注。其余脑梗死患者不同时相高、低灌注情况均出现。脑肿瘤病例中,部分肿瘤早、中、晚期灌注状态一致,如胶质瘤和部分脑膜瘤病例。部分肿瘤不同时相显示不同的灌注状态。结论本研究表明评估脑内病变的灌注情况具有时间依赖性。多相位ASL对于早期诊断脑缺血性疾病,评估脑梗死后的再灌注有独特的优势。     

Usefulness of 99mTc-ECD SPECT in diseases of the central nerve system: special reference to a comparison with 123I-IMP and 99mTc-HM-PAO SPECT]

The usefulness of a new cerebral perfusion imaging radiopharmaceutical, 99mTc-ethyl cysteinate dimer (ECD), was clinically evaluated. The subjects of this study were 14 patients with neurological disorders including 10 patients with cerebral infarction and 4 patients with other diseases. A total of 15 examinations was performed. 99mTc-HM-PAO or 123I-IMP SPECTs were performed simultaneously, and the findings from those examinations were compared with 99mTc-ECD. As to the count ratio of lesions to normal area (L/N), the L/N ratio in severe ischemic patients was lower in 99mTc-ECD than in 99mTc-HM-PAO or 123I-IMP. In mild ischemic patients, on the other hand, the L/N ratio was the lowest in 123I-IMP. When the relationship between rCBFs obtained from 123I-IMP and the values of L/N in 99mTc-ECD or 99mTc-HM-PAO was compared, the values of L/N in 99mTc-ECD or 99mTc-HM-PAO were found to have decreased linearity with increasing rCBF. In a patient showing luxury perfusion, the accumulation pattern of 99mTc-ECD was different from that of the other two radiopharmaceuticals, and focal defect was revealed in 99mTc-ECD SPECT. On the dynamic SPECT of 99mTc-ECD in a patient with meningioma, the tumor showed a change from high to low perfusion with the passage of time. This finding indicated that care should be taken in the evaluation of accumulation of 99mTc-ECD. Therefore, 99mTc-ECD was found to be useful as a cerebral perfusion agent. In addition, as accumulation of 99mTc-ECD might somehow reflect metabolism in some cases, further careful investigation of many cases should be carried out.     

Parametric imaging of cerebral vascular reserves

We describe the theoretical basis and practical details of a method for creating parametric images of the ratio of regional cerebral blood flow (rCBF) to volume (rCBV) from planar gamma-camera images following intravenous injection of any intravascular tracer and after correction for dispersion of the bolus before it arrives at the head. This ratio, which is the most sensitive index of the extent to which perfusion is being maintained by vasodilatation in patients with cerebro-vascular disease, indicates whether the limits of compensation have been, or are in danger of being, exceeded and identifies any ischaemic penumbra. Evidence is provided of the validity of the correction and the accuracy of calculation of the ratio. The range of normal values established is not significantly different from that previously reported using positron emission tomography. This technique has proved sufficiently sensitive to be clinically useful in patients with abnormalities of cerebral perfusion.     

Morphologic (CT) and functional (rCBF-SPECT) correlates in Alzheimer's disease.

Thirty-five patients with a clinical diagnosis of probable Alzheimer's disease underwent computed tomography (CT) and regional cerebral blood flow (rCBF) studies using single photon emission computed tomography (SPECT). Two sets of images in each subject were scored for the extent of structure and function changes. Thirty-four of 35 patients had various degrees of atrophy on CT, 33 of whom also had perfusion deficits of varying severity. One patient with normal CT had perfusion deficits, and another patient with a normal perfusion pattern had changes on CT. Regional perfusion deficits on SPECT were seen with and without associated changes on CT. Correlations were studied between CT and SPECT scores using Spearman's rank correlation coefficients. While regional scores on CT and SPECT did not significantly correlate, the total and left hemisphere scores on two sets of images showed fair correlations (r = 0.425 and r = 0.535, respectively, P less than 0.01). The correlations between cognitive performance in patients as assessed on Mini-Mental State Examination (MMSE) and CAM-COG and perfusion scores were highly significant while CT scores showed lower correlations. These findings suggest that the relationship between structural and functional changes in Alzheimer's disease is not straightforward and that the extent of changes in function as assessed by regional cerebral blood flow studies is a reliable measure of deficits in cognitive function.     

128层4D CT全肝灌注成像在肝细胞癌中的初步应用

目的:探讨128层4D CT全肝灌注成像在原发性肝癌(HCC)灌注中的参数特征及其初步临床应用价值。方法:对20例正常对照组、40例经临床或手术病理证实为HCC的患者行128层4D CT灌注扫描,获得灌注参数血流量(BF)、肝动脉灌注量(ALP)、门静脉灌注量(PVP)、肝动脉灌注指数(HAPI)。根据各灌注图像及相关参数评价正常组织与恶性肿瘤、高分化HCC与低分化HCC的血流动力学状态。同时获得270mm扫描覆盖范围内动态4D CTA图像,动态观察对比剂流入及流出情况,判断肿瘤供血动脉的增粗、僵直、门静脉癌栓等。结果:①HCC患者ALP、HAPI、BF明显高于正常组(P<0.01),PVP明显降低(P<0.01)。②高分化HCC患者灌注参数ALP、HAPI低于低分化HCC,PVP明显升高,二者差异有统计学意义(P<0.01)。灌注参数从一方面反映了肿瘤的恶性程度。③40例HCC中,4D CTA显示肿瘤供血动脉25例,13例供血动脉增粗、僵直,门静脉癌栓15例。结论:128层4D CT灌注成像可以通过一次注射对比剂,获得全肝灌注信息及动态的4DCTA,肝灌注模式成像克服了以往灌注成像的不足,简单实用,具有一定的优势。此技术能很好地反映HCC的血流动力学变化,为HCC的早期诊断、指导临床治疗及判断预后提供可靠的依据,具有重要的临床应用价值和广阔的应用前景。     

Significance of the perfusion-diffusion mismatch in chronic cerebral ischemia

PURPOSE: To determine whether the perfusion deficit could predict brain infarction in patients with chronic cerebral ischemia who experienced recurring episodes of neurological symptoms and showed a perfusion-diffusion mismatch on magnetic resonance (MR) images. MATERIALS AND METHODS: In 53 consecutive patients (38 males and 15 females, 62+/-13 years old) with ischemia in the middle cerebral artery (MCA) territory, lesion volumetry was performed on parametric maps of the time-to-peak, the cerebral blood volume, and diffusion-weighted (DW) images. The infarct lesions were assessed on follow-up T2-weighted (T2W) MR images after eight days. Cerebrovascular changes were determined by time-of-flight (TOF) MR angiography (MRA). Inferential and correlation statistics were used. RESULTS: Patients with chronic ischemic brain disease (N=39) who presented with a severe perfusion-diffusion mismatch in the presence of a normal cerebral blood volume had no or small brain infarctions as found on follow-up T2W images. MRA revealed widespread abnormalities of the basal cerebral arteries compatible with brain perfusion abnormalities. In contrast, in acute stroke patients (N=14) the deficit of cerebral perfusion predicted the infarct lesion in the T2W images. CONCLUSION: Our results suggest that in chronic cerebral ischemia the normal blood volume was maintained despite the depression of cerebral perfusion and recurring minor insults.     

超顺磁性氧化铁灌注T_2WI诊断超急性脑缺血的实验研究

目的观察国产超顺磁性氧化铁（ＳＰＩＯ）灌注Ｔ２ＷＩ诊断超急性期脑缺血的可行性。方法正常大鼠５只和右侧大脑中动脉闭塞（ＭＣＡＯ）大鼠２６只,行ＳＰＩＯ灌注前后Ｔ２ＷＩ,后者在ＭＣＡＯ后４０～５０分钟行ＭＲ检查。ＭＲ检查后４只行墨汁灌注检查,６只在ＭＣＡＯ后２４小时行ＭＲ复查和病理检查。ＳＰＩＯＩ颗粒直径２０ｎｍ、ＳＰＩＯＩ颗粒直径６～９ｎｍ,剂量为０６ｍｍｏｌ／ｋｇ。采用ＳＰＩＯＩ做了６只、ＳＰＩＯＩ做了２０只灌注检查。结果在ＭＣＡＯ后５０分钟,平扫Ｔ２ＷＩ仅３７％表现右侧大脑中动脉（ＭＣＡ）供血区信号稍高;两种型号的ＳＰＩＯ灌注后１００％或８０％的右侧ＭＣＡ供血区呈相对高信号,与墨汁灌注检查的灌注缺损区及ＭＣＡＯ后２４小时复查Ｔ２ＷＩ的高信号范围一致。病理检查证实右侧ＭＣＡ供血区的缺血、梗死。在剂量相同情况下,ＳＰＩＯＩ灌注Ｔ２ＷＩ显示缺血区与非缺血区的对比度明显高于ＳＰＩＯＩ。结论ＳＰＩＯ相当于一种阴性造影剂,国产ＳＰＩＯ“灌注”常规Ｔ２ＷＩ可以诊断血管闭塞５０分钟的急性脑缺血,ＳＰＩＯＩ灌注的诊断效果优于ＳＰＩＯＩ。