SPECT/CT脑血流灌注显像的临床应用进展

SPECT/CT脑血流灌注显像是SPECT(单光子发射计算机断层显像)技术和CT(计算机断层扫描技术)同机融合的一种检查方法,能够将解剖显像与功能显像完美的结合在一起,提高定位准确率的同时还可以对疾病进行多角度的分析,兼具了SPECT灵敏度高和CT特异性、分辨率高的优点,因此,对很多疾病如脑梗、TIA、癫痫等缺血性病变的病灶定位、治疗指导和预后评估以及正常脑功能的研究有着独特的优势.本文结合国内外资料对SPECT/CT脑血流灌注显像的原理、技术和临床应用的进展进行综述.     

Persistent pain inhibits contralateral somatosensory cortical activity in humans

To assess cortical activity during pain perception, regional cerebral blood flow (rCBF) studies were done in humans using single photon emission computed tomography (SPECT) with the radiotracer Tc99m-HMPAO and magnetic resonance imaging localization. Normalized SPECT data were analyzed by region of interest and change distribution. Contralateral somatosensory rCBF was decreased when the digits of the hand were immersed in a hot water bath for 3 min which was rated as moderately painful (persistent pain). No decrease was observed when the hand was immersed in tepid water (control). In contrast, cortical rCBF was increased during vibratory and sensorimotor tasks, in the contralateral somatosensory and sensorimotor areas, respectively. These results indicate that pain perception in man is associated with somatosensory cortical inhibition.     

Contributing factors to changes of cerebral blood flow in major depressive disorder

BACKGROUND: Results of single photon emission computed tomography (SPECT) regarding mood disorders have been inconsistent. The aim of the study was to elucidate factors contributing to changes in cerebral blood flow in patients with major depressive disorder. METHODS: A total of 89 consecutive patients diagnosed with major depressive disorder using DSM-IV semistructured interviews were evaluated using single photon emission computed tomography, the 17-item Hamilton Rating Scale for Depression (HRSD), and the Global Assessment of Function (GAF) scale. Nineteen of these patients also underwent the same tests during remission. RESULTS: Global cerebral blood flow (gCBF) was significantly higher during remission than at the time of enrollment. Significant correlations were seen between gCBF and age, duration of previous episode of depression, and hypochondriasis. However, no correlation was seen between gCBF and HRSD, GAF, severity and duration of depressive episode, or melancholia-type depression. Correlations between gCBF and age were seen only at enrollment and disappeared during remission. No differences in regional cerebral blood flow at any site were seen between time of enrollment and remission for the same patient. LIMITATION: Analysis that adequately accounts for these factors to changes of cerebral blood flow in major depressive disorder will require a large subject population. CONCLUSIONS: These results suggest that although there is a decrease in gCBF in major depressive disorder, the level of the decrease is determined by conditions present before episode onset, rather than by the characteristics of the episode itself. The findings also suggest that the correlation between gCBF and age is state-dependent.     

Cold-induced reversible brain ischemia in mixed connective tissue disease, a case report]

A 19-year-old woman with long-standing mixed connective tissue disease was admitted for dizziness. We examined cerebral blood flow quantitation using 99mTc-hexamethylpropyleneamine oxime (HMPAO) and single photon emission computed tomography (SPECT) at rest and after cold pressor test. Mean cerebral blood flow reduced remarkably when she complained dizziness and showed peripheral Raynaud's phenomenon after cold exposure. We concluded cold-induced reversible brain ischemia was the reason of dizziness. Our finding suggests brain Raynaud's phenomenon. Further studies are necessary to clarify this phenomenon.     

精神分裂症患者的脑功能显像与神经心理测验的相关研究

本研究应用单光子发射断层摄影术（ＳＰＥＣＴ）、ＨＲ成套神经心理测验（成人）修订本［ＨＲＢ（Ａ）－ＲＣ］和修订韦氏记忆测验（ＷＭＳ－ＲＣ）对３２例住院精神分裂症患者的脑功能改变及脑功能显像与神经心理测验之关系进行探讨。结果显示，精神分裂症患者存在额叶、颞叶和基底节的脑血灌流量降低，同时表现程度不同的神经心理功能损害，此改变在阴性症状和阳性症状的病人间无差异。脑血灌流量降低与损伤指数（ＤＱ）和记忆商数（ＭＱ）未见明显关系。相关分析表明，ＤＱ与ＴＥＳＳ评分呈显著正相关（ｒ＝０．３６，Ｐ＜０．０５）；ＭＱ与住院次数（ｒ＝－０．４２，Ｐ＜０．０５）、ＢＰＲＳ评分（ｒ＝－０．５６，Ｐ＜０．０１）、ＳＡＰＳ评分（ｒ＝－０．３９，Ｐ＜０．０５）和ＳＡＮ评分（ｒ＝－０．３７，Ｐ＜０．０５）呈显著负相关，与ＧＡＳ评分（ｒ＝０．５３，Ｐ＜０．０１）呈显著正相关     

阻塞性睡眠呼吸暂停的脑血流灌注成像研究进展

阻塞性睡眠呼吸暂停（OSA）是一种常见的睡眠呼吸障碍,可致局部脑血流量改变,脑血流灌注成像对于评估OSA严重程度及预后进展具有重要意义。目前应用于评估OSA患者脑血流灌注的成像技术主要包括单光子发射计算机断层显像、磁共振脑血流灌注成像等。本研究旨在对脑血流灌注成像技术在OSA的研究进展进行综述,客观分析各脑血流灌注技术的优势和局限,以期提高各技术在OSA的早期筛查、评价疾病严重程度以及预后进展的临床适用性,并展望未来研究方向和提出目前潜在的挑战。     

Neuroimaging insights into the pathophysiology of sleep disorders

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modem neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans.     

Rodent brain imaging with SPECT/CT

We evaluated methods of imaging rat models of stroke in vivo using a single photon emission computed tomography (SPECT) system dedicated to small animal imaging (X-SPECT, Gamma Medica-Ideas, Northridge, CA). An animal model of ischemic stroke was developed for in vivo SPECT/CT imaging using the middle cerebral artery occlusion (MCAO) technique. The presence of cerebral ischemia was verified in ex vivo studies using triphenyltetrazolium chloride (TTC) staining. In vivo radionuclide imaging of cerebral blood flow was performed in rats following MCAO using dynamic planar imaging of 99mTc-exametazime with parallel hole collimation. This was followed immediately by in vivo radionuclide imaging of cerebral blood flow with 99mTc-exametazime in the same animals using 1-mm pinhole SPECT. Correlated computed tomography imaging was performed to localize radiopharmaceutical uptake. The animals were allowed to recover and ex vivo autoradiography was performed with separate administration of 99mTc-exametazime. Time activity curve of 99mTc-exametazime showed that the radiopharmaceutical uptake could be maintained for over 9 min. The activity would be expected to be relatively stable for a much longer period, although the data were only obtained for 9 min. TTC staining revealed sizable infarcts by visual observation of inexistence of TTC stain in infracted tissues of MCAO rat brains. In vivo SPECT imaging showed cerebral blood flow deficit in the MCAO model, and the in vivo imaging result was confirmed with ex vivo autoradiography. We have demonstrated a capability of imaging regions of cerebral blood flow deficit in MCAO rat brains in vivo using a pinhole SPECT dedicated to small animal imaging.     

Impact of acute hypobaric hypoxia on blood flow distribution in brain

Aim: Acute hypobaric hypoxia is well known to alter brain circulation and to cause neuropsychological impairment. However, very few studies have examined the regional changes occurring in the brain during acute exposure to extreme hypoxic conditions. Methods: Regional cerebral blood flow (rCBF) response to hypoxia was investigated in six healthy subjects exposed to either normobaric normoxia or hypobaric hypoxia with ambient pressure/inspired oxygen pressure of 101/21 kPa and 50/11 kPa respectively. After 40 min at the desired pressure they were injected ^99mTc‐HMPAO and subsequently underwent single photon emission computed tomography. Regional cerebral blood flow distribution changes in the whole brain were assessed by Statistical Parametric Mapping, a well established voxel‐based analysis method. Results: Hypobaric hypoxia increased rCBF distribution in sensorymotor and prefrontal cortices and in central structures. PCO₂ correlated positively and SatO₂ negatively with rCBF in several temporal, parahippocampal, parietal and central structures. Conclusions: These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.     

Assessment of regional cerebral blood flow (rCBF) in ischemic stroke using Tc-99m HMPAO SPECT--comparison with CT and MR findings

To assess the regional cerebral blood flow (rCBF) in ischemic stroke, we analyzed the findings of single photon emission computed tomography (SPECT) using technetium-99m hexamethyl propyleneamine oxime (Tc-99m HMPAO). The SPECT images revealed abnormal areas of decreased perfusion in 29 out of 31 subjects (93.5%), which represented a higher detection rate than those for CT and MR (89.5%, respectively). Also, the areas of decreased perfusion were frequently larger than the lesions on CT and MR. Areas of decreased perfusion remote from the CT/MR lesions were found in 10 patients, including 8 with crossed cerebellar diaschisis (CCD). Thus, studies of rCBF by Tc-99m HMPAO SPECT can be useful in the assessment of ischemic stroke.     

Brain imaging studies of cocaine abuse: implications for medication development

Contemporary in vivo brain imaging techniques confer the ability to assess brain function and structure noninvasively, and thereby can yield information to help guide the development of new treatments for substance abuse. The advantages and limitations of the major imaging modalities (positron emission tomography [PET], single photon emission computed tomography [SPECT], structural and functional magnetic resonance imaging [MRI, fMRI, respectively]) are discussed with respect to their applicability to research on cocaine abuse. The effects of acute administration of cocaine have been studied using PET and fMRI, with PET manifesting decreases in cerebral glucose metabolism and blood flow, and fMRI revealing regional effects that are correlated temporally with subjective responses. In addition, studies of drug abusers, abstinent from cocaine for various lengths of time, have revealed persistent differences in brain function and structure, especially in the frontal cortex, when compared with parameters in the brains of subjects who do not use illicit drugs of abuse. PET studies also have revealed abnormalities in markers for dopaminergic and opioid systems during withdrawal from cocaine. Moreover, studies of cue-elicited craving for cocaine demonstrate a connection between the response to drug-related stimuli and neural elements of cognition and emotion. The future directions of in vivo brain imaging to identify functional and structural alterations in the brains of cocaine abusers are discussed in relation to the development of medications to treat cocaine dependence.     

功能成像及其在肺癌放疗中的应用研究

功能成像在现在的放疗计划设计中具有十分重要的作用,在放疗中如何利用肺通气和灌注信息更好的保护肺功能已经引起了越来越多的关注。本文概述了一些用来评价肺通气和灌注水平的技术,包括单光子发射计算机断层扫描(SPECT)、正电子发射计算机断层扫描(PET)、磁共振成像(MRI)及计算机断层显像(CT)。这些技术都可以应用到肺癌患者的放疗计划设计中,在给予肿瘤足够治疗剂量的同时更好的保护具有正常功能的肺组织。文中分别对各种评价技术的临床应用方法进行了介绍。这些技术都具有各自不同的特点,其中4D-CT的发展最具前景,因此文中特别概述了在4D-CT中利用变形图像配准产生三维通气图像的技术。各种肺功能成像在图像引导放疗中的临床应用也在文中进行了概述。在所有肺功能成像技术中,4-D CT操作简便,空间分辨率高,因此具有更加广泛的应用价值。     

Hyperbaric oxygen therapy may improve symptoms in autistic children

Autism is a neurodevelopmental disorder that currently affects as many as 1 out of 166 children in the United States. Recent research has discovered that some autistic individuals have decreased cerebral perfusion, evidence of neuroinflammation, and increased markers of oxidative stress. Multiple independent single photon emission computed tomography (SPECT) and positron emission tomography (PET) research studies have revealed hypoperfusion to several areas of the autistic brain, most notably the temporal regions and areas specifically related to language comprehension and auditory processing. Several studies show that diminished blood flow to these areas correlates with many of the clinical features associated with autism including repetitive, self-stimulatory and stereotypical behaviors, and impairments in communication, sensory perception, and social interaction. Hyperbaric oxygen therapy (HBOT) has been used with clinical success in several cerebral hypoperfusion syndromes including cerebral palsy, fetal alcohol syndrome, closed head injury, and stroke. HBOT can compensate for decreased blood flow by increasing the oxygen content of plasma and body tissues and can even normalize oxygen levels in ischemic tissue. In addition, animal studies have shown that HBOT has potent anti-inflammatory effects and reduces oxidative stress. Furthermore, recent evidence demonstrates that HBOT mobilizes stem cells from human bone marrow, which may aid recovery in neurodegenerative diseases. Based upon these findings, it is hypothesized that HBOT will improve symptoms in autistic individuals. A retrospective case series is presented that supports this hypothesis.     

阴性精神分裂症患者局部脑血流与威斯康星卡片分类测验的相关分析

目的：为探讨阴性精神分裂症患者脑结构与认知功能缺陷的关系。方法：运用单光子发射计算机断层扫描（ＳＰＥＣＴ），测定了１２例阴性精神分裂症患者在安静状态与威斯康星卡片分类测验的负荷状态下的局部脑血流。结果：在安静状态下阴性精神分裂症病人的脑局部放射性分布是对称的，但在威斯康星卡片分类测验的刺激状态下左、右侧额叶的局部脑放射性计数是不对称的。结论：提示精神分裂症的阴性症状与左侧额叶的功能状态有关。     

Reduced temporal lobe blood flow in Alzheimer's disease.

We used single photon emission computed tomography with the blood flow tracer [123I]N-isopropyl-p-iodoamphetamine (IMP) to study regional cerebral blood flow (rCBF) in 50 mildly and moderately demented Alzheimer's disease (AD) patients to evaluate rCBF as a function of disease severity. Relative rCBF (normalized to occipital cortex) was significantly lower than controls in temporal cortex for both mildly and moderately demented patients. Similar numbers of patients in both groups demonstrated perfusion abnormalities in temporal neocortex. Parietal cortex was more variably involved with greater numbers of moderately than mildly demented patients showing perfusion abnormalities. Relative rCBF in dirsolateral frontal cortex was reduced only in the moderately demented patients. Disease severity, as measured by the Mini Mental Status Examination, was associated with relative rCBF only in dorsolateral frontal and parietal cortex. These results suggest that the temporal lobes are the first neocortical regions affected by AD and that other cortical areas become involved as the disease progresses.     

Technetium-99m HM-PAO SPECT in patients with delayed neurologic sequelae after carbon monoxide poisoning.

We used single photon emission computed tomography (SPECT) with technetium-99m hexamethylpropylene amine oxime (99mTc-HM-PAO) in 14 studies on 6 patients with delayed neurologic sequelae from carbon monoxide (CO) poisoning to determine whether any changes in cerebral blood flow could be correlated with clinical or computed tomographic evidence of delayed deficits. Among the six initial CT brain scans, two showed low density of both basal ganglia and two showed decreased density of the cerebral white matter. There was no correlation between the clinical outcome and the findings of the follow-up CT brain scans. Of the two SPECTS with 99mTc-HM-PAO performed during acute anoxic insult, one showed focal hypoperfusion which appeared 20 days prior to the onset of delayed neurologic sequelae after CO poisoning. Seven SPECTs in the six patients performing the delayed phase showed diffuse patched patterns of hypoperfusion which improved on follow-up images. There was good correlation between the clinical outcome and the findings of the 99mTc-HM-PAO SPECT. In preliminary conclusion, 9Tc-HM-PAO brain SPECT can be used for predicting or evaluating the outcome of delayed neurologic sequelae after CO poisoning. Cerebral vascular changes may be the possible cause of hypoperfusion in patients with CO poisoning.     

SPECT显像在NPC放疗后所致脑损伤中的初步应用

目的 评价单光子发射型电子计算机断层（ＳＰＥＣＴ）脑血流灌注显像在鼻咽癌（ＮＰＣ）放射治疗后放射性脑损伤中的临床价值。方法 采用ＳＰＥＣＴ脑血流灌注显像检查,对１６例鼻咽癌放射治疗后有放射性脑损伤症状的患者和８例示经放疗的鼻咽癌患者作半定时分析对测量结果作统计学分析。１６例放射性脑损伤患者同期做电子计算机体层检查（ＣＴ）对比。结果 １６例有放射性脑损伤症状的鼻咽癌患者双侧颞叶局部脑血流灌注（ｒＣＢＦ）在横断面层面－放射性曲线相应部位上可见局部放射性下降峰或曲线变窄小,峰值降低,其曲线局部下降峰值与鼻咽癌放疗效量的生物效应剂量（ＢＥＤ）值呈正相关（ｒ＝０．８９７６,Ｐ〈０．０１）。８例未经放疗的鼻咽癌患者,在横断面图像上其双侧颞叶局部脑血流灌注的层面－放射性曲线大致呈正态分布曲线,未见异常的局部下降峰或曲线变窄小     

Episodic diencephalic hypoperfusion in Kleine-Levin syndrome

A 22 year-old woman suffered from recurrent episodes of hypersomnia, apathy, and hyperphagia. The symptoms occurred 3 to 4 times per year, and each attack lasted 2 to 3 weeks. 99mTc-ethylcysteinate dimer brain single photon emission computed tomography (SPECT) was performed during symptomatic and asymptomatic periods. To localize brain regions with perfusion changes during symptomatic period, asymptomatic SPECT was subtracted from symptomatic SPECT. The subtracted SPECT showed significant hypoperfusion in the left hypothalamus, bilateral thalami, basal ganglia, bilateral medial and dorsolateral frontal regions, and left temporal lobe during the symptomatic period. These cerebral hypoperfusion areas support the diencephalic hypothesis and clinical symptoms of Kleine-Levin syndrome.     

What predicts cognitive decline in de novo Parkinson's disease?

Subtle cognitive impairment can be detected in early Parkinson's disease (PD). In a consecutive series of de novo, drug-naive PD patients, we applied stepwise regression analysis to assess which clinical, neuropsychological, and functional neuroimaging (dopamine transporter [DAT] and perfusion single photon emission computed tomography [SPECT]) characteristics at baseline was predictive of cognitive decline during an average follow-up time of about 4 years. Decline both in executive (R(2) = 0.54; p = 0.0001) and visuospatial (R(2) = 0.56; p = 0.0001) functions was predicted by the couple of Unified Parkinson's Disease Rating Scale (UPDRS)-III score and caudate dopamine transporter (DAT) uptake in the less affected hemisphere (LAH). Verbal memory and language decline was predicted instead by caudate DAT uptake and brain perfusion in a posterior parieto-temporal area of the less affected hemisphere (R(2) = 0.42; p = 0.0005). No significant effect was shown for age, baseline neuropsychological scores, and levodopa equivalent dose at follow-up. The combined use of clinical structured examination and brain functional assessment by means of dual single photon emission computed tomography imaging appears as a powerful approach to predict cognitive decline in de novo PD patients.     

Imaging markers of mild cognitive impairment: multivariate analysis of CBF SPECT

This study aimed to investigate cross-sectional and longitudinal changes of regional cerebral blood flow (rCBF) in preclinical dementia using single photon emission computed tomography (SPECT). SPECT and cognitive function were investigated in 39 mild cognitive impairment (MCI) subjects and 20 age-matched controls. All subjects were followed longitudinally 19 months on average, 16 MCI subjects progressed to Alzheimer's disease (AD), who were retrospectively defined as progressive mild cognitive impairment (PMCI) at baseline and 23 MCI subjects remained stable and were defined as stable mild cognitive impairment (SMCI) at baseline. SPECT was performed both at the initial investigation and at follow-up. Image data were analyzed using multivariate analysis, SPM and volume of interest (VOI)-based analysis. Significant covariate patterns were derived, which differentiate among PMCI, SMCI and controls at baseline as well as describe the longitudinal progression of PMCI. The combined SPECT and neuropsychology increased the diagnostic accuracy of PMCI at baseline. SPECT and neuropsychological testing can be used objectively for both baseline diagnosis and to monitor changes in brain function during very early AD.