Functional interactions between entorhinal cortex and posterior cingulate cortex at the very early stage of Alzheimer's disease using brain perfusion single-photon emission computed tomography

OBJECTIVE: The cause of the reduced regional cerebral blood flow (rCBF) in the posterior cingulate cortex in the early stage of Alzheimer's disease has not been clarified. In Alzheimer's disease, the posterior cingulate cortex itself shows little neuropathologic degeneration, and a hypothesis explaining such a discrepancy is that the functional impairment in the posterior cingulate cortex reflects remote effects caused by degeneration in distant but connected areas, such as the entorhinal cortex. To test the hypothesis, we investigated the functional connectivity between the entorhinal cortex and posterior cingulate cortex. METHODS: Sixty-one patients with probable Alzheimer's disease at a very early stage and 61 age-matched healthy controls underwent both brain structural magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT). Voxel-based morphometry was performed on MRI data to identify clusters of significantly reduced grey matter concentration in patients with Alzheimer's disease relative to controls, which were set as volumes of interest (VOIs) for correlation analyses of SPECT images. We then used adjusted rCBF values in the VOIs as covariates of interest in statistical parametric mapping. RESULTS: Voxel-based morphometry demonstrated a significant reduction in grey matter concentration in the bilateral entorhinal cortex in Alzheimer's disease. A positive correlation between rCBF in the entorhinal cortex as VOI and that in the limbic and paralimbic systems, including the posterior cingulate cortex, anterior cingulate cortex, lingual gyri and left middle temporal gyrus (P<0.001), was observed in Alzheimer's disease. Control subjects also showed a similar correlation in the limbic and paralimbic systems, but not in the posterior cingulate cortex. CONCLUSION: These results indicate that rCBF changes in the posterior cingulate cortex may be closely related to those in the entorhinal cortex in patients with Alzheimer's disease, thereby supporting the 'remote effect' hypothesis.     

Evaluating dopamine transporter activity with 99mTc-TRODAT-1 SPECT in drug-naive Tourette's adults

OBJECTIVES: Findings on imaging of dopamine transporter (DAT) activity in patients with Tourette's syndrome remain inconclusive. The present study was carried out to observe DAT activity in patients with well-controlled Tourette's syndrome by using (99m)Tc-TRODAT-1 single photon emission computerized tomography (SPECT). METHODS: Six drug-naive patients with Tourette's syndrome (mean age+/-SD, 21.2+/-1.5 years) were recruited. All met the criteria for Tourette's syndrome established in the DSM-IV. Seventeen age-matched and sex-matched healthy subjects served as the controls. Brain SPECT were acquired 165-195 min after administrating 740 MBq of (99m)Tc-TRODAT-1, using a double-headed camera equipped with ultra-high-resolution fan-beam collimators. The specific uptake ratio was calculated by subtracting the mean counts per pixel in the occipital cortex from the mean counts per pixel in the striatum, putamen or caudate nucleus and by dividing the result by the mean counts per pixel in the occipital cortex. Tic-severity scores were also measured and correlated with the specific uptake ratios. RESULTS: No significant difference in DAT activity between patients with Tourette's syndrome and control subjects was found in the striatum and its sub-regions. Tic-severity scores were also not correlated with specific uptake ratios measured from the striatum and its sub-regions. CONCLUSIONS: In conjunction with previous findings, our results suggested that functional abnormality of the dopamine system in patients with Tourette's syndrome might be evident only in its early stage. Adaptation to tic symptoms might play a role in regulating the neural system.     

Comparison of cardiac to hepatic uptake of 99mTc-tetrofosmin with and without adenosine infusion to predict the presence of haemodynamically significant coronary artery disease

BACKGROUND: Coronary artery disease impairs cardiac vasodilatory reserve. A low ratio of cardiac to hepatic vasodilatory reserve may be diagnostic for coronary artery disease. AIM: To compare the ratio of cardiac to hepatic uptake of 99mTc-tetrofosmin during adenosine infusion and at rest in patients with and without coronary artery disease in order to determine whether the ratio was significantly different between the two groups. METHODS: Fifty-one patients who underwent coronary angiography and adenosine stress myocardial perfusion imaging using 99mTc-tetrofosmin were studied retrospectively. Anterior planar images from the single photon emission computed tomography (SPECT) raw data were used to draw regions of interest around the heart and liver. The counts per pixel in each region were used to calculate the stress ratio (SR) and the rest ratio (RR) as follows: SR = (cardiac counts per pixel)at stress/(hepatic counts per pixel)at stress; RR = (cardiac counts per pixel)at rest/(hepatic counts per pixel)at rest. The SR and SR/RR ratios were compared in patients with and without significant coronary artery disease. Receiver operating characteristic curves were drawn for SR and SR/RR. RESULTS: The SR and SR/RR ratios were significantly lower in patients with significant coronary artery disease than in patients without (P<0.001). A cut-off ratio of SR/RR = 1.00 yielded 87% sensitivity and 74% specificity for the detection of significant coronary artery disease. Combining SR/RR with standard SPECT image interpretation increased the sensitivity without substantially changing the specificity in comparison with standard SPECT image interpretation only. CONCLUSION: Comparison of cardiac to hepatic 99mTc-tetrofosmin concentration at rest and under adenosine stress provides useful diagnostic information for the assessment of the presence of significant coronary artery disease.     

~(18)F-FDGPET显像诊断老年性痴呆初步研究

目的　探讨18F 脱氧葡萄糖 (FDG)PET显像诊断老年性痴呆 (AD)的影像特征和诊断标准。方法　静脉注射18F FDG后行脑断层显像 ,获得顶叶、颞叶、额叶单位面积放射性计数与小脑计数的比值 ,以此作为半定量指标。结果　 12例正常人可见大脑皮质各叶、基底神经节、丘脑及小脑放射性分布均匀对称。 12例AD影像分为 3种 :双侧顶叶放射性减低 5例 ,双侧颞顶叶减低 4例 ,单侧颞顶叶减低 3例。半定量分析显示AD患者顶颞叶代谢显著低于正常人 ,并与痴呆程度相关。 11例非AD痴呆影像也分 3种 :多发性非对称性放射性减低 8例 ,双侧颞顶叶伴其他多灶性放射性减低 2例 ,显像正常 1例。MRI检查 10例AD可见颞叶、杏仁核、海马体积缩小 ;2例轻度AD虽有代谢减低 ,但MRI未见海马体积缩小。 10例非AD痴呆MRI可见脑内陈旧出血、梗死、软化灶等病灶 ,而这些表现AD患者未见到。结论　在MRI除外脑内结构损害病灶基础上 ,18F FDGPET发现双侧或单侧顶叶或颞顶叶代谢减低可诊断AD ;半定量分析有助于痴呆程度的评价。     

Can dynamic susceptibility contrast magnetic resonance imaging replace single-photon emission computed tomography in the diagnosis of patients with Alzheimer's disease? A pilot study

Purpose: To compare single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer's disease (AD).

Material and Methods: Twenty-four patients, eight with AD, 10 with MCI, and six controls were investigated with SPECT using ^99mTc-hexamethylpropyleneamine oxime (HMPAO) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with gadobutrol. Three observers performed a visual interpretation of the SPECT and MR images using a four-point visual scale.

Results: SPECT was superior to DSC-MRI in differentiating normal from pathological. All three observers showed statistically significant results in discriminating between the control group, AD, and MCI by SPECT, with a P value of 0.0006, 0.04, and 0.01 for each observer. The statistical results were not significant for MR (P values 0.8, 0.1, and 0.2, respectively).

Conclusion: DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer's disease. Several patient- and method-related improvements should be made before this method can be recommended for clinical practice.     

Differential diagnosis of bilateral parietal abnormalities in I-123 IMP SPECT imaging

This report discusses the clinical significance of bilateral parietal abnormalities on I-123 IMP SPECT imaging in 158 patients with cerebral disorders. This pattern was seen in 15 out of 21 patients with Alzheimer's disease; it was also seen in 4 out of 5 patients with Parkinson's disease with dementia, in 3 out of 17 patients with vascular dementia, in 1 out of 36 patients with cerebral infarction without dementia, in 1 out of 2 patients with hypoglycemia, and in 1 out of 2 patients with CO intoxication. Detection of bilateral parietal abnormalities is a useful finding in the diagnosis of Alzheimer's disease, but one should keep in mind that other cerebral disorders may also show a similar pattern with I-123 IMP SPECT imaging.     

N-isopropyl I-123 p-iodoamphetamine (IMP) brain SPECT in Alzheimer's disease

Eighteen patients with Alzheimer's disease (AD), 5 patients with Pick disease (PD), 6 patients with other types of degenerative dementia (O) and 12 age-matched normal control subjects (N) were studied using N-isopropyl p-[I-123]iodoamphetamine (I-123 IMP) with SPECT. Regional to cerebellar activity (R/CE) ratio and frontal to parietal (F/P) activity ratio were evaluated in each case. I-123 IMP-SPECT revealed focal abnormality in all cases in AD, PD, O group, while XCT and/or MRI were normal or showed cerebral atrophy without focal abnormal density or intensity. In AD group, R/CE ratio in all the regions except for bilateral Rolandic area and left primary visual cortex were significantly lower (p less than 0.05 or p less than 0.01) than that in N group, and F/P ratio were significantly higher (p less than 0.01) than that in P and O group. In conclusion, I-123 IMP-SPECT is useful to detect focal perfusion abnormality in dementia and may be of value in differentiating Alzheimer's disease from dementia of non-Alzheimer type.     

Alzheimer病与轻度认知功能障碍的脑SPECT显像

目的探讨脑SPECT显像对阿尔茨海默病（AD）和轻度认知功能障碍（MCI）的早期诊断及预后判定价值。方法对33例AD、17例MCI患者和12例认知正常者进行SPECT检查及随访研究。结果AD组典型表现是双侧颞顶叶低灌注，在颞叶、顶叶、额叶、丘脑和扣带回血流灌注均明显低于MCI和认知正常组（P〈0．05）；MCI组仅在颞叶血流灌注明显低于认知正常组（P〈0．05）。不稳定型MCI组扣带回血流灌注明显低于稳定型MCI组（P〈0．05）。结论SPECT显像可为早期诊断AD和MCI提供客观评定脑功能的指标，对MCI预后判定有重要价值。     

The contribution of statistical parametric mapping in the assessment of precuneal and medial temporal lobe perfusion by 99mTc-HMPAO SPECT in mild Alzheimer's and Lewy body dementia

AIM: To assess the role of 99mTc-hexamethylpropyleneamine oxime single-photon emission computed tomography (99mTc-HMPAO SPECT) imaging of the precuneus and medial temporal lobe in the individual patient with mild Alzheimer's disease and dementia with Lewy bodies (DLB) using statistical parametric mapping and visual image interpretation. METHODS: Thirty-four patients with mild late-onset Alzheimer's disease, 20 patients with early-onset Alzheimer's disease, 15 patients with DLB and 31 healthy controls were studied. All patients fulfilled appropriate clinical criteria; the DLB patients also had evidence of dopaminergic presynaptic terminal loss on 123I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl)-tropane imaging. 99mTc-HMPAO SPECT brain scans were acquired on a multidetector gamma camera and images were assessed separately by visual interpretation and with SPM99. RESULTS: Statistical parametric maps were significantly more accurate than visual image interpretation in all disease categories. In patients with mild late-onset Alzheimer's disease, statistical parametric mapping demonstrated significant hypoperfusion to the precuneus in 59% and to the medial temporal lobe in 53%. Seventy-six per cent of these patients had a defect in either location. No controls had precuneal or medial temporal lobe hypoperfusion (specificity, 100%). Statistical parametric mapping also demonstrated 73% of patients with DLB to have precuneal abnormalities, but only 6% had medial temporal lobe involvement. CONCLUSION: These findings illustrate the capability of statistical parametric mapping to demonstrate reliable abnormalities in the majority, but not all, patients with either mild Alzheimer's disease or DLB. Precuneal hypoperfusion is not specific to Alzheimer's disease and is equally likely to be found in DLB. In this study, medial temporal hypoperfusion was significantly more common in Alzheimer's disease than in DLB. Statistical parametric maps appear to be considerably more reliable than simple visual interpretation of 99mTc-HMPAO images for these regions.     

Measurement of cerebral perfusion volume and 99mTc-HMPAO uptake using SPECT in controls and patients with Alzheimer's disease

Methods for quantifying the changes in brain function observed in single photon emission computed tomography (SPECT) using hexamethylenepropylene amine oxime (HMPAO) for patients with Alzheimer's disease have the potential of improving the diagnostic accuracy of the procedure and its ability to monitor response to treatment. The absolute percentage uptake of HMPAO and the cerebral perfusion volume (CPV) of the brain were assessed using SPECT in 26 patients with mild to moderate Alzheimer's disease (AD) and 24 control subjects. A subset of 15 control subjects, which was age-matched to the AD patients, was selected to allow fair statistical comparison of parameters between groups. The percentage of brain volume with reduced perfusion (R) and a volume loss index (VLI), given by /CPV, were also calculated. Eight of the control subjects were studied on a second occasion after a mean period of 6 months. There was no significant difference in percentage uptake between controls and AD patients, the mean value being 5.8%. Cerebral perfusion volume in controls was found to depend on sex (mean value in males and females being 1327 ml and 1222 ml, respectively) and on age. The volume loss index corrected for age and sex provided good discrimination between controls and AD subjects giving a sensitivity and specificity of 81% and 96%, respectively. The repeatability coefficient, the 95% confidence limit for the difference between repeat measurements, on controls was 67 ml (5%). The measurement of cerebral perfusion volume and related indices may be of value in identifying patients with early Alzheimer's disease and in following their response to treatment.     

Longitudinal evaluation of both morphologic and functional changes in the same individuals with Alzheimer's disease.

Morphologic and functional imaging studies have not always given concordant results about brain areas showing atrophic changes and reduced flow or metabolism in Alzheimer's disease (AD). The aim of this study was to determine the initial abnormality and the longitudinal changes in both morphologic and functional measurements for the same individuals with AD. METHODS: We investigated 15 patients with mild AD and 25 age-matched healthy volunteers. The AD patients underwent both MRI and SPECT 3 times at intervals of approximately 1 y. The gray matter volume, as segmented from MRI, and the regional cerebral blood flow (rCBF), as measured by SPECT, of AD patients were compared with those of healthy volunteers using statistical parametric mapping, which is a voxel-based analysis in stereotactic space. RESULTS: Considerable discordance between areas of regional atrophy and areas of decreased rCBF was observed. The medial temporal areas showed a faster and more extensive reduction of gray matter volume than of rCBF. In comparison with the value at the baseline study, rCBF in the posterior cingulate gyrus and precuneus and the associative parietal cortex was extensively decreased. In contrast, the extent of significant decrease in this area continued to be much narrower for gray matter volume than for rCBF, even in the follow-up studies. Frontal areas, including the anterior cingulate gyrus and the orbitofrontal areas, showed a progressive reduction in both rCBF and gray matter volume. The reduction in rCBF was in a more posterior part of the associative temporal cortex than was the reduction in gray matter volume. CONCLUSION: These results indicate a distinct discordance between morphologic and functional changes in a longitudinal study of AD. Functional changes may be caused partly by remote effects from the morphologically involved areas with decreased connectivity and partly by a compensatory response by neuronal plasticity.     

Single photon tomography in Alzheimer's disease and the dementias

Measurements of brain blood flow has evolved over the past 50 years, and during the latter half of that time radionuclide techniques have been used to study this important function. Using Xenon 133 and scintillation multiprobe systems, several teams of investigators measured regional cerebral blood flow (rCBF), and noted that under many circumstances it could be equated with local brain physiological activity. The dementias were investigated using the scintillation multiprobe method, and posterior flow deficits were described in patients who were thought to have Alzheimer's disease. The multiprobe technique gave way first to planar, and then tomographic imaging, with initial favorable results achieved by positron emission tomography (PET). Soon investigators learned to measure rCBF with single-photon emission computed tomography (SPECT) using high-sensitivity systems and 133Xe as a tracer, or high-resolution systems with 123I-iodoamphetamine (IMP), and later, 99mTc-HMPAO. Three-dimensional tomographic imaging shows to advantage the flow patterns that characterize Alzheimer's disease, with rCBF reductions in temporal, parietal, and sometimes frontal areas, as opposed to randomly distributed deficits in multiinfarct dementia, reduced frontal flow in entities such as Pick's disease, and others. Herein we will review our own experience with high-sensitivity rCBF SPECT in 119 patients with dementia, and with high-resolution SPECT, using a new, three-camera scanner and 99mTc-HMPAO in an additional 39 patients. SPECT rCBF study of patients with dementia and Alzheimer's disease, will aid in separating patients with untreatable Alzheimer's from those patients who may have treatable causes of dementia, and will be useful in evaluating experimental drugs for the treatment of Alzheimer's disease.     

Dynamic susceptibility contrast MR imaging of regional cerebral blood volume in Alzheimer disease: a promising alternative to nuclear medicine.

BACKGROUND AND PURPOSEThe goal of our study was to evaluate the sensitivity and specificity for Alzheimer disease of semiquantitative dynamic susceptibility contrast (DSC) MR imaging as compared with results of qualitative single-photon emission computed tomography (SPECT) in the same patients and with previously published semiquantitative SPECT results.METHODSFifty subjects were studied: 19 patients with probable Alzheimer disease with moderate cognitive impairment, eight mildly impaired patients with possible or probable Alzheimer disease, 18 group-matched elderly healthy comparison subjects, and five elderly comparison patients with psychiatric diagnoses. Relative values of temporoparietal regional cerebral blood volume (rCBV) were measured as a percentage of cerebellar rCBV, and group classification was assessed with logistic regression. The DSC MR imaging results were compared with SPECT scans in these same subjects and with previously published semiquantitative SPECT data.RESULTSTemporoparietal rCBV ratios were reduced 20% bilaterally in the patients with Alzheimer disease. Using left and right temporoparietal rCBV as index measures, sensitivity was 95% in moderately affected patients with Alzheimer disease and 88% in patients with mild cases. Specificity was 96% in healthy comparison subjects and in psychiatric comparison subjects. Sensitivity with DSC MR imaging was considerably better than with visual clinical readings of SPECT scans (74% in moderate and 50% in mild Alzheimer disease cases), and was similar to previous published SPECT temporoparietal measurements (90%). Specificity with SPECT was 100% visually and 87% based on previous temporoparietal measurements.CONCLUSIONSDSC MR imaging of rCBV is promising as a safe, potentially lower-cost alternative to nuclear medicine imaging for the evaluation of patients with dementia.     

Comparison of I-123 IMP and Tc-99m HMPAO SPECT studies with PET in dementia

We compared I-123 IMP and 99m-Tc HMPAO SPECT studies with 0-15 H2O and F-18 FDG PET studies, and evaluated the clinical significance of SPECT studies in dementia. Seventeen patients including 9 patients with Alzheimer's disease, 3 patients with Pick's disease and 5 patients with multi-infarct dementia were studied. IMP and HMPAO SPECT studies could not detect mildly affected areas when compared with FDG PET. However, they revealed decreased perfusion in the bilateral parietal regions in Alzheimer's disease and in the bilateral frontal regions in Pick's disease, while MRI and/or CT showed mild to moderate cerebral atrophy. IMP and HMPAO SPECT studies can be easily performed in clinical practice, and these findings were useful in the differential diagnosis of dementia. Our preliminary results suggested that SPECT studies with I-123 IMP and Tc-99m HMPAO, despite their limitations, are useful in the differential diagnosis of dementia.     

脑SPECT诊断早期阿茨海默氏病的初步探讨

目的：本文旨在初步探讨脑ＳＰＥＣＴ在诊断早期阿茨海默氏病中的价值。材料和方法：采用Ｍａｙｂｅｒｇ氏的断面划分感兴趣区的方法，使用放射性药物９９ｍ锝──六甲基丙叉二胺肟（９９ｍＴｃ－ＨＭＰＡＯ），比较１８例早期阿茨海默氏病患者及１１名正常老年人脑ＳＰＥＣＴ的血流灌注显像特点。结果：早期阿茨海默氏病患者脑ＳＰＥＣＴ可见不同程度的弥漫性大脑皮质血流灌注减低，左颞叶、扣带回、左额叶的血流灌注减低与正常老年人相比有显著差异（Ｐ＜０．０５），而皮质下血流灌注则未受影响。结论：早期阿茨海默氏病患者大脑半球血流灌注为左右非对称性减低，脑ＳＰＥＣＴ的血流灌注显像有助于诊断早期阿茨海默氏病。     

Evaluation of Tourette’s syndrome by 99mTc-TRODAT-1 SPECT/CT imaging

Objective

Clinical evidence indicates that the Tourette’s syndrome (TS) is associated with hyperactivity of the dopaminergic system; however, imaging studies of dopamine transporter (DAT) in TS patients remain controversial. In this study, we aimed to study DAT binding capacities in a relatively larger sample of drug-naive patients with TS in comparison with controlled subjects by ^99mTc-TRODAT-1 SPECT/CT imaging. We also aimed to look for any possible correlations between DAT and age, disease duration or tic severity of TS, which have not been thoroughly investigated in previous studies. We tried to provide more evidence for the understanding of the physiopathological mechanism of TS from the molecular imaging perspective.

Methods

Eighteen drug-naive patients with TS and 8 age- and gender-matched healthy subjects were recruited. Severity of TS was measured with Yale Global Tic Severity Scale. Brain SPECT/CT was performed 2.5 h after injection of ^99mTc-TRODAT-1. Regions of interest were drawn on the striatum including its sub-regions of caudate and putamen. The cerebellum was used as the reference region. DAT uptake ratio was calculated by subtracting the mean counts per pixel in the cerebellum from the mean counts per pixel in the striatum, caudate or putamen and by dividing the result by the mean counts per pixel in the cerebellum. Comparisons of DAT uptake ratios between TS patients and controls, and comparisons in bilateral striatum and sub-regions in TS patients were carried out. Correlation analysis between DAT uptake ratios and clinical data were also conducted.

Results

TS patients showed significantly higher uptake of ^99mTc-TRODAT-1 in bilateral striatum in comparison with the controls. There was no group-specific preferential lateralization in striatal uptake. DAT uptake ratios were not correlated with age and tic severity scores, but significant negative correlation with disease duration was found.

Conclusions

High level of DAT was demonstrated in drug-naive TS patients compared with normal controls, and it was negatively correlated with TS duration. Therefore, with the extension of the disease duration, certain degree of adaptation might occur in TS patients to compensate for the DAT increase, which suggested that hyper-functional DAT might be involved in the early pathophysiological changes of TS.     

Detecting regional cerebral blood flow changes in Alzheimer's patients after milameline treatment: activation or baseline SPECT?

The purpose of this study was to evaluate the effectiveness of activation versus baseline SPECT in detecting the regional cerebral blood flow (rCBF) changes in Alzheimer's disease (AD) patients after milameline (CI979/RU35926) treatment. METHODS: Ten patients with AD who took part in a milameline drug trial were examined by (99m)Tc-hexamethylpropyleneamine oxime SPECT before and after the medication. A split-dose technique was used for the acquisition of baseline and activation images within a single session. Two patients were unable to complete the activation challenges. rCBF changes were assessed using the statistical parametric mapping program. Both increased and decreased contrasts were used to test rCBF changes on activation and baseline images, respectively. rCBF changes caused by activation were also examined before and after milameline treatment. RESULTS: Decreased rCBFs were observed at the temporal cortex on both sides of the brain and at the left parietal cortex on the activation SPECT images after milameline, whereas no statistically significant rCBF change was found on the baseline SPECT images. Memory stress caused not only increased rCBF in many areas of the brain, including the parietotemporal cortex, but also decreased rCBF at the splenium of the corpus callosum. CONCLUSION: Cognitive activation scans are more effective than baseline scans in detecting rCBF changes in AD patients after milameline.     

脑SPECT血流灌注显像对老年人Alzheimer病和多发性梗塞痴呆的诊断研究

目的：本文旨在研究脑SPECT血流灌注显像对老年人阿尔海默氏病和多发性梗塞痴呆的诊断价值。材料和方法：对6例阿尔海默氏病及6例多发性梗塞痴呆患者进行脑SPECT血流灌注显像，使用放射性药物为^99m锝-六甲基丙叉二胺肟(^99mTc—HMPAO),SPECT结果与MRI、CT相比较。结果：阿尔海默氏病表现为大脑皮质血流灌注的广泛减低，以颞，顶叶较为明显．个别病例一侧大脑皮质灌注减低较对侧明显者伴有同侧基底节或对侧小脑的低灌注，可能与“神经机能联系不能”有关。多发性梗塞痴呆患者，呈不规则、局灶性大脑皮质灌注减低；伴有基底节或小脑的低灌注，与阿尔海默氏病的脑SPECT图像有明显区别。结论：脑SPECT血流灌注显像对阿尔海默氏病与多发性梗塞痴呆的诊断与鉴别诊断有重要价值。     

Synthesis, radiolabeling and baboon SPECT imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl)tropane ([(123)I]YP256) as a serotonin transporter radiotracer

To develop a potential SPECT probe to evaluate the integrity of the serotoninergic system (5-HTT) whose dysfunction is linked to several disease conditions such as Parkinson's disease, Alzheimer's disease and depression, we report the synthesis, radiolabeling and in vivo baboon imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl) tropane (YP256, 6). The radiolabeling was performed by iododestannylation using sodium [(123)I]iodide and peracetic acid. Although the ligand displayed high selectivity for 5-HTT over dopamine transporter in vitro, SPECT imaging in baboons did not reveal selective 5-HTT accumulation in brain in vivo.     

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.