Regional cerebral blood flow assessed with <Superscript>99m</Superscript>Tc-ECD SPET as a marker of progression of mild cognitive impairment to Alzheimer's disease

Patients diagnosed with mild cognitive impairment (MCI) have a higher risk of developing Alzheimer's disease (AD). However, not all such patients develop this kind of dementia. The purpose of this prospective study was to assess whether regional cerebral blood flow (rCBF) patterns measured with technetium-99m ethyl cysteinate dimer single-photon emission tomography (^99mTc-ECD SPET) in patients suffering from MCI are useful in predicting progression to AD. The study group comprised 42 patients who fulfilled MCI criteria according to the International Psychogeriatric Association and the Alzheimer's Disease Cooperative Study. rCBF was calculated in 16 regions of interest (ROIs). All patients were clinically assessed for 1–3 years. Twenty-one developed AD (group I) while the initial diagnosis of MCI was retained in the other 21 (group II). ROC curves were designed, and sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were determined for each ROI. Compared with group II (MCI), group I (AD) showed a significant reduction of relative blood flow (RBF), ranging from 7% to 10%, in the following areas: right and left prefrontal, right and left frontal, right and left parietal, right and left temporal, right and left frontoparietotemporal and left posterior lateral temporal. Left prefrontal, left frontal and left parietal areas showed sensitivities and specificities higher than 75% and areas below the ROC curve close to 80%. This study shows that RBF patterns in the right and left prefrontal, right and left frontal and left parietal areas are sensitive early markers of progression towards AD. Reduction of rCBF in the medial temporal and anterior lateral temporal cortex has no value as a predictor since it also occurs in patients with MCI who remain stable.     

Regional cerebral blood flow in Parkinson's disease as an indicator of cognitive impairment

OBJECTIVE: To investigate the pattern of regional cerebral blood flow (rCBF) deficits in Parkinson's disease patients in relation to cognitive decline and to assess the clinical usefulness of single photon emission tomography (SPET) scanning in differentiation between Parkinson's disease patients with dementia and those without cognitive deficits. METHODS: We performed Tc-ECD SPET in 60 patients with idiopathic Parkinson's disease (F: 25, M: 35), with average age of 68.4 years (SD+/-7.3, range 51-81 years). All patients were examined neurologically with the assessment of stage and severity of Parkinson's disease (Hoehn-Yahr scale, UPDRS, Schwab-England scale). Detailed neuropsychological examination was performed in each Parkinson's disease patient. On the basis of DSM-IV criteria of dementia and the results obtained in psychological examination, the whole group was divided into three subgroups: I, with no cognitive changes (n = 17); II, with mild cognitive impairment (n = 25); and III, with dementia (n = 18). RESULTS: There was noticeable significant decrease of perfusion in all areas in Parkinson's disease patients when compared to the age-matched control group of healthy volunteers (n = 20). In group III, perfusion was significantly decreased (when compared to groups I and II), particularly in parietal and temporal areas with the predominance of the left side. Regression analysis revealed two independent factors related to dementia: decrease of perfusion within left temporal lobe and its increase within left thalamus. CONCLUSION: Parkinson's disease patients with dementia showed left temporo-parietal hypoperfusion as compared to a group of patients without dementia, which resembles perfusion deficits described in Alzheimer's disease. The hypoperfusion of the left temporal lobe with increase of rCBF within the left thalamus might be clinically useful in discrimination of Parkinson's disease patients with dementia against those without cognitive impairment.     

Brain single-photon emission tomography with technetium-99m hexamethylpropylene amine oxime in adolescents with initial-stage schizophrenia

The objective of this study was to search for regional cerebral blood flow (rCBF) abnormalities in adolescents with initial-stage schizophrenia by means of brain single-photon emission tomography (SPET) using technetium-99m hexamethylpropylene amine oxime (HMPAO). SPET studies were performed on a homogeneous sample of 15 carefully selected adolescents with a recent diagnosis of schizophrenia, and without previous electroconvulsive or antipsychotic drug treatment. Computed tomography (CT) and electro-encephalographic (EEG) studies were performed in all patients. Qualitative and semiquantitative analysis of^99mTc-HMPAO SPET studies showed an impaired rCBF in 12 patients (80%). The most common pattern was a decreased uptake of^99mTc-HMPAO in the frontal lobes, usually in the left hemisphere. Conventional and quantitative EEG was positive in 12 (80%) and 15 (100%) patients, respectively. CT findings were positive in two patients (13%). There was a high level of concordance between SPET and EEG results and between SPET and clinical features (P>0.05). This study suggests that previously untreated patients in the first stages of schizophrenia present functional abnormalities that are revealed by brain SPET.     

白质疏松病人局部脑血流变化的初步研究

为探讨白质疏松（ＬＡ）病人ＬＡ区域和皮质部位的局部脑血流（ｒＣＢＦ）变化及与痴呆的关系，对２４例伴有ＬＡ〔ＬＡ（＋）〕、２５例无ＬＡ〔ＬＡ（－）〕的皮质下多发性脑梗塞病人及１０例正常对照者行脑血流ＳＰＥＣＴ显像，并与智能评分进行相关分析。结果：ＬＡ（＋）组与正常组相比，额叶、颞叶、顶叶、ＬＡ区域ｒＣＢＦ显著降低（ｔ＝２１２～２５４，Ｐ＜００５）；与ＬＡ（－）组相比，额叶和顶叶皮质、ＬＡ区域ｒＣＢＦ显著减少（ｔ＝２１１～２６０，Ｐ＜００５）；ＬＡ（＋）组长谷川智能评分与额叶皮质、ＬＡ区域ｒＣＢＦ变化呈显著正相关（ｒ＝０７６５，Ｐ＜００１和ｒ＝０４３９，Ｐ＜００５）。结果表明，伴ＬＡ的多发性脑梗塞病人，ＬＡ区和皮质区域存在广泛血流灌注不足，持续的低灌注状态可引起脑功能低下，并与痴呆的程度有一定关系；脑血流ＳＰＥＣＴ显像具有独特优势和价值。     

Changes in the rCBF images of patients with Alzheimer's disease receiving Donepezil therapy

Alzheimer's disease is associated with a loss in presynaptic cholinergic function. It has been suggested that cholinergic inhibitors such as donepezil hydrochloride (Donepezil) could restore this function and improve some of the symptoms of Alzheimer's disease. Previous work has shown that Donepezil improves cognitive and global function in patients with mild to moderate Alzheimer's disease. This study reviewed retrospectively 12 patients who had previously had a 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) single photon emission tomography (SPET) regional cerebral blood flow (rCBF) examination and had gone on to receive Donepezil therapy. These patients were recalled for a further 99Tcm-HMPAO SPET rCBF examination and the image data sets were compared. The results showed an overall increase in global cerebral blood flow (P = 0.04) averaged over the group with a percentage change in blood flow ranging from -1.8% to 6.4%. However, some patients showed a slight decrease in blood flow. When the data were analysed in terms of regional cerebral blood flow, we found that the most significant increase in blood flow occurred in the frontal lobes (P = 0.02).     

五例艾滋病患者~(99)Tc~m-ECD脑SPECT显像

目的　观察艾滋病 (AIDS)患者局部脑血流 (rCBF)的变化。方法　对 5例男性AIDS患者 (IV期 )进行了99Tcm 双半胱乙酯 (ECD)脑血流灌注显像 ,半定量测定rCBF。 16例性别、年龄匹配的健康者作正常对照。结果　 1例有痴呆临床表现的AIDS患者存在双侧额、顶、颞叶和基底节及左侧丘脑rCBF低灌注 ,4例无痴呆临床表现的AIDS患者亦出现双侧额、顶叶rCBF低灌注。AIDS组患者双侧额、顶、颞叶、基底节和丘脑以及直回和桥脑rCBF明显低于对照组。结论　AIDS患者存在脑皮层和皮层下rCBF减少     

HMPAO SPET and FDG PET in Alzheimer's disease and vascular dementia: comparison of perfusion and metabolic pattern

Positron emission tomography (PET) of ¹⁸F-2-fluoro-2-shirlyD-glucose (FDG) and single-photon emission tomography (SPET) of ^99mTc-hexamethyl-propylene amine oxime (HMPAO) were performed under identical resting conditions within 3 h in 20 patients with probable Alzheimer's disease (AD), 12 patients with vascular dementia (VD) and 13 normal persons. In the temporoparietal association cortex similar impairment of relative regional cerebral glucose metabolism (rCMRGI) and relative HMPAO uptake (rCBF) was found. In addition PET showed hypometabolism in the occipital association cortex. The functional pattern was condensed to a ratio of regional values of association areas divided by regional values of structures that are typically less affected by AD. In normals this ratio was significantly related to age for PET metabolic data (r = –0.66, P = 0.01). The ratio was significantly lower in AD than in VD and controls for both rCMRGI and rCBF. In AD only, the metabolic ratio was related to severity of dementia (r = 0.54, P = 0.003) and age (r = 0.64, P = 0.003). Metabolic differences between normals and AD patients were less obvious in old age. In contrast, there were no significant correlations between the perfusion ratio and severity of dementia or age. Comparing the metabolic and perfusion ratio by receiver operating characteristic curves, PET differentiated AD from normals only marginally better than SPET. Differentiation between AD and VD was much better achieved by PET. Our results suggest that both PET and SPET can distinguish AD patients from controls, whereas for differentiation between AD and VD SPET is of little value.     

A study of the acute effect of smoking on cerebral blood flow using 99mTc-ECD SPET

Cigarette smoking is known to be associated with atherosclerosis, is an important risk factor for stroke and has other serious effects. The aim of this study was to evaluate the acute effect of cigarette smoking on cerebral blood flow using statistical parametric mapping (SPM). Ten healthy volunteers with a smoking habit were studied using technetium-99m-labelled ethylcysteinate dimer single-photon emission tomography (SPET). We evaluated the regional cerebral blood flow under the smoking and resting states. The regional cerebral blood flow on smoking-activated SPET was significantly decreased in the whole brain as compared with that on resting SPET. Our findings therefore suggest that one of the acute effects of cigarette smoking is to induce a diffuse decrease in cerebral blood flow.     

Regional cerebral blood flow single-photon emission tomography with 99mTc-HMPAO and the acetazolamide test in the evaluation of vascular and Alzheimer’s dementia

The diagnostic potential of technetium-99m hexamethylpropylene amine oxime (HMPAO) following systemic administration of the cerebral vasodilator acetazolamide (acetazolamide test) was evaluated by regional cerebral blood flow (rCBF) single-photon emission tomography (SPET) in patients with Alzheimer’s disease (AD) or vascular dementia (VD). An initial, high-resolution SPET study was performed with ^99mTc-HMPAO, and after 2 days the patients were re-evaluated with ^99mTc-HMPAO following systemic administration of acetazolamide. Reconstructed SPET slices were evaluated visually and semiquantitatively by a semi-automatic rCBF map method. When ^99mTc-HMPAO alone was used, bilateral hypoperfusion was found in the temporal and/or parietal regions in 33% (6/18) of the VD patients and in 70% (23/33) of the AD patients. The corresponding data obtained by quantitative evaluation were 41% (7/17) and 71% (15/21), respectively. The vascular reserve capacity, as determined with the acetazolamide test, was preserved visually in 22% (4/18) and quantitatively in 29% (5/17) of the VD patients, but in 73% (24/33) and 76% (16/21) of the AD patients. The differences in the perfusion patterns between the VD and AD patients were statistically significant (P<0.01, Fischer’s exact test). Of the VD patients with hypoperfusion (bilateral temporal and/or parietal), 4/6 (67%, visual evaluation) and 4/7 (57%, quantitative evaluation) had a decreased vascular reserve capacity as determined with the acetazolamide test. In the AD group of patients the corresponding results were 3/23 (13%) and 4/15 (27%). It is concluded that the acetazolamide test is promising in rCBF SPET to differentiate VD from AD. Received 1 August and in revised form 30 October 1998     

Choice of reference region in the quantification of single-photon emission tomography in primary degenerative dementia

This study evaluated the effect of using two different reference regions in the quantification of single-photon emission tomography (SPET). SPET scans of 30 patients with Alzheimer's disease (AD) and 30 patients with frontotemporal dementia were compared with the scans of ten age-matched controls. Regions of interest (RO1s) were defined on transaxial slices by a semi-automatic method. Regional cerebral blood flow indices (rCBFi) in each R01 were determined by normalizing the count densities to both cerebellar and occipital cortex reference regions. Mean rCBFi for each ROI were calculated for the patient and control groups and significant group differences determined. The number and topographical distribution of ROIs with significant group differences varied depending upon the choice of reference region. The magnitude of these differences was greatest when the cerebellum was used as the reference region. The disparity between results obtained with the two reference regions was most apparent in the AD group. The reasons for these differences are discussed and we conclude that the cerebellum is the more appropriate choice of reference region in the quantification of SPET in primary degenerative dementia.     

Cerebral perfusion pattern of idiopathic normal pressure hydrocephalus studied by SPECT and statistical brain mapping

OBJECTIVES: To investigate the specific pattern of cerebral blood flow (CBF) in subjects with idiopathic normal pressure hydrocephalus (iNPH) using voxel-based analysis. METHODS: N-isopropyl-p-[123I]iodoamphetamine (IMP) single photon emission computed tomography (SPECT) images were performed in 30 iNPH patients, who met probable iNPH criteria, 30 Alzheimer disease (AD) patients and 15 normal control (NC) subjects. Inter-group comparisons between iNPH patients and NC subjects and between AD patients and NC subjects were performed using three-dimensional stereotactic surface projection (3D-SSP) analysis. Individual 3D-SSP images of the iNPH patients were assessed by visual inspection. RESULTS: On the Z-score maps, areas of relative hypoperfusion were recognized around the corpus callosum in all 30 iNPH patients, as well as in the Sylvian fissure regions in 19 of 30 iNPH patients which included artifacts by dilated ventricles and the Sylvian fissures. Ten frontal dominant, eight parietotemporal dominant, and 12 diffuse hypoperfusion types were demonstrated. Inter-group comparison between iNPH and NC subjects showed relative hypoperfusion in the frontal and parietotemporal areas and severe hypoperfusion around the corpus callosum and Sylvian fissure regions, while parietotemporal and posterior cingulate CBF reduction was demonstrated between the AD and NC groups. CONCLUSION: Voxel-based analysis showed a characteristic pattern of regional CBF reduction with frontal dominant or diffuse cerebral hypoperfusion accompanying severe hypoperfusion around the corpus callosum and Sylvian fissures with artifacts.     

Use of technetium-99m hexamethylpropylene amine oxime SPET for the study of cerebral blood flow reactivity after acetazolamide infusion in patients with Behçet's disease

The purpose of this study was to characterise the nature of the baseline perfusion defects found in patients with Beh?et's disease using hexamethylpropylene amine oxime single-photon emission tomography in conjunction with acetazolamide test (Acz SPET). Eleven patients underwent both baseline and Acz SPET. Regions of interest (ROIs) were drawn on the areas with decreased perfusion (D-ROI) and, in the same section, on areas with normal perfusion (N-ROI). The ROIs were then repositioned on the corresponding section on Acz SPET. The mean ROI counts were then transformed into a perfusion index value (PIV) with reference to the global brain counts. In total we found 24 D-ROIs (17 in the cortical and 7 in subcortical grey matter). The influence of Acz infusion was selectively registered in the D-ROIs, where PIVs changed from 1.23+/-0.17 (baseline SPET) to 1.63+/-0.23 (Acz SPET) (P<0.001). No significant difference was seen in the N-ROIs (1.46+/-0.21 and 1.40+/-0.17, respectively, on baseline SPET and Acz SPET). Our results demonstrate that Acz infusion increases the regional cerebral blood flow within baseline grey matter perfusion defects. This finding suggests that baseline perfusion abnormalities could reflect a disconnection rather than local vasculitic involvement.     

A comparison of 99mTc-HMPAO SPET changes in dementia with Lewy bodies and Alzheimer's disease using statistical parametric mapping

Differences in regional cerebral blood flow (rCBF) between subjects with Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and healthy volunteers were investigated using statistical parametric mapping (SPM99). Forty-eight AD, 23 DLB and 20 age-matched control subjects participated. Technetium-99m hexamethylpropylene amine oxime (HMPAO) brain single-photon emission tomography (SPET) scans were acquired for each subject using a single-headed rotating gamma camera (IGE CamStar XR/T). The SPET images were spatially normalised and group comparison was performed by SPM99. In addition, covariate analysis was undertaken on the standardised images taking the Mini Mental State Examination (MMSE) scores as a variable. Applying a height threshold of P < or = 0.001 uncorrected, significant perfusion deficits in the parietal and frontal regions of the brain were observed in both AD and DLB groups compared with the control subjects. In addition, significant temporoparietal perfusion deficits were identified in the AD subjects, whereas the DLB patients had deficits in the occipital region. Comparison of dementia groups (height threshold of P < or = 0.01 uncorrected) yielded hypoperfusion in both the parietal [Brodmann area (BA) 7] and occipital (BA 17, 18) regions of the brain in DLB compared with AD. Abnormalities in these areas, which included visual cortex and several areas involved in higher visual processing and visuospatial function, may be important in understanding the visual hallucinations and visuospatial deficits which are characteristic of DLB. Covariate analysis indicated group differences between AD and DLB in terms of a positive correlation between cognitive test score and temporoparietal blood flow. In conclusion, we found evidence of frontal and parietal hypoperfusion in both AD and DLB, while temporal perfusion deficits were observed exclusively in AD and parieto-occipital deficits in DLB.     

Cerebral blood flow measurement in patients with impaired consciousness: usefulness of 99mTc-HMPAO single-photon emission tomography in clinical practice

The relationship between impairment of consciousness and quantitative cerebral blood flow (CBF) was investigated. The mean CBF of the whole brain was measured by the Patlak-plot method using technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (^99mTc-HMPAO SPET) in patients with the following diseases: cerebral infarction, intraparenchymal haemorrhage, subarachnoid haemorrhage, brain tumour and cerebral contusion. The clinical symptoms were evaluated according to the severity of impaired consciousness, aphasia and dementia. Four hundred and eighty-five CBF measurements were performed. Patients with alert consciousness showed an age-related decline in mean CBF. Patients with aphasia showed a significant reduction in mean CBF compared with those without aphasia. Impaired consciousness was proportional to reduction in mean CBF regardless of types of pathology, and the size of lesion did not influence the mean CBF. Patients with dementia showed a significant reduction in mean CBF proportional to the severity of dementia. The quantitative measurement of CBF using ^99mTc-HMPAO SPET is reliable in clinical evaluations. Received 9 March and in revised form 23 May 1998     

Cerebral blood flow and oxygen metabolism in senile dementia of Alzheimer's type and vascular dementia with deep white matter changes

Regional cerebral blood flow (rCBF), cerebral metabolic rate of oxygen (rCMRO₂), oxygen extraction fraction (rOEF), and cerebral blood volume (rCBV) were investigated using positron emission tomography (PET) in 16 patients with senile dementia of Alzheimer's type (SDAT), and compared with those of 6 nondemented and 3 demented patients with deep white matter high signal (DWMH) on T2-weighted MRI and 6 controls. rCBF, rCMRO₂ and rCBV were determined using C¹⁵O₂, ¹⁵O₂ and C¹⁵O, respectively. rCBF and CMRO₂ were significantly decreased in the frontal, parietal and temporal cortex (P < 0.05) in patients with SDAT, and showed a significant correlation with the severity of dementia (P < 0.05). In patients with DWMH rCBF was significantly decreased in the parietal cortex and in the frontal white matter in nondemented patients, and in the cerebral cortex and white matter of most regions studied in demented patients (P < 0.05), whereas rCMRO₂ was significantly reduced in only the frontal and temporal cortex of demented patients (P < 0.05). rOEF was significantly increased in the parietal cortex of patients with SDAT and in the white matter of patients with SDAT or DWMH (P < 0.05), and the increase in the frontal white matter significantly paralleled the progression of dementia in patients with SDAT (P < 0.05). rCBV was significantly decreased in the parietal and temporal cortex of patients with SDAT (P < 0.05), but not in any areas of those with DWMH. These results suggest that rOEF is increased in both SDAT and patients with DWMH. The increase in rOEF in patients with SDAT may be accounted for by reduction in rCBV resulting from decreased activity in the vasodilatory cholinergic system, impairment of glucose metabolism and white matter changes; the rOEF increase in patients with DWMH suggests relative preservation of oxidative metabolism compared to disturbed perfusion. Received: 24 October 1996 Accepted: 30 June 1997     

Technetium-99m hexamethylpropylene amine oxime single-photon emission tomography of regional cerebral blood flow in insulin-dependent diabetes

The study was performed to investigate subclinical abnormalities in regional cerebral blood flow (rCBF) in patients with insulin-dependent diabetes mellitus (IDDM) and to correlate them with patients' characteristics. After intravenous injection of technetium-99m hexamethylpropylene amine oxime (HMPAO), tracer uptake of the prefrontal, frontal and parieto-occipital zones was measured with a triple-head single-photon emission tomography (SPET) camera system in 35 IDDM patients outside an episode of hypoglycaemia. Tracer uptake values in 16 age- and sex-matched healthy volunteers served as reference values. Compared with healthy subjects, increased tracer uptake of both prefrontal regions and the left frontal region could be shown in diabetes. Tracer uptake was negatively correlated with the duration of diabetes in all investigated regions. In diabetic patients with a disease duration of more than 5 years (n=26), stepwise regression analysis revealed a significant positive correlation between their HbA1c levels and tracer uptake. Long-term diabetic patients with reduced (pre)frontal tracer uptake (n=8) had lower HbA1c levels than those without (8.4%±0.2% vs 9.3%±0.3%,P<0.05) and tended to have more frequently a history of hypoglycaemic coma (6/8 vs 6/18,P=0.06). It can be concluded that duration of diabetes contributes to subclinical changes in basal rCBF in IDDM as detected with HMPAO SPET of the brain. The positive correlation between the presence of regional hypoperfusion and lower HbA1c levels in long-term diabetic patients may be interpreted in the light of a presumed higher incidence of hypoglycaemia as metabolic control improves.     

Cerebral blood flow in Sjögren's syndrome using 99Tcm-HMPAO brain SPET

Neuropsychiatric disturbances are frequent in connective tissue diseases. Little is known about the cerebral pathophysiology of Sj?gren's syndrome, including cerebral blood flow disturbances. 99Tcm-HMPAO brain SPET was performed in 21 Sj?gren's syndrome patients. We also studied 77 patients with systemic lupus erythematosus and 27 healthy individuals. Our results demonstrate the high rate of alterations in cerebral blood flow in Sj?gren's syndrome, both psychoneurologically symptomatic and asymptomatic. Focal interhemispherical perfusion deficits were seen in 17 of 21 patients (80.9%) with Sj?gren's syndrome: 13/15 symptomatic (86.6%) and 4/6 asymptomatic (66.6%). These changes were mostly localized in the prefrontal and frontal areas, occipital lobes and occipitoparietal area, and less frequently so in the temporal, parietal and central areas. Diffuse hypoperfusion of the frontal lobes (bilateral hypofrontality) was seen in 29% of patients in the Sj?gren's group. An acetazolamide stress test was performed in seven patients. There was an increase in perfusion deficits in two patients, no change in two patients, and hypoperfusion decreased in three patients compared with baseline. The results indicate that most Sj?gren's syndrome patients experience alterations in cerebral blood flow that are consistent with systemic lupus erythematosus, with heterogeneous reactivity to acetazolamide-induced hypercapnia. These alterations present as focal perfusion deficits and bilateral diffuse hypoperfusion of the lobes. The mechanism of cerebral blood flow alterations is unknown, although it might be the result of diffuse cerebral vasculitis.     

A semi-quantitative method for correlating brain disease groups with normal controls using SPECT: Alzheimer's disease versus vascular dementia

PurposeTo demonstrate the utility of semi-quantitative circumferential-profile analysis of regional cerebral blood flow (rCBF) SPECT in Alzheimer's disease (AD) versus white matter vascular dementia (WM-VaD).MethodsSubjects underwent dementia evaluation, MRI and Tc-99m HMPAO SPECT. rCBF patterns from 11 AD and 20 WM-VaD patients were compared to 17 controls using semi-quantitative circumferential-profile analysis.ResultsAD patients showed more significant semi-quantitative circumferential-profile reductions in the posterior temporo-parietal regions, whereas WM-VaD patients demonstrated greater reductions involving the frontal regions of the brain.ConclusionSemi-quantitative circumferential-profile analysis provides a practical semi-quantitative method to evaluate brain SPECT scans in AD versus WM-VaD patients.     

Quantification of cerebral blood flow using technetium-99m ethyl cysteinate dimer and single-photon emission tomography

The aim of this study was to develop a new method for quantifying regional cerebral blood flow (rCBF) with technetium-99m ethyl cysteinate dimer (ECD) and single-photon emission tomography (SPET). Employing a three-compartment model, we introduced a parameter, regional brain fractionation index (BFI), that reflects rCBF values and is obtained by a single SPET scan at optimum time T (min) after tracer injection and the integral of arterial input. By analysing the dynamic SPET and arterial blood sampling data of 15 subjects, including the results of acetazolamide challenges, with the graphical plot method, optimum time T was determined to be approximately 20 min post injection. Regional BFI values of each subject were calculated from the single SPET data at 20 min and arterial input. The relationship between the values of regional BFI and rCBF obtained by xenon-133 inhalation SPET was analysed by approximation with an exponential function, resulting in good agreement (r = 0.907). In the present method, rCBF values were determined from regional BFI values by using the inverse exponential function as a non-linear regression curve. To validate the method, we applied it to six other subjects, in whom acetazolamide challenges were also performed. In comparing rCBF values thus obtained and those obtained by ¹³³Xe inhalation SPET, we found a good correlation (r = 0.901) with an inclination approximating 1 (= 1.02) and without underestimation of rCBF in the high-flow range. Since the present method does not require dynamic planar imaging or dynamic SPET scanning, it can be applied to any type of SPET scanner and is useful in clinical SPET studies. Received 1 August 1998 and in revised form 28 October 1998     

A technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography study in adolescent patients with major depressive disorder

We have not encountered any brain single-photon emission tomography (SPET) study performed in adolescent depressed patients in the literature. Therefore, we used technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) brain SPET in adolescent patients with major depressive disorder (MDD) to examine the possible changes in cerebral perfusion and the possible association between perfusion indices and clinical variables. Fourteen adolescent out-patients (nine females, five males; mean±SD age: 13.11±1.43 years; range: 11–15 years) fulfilling the DSM-IV criteria for MDD and 11 age-matched healthy control subjects (six females, five males; mean±SD age: 13.80±1.60 years; range: 12–15 years) were included in the study. ⁹⁹Tc-HMPAO brain SPET was performed twice in the patient group and once in the control group. The first SPET investigation was performed under non-medicated conditions and the second was performed after depressive symptoms had subsided. A relative perfusion index (PI) was calculated as the ratio of regional cortical activity to the whole brain activity. We found significant differences between the PI values of the untreated depressed patients and those of the controls, indicating relatively reduced perfusion in the left anterofrontal and left temporal cortical areas. No significant differences in regional PI values were found between the remitted depressed patients and the controls. Our study suggests that adolescent patients with MDD may have regional cerebral blood flow deficits in frontal regions and a greater anterofrontal right-left perfusion asymmetry compared with normal subjects. The fact that these abnormalities in perfusion indices have a trend toward normal values with symptomatic improvement suggests that they may be state-dependent markers for adolescent MDD. Received 11 January and in revised form 11 February 1998