technetium-tc-99m-exametazime and Dementia--Vascular

Investigators have reported high sensitivity and specificity values for single photon emission computerized tomography (SPECT) when distinguishing Alzheimer's disease (AD) patients from normal elderly controls or from selected patient groups. The role of SPECT in identifying AD among unselected patients with memory complaints requires investigation. We examined 139 consecutive patients with 99Tc-HMPAO SPECT. NINCDS-ADRDA diagnoses were determined blind to SPECT results, and scans were read and classified by visual inspection blind to clinical diagnoses. Bilateral temporoparietal hypoperfusion (TP) occurred in 75% of probable, 65% of possible, and 45% of unlikely AD patients, yielding a sensitivity of 75% and a specificity of 52% when comparing probable AD versus unlikely AD groups. A positive predictive value of 78% was obtained based on a 69% prevalence of AD in our total clinic population. Patients with false-positive results included a variety of dementing illnesses; all patients with bilateral hypoperfusion had dementia. A pattern of TP on SPECT scans is seen in most patients with AD, but could be found in other dementias as well and cannot be regarded as specific to AD. Reduced TP perfusion discriminated between demented and nondemented individuals. Further strategies for SPECT interpretation that improve diagnostic specificity should be sought.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Dementia; Dementia, Vascular; Diagnosis, Differential; Dominance, Cerebral; Humans; Organotechnetium Compounds; Oximes; Parietal Lobe; Reference Values; Regional Blood Flow; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

In vascular dementia (VaD), assessment of cerebral blood flow by single photon emission computed tomography (CBF SPECT) has been used to detect a patchy decrease of blood flow or a frontal reduction. In addition to reduced blood flow, the heterogeneous distribution of cerebral blood flow is often observed in VaD. However, no objective method to evaluate the heterogeneity has been established. In this study, we applied three-dimensional fractal analysis (3D-FA) to CBF SPECT images as a method for assessing the heterogeneity of the cerebral blood flow distribution in VaD.. The subjects included 18 patients with a diagnosis of VaD (aged 69.7 +/- 8.3) based on neuropsychological testing and imaging findings and 18 age-matched controls (aged 66.9 +/- 10.3). CBF SPECT images were obtained with (99m)Tc-hexamethyl propyleneamine oxime. On the reconstructed images, we obtained a linear regression equation between the cut-off values (from 35 to 50 %) and the number of voxels with a radioactivity exceeding the cut-off value transformed into natural logarithms, and then calculated the fractal dimension from the slope of the regression line thus obtained. The Mini-Mental State Examination (MMSE) was used to evaluate cognitive function.. The fractal dimensions were 1.084 +/- 0.153 and 0.853 +/- 0.062 (mean +/- SD) in the VaD and control groups, respectively. The fractal dimension was significantly greater in the VaD group than in the control group (p < 0.0001). A significant negative correlation was observed between the fractal dimension and the MMSE score in the VaD group (r = 0.871, p < 0.0001).. Because the CBF SPECT images of VaD patients showed a higher fractal dimension, these images were quantitatively more heterogeneous than those of age-matched controls. In the VaD group, cognitive function was shown to decline as the fractal dimension increased and images became more heterogeneous.

Topics: Aged; Algorithms; Capillaries; Cerebrovascular Circulation; Dementia, Vascular; Female; Fractals; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Small-vessel disease with dementia, which is the most frequent type of vascular dementia (VaD), often shows a cerebral blood flow (CBF) distribution with no obvious focal abnormalities and is therefore difficult to evaluate objectively. In this study, we combined CBF SPECT with 3-dimensional fractal analysis (3D-FA) to quantitatively assess the heterogeneity of CBF distribution and with 3-dimensional stereotactic surface projections (3D-SSP) to evaluate the distribution of CBF. We then evaluated the clinical validity of these techniques for the imaging diagnosis of VaD.. The subjects consisted of 17 patients who were diagnosed as having VaD due to small-vessel disease (VaD group) on the basis of a full clinical examination, including history, neuropsychologic tests, neurologic examination, and neuroimaging methods, and 20 healthy volunteers (control group). CBF SPECT was performed with (99m)Tc-hexamethylpropyleneamine oxime, and the reconstructed images were subjected to image processing by 3D-FA and 3D-SSP. Based on the results, the fractal dimension (FD) was compared between the VaD and control groups, and the distribution pattern of CBF was examined in the VaD group.. The mean FD values in the VaD group and the control group were 1.093 +/- 0.153 and 0.853 +/- 0.062 (mean +/- SD), respectively. The mean FD value in the VaD group was significantly higher than that in the control group (P < 0.0001). 3D-SSP analysis in the VaD group showed that there were 2 abnormal patterns: One was globally reduced blood flow in the whole cerebral cortex, and the other was a reduction mainly confined to the frontal region.. CBF SPECT images showed higher mean FD values in the VaD group than in the control group, suggesting a difference in the heterogeneity of CBF. Image processing with 3D-SSP successfully revealed that reduced cortical blood flow could be divided into 2 patterns. Because image analysis techniques, such as 3D-FA and 3D-SSP, allowed the simple and objective evaluation of CBF in patients with VaD, these methods seem to be useful for detailed examination of the blood flow pattern detected by CBF SPECT in patients with VaD.

Topics: Aged; Aged, 80 and over; Cerebrovascular Circulation; Dementia, Vascular; Female; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Male; Middle Aged; Models, Statistical; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral blood flow (CBF) at rest was measured by 123I-IMP SPECT and the standing test was conducted by 99mTc-HMPAO SEPCT in patients with dementia of Alzheimer's type (DAT) and vascular dementia (VD) in order to evaluate cerebral autoregulation and to consider the diagnostic significance of this determination and test. CBF at rest decreased significantly in all regions in the DAT and VD groups compared to the control groups (healthy aged persons, group C). The value of mean CBF also decreased significantly in the DAT (40.1 micromilligrams/100 g/min) and VD groups (41.3) as compared to group C (51.0). In the DAT groups, the CBF was significantly lower in the parietal region compared to VD groups, and CBF and Hasegawa's dementia score showed a positive correlation in the temporal and parietal regions. Decreases in blood pressure upon standing were about 10 mmHg in all three groups, but the decrease rate in mean CBF was significantly greater in the VD groups (20.2%) than in the C (5.0%) and DAT groups (4.0%). The dysautoregulation index (D.I. delta; % CBF mmHg), used as a measurement of cerebral autoregulation, was significantly higher in the VD groups (1.7) than in the C(0.5) and DAT groups (0.3). This index made it possible to make differential diagnosis in some patients in whom it was impossible using CBF at rest, probably due to impaired cerebral autoregulation and atherosclerotic changes in VD patients. Our findings suggest that D.I. provides information on the condition of patients that cannot be obtained with CBF at rest and assists in differential diagnosis.

Topics: Aged; Alzheimer Disease; Amphetamines; Brain; Cerebrovascular Circulation; Dementia, Vascular; Female; Hemodynamics; Humans; Iodine Radioisotopes; Iofetamine; Male; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

I devised the convenient semiquantitative measurement method of cerebral blood flow using single photon emission computerized tomography (SPECT) and adapted clinically the method to vascular dementia. SPECT imaging utilized the tracer N-isopropyl-p-[I-123] iodo amphetamine (IMP) and 99mTc-hexamethyl-propyleneamineoxime (HMPAO) with a relative measure of regional tracer uptake normalized to cerebellar radiotracer uptake (rCBF ratios). In order to investigate relationships between dementia and cerebral blood flow, I studied 34 patients with vascular dementia and 20 control subjects by the semiquantitative measurements of relative regional cerebral blood flow (rCBF). In this study I set the lower most normal rCBF ratio (NFL) in IMP-SPECT and HMPAO-SPECT. These NFL of IMP-SPECT were higher than those NFL of HMPAO-SPECT in all cerebral cortices. NFL of IMP-SPECT were nearer to PET's than NFL of HMPAO-SPECT. I indicated rCBF ratio in each region of cerebrum by distinguishing color of SPECT image. In vascular dementia, while IMP-SPECT imaging showed the reduction of rCBF ratio in both of frontal lobes and temporal lobes, HMPAO-SPECT imaging indicated several groups which showed no reduction in temporal lobes. This difference may be due to the lower detection rate of ischemic change in HMPAO-SPECT than IMP-SPECT and it was consistent with many of other reports. This result may suggest usefulness of this method.

Topics: Aged; Aged, 80 and over; Amphetamines; Brain; Cerebrovascular Circulation; Dementia, Vascular; Female; Humans; Iodine Radioisotopes; Iofetamine; Male; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Positron emission tomography (PET) of 18F-2-fluoro-2-deoxy-D-glucose (FDG) and single-photon emission tomography (SPET) of 99mTc-hexamethylpropylene 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 (rCMRGl) 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 rCMRGl 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.

Topics: Aged; Aging; Alzheimer Disease; Brain; Cerebrovascular Circulation; Dementia, Vascular; Deoxyglucose; Diagnosis, Differential; Female; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Glucose; Humans; Male; Organotechnetium Compounds; Oximes; ROC Curve; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

To 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).. Subjects 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.. AD 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.. Semi-quantitative circumferential-profile analysis provides a practical semi-quantitative method to evaluate brain SPECT scans in AD versus WM-VaD patients.

Topics: Aged; Alzheimer Disease; Case-Control Studies; Cerebrovascular Circulation; Dementia, Vascular; Female; Humans; Image Processing, Computer-Assisted; Linear Models; Magnetic Resonance Imaging; Male; Radiopharmaceuticals; Retrospective Studies; Statistics, Nonparametric; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Subcortical ischemic vascular dementia (SVD) caused by small-artery disease is a major cause of dementia. It still remains unclear, however, whether SVD may present with localized regional cerebral blood flow (rCBF) changes. We aimed to clarify the local rCBF changes associated with dementia in patients with early-stage SVD.. The subjects consisted of 15 patients with early-stage SVD [Mini Mental State Examination (MMSE) score: 20 +/- 3.5] without apparent brain atrophy (SVD group), 11 patients without dementia with white matter lesions (non-dementia-WML group) and 16 age-matched controls. All the subjects were right-handed and underwent brain perfusion single photon emission computed tomography (SPECT), magnetic resonance imaging and cognitive function testing. Statistical analysis of the differences in the SPECT rCBF was performed by SPM2. The degree of severity of the WMLs was evaluated based on the Scheltens rating scale.. The results of SPM analysis revealed that the rCBF in the SVD group was significantly decreased in the pulvinar nuclei of the thalamus of both sides as compared with that in the controls, and in the left pulvinar nucleus as compared with that in the non-dementia-WML group. On the other hand, SPM analysis revealed no significant reduction in rCBF in the non-dementia-WML group as compared with that in the controls. The WMLs in the left parietal region were severer in the SVD group than in the non-dementia-WML group.. In patients with early-stage SVD without apparent brain atrophy, significant rCBF reduction in the bilateral pulvinar nuclei as compared with that in normal controls, and in the left pulvinar nucleus as compared with that in patients without dementia with WMLs was found.

Topics: Aged; Case-Control Studies; Cerebrovascular Circulation; Cognition; Dementia, Vascular; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Models, Cardiovascular; Models, Statistical; Neuropsychological Tests; Pulvinar; Radiopharmaceuticals; Regional Blood Flow; Severity of Illness Index; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Aged; Aged, 80 and over; Algorithms; Cerebrovascular Circulation; Dementia, Vascular; Female; Fractals; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Male; Middle Aged; Models, Statistical; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Vasomotor reactivity is decreased in terms of cerebral blood flow (CBF) response to hypercapnia in patients with cerebrovascular white matter (WM) lesions. This study evaluated whether vasomotor reactivity is altered during postural change in these patients. We examined 28 consecutive patients with cerebrovascular WM lesions, subgrouped into 19 with Schmidt scale 2 and 9 with scale 3 WM lesions. These patients were compared with 15 age-matched patients with lacunar infarction but without significant WM lesions and 6 controls without cerebrovascular disease. With blood pressure monitoring, brain SPECT scans were done in the supine and upright position using HMPAO as a tracer. The ratio of radioisotope (RI) counts in the frontal and parieto-temporal lobes to those in the cerebellar hemispheres (CBF ratio) was evaluated. In the comparison among the three groups, there were no significant differences in the changes of systemic blood pressure after rising. The baseline CBF ratio in the supine position was also not different among the three groups. After rising, the CBF ratio in each region of interest (ROI) did not change significantly in either lacunar infarction or control groups. By contrast, in patients with WM lesions, the CBF ratio in the frontal lobe decreased after rising (p < 0.0001). In the subgroup analysis, there was a significant increase in blood pressure 1, 2 and 3 min after rising (p < 0.05), with a higher tendency in the scale 3 WM lesion group as compared to the scale 2 WM lesion group. The CBF ratio was decreased in both frontal and parieto-temporal areas in the scale 2 WM lesion group, whereas this was significant only in the frontal areas in the scale 3 WM lesion group. Vasomotor reactivity is impaired in cerebrovascular WM lesions, suggesting a susceptibility to postural changes in these patients.

Topics: Aged; Blood Pressure; Cerebral Cortex; Dementia, Vascular; Female; Humans; Male; Middle Aged; Posture; Radiopharmaceuticals; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vasomotor System

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.

Topics: Acetazolamide; Aged; Alzheimer Disease; Brain; Cerebrovascular Circulation; Dementia, Vascular; Diagnosis, Differential; Female; Humans; Image Processing, Computer-Assisted; Male; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vasodilator Agents

Cerebral microangiopathy, indicated in MRI by lacunar infarctions (LIs) and deep white matter lesions (DWMLs), is said to be accompanied by vascular dementia, which is reportedly caused by LI and DWML.. To confirm this assumption, 57 patients with cerebral microangiopathy were assessed for changes in regional cerebral blood flow (rCBF) and glucose utilization (rMRGlu) in both white matter and cortex, and these findings were correlated to the results of extensive neuropsychological testing (cognitive, mnestic and attentiveness tests), as well as to MRI findings. A special head holder ensured reproducibility of positioning during measurement of rCBF (99mTc-HMPAO SPECT) and rMRGlu (18F-FDG PET) and MRI. White matter and cortex were quantified with regions of interest defined on MRI and superimposed to corresponding PET/SPECT slices. The rMRGlu was calculated according to Sokoloff, and rCBF was determined from normalization to the cerebellum. LI and DWML were graded by number and extent. Brain atrophy was classified as no to slight inner and/or outer atrophy (Group A) or moderate-to-severe inner and outer atrophy (Group B).. Even in severe DWMLs and in multiple LIs, rCBFs and rMRGlu values were not reduced. Analysis of variance identified atrophy and neuropsychological deficits as the main determinants for reduced rCBF and rMRGlu values (p < 0.05). However, 60% of patients (19 of 31) with neuropsychological deficits in attentiveness tests and 61% of patients (23 of 38) with mnestic deficits belonged to Group A and revealed decreased rCBF and rMRGlu values. Neuropsychological deficits correlated well with decreased rCBF and rMRGlu, whereas MRI patterns, such as LI and DWML, did not.. We conclude that LI and DWML are epiphenomena that morphologically characterize cerebral microangiopathy. Dementia or neuropsychological deficits, however, are exclusively reflected by functional criteria (rCBF and rMRGlu), as long as cerebral atrophy does not occur.

Topics: Aged; Brain; Cerebral Infarction; Cerebrovascular Circulation; Cohort Studies; Dementia, Vascular; Female; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Glucose; Humans; Magnetic Resonance Imaging; Male; Neuropsychological Tests; Radiopharmaceuticals; Reproducibility of Results; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

To provide the clinician with a guide to the clinical utility of 99mTc-HMPAO single photon emission computed tomography (SPECT) and to the interpretation of specific test results in the differential diagnosis of dementia.. Three hundred and sixty three patients with dementia were studied prospectively for a median three (range 1-6) years and classified into disease groups on the basis of established clinical criteria. The degree to which different patterns of cerebral blood flow (CBF) abnormality found on 99mTc-HMPAO SPECT imaging at the time of initial patient presentation modified clinical diagnoses was determined by calculating the likelihood ratios for pairwise disease group comparisons. The optimal clinical usage of 99mTc-HMPAO SPECT was determined by calculating the percentage of significant test results for each pairwise disease group comparison.. Bilateral posterior CBF abnormality was found to significantly increase the odds of a patient having Alzheimer's disease as opposed to vascular dementia or frontotemporal dementia. Bilateral anterior CBF abnormality significantly increased the odds of a patient having frontotemporal dementia as opposed to Alzheimer's disease, vascular dementia, or Lewy body disease. "Patchy" CBF changes significantly increased the odds of a patient having vascular dementia as opposed to Alzheimer's disease. Unilateral anterior, unilateral anterior plus unilateral posterior, and generalised CBF abnormality failed to contribute to the differentiation of any of these forms of dementia.. 99mTc-HMPAO SPECT was found to be most useful in distinguishing Alzheimer's disease from vascular dementia and fronto temporal dementia, and least useful in differentiating between Alzheimer's disease and Lewy body disease, and between vascular dementia, frontotemporal dementia, and progressive aphasia. It is suggested that CBF SPECT should be used selectively and as an adjunct to clinical evaluation and CT.

Topics: Aged; Alzheimer Disease; Aphasia, Primary Progressive; Dementia; Dementia, Vascular; Diagnosis, Differential; Female; Humans; Likelihood Functions; Male; Middle Aged; Odds Ratio; Parkinson Disease; Prospective Studies; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Brain; Dementia, Vascular; Humans; Neuropsychological Tests; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

Psychiatric, neuropsychological, and cerebral blood flow differences between patients with ischemic vascular dementia (IVD) or Alzheimer's disease (AD) were examined.. A consecutive series of patients who met either the criteria of the National Institute of Neurological Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association for probable AD or the State of California AD Diagnostic and Treatment Centers criteria for probable IVD were included in the study. Twenty consecutive patients with IVD were matched for age, sex, and Mini-Mental State Examination scores with 40 consecutive patients with probable AD. Patients underwent a psychiatric interview, a neuropsychological assessment, and single-photon emission CT imaging with 99mTc-hexamethylpropyleneamine oxime.. Patients with IVD showed significantly more severe anosognosia (P<.05) and emotional lability (P<.01) than AD patients, but no significant between-group differences were found in the frequency and severity of depression. IVD patients showed significantly more severe deficits in tests of planning, sequencing (P<.05), and verbal fluency (P<.05) as well as significantly more severe cerebral blood flow deficits in the basal ganglia (P<.01) and the frontal lobes (P<.001) than AD patients.. Patients with IVD showed a relatively more severe dysfunction of the frontal lobes as demonstrated by single-photon emission CT and expressed in specific psychiatric and neuropsychological changes than AD patients matched for age, sex, and severity of dementia.

Topics: Aged; Alzheimer Disease; Basal Ganglia; Brain Ischemia; Case-Control Studies; Cerebrovascular Circulation; Cognition Disorders; Dementia, Vascular; Depression; Emotions; Female; Frontal Lobe; Humans; Interview, Psychological; Male; Mental Health; Neuropsychological Tests; Neuropsychology; Organotechnetium Compounds; Oximes; Self Concept; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Verbal Behavior

In 24 patients with vascular dementia of Binswanger's type (VDBT) and 14 age-matched neurologically normal volunteers, we investigated the relationship between clinical features, white matter lesions (leuco-araiosis) and cerebral atrophy on computed tomographic (CT) scan, and regional cerebral blood flow. All subjects underwent the Mini-Mental State Examination of Taiwan, version 1 (MMSE-T1), for assessing the severity of cognitive impairment. The patients were subdivided into two groups, one with mild to moderate (group I, MMSE-T1 scores: 11-24, n=11), and the other with severe dementia (group II, MMSE-T1 scores: below 10, n=13). White matter degeneration was evaluated with densitometric methods. Loss of brain parenchyma was estimated with seven linear measurements (Evan's ratio, third ventricle ratio, width of temporal horn tip, anterior-posterior length of temporal horn, anterior-posterior length of Sylvian fissure and width of frontal interhemispheric fissure) by CT scans. Regional cerebral blood flow was determined with technetium-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission tomography (SPET). In neuroimaging studies, subcortical leuco-araiosis was localized at the frontal region in group I patients and scattered diffusely in group II patients. 99mTc-HMPAO SPET analysis revealed reduction of regional cerebral blood flow in the frontal lobe in group I patients and widespread reduction of regional cerebral blood flow in group II patients. A correlation between frontal leuco-araiosis and perfusion defect of the frontal pole was demonstrated in group I patients, showing findings typical of subcortical dementia. There was no difference in frontal atrophic measurements between group I patients and controls. Ratios of volumes of lost brain parenchyma and leuco-araiosis were significantly higher in group II patients than in the age-matched controls, corresponding to a diffuse cerebral perfusion defect. These results suggest that patients with VDBT have early frontal lobe involvement with posterior progression. Patients with mild VDBT are more likely to show reduction of frontal cerebral blood flow and leuco-araiosis, while those with severe VDBT are more likely to have diffuse leuco-araiosis, cerebral hypoperfusion and brain atrophy.

Topics: Aged; Atrophy; Brain; Case-Control Studies; Cerebrovascular Circulation; Dementia, Vascular; Female; Humans; Male; Neuropsychological Tests; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Topics: Aged; Aged, 80 and over; Brain; Cerebrovascular Circulation; Dementia, Vascular; Female; Giant Cell Arteritis; Humans; Organotechnetium Compounds; Oximes; Prednisone; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Single photon emission with computed tomography (SPECT) hexamethylphenylethyleneamineoxime technetium-99 images were analyzed by an optimal interpolative neural network (OINN) algorithm to determine whether the network could discriminate among clinically diagnosed groups of elderly normal, Alzheimer disease (AD), and vascular dementia (VD) subjects. After initial image preprocessing and registration, image features were obtained that were representative of the mean regional tissue uptake. These features were extracted from a given image by averaging the intensities over various regions defined by suitable masks. After training, the network classified independent trials of patients whose clinical diagnoses conformed to published criteria for probable AD or probable/possible VD. For the SPECT data used in the current tests, the OINN agreement was 80 and 86% for probable AD and probable/possible VD, respectively. These results suggest that artificial neural network methods offer potential in diagnoses from brain images and possibly in other areas of scientific research where complex patterns of data may have scientifically meaningful groupings that are not easily identifiable by the researcher.

Topics: Aged; Aged, 80 and over; Algorithms; Alzheimer Disease; Brain; Dementia, Vascular; Female; Humans; Male; Middle Aged; Neural Networks, Computer; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

A 76-year-old, right-handed man developed posttraumatic dural arteriovenous fistula (DAVF) involving the superior sagittal sinus. He developed slow but progressive intellectual deterioration and gait disturbance after a minimal head trauma. Cerebral angiography demonstrated a DAVF of the superior sagittal sinus with sinus thrombosis supplied by branches of the bilateral external carotid arteries, and a DAVF of the right sigmoid sinus supplied by the right occipital artery. Selective embolization was carried out. He showed marked improvement on neuropsychological testing, especially on test items which are supposed to tap functions of the right cerebral hemisphere which showed an improved cerebral blood flow. We concluded that the intellectual impairment of our patient was caused by cerebral hypoperfusion, especially of the right cerebral hemisphere.

Topics: Aged; Arteriovenous Fistula; Brain Ischemia; Cerebral Angiography; Cerebral Cortex; Dementia, Vascular; Dominance, Cerebral; Dura Mater; Embolization, Therapeutic; Head Injuries, Closed; Humans; Male; Mental Recall; Neurologic Examination; Neuropsychological Tests; Organotechnetium Compounds; Oximes; Psychomotor Performance; Regional Blood Flow; Sinus Thrombosis, Intracranial; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Alzheimer's disease produces regional abnormalities in brain blood flow and metabolism that may result in recognizable scintigraphic patterns. We determined the predictive value of 99mTc-HMPAO SPECT for the presence of Alzheimer's disease based on a prospective study of 132 consecutive patients coming to our nuclear medicine clinical unit for evaluation of their memory loss or cognitive abnormalities. During clinical follow-up averaging 10.1 mo, a final diagnosis was established in 113 patients, 52 of which had Alzheimer's disease. The probability of Alzheimer's disease was determined for seven scintigraphic patterns. The probability was 19% that patients with memory loss and normal perfusion had Alzheimer's disease. For abnormal perfusion patterns, the probability of Alzheimer's disease was 82% with bilateral temporoparietal defects, 77% with bilateral temporoparietal defects with additional defects, 57% with unilateral temporoparietal defects, 43% with frontal defects only, 18% with other large defects and 0% with multiple small cortical defects. We conclude that for 99mTc-HMPAO SPECT the predictive value of bilateral temporoparietal defects for Alzheimer's disease is high, while the perfusion patterns of unilateral temporoparietal perfusion defects and frontal defects only, which occur in 20% of patients with Alzheimer's disease, are not predictive of that disease.

Topics: AIDS Dementia Complex; Alzheimer Disease; Cerebrovascular Circulation; Dementia, Vascular; Diagnosis, Differential; Humans; Organotechnetium Compounds; Oximes; Parkinson Disease; Predictive Value of Tests; Probability; Prospective Studies; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon