Single photon emission computerised tomography in elderly patients with Alzheimer's disease and multi-infarct dementia. Regional uptake of technetium-labelled HMPAO related to clinical measurements

Hybrid Imaging of Vascular Cognitive Impairment

Cerebrovascular disease is a significant cause of cognitive impairment leading to a reduction or loss of functioning, including social and occupational. The connection cause-effect between cerebrovascular disease and cerebral infarction was originally theorized by the studies from Newcastle-Upon-Tyne, England, in the 1960s, where vascular dementia (VaD) was defined as a disease originated from several infarctions that overcome a determined threshold. It differs from Alzheimer's disease (AD), although there are various overlaps in risk factors, symptomatology, the similarity of vascular lesions, and treatment benefits. Nevertheless, AD is one-half of all cases of dementia. Cognitive impairment and dementia (VCID) has recently been proposed to include different entities such as VaD, Vascular cognitive impairment, subcortical (ischemic) VaD, and vascular cognitive disorders. VaD is the most common cause of dementia after AD. Neuroimaging is an essential part of the workup of patients with cognitive decline and in those with suspected VCID it should be used to assess the extent, location, and type of vascular lesions. Computed tomography (CT) or structural magnetic resonance imaging (MRI) are usually used for the diagnosis of vascular diseases of the brain. However, images obtained from new hybrid devices could help the neurologist in the differential diagnosis between various neuropathological entities related to VCID. Single-photon emission computed tomography (SPECT) combined with CT or MRI and positron emission tomography (PET) combined with CT or MRI represent the future of neuroimaging tools as morphological and functional data can be provided simultaneously. New prospects have been developed such as hybrid PET/SPECT/CT, a high-performance prototype able to produce high-quality images but for now suitable only for small animals. Nowadays, PET/CT and PET/MRI are good performance and high-quality instruments, even if the magnetic field of MRI represents a limitation that affects the PET electronics and positron detection ability. SPECT/MRI delineates as a potential and tempting device. It could give us both functional and anatomical details, with the advantage of lack of extra ionizing radiation and high soft-tissue contrast, important features, and considerable auxiliary for differential diagnosis in the variegate word of vascular cognitive impairment. The aim of this review is to summarize the newest viewpoints in hybrid imaging in the diagnosis of VaD and to highlight pros and cons of each methodic.

Relationships between cognitive impairment on ADAS-cog and regional cerebral blood flow using SPECT in late-onset Alzheimer's disease

The aim of this study was to examine brain hypoperfusion and its relationship with cognitive dysfunction in late-onset Alzheimer's disease (AD). Forty patients with late-onset AD and not receiving acetylcholinesterase inhibitors were recruited from outpatient clinics. We examined cognitive function using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and brain perfusion using single-photon emission computed tomography, and analyzed classified gyrus level segments with three-dimensional stereotactic surface projection and the stereotactic extraction estimation method level 3. ADAS-cog subscales were grouped into three domains: language, memory, and praxis. Patients with late-onset AD showed an apparent reduction in regional cerebral blood flow (rCBF) with a z score >1.5 in the frontal, temporal, and limbic lobes, with lesser reduction in the parietal and occipital lobes. Although hypoperfusion in the orbital, rectal, and subcallosal gyri of the frontal lobe was prominent, rCBF in the inferior frontal gyrus of the frontal lobe was significantly correlated with ADAS-cog total and language and praxis subscale scores. The parahippocampal gyrus of the limbic lobe was also significantly correlated with the ADAS-cog total, language, and praxis subscale scores. Additionally, the cingulate of the limbic lobe was significantly related with ADAS-cog memory. In spite of lesser hypoperfusion, the posterior cingulate gyrus of the limbic lobe was significantly related with ADAS-cog total, language, and memory subscale scores. Further, each subdivision of ADAS-cog was found to be related with various brain regions.

Relationship between cognitive function and regional cerebral blood flow in different types of dementia

PURPOSE

We assessed relationships between cognitive impairment and regional cerebral blood flow (rCBF) in the different types of dementia.

SUBJECTS AND METHODS

Subjects, who included 27 with Alzheimer's disease (AD), seven with frontotemporal dementia (FTD), six with vascular dementia (VaD), and 12 normal controls, were evaluated using the Mini-mental State (MMS), Kana-hiroi Test, an auditory verbal learning test (AVLT), a word fluency test (WFT) and Raven's Coloured Progressive Matrices (RCPM). The rCBF was measured using a three-dimensional stereotaxic ROI template method (3DSRT).

RESULTS

In all dementia types, left superior frontal hypoperfusion was demonstrated. In AD and VaD significant CBF reduction also was seen in both angular, temporal, occipital, and precentral, both hippocampi, thalami, and pericallosal regions, and the left lenticular nucleus. MMS, Kana-hiroi Test, and AVLT scores correlated with CBF in all regions. WFT scores were correlated highly with CBF in the left side in frontal, temporal, and angular regions and right and left lenticular nuclei, thalami, and pericallosal regions. RCPM scores correlated with CBF in posterior regions.

CONCLUSION

Close coupling was evident between reduced rCBF and cognitive dysfunction in patients with dementia. Use of neuropsychologic tests and rCBF determinations in combination should enhance diagnostic accuracy.

Symptomatic treatment of Alzheimer’s disease: identification of biomarkers to aid translation from bench to bedside

In the absence of robust pharmacodynamic markers, the potential success of novel therapeutic agents for the symptomatic relief of Alzheimer’s disease is largely unknown until the drugs enter relatively large studies, assessing clinical outcome over a 6-month period. In order to increase the efficiency of future clinical development there is, therefore, a need to identify pharmacodynamic markers of drug response, pharmacodynamic models that allow early prediction of efficacy and markers to aid the stratification of the patient population. Using literature available from cholinesterase inhibitors, memantine and Ginkgo biloba, this review focuses on the identification of potential pharmacodynamic markers/models and highlights the utility of these end points throughout the drug discovery process, from preclinical to clinical development.

Does perfusion CT enable differentiating Alzheimer's disease from vascular dementia and mixed dementia? A preliminary report

The purpose of the study was to evaluate the usefulness of perfusion CT (pCT) in differentiating Alzheimer's disease (AD) from vascular dementia (VaD) and mixed dementia (MixD). pCT was performed in 41 patients (mean age, 68.3 years): 24 with AD, 8 with VaD, and 9 with MixD. Regional perfusion parameters (rCBF, rCBV, and rMTT) were calculated from 31 ROIs in the grey and white matter of the frontal and temporal lobes, basal ganglia, and internal capsules bilaterally. The obtained data for the subgroups of AD, VaD, and MixD patients were compared statistically.

CONCLUSIONS

On the basis of rCBF and rCBV values, pCT may be a valuable method of distinguishing between AD and VaD but it seems to be of little significance in differentiating MixD from VaD and of no usefulness in distinguishing between AD and MixD.

Accuracy of single-photon emission computed tomography in differentiating frontotemporal dementia from Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are the commonest causes of presenile dementia. In the absence of a biological marker, diagnosis is reliant on clinical evaluation. Confirmation is often sought from neuroimaging, including single-photon emission computed tomography (SPECT). Most previous SPECT studies lack pathological validation.

AIM

To examine the accuracy of SPECT in differentiating FTD from AD in patients with subsequent pathological confirmation.

METHODS

Technetium-99-labelled hexamethyl propylene amine oxime SPECT images obtained at initial evaluation in 25 pathologically confirmed cases of FTD were examined. These images were visually rated by an experienced blinded nuclear medicine consultant and compared with those of 31 patients with AD, also with pathological validation.

RESULTS

A reduction in frontal cerebral blood flow (CBF) was more common in FTD and was of diagnostic value (sensitivity 0.8, specificity 0.65 and likelihood ratio (LR) 2.25; 95% CI 1.35 to 3.77). A pattern of bilateral frontal CBF reduction without the presence of associated bilateral parietal CBF change is diagnostically more accurate (sensitivity 0.80, specificity 0.81 and +LR 4.13, 95% CI 1.96 to 8.71). Diagnostic categorisation (FTD or AD) on the basis of SPECT alone was less accurate than clinical diagnosis (based on neurology and detailed neuropsychological evaluation). One patient with FTD was initially clinically misdiagnosed as AD, owing to the lack of availability of full neuropsychological assessment. However, SPECT correctly diagnosed this patient, providing a diagnostic gain of 4%.

CONCLUSION

Technetium-99-labelled hexamethyl propylene amine oxime SPECT CBF patterns provide valuable information in the diagnosis of FTD and AD. These data can be better used as an adjunct to clinical diagnosis if pathology is to be correctly predicted in life.

The effect of cholinesterase inhibitors on the regional blood flow in patients with Alzheimer's disease and vascular dementia

The effects of therapy with cholinesterase inhibitors (ChE-I) on regional cerebral blood flow (rCBF) disturbances were investigated by means of single photon emission computed tomography (SPECT). The changes in rCBF were compared with the results of the medical examination and neuropsychological tests. The sample consisted of 41 patients with the Alzheimer's dementia (AD) and vascular dementia (VaD). The effect of ChE-I (rivastigmine) treatment was studied on 33 patients, while the nontreated control group consisted of 8 patients. In the treated patients, an increase in the rCBF was observed, while the scores of the neuropsychological tests decreased slightly. In the VaD group, the increase in rCBF was more significant in the frontal regions, whereas in the group with AD in the temporal regions, respectively. In the nontreated patients, a decrease of both rCBF and scores of neuropsychological tests were observed. The scores of the neuropsychological tests correlated with the results of rCBF. Increased levels of acetylcholine in the brain after ChE-I treatment may support the cholinergic regulation of rCBF, and in result increase it. Such effects seem to be more pronounced in the more affected brain regions.

SPECT as a diagnostic test in the investigation of dementia

Single photon emission tomography (SPECT) permits the assessment of the decrease of regional cerebral blood flow (rCBF). The aim of this study was to assess the relationship between the different types of dementia (Alzheimer's disease (AD), vascular dementia (VaD) and frontotemporal dementia (FTD)) and the rCBF in the SPECT examination. In patients with AD, the SPECT examination showed hypoperfusion in temporoparietal regions, contrary to patients with frontotemporal dementia, where hypoperfusion was limited to the frontal area, and compared to patients with VaD, where "patchy" rCBF changes were observed in different regions. In mild cases of AD, perfusion deficits were observed in the frontal regions equal to those in VaD. The study shows that the SPECT examination may be useful in distinguishing between AD, VaD, and FTD; however, for proper diagnosis in the early stages of AD, additional factors must be taken into consideration.

Diagnostic patterns of regional atrophy on MRI and regional cerebral blood flow change on SPECT in young onset patients with Alzheimer's disease, frontotemporal dementia and vascular dementia

OBJECTIVES

Alzheimer's disease (AD), frontotemporal dementia (FTD) and vascular dementia (VaD) are the three most common causes of young onset dementias. Most neuroimaging studies of these disorders have involved comparisons with normal controls. The aims of this study were to examine the clinical diagnostic value of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) (in combination and in isolation) in the differentiation of one form of dementia from another from amongst a group of AD, FTD and VaD.

METHODS

T1 weighted MRI images and 99mTc-HMPAO SPECT images were obtained from consecutive patients with FTD (n=21), AD (n=23) and VaD (n=20) and rated visually by experienced neuroradiologists and nuclear medicine physicians.

RESULTS

Asymmetrical atrophy was seen only in FTD. Frontotemporal dementia patients were the most atrophic whereas severe atrophy was rarely observed in VaD. Severe frontal atrophy (unilaterally or bilaterally) and/or asymmetrical atrophy on MRI is highly diagnostic (sensitivity 0.71, specificity 0.93, LR 10.24) of FTD from within a group of FTD and non-FTD (AD, VaD) patients. Mild or severe parietal atrophy with severe reduction in parietal regional cerebral blood flow on SPECT is diagnostic (sensitivity 0.71, specificity 0.76, LR 3.02) of AD from within a group of AD and non-AD (VaD, FTD) patients.

CONCLUSION

Anatomical (MRI) and functional (SPECT) imaging provide different information and a combination of these modalities improves diagnostic specificity.

Efficacy of naftidrofuryl in patients with vascular or mixed dementia: results of a multicenter, double-blind trial

BACKGROUND

Dementia is a cerebral disorder resulting in a progressive deterioration of intellectual function that compromises the patient's ability to function. The diagnostic criteria for dementia are primarily clinical and are based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The Hachinski score and computed tomography of the brain help distinguish between degenerative and vascular dementias.

OBJECTIVE

This study examined the efficacy of naftidrofuryl in patients with vascular or mixed dementia.

METHODS

This multicenter, randomized, double-blind study compared naftidrofuryl 600 mg/d with placebo for 1 year in patients with vascular or mixed dementia. A preliminary 2-month washout period allowed selection of patients who were compliant with treatment. The end point was change in the scores on the Alzheimer Disease Assessment Scale cognitive subscale and the Mini-Mental State Examination.

RESULTS

Eighty-four patients were assessable on an intent-to-treat basis, and 74 were assessable for the per-protocol analysis (on-treatment). Statistically significant improvements in cognitive and global function were observed in patients receiving naftidrofuryl. Naftidrofuryl was well tolerated, and produced no clinically significant abnormalities in laboratory test results.

CONCLUSION

The results of this study suggest that naftidrofuryl is effective and well tolerated in treating the symptoms of vascular and mixed dementia.

Cerebral blood flow and metabolism in late-life depression and dementia

Late-life depression (LLD) is characterized by abnormalities in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) for glucose. Unlike younger adults with major depression, global cortical CBF and CMR reductions have been reported in LLD. Patients with LLD are also characterized by topographic abnormalities, most commonly involving selective prefrontal, superior temporal, and anterior parietal cortex. The fate of these abnormalities with response to antidepressant treatment is highly uncertain, and heterogeneous findings have been reported in younger samples with major depression. The limited data in LLD suggest that response to electroconvulsive therapy or antidepressant medications does not involve reversal of baseline abnormalities but rather accentuation of prefrontal deficits. At minimum, these paradoxical findings suggest that abnormalities in CBF and CMR may be persistent in LLD and a trait characteristic. Characteristic profiles of CBF and CMR abnormalities have also been demonstrated in samples with Alzheimer's disease (AD) and other types of dementia. Functional imaging has shown sensitivity to disease severity and progression. Nonetheless, there is limited information regarding the sensitivity and specificity of the functional imaging modalities in the differential diagnosis of dementias. At present, the evidence does not support the use of functional imaging in isolation as a diagnostic tool. Rather, these imaging modalities may be considered as an adjunct to careful clinical assessment, either to improve diagnosis in early cases or to assist in subtyping difficult cases.

Organic brain disease in psychogeriatric patients: impact of symptoms and screening methods on the diagnostic process

Psychogeriatric patients are mentally affected by a heterogeneous group of diseases, traditionally classified as functional or organic brain disorders (OBDs). Here, we evaluate screening procedures with respect to revelation of underlying OBD. Fifty consecutive patients admitted to a psychogeriatric unit dedicated to late-onset psychiatric disease were included. Diagnosis at admission, symptoms, and time of onset of disease were determined blindly by an independent, experienced psychiatrist on the basis of referral documents and the interview written at admission. Subsequently, consensus established a clinical diagnosis (after psychiatric and neurologic evaluations) and a final diagnosis after the screening procedures (Cognistat and MMS-tests, electroencephalograms, computed tomography, and SPECT). Conventional criteria (ICD-10, ICPC) were used for diagnostic classification. Only 10 of the 50 patients were diagnosed with OBD at admission and an additional 7 patients following full clinical evaluations. At final diagnosis, 34 (of 46) patients were diagnosed with significant OBD. The Cognistat test had the largest diagnostic impact, with sensitivity/specificity values of 81%/60% for OBD.

[Vascular dementia: diagnostic challenge and treatment]

BACKGROUND

Treatment of vascular dementia depends on accurate diagnosis and criteria for evaluation of therapeutic responses that are not well standardized.

METHODS

Diagnostic criteria for vascular dementia, tools for the assessment of its clinical course and current treatment options are sequentially reviewed.

RESULTS

Strict diagnostic criteria with high specificity should be selected in clinical trials. Tools for sequential assessment are not standardized. Clinical endpoints of real value for patients and caregivers are usually excluded from analysis. Prevention of recurrent cerebrovascular events is the only known treatment for stabilization and eventually recovery of cognitive and behaviour disturbances. Benefit may be obtained by adapting hospital or home environment and introducing daily routines minimizing stress and fatigue. The use of non-specific cerebral stimulants and so-called neuroprotective drugs is controversial. Careful neuropsychological evaluation guiding management of specific deficits and the use of psychiatric drugs in selected situations may also be useful.

CONCLUSION

Strict criteria for the diagnosis of vascular dementia and for the evaluation of treatment responses should be used in drug trials. Aside the secondary prevention of stroke, no drug therapy influencing cognition or neuronal damage has been proved to be useful in patients with vascular dementia.

The role of SPECT scanning in a neuropsychiatry unit

OBJECTIVES

Single photon emission computerised tomography (SPECT) studies allow the assessment of cerebral blood flow and have been increasingly used as a clinical tool in neurology and neuropsychiatry. This paper examines the contribution of SPECT to the clinical management of patients with neuropsychiatric disorders, in particular patients with atypical or early onset dementia.

METHOD

All patients admitted to an eight-bed neuropsychiatry unit in a general hospital setting who had undergone SPECT scanning over a 15-month period were reviewed. Information was collected on clinical diagnosis, neuropsychological testing, structural neuroimaging and SPECT.

RESULTS

SPECT abnormalities were present in 88% of patients. The pattern of SPECT abnormality was concordant with structural neuroimaging in 65% of patients and concordant with neuropsychological testing in 82% of patients. The sensitivity and specificity of SPECT was 89%/79% for Alzheimer's disease and 56%/79% for frontotemporal dementias.

CONCLUSIONS

SPECT results must be interpreted in the context of other clinical and diagnostic assessments. In no single case was the clinical diagnosis made solely on the basis of a SPECT result. SPECT was of maximum clinical use in the diagnosis of frontotemporal dementias and in confirming the diagnosis of Alzheimer's dementia. SPECT was valuable in Lewy body dementia, vascular dementia and head injury. Its clinical utility in other psychiatric disorders remains unclear.

A clinical role for 99mTc-HMPAO SPECT in the investigation of dementia?

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Regional cerebral blood volume measured by dynamic susceptibility contrast MR imaging in Alzheimer's disease: a principal components analysis

Dynamic susceptibility contrast (DSC) MRI is an alternative to positron emission tomography (PET) and single photon emission computed tomography (SPECT) for the evaluation of cerebral hemodynamics in patients with Alzheimer's disease. DSC MRI allows the construction of high resolution images of cerebral blood volume (CBV) without the use of radionuclides or ionizing radiation. In this study, DSC MRI data were collected from 16 patients with probable Alzheimer's disease and 16 age-matched control subjects. Characteristic patterns of regional CBV variation were found using principal component analysis. Three such patterns were identified: a global variation pattern, an anterior-to-posterior CBV gradient, and a temporoparietal pattern. Group differences in the principal component scores associated with the global and temporoparietal patterns (P = .08 and P = .007, respectively) suggest that these deficits reflect characteristic CBV abnormalities in Alzheimer's disease. Using only these two scores, the Alzheimer's disease group was classified with a sensitivity of 81% and a specificity of 88%. Additionally, disease severity, as measured by the Mini-Mental State Examination (MMSE), was correlated significantly with the third principal component score (Pearson's r = .50, P = .05).

SPECT measurements of brain function in dementia; a review

A brief review of the role of SPECT (single photon emission computed tomography) in the diagnosis of dementing brain disease is given. Between 1990 and 1995 some 100 original articles deal with SPECT measurements with radioactive tracers of brain function in demented patients. The main field is measurement of regional cerebral blood flow (rCBF) but there is an increasing number of studies concerning receptor functions in the demented brain.

Neuropsychological, psychiatric, and cerebral blood flow findings in vascular dementia and Alzheimer's disease

BACKGROUND AND PURPOSE

Psychiatric, neuropsychological, and cerebral blood flow differences between patients with ischemic vascular dementia (IVD) or Alzheimer's disease (AD) were examined.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Neuropsychology of memory and SPECT in the diagnosis and staging of dementia of Alzheimer type

We studied the role of neuropsychology and SPECT imaging in the diagnosis and staging of dementia of Alzheimer type (DAT) in 33 patients with mild disease and 30 matched controls. Working, episodic, semantic and remote memory were assessed. For diagnosis, it was determined by logistic regression analysis that one of the memory tests (delayed verbal recall of the Doors and People Test) could correctly classify subjects as DAT or controls in 97% of cases. For staging, stepwise regression analysis using five of the memory tests could predict 70% of the variance in Mini Mental State Examination (MMSE) scores. The measures most useful for staging were tests of immediate recall, and tests of working, semantic and autobiographical memory. In a separate experiment, SPECT imaging on 31 of the above 33 patients and 24 different controls was used to address the issue of diagnosis and staging. 99Tc-HMPAO SPECT scans were analysed quantitatively to obtain measures of regional cerebral blood flow (rCBF). Logistic regression analysis showed that three of the SPECT regions of interest (left posterior temporal, right high frontal and right posterior temporal) could correctly classify subjects in 75% of cases. Of note was the fact that 39% of the DAT patients had normal SPECT scans. SPECT data were of limited use in modelling disease severity; only 38% of the variance in MMSE scores could be predicted from SPECT data. In addition, we found that the pattern of rCBF in DAT was much more heterogeneous than previously described.

Brain SPECT imaging of neuropsychiatric disorders

Brain imaging has become an integral part of the evaluation of neurological and psychiatric disorders. Functional imaging techniques, SPECT and PET, together with structural modalities, CT and MRI, are widely employed. Functional imaging studies are routinely used in the diagnostic workup of patients with well-characterized neurological disorders, such as epilepsy and brain tumors, and have a growing role in research on psychiatric disorders without known mechanisms such as depression and schizophrenia. Furthermore, many well-defined neurological disorders manifest prominent psychiatric symptomatology which may pose difficulties in differential diagnosis. This review addresses the current knowledge of SPECT findings in patients who present with psychiatric phenomena, associated with disorders at the interface of neurology and psychiatry.

Cerebral perfusion and psychometric testing in military amateur boxers and controls

The objective was to compare two neurophysiological variables in active amateur boxers with non-boxing sportsmen. 41 boxers and 27 controls were given psychometric tests: 34 boxers and 34 controls underwent technetium-99m hexamethylpropyleneamineoxime single photon emission computerised tomography (Tc-99m HMPAO SPECT) cerebral perfusion scans. The controls performed better at most aspects of the psychometric tests. Boxers who had fought fewer bouts had a tendency to perform better at psychometric tests than those boxers who had fought more bouts. Tc-99m HMPAO SPECT cerebral perfusion scanning showed that controls had less aberrations in cerebral perfusion than the boxers. In conclusion, significant differences were shown in two neurophysiological variables between young amateur sportsmen who box and those who do not. The long term effects of these findings remain unknown.

Electroencephalography and single photon emission computed tomography in dementia: a comparative study

A series of elderly patients with dementia of Alzheimer type (AD), multi-infarct dementia (MID) and functional (non-organic) psychiatric illness (major depressive disorder) were selected according to DSM-III-R criteria and received: a battery of cognitive tests, EEG and Single Photon Emission Computed Tomography (SPECT) using 99mTc HMPAO. The EEG and SPECT scans were examined independently of the clinical data. The former were divided into two abnormal categories, those showing AD type change and vascular change respectively, and a normal group. The SPECT scans were classified as follows: a SPECT rCBF pattern showing bilateral temporoparietal perfusion deficits (AD type); those showing single focal perfusion deficits or multiple areas of low perfusion in the cerebral cortex suggestive of ischaemic change (vascular type SPECT picture); a mixed AD/MID pattern; and those with normal scan findings. There were significant associations between clinical diagnosis, EEG rating and SPECT rCBF pattern, approximately three-quarters of AD and MID patients having the predicted EEG and scan changes. Normal EEG recordings were more common in the MID patients. The two tests agreed in about two-thirds of cases, with no consistent pattern apparent in the cases with divergent findings. Each test misclassified a minority of dementia patients, but in only one patient were both investigations normal. Almost half of the so called 'functionally ill' patients had abnormal rCBF changes, showing mainly vascular changes while one-fifth had abnormal EEGs.