technetium-tc-99m-bicisate and Dementia

Over the last decade the interest towards functional neuroimaging has gradually increased, especially in the field of neurodegenerative diseases. At present, diagnosis of dementia is mostly clinical. Numerous modalities of neuroimaging are today available, each of them allowing a different aspect of neurodegeneration to be investigated. Although during the last period many have predicted a forthcoming disappearance of SPECT imaging in favour of the PET imaging, many new radiotracers SPECT, dual-SPECT tracers techniques and receptor targeting designed radiopharmaceuticals are currently at study. Besides, last decade has also assisted to the development of new SPECT imaging systems, most of them integrated with other imaging modalities (MRI, CT, ultrasound techniques), granting improved imaging capabilities. All these improved conditions, especially appealing for the neuroimaging, together with the new radiopharmaceuticals in development may renovate the interest for SPECT clinical applications.

Topics: Cysteine; Dementia; Functional Neuroimaging; Humans; Magnetic Resonance Imaging; Organotechnetium Compounds; Positron-Emission Tomography; Practice Guidelines as Topic; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Establishing survival rate in frontotemporal lobar degeneration (FTLD) is a clinical challenge for defining disease outcomes and monitoring therapeutic interventions. Using the latent profile analysis (LPA) approach, we have previously suggested that FTLD patients can be grouped into specific phenotypes- "pseudomanic behavior" (LC1), "cognitive" (LC2), and "pseudodepressed behavior" (LC3)-on the basis of neuropsychological, functional, and behavioral data.. The aim of this study was to evaluate the rate of survival in FTLD, to identify predictors of survival, and to determine the likely usefulness of LPA in defining prognosis.. A total of 252 FTLD patients entered the study. A clinical evaluation and standardized assessment were carried out, as well as a brain imaging study. LPA on neuropsychological, functional, and behavioral data was performed. Each patient was followed up over a 5-year period, and institutionalization or death was considered.. The survival rate was associated neither with demographic characteristics, co-morbidities, family history for dementia, nor clinical diagnosis. The presence of the three LC phenotypes was confirmed by LPA. A different survival rate was predicted by LCs, the worse prognosis being found in LC1 (hazard ratio [HR] = 15.7, 95% confidence interval [CI] = 7.2-34.9, p < 0.001, reference LC3). LC2 had a worse prognosis compared to LC3 (HR = 2.07, 95% CI = 0.98-4.37, p = 0.06). Greater hypoperfusion in the orbitomesial frontal cortex was specifically associated with LC1 compared with the other LCs.. A data-driven approach regarding neuropsychological and behavioral assessment might be useful in clinical practice for defining a FTLD prognosis and hopefully will lead to the possibility of identifying patient groups for the evaluation of treatment response in future trials.

Topics: Adult; Aged; Brain; Cognition Disorders; Cysteine; Dementia; Female; Follow-Up Studies; Humans; Male; Middle Aged; Neuropsychological Tests; Organotechnetium Compounds; Prognosis; Radioactive Tracers; Severity of Illness Index; Survival Rate

A technique for serial noninvasive cerebral blood flow measurements at pre- and post-acetazolamide (Diamox) test was newly developed using 99mTc-ECD without blood sampling. Baseline mean cerebral blood flow (mCBF) was measured from graphical analysis of time activity curves for brain and aortic arch obtained from radionuclide angiography by injection of 370-555 MBq 99mTc-ECD. The first SPECT study was performed immediately after intravenous administration of 1 g of Diamox, then baseline regional cerebral blood flow (rCBF) was calculated using Lassen's correction algorithm. Immediately after the stop of the first SPECT study, additional 555-740 MBq of 99mTc-ECD was administered, thereafter the second SPECT study was started. Post-Diamox SPECT images were obtained by subtraction of the first baseline images from the second images. Using Lassen's algorithm, post-Diamox mCBF was estimated from the baseline mCBF, the baseline mean SPECT counts, and post-Diamox mean SPECT counts corrected for administered dose and imaging time. Post-Diamox rCBF was obtained from the post-Diamox mCBF and the post-Diamox mean SPECT counts using Lassen's algorithm. Coefficient variation was shown 2.7% and 3.5%: mCBF and rCBF, respectively in test-retest results in six patients without Diamox administration. Nine demented patients without vascular disorders showed significant mCBF increase of 35.7% on the average by post-Diamox. In conclusion, this simplified method is practically useful for measuring CBF at pre- and post-Diamox test within short period of time without any blood sample.

Topics: Acetazolamide; Aged; Aged, 80 and over; Brain; Cysteine; Dementia; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Regional Blood Flow; Tomography, Emission-Computed, Single-Photon

We herein report the case of a 65-year-old woman who presented with the subacute onset of dementia and subsequently developed abnormal behavior and a gait disturbance. Her condition transiently improved; however, within one month, she became drowsy and poorly responsive, with limb chorea and urinary incontinence. Her history of frequently using charcoal led us to diagnose her with carbon monoxide (CO) poisoning. The findings of this case and a literature review suggest that subacute dementia due to CO poisoning recovers late, after a year or more, in patients above sixty years of age, and both hyperbaric oxygen and corticosteroid pulse therapy should be considered in such cases, even after one month.

Topics: Adrenal Cortex Hormones; Aged; Brain; Carbon Monoxide Poisoning; Cysteine; Dementia; Female; Gait; Humans; Hyperbaric Oxygenation; Leukoencephalopathies; Magnetic Resonance Imaging; Movement Disorders; Organotechnetium Compounds; Radiopharmaceuticals; Time Factors; Tomography, Emission-Computed, Single-Photon

While lesion patterns in white matter have been extensively reported in the literature on carbon monoxide (CO) intoxication, reports on the effects on gray matter damage are less common. The aim of this study was to investigate regional damage patterns focusing on gray matter using (99m)Tc ethyl cysteinate dimer (ECD) brain single photon emission computed tomography (SPECT) and brain magnetic resonance imaging (MRI) with clinical correlation.. Thirty CO intoxication patients and 15 age-matched controls were enrolled for standard neuropsychological tests. Six regions of interest (ROI) were analyzed qualitatively and quantitatively in both SPECT and MRI. The patients were further grouped according to clinical dementia rating score. The sensitivity, specificity, and positive and negative predictive ratios related to dementia from both imaging modalities were further examined.. In SPECT qualitative analysis, basal ganglia (n = 16) were the most common regions showing lower perfusion patterns. The basal ganglion and temporal, frontal, and parietal regions of the patients with dementia showed significantly lower perfusion patterns. MRI had a higher sensitivity while SPECT had a higher specificity and positive and negative predictive ratios in correlation with dementia among the ROI. The perfusion indices of the frontal, temporal, basal ganglion, and thalamus were inversely correlated with clinical severity (all P < 0.05).. Our findings suggest that a multiparametric neuroimaging approach may provide more information in revealing the anatomical and neurobehavioral results in patients after CO intoxication. The atrophy pattern seen in MRI may explain in part the possible mechanism of the hypoperfusion state seen in SPECT.

Topics: Adult; Brain; Carbon Monoxide Poisoning; Cerebrovascular Circulation; Cognition; Cysteine; Dementia; Female; Humans; Magnetic Resonance Imaging; Male; Neuropsychological Tests; Organotechnetium Compounds; Predictive Value of Tests; Tomography, Emission-Computed, Single-Photon

The main clinical feature of dementia in Parkinson's disease is a dysexecutive syndrome. The neuropathology of PD dementia (PDD) is likely multifactorial and affects several neuronal populations. There is evidence that Parkinson's disease dementia is associated with a cholinergic deficit, supporting the therapeutic role of cholinesterase inhibitors, which are already first-line agents in the treatment of Alzheimer's disease. The paper includes short report on a pilot study with description of cognitive and imaging profiles in patients with mild to moderate stage of Parkinson disease dementia (PDD).. A random sample of 16 patients with clinical diagnostic criteria for probable PDD was included in the study. Patients were characterized with mild to moderate cognitive decline slightly depressive mood and moderate motor performance. Brain perfusion [(99m)Tc]ECD / SPECT and structural MRI with emphasis on evaluation of the degree of cortical atrophy and the medial temporal atrophy index was performed. All patients had detailed neuropsychological evaluation using a "cognitive process approach". Neuropsychological data were correlated voxel-wise with normalized brain perfusion images, creating whole-brain correlation maps.. Previously reported generalized cognitive impairment in PDD with predominant executive, visouspatial and attentional deficits was confirmed. Performance on specific cognitive measures was correlated with perfusion brain SPECT findings. It could be speculated that different pathological mechanisms underlie widespread significant brain perfusion decrements in temporal, parietal and frontal regions.

Topics: Aged; Antiparkinson Agents; Atrophy; Brain Mapping; Cerebral Cortex; Cholinesterase Inhibitors; Cysteine; Dementia; Female; Humans; Magnetic Resonance Imaging; Male; Neuropsychological Tests; Organotechnetium Compounds; Parkinson Disease; Pilot Projects; Psychometrics; Statistics as Topic; Tomography, Emission-Computed, Single-Photon

Literature data on Alzheimer's disease suggest that years of schooling and occupational level are associated with a reserve mechanism. No data on patients with behavioral variant frontotemporal dementia (bvFTD) are available yet.. To evaluate the impact of education, occupation, and midlife leisure activities on brain reserve in bvFTD.. Fifty-four bvFTD patients entered the study and underwent neuropsychological and behavioral assessment, including the FTD-modified Clinical Dementia Rating for FTD (FTD-modified CDR), and SPECT imaging. We tested for the linear correlation of educational and occupational level, and midlife leisure activities with regional cerebral blood flow (rCBF), controlling for demographic variables (age and gender) and for cognitive performance (FTD-modified CDR) (statistical parametric mapping).. A significant relationship between higher educational and occupational attainments and lower rCBF in medial frontal cortex and dorsolateral frontal cortex, bilaterally, was found (p < 0.005). When midlife leisure activities were considered, no correlation was found. The correlation between a reserve index, accounting for both educational and occupational level, and rCBF showed the same pattern of hypoperfusion.. This study suggests that education and occupation act as proxies for reserve capacity in bvFTD. These lifestyle attainments may counteract the onset of this genetic-based disease in at-risk individuals.

Topics: Aged; Aging; Behavior; Brain; Brain Mapping; Cerebrovascular Circulation; Cysteine; Dementia; Education; Female; Humans; Image Processing, Computer-Assisted; Leisure Activities; Male; Middle Aged; Neuropsychological Tests; Occupations; Organotechnetium Compounds; Radionuclide Imaging; Radiopharmaceuticals

To clarify the features of pure akinesia (PA) and progressive supranuclear palsy (PSP) in the early stage of disease.. We investigated 15 PA and 41 PSP patients' clinical and radiologic features including head MRI, ethyl cysteinate dimmer-single photon emission-computed tomography (ECD-SPECT) and iodine-123 meta-iodobenzyl guanidine (123I-MIBG) myocardial scintigraphy. In ECD-SPECT study, cerebral blood flow (CBF) reduction was quantitatively expressed as Z-score, and that in the frontal lobe was evaluated.. Many PSP patients claimed falls as the initial symptom but no PA patients did. Eye movement, as well as optokinetic nystagmus elicitation, was more frequently disturbed in PSP. Dementia, dysarthria and rigidity were also more frequent in PSP than in PA. Midbrain tegmentum atrophy in head MRI was more frequently observed in PSP. CBF in the frontal lobe, especially in the frontal eye field, was significantly lower in PSP than in PA. MIBG myocardial scintigraphy showed no difference between two groups.. PA and PSP show distinct symptoms from the early stage, indicating that they are distinct disorders. The occurrence of falls and eye movement disturbance, as well as CBF reduction at the frontal eye field, is very important for distinguishing these disorders.

Topics: Aged; Atrophy; Cerebrovascular Circulation; Cysteine; Dementia; Diagnosis, Differential; Eye Movements; Female; Frontal Lobe; Humans; Iodine Radioisotopes; Magnetic Resonance Imaging; Male; Movement Disorders; Muscle Rigidity; Nystagmus, Optokinetic; Organotechnetium Compounds; Radiography; Supranuclear Palsy, Progressive; Time Factors; Tomography, Emission-Computed, Single-Photon

We performed brain perfusion single photon emission computed tomography (SPECT) to evaluate computer-assisted automated discrimination of early Alzheimer's disease (AD) from other types of dementia using the easy Z-score imaging system (eZIS).. eZIS analysis of brain perfusion SPECT images was used in patients with early AD, vascular dementia (VD), mixed dementia (VD + AD), frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), and normal controls. Significant changes in regional cerebral blood flow (rCBF) in the volume of interest were assessed in the posterior cingulate gyrus, precuneus and parietal cortices; the severity and extent of decreases in rCBF and the ratio of the extent of the decrease in rCBF to the decrease in whole-brain blood flow (rCBF ratio) were determined.. The severity of the decrease in rCBF in AD patients was significantly greater than in VD and FTD patients and controls. The extent of the decrease in rCBF in AD patients was significantly greater than in FTD patients and controls. The rCBF ratio in AD patients was higher than in VD and FTD patients and controls.. The eZIS indices, especially the rCBF ratio, may be useful in establishing the differential diagnosis between early-stage AD and FTD or VD, but the differentiation of AD from VD + AD or DLB remains difficult.

Topics: 3-Iodobenzylguanidine; Aged; Aged, 80 and over; Alzheimer Disease; Brain; Cysteine; Dementia; Dementia, Vascular; Diagnosis, Differential; Disease Progression; Female; Humans; Image Processing, Computer-Assisted; Lewy Body Disease; Male; Middle Aged; Neuropsychological Tests; Organotechnetium Compounds; Predictive Value of Tests; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon

Syphilis is a recurrent treponematosis of acute and chronic evolution. In general it is either sexually or congenitally transmitted. Primary syphilis appears as a single and painless lesion. Secondary syphilis may manifest years later, the secondary bacteremic stage is accompanied by generalized mucocutaneous lesions. Tertiary disease can be disseminated to bones and virtually any organ, involving principally the ascending aorta and the central nervous system. Nuclear medicine provides diagnostic methods in case of skeletal manifestations by bone scan - identifying periostitis and osteomyelitis. Hepatic gummas can be imaged by 99m-Tc-colloid liver scintigraphy. In neurosyphilis brain perfusion SPECT enables imaging of cerebral involvement by small vessel endarteritis resulting from syphilitic vascular disease. 18-FDG PET is also useful to evaluate neurosyphilis, a reduction of brain glucose consumption is observed. The technique adequately enables imaging of therapeutic response and might be superior to morphologic imaging. We present our experiences with these nuclear medicine methods in patients with neurolues. The incidence of neurolues is estimated at 2 per 100.000 inhabitants worldwide, migration processes might bring a re-emergence of this disease to Austria and other developed countries of the EU. Scintigraphic methods should be kept in mind for diagnostic evaluation of neurosyphilis.

Topics: Adult; Basal Ganglia; Blood Glucose; Brain; Cysteine; Dementia; Diagnosis, Differential; Diseases in Twins; Fluorodeoxyglucose F18; Frontal Lobe; Humans; Male; Middle Aged; Neurosyphilis; Organotechnetium Compounds; Positron-Emission Tomography; Sensitivity and Specificity; Syphilis, Cardiovascular; Syphilis, Congenital; Tomography, Emission-Computed, Single-Photon

In the present study we aimed at evaluating the prevalence and the associated clinical, neuropsychological and behavioral features of extrapyramidal symptoms in Frontotemporal Dementia (FTD) patients. Seventy-five patients fulfilling clinical criteria of FTD were consecutively enrolled. Each patient underwent clinical and extrapyramidal sign examination, and neuropsychological and behavioral disturbance evaluation. Each patient was submitted to both brain MRI and SPECT, documenting frontotemporal atrophy/hypoperfusion pattern. Parkinsonian symptoms in FTD were associated with a specific endophenotype characterized by higher incidence of psychotic symptoms, memory deficits and psychomotor speed ability abnormalities. Careful description of the spectrum of presentation of FTD may be of help for further understanding the underpinnings of the disease.

Topics: Activities of Daily Living; Aged; Basal Ganglia Diseases; Cognition; Cysteine; Dementia; Female; Humans; Magnetic Resonance Imaging; Male; Neuropsychological Tests; Organotechnetium Compounds; Psychiatric Status Rating Scales; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon

Topics: Aged; Brain; Carotid Artery, Internal; Carotid Stenosis; Cerebrovascular Circulation; Cysteine; Dementia; Humans; Magnetic Resonance Angiography; Male; Organotechnetium Compounds; Radiography; Sensitivity and Specificity; Syncope; Tomography, Emission-Computed, Single-Photon

We present a 61-year-old male patient with progressive dementia. A brain SPECT with Tc-99m-bicisate was performed for confirmation of clinically suspected Alzheimer-dementia. At the time of the SPECT-investigation marked apraxia and aphasia besides severe dementia were present. Electrophysiological as well as anatomical neuroimaging findings showed non-diagnostic alterations. SPECT revealed distinct perfusion defects, which made Alzheimer Dementia unlikely. The further course of the patient was determined by rapidly progressive deterioration with development of akinetic mutism. Thereafter, increased levels of neuron-specific enolase as well as 14-3-3 proteins were found in the cerebro-spinal fluid (CSF). The patient finally died with signs of cerebral decortication. Due to the clinical course and the CSF-findings the patient's final diagnosis was Creutzfeldt-Jakob-disease, nevertheless no autopsy was performed. The presented case report underscores the clinical utility of perfusion brain SPECT in the differential diagnosis of dementias.

Topics: Brain; Cysteine; Dementia; Diagnosis, Differential; Disease Progression; Humans; Male; Middle Aged; Mutism; Organotechnetium Compounds; Radiopharmaceuticals; Syndrome; Tomography, Emission-Computed, Single-Photon

Anatomical localization requires establishing an anatomical space within the image matrix. We developed a fast, fully automated method to establish the image orientation for 99mTc-ethylcysteinate dimer (ECD) brain SPECT images.. The image orientation of ECD brain SPECT images was established in four stages. First, the brain surface was edge-detected as an isosurface at an adaptive threshold. Second, a "convex hull" was determined for the isosurface to minimize regional variability in brain shape. A principal axis transformation and a symmetry vector analysis were applied to the convex hull to resolve the craniocaudal direction and to estimate the midsagittal plane. Third, the brain orientation was refined from this estimate by location of the interhemispheric fissure, the tentorial groove and the frontotemporal groove on the isosurface. Last, the intercommissural (anterior commissure-posterior commissure, or AC-PC) line was detected on the midsagittal slice, and the Talairach grid was scaled to fit the maximal brain dimensions from the AC-PC line.. The average absolute errors were 2.3 degrees +/- 1.5 degrees and 1.08 mm +/- 1.11 mm for the midsagittal plane (n = 24) and 2.04 degrees +/- 0.80 degrees, 2.0% +/- 1.8% of the brain length and 2.3% +/- 2.2% of the brain height for the AC-PC line (n = 8). In addition, this program successfully established the image orientation in 94 of 100 clinical ECD brain SPECT studies. Processing time was <40 sec for 128 x 128 x 50 matrices on a DEC Alpha workstation.. We have developed a fast, robust and fully automated method that determines the orientation of ECD brain SPECT images. This objective method of standardizing the image orientation should be useful for anatomical localization and clinical interpretation of these images.

Topics: Adult; Aged; Algorithms; Brain; Cysteine; Dementia; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Radiopharmaceuticals; Reference Values; Stereotaxic Techniques; Tomography, Emission-Computed, Single-Photon

Topics: Adult; Aged; Brain; Cerebrovascular Disorders; Child, Preschool; Cysteine; Dementia; Epilepsy; Humans; Organotechnetium Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Amyotrophic Lateral Sclerosis; Cerebrovascular Circulation; Cysteine; Dementia; Female; Frontal Lobe; Humans; Middle Aged; Organotechnetium Compounds; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon

Dementia of the Alzheimer-type (DAT) is characterized by progressive cognitive decline, variably combined with frontal lobe release signs, parkinsonian symptoms and myoclonus. The features of diffuse Lewy body disease (DLBD), the second most common cause of degenerative dementia, include progressive cognitive deterioration, often associated with levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, psychotic symptoms (visual and auditory hallucinations, depression), hypersensitivity to neuroleptics and orthostatic hypotension. A recent report suggests that positron emission tomography studies in patients with degenerative dementia may be useful in the differential diagnosis of DAT and DLBD. However, the diagnostic role of single-photon emission tomography (SPET) studies remains to be established. The aim of this study was therefore to evaluate regional cerebral perfusion [with either technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPET] and striatal dopamine transporter density [using iodine-123 2 beta-carboxymethoxy-3 beta-[4-iodophenyl]tropane (123I-beta-CIT) SPET] in patients with DAT and DLBD. Six patients with probable DAT and seven patients with probable DLBD were studied. Blinded qualitative assessment by four independent raters of 99mTc-HMPAO or 99mTc-ECD SPET studies revealed bilateral temporal and/or parietal hypoperfusion in all DAT patients. There was additional frontal hypoperfusion in two patients and occipital hypoperfusion in one patient. In the DLBD group, regional cerebral perfusion had a different pattern. In addition to temporoparietal hypoperfusion there was occipital hypoperfusion resembling a horseshoe defect in six of seven patients. In the DAT group, the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was 2.5 +/- 0.4, with an increase to 5.5 +/- 1.1 18 h after tracer injection. In comparison, in the DLBD patients the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was significantly reduced to 1.7 +/- 0.3, with a modest increase to 2.1 +/- 0.4 18 h after tracer injection (P < 0.05, Scheffe test, ANOVA). These results suggest that 99mTc-HMPAO or 99mTc-ECD and 123I-beta-CIT SPET may contribute to the differential diagnosis between DAT and DLBD, showing different perfusion patterns and more severe impairment of dopamine transporter function in DLBD than in DAT.

Topics: Aged; Alzheimer Disease; Brain; Carrier Proteins; Case-Control Studies; Cocaine; Cysteine; Dementia; Diagnosis, Differential; Dopamine; Dopamine Plasma Membrane Transport Proteins; Female; Humans; Iodine Radioisotopes; Male; Membrane Glycoproteins; Membrane Transport Proteins; Middle Aged; Nerve Tissue Proteins; Organotechnetium Compounds; Oximes; Parkinson Disease; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Mean cerebral blood flow (mCBF) was measured by SPECT using the 99mTc-ECD-Patlak-Plot method in a selected group of 61 normal non-hospitalized subjects aged 51 to 91 years. The mCBF values showed 48.4 +/- 4.7 ml/100 g/min in aged 50-59 years group, 49.9 +/- 5.9 ml/100 g/min in aged 60-69 years group, 46.4 +/- 6.5 ml/100 g/min in aged 70-79 group, 38.0 +/- 3.7 ml/100 g/min in aged 80-89 years group, 38.9 ml/100 g/min in aged 90-99 years group. There was a statistically significant reduction of mCBF with advancing age (R = -0.41; p = 0.001). Women have significantly higher mCBF values than men up to aged 70 years group. In this study, there was no significant laterality in the mCBF between right and left hemispheres in all decade groups. The history of hypertension, alcohol consumption, and cigarette smoking failed to show significant difference in the mCBF values. The present study shows that normal aging is associated with mCBF reduction.

Topics: Aged; Aged, 80 and over; Aging; Brain; Cerebral Infarction; Cerebrovascular Circulation; Cysteine; Dementia; Female; Humans; Male; Organotechnetium Compounds; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon

To characterize a recently introduced cerebral perfusion tracer, 99mTc-bicisate, single photon emission computed tomography (SPECT) images of 99mTc-bicisate were compared with CBF images obtained by positron emission tomography (PET) using the 15O steady-state method in 10 cases of cerebrovascular disease and dementia. 99mTc-Bicisate SPECT and PET CBF images showed a similar distribution pattern except for two cases with subacute stroke, in which 99mTc-bicisate showed less uptake than CBF in the infarcted area where oxygen metabolism was severely diminished. Comparison of 99mTc-bicisate uptake and CBF in the other eight cases showed less contrast between high- and low-flow regions in 99mTc-bicisate SPECT. Although the SPECT count ratio of cerebral structures to cerebellum showed a good correlation with CBF ratio, it gradually deviated from the linear relationship in the high-flow range. Assuming this nonlinear relationship is due to the limited extraction of the tracer, we estimated the permeability-surface area product (PS) value by a nonlinear least-squares curve-fitting procedure. The correction of the nonlinear relationship using the estimated PS value and a table lookup method resulted in an excellent linear relationship between corrected SPECT counts and CBF.

Topics: Adult; Aged; Brain; Capillary Permeability; Cerebrovascular Circulation; Cerebrovascular Disorders; Cysteine; Dementia; Female; Humans; Male; Middle Aged; Models, Cardiovascular; Organotechnetium Compounds; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed