Showing papers on "Perfusion scanning published in 1993"

Selection of the optimal nonexercise stress for the evaluation of ischemic regional myocardial dysfunction and malperfusion. Comparison of dobutamine and adenosine using echocardiography and 99mTc-MIBI single photon emission computed tomography.

Abstract: BACKGROUND. The mechanisms of action of exercise-simulating and vasodilator stressors support their combination with imaging techniques that evaluate left ventricular function and perfusion, respectively. However, reported accuracies of either pharmacological stress together with two-dimensional echocardiography (2DE) or single photon emission computed tomography (SPECT) of myocardial perfusion are similar. The purpose of this study was to establish the optimal stress for each imaging technique by comparing the results of digitized 2DE and 99mTc-methoxyisobutyl isonitrile (MIBI) SPECT using both dobutamine and adenosine stresses in the same patients and conditions. METHODS AND RESULTS. Ninety-seven consecutive patients without evidence of previous infarction undergoing coronary angiography for clinical indications were studied prospectively. Dobutamine was infused during clinical, ECG, and echocardiographic monitoring in dose increments from 5 to 40 micrograms.kg-1.min-1. Adenosine was infused under the same conditions in doses of 0.10, 0.14, and 0.18 mg.kg-1.min-1. For each protocol, the end points were achievement of peak dose, development of severe ischemia, or intolerable side effects. At peak stress, 20 mCi of MIBI was injected, and SPECT imaging was performed 2 hours later; abnormal poststress images were compared with resting SPECT. Digitized 2DE images were compared qualitatively before, during, and after stress in a cine-loop display. Significant coronary disease (n = 59 patients) was defined by the quantification of > 50% stenosis in a major epicardial vessel. The sensitivity of adenosine 2DE was 58%, less than those of adenosine MIBI (86%, p = 0.001), dobutamine 2DE (85%, p = 0.001), and dobutamine MIBI (80%, p = 0.01). Their respective specificities were 87%, 71%, 82%, and 74% (p = NS). The accuracy of adenosine 2DE was 69%, compared with 80% for adenosine MIBI (p < 0.001), 84% for dobutamine 2DE (p = 0.001), and 77% for dobutamine MIBI (p = 0.005); the latter three did not differ significantly in either sensitivity or accuracy. CONCLUSIONS. This prospective, direct comparison of alternative pharmacological stresses in patients without myocardial infarction shows vasodilator stress scintigraphy and dobutamine stress echocardiography and scintigraphy to share equivalent levels of sensitivity. All three are significantly more sensitive than adenosine stress echocardiography. Dobutamine stress may be used for wall motion or perfusion imaging, but adenosine stress is best combined with perfusion scintigraphy.

Contrast-enhanced first pass myocardial perfusion imaging: Correlation between myocardial blood flow in dogs at rest and during hyperemia

Abstract: The sensitivity of contrast-enhanced MR first pass perfusion imaging in detection and quantification of hypoperfused myocardium was evaluated using an instrumented, closed-chest dog model where graded regional hypoperfusion was induced by applying predetermined levels of stenosis to the left anterior descending artery (LAD). All measurements were performed at rest and under stress induced by dipyridamole (DIP). Myocardial perfusion was assessed both with MR and radiolabeled microspheres injected immediately before the administration of the MR contrast agent. Ultrafast MR imaging was performed using a Turbo FLASH sequence with a 180 degrees inversion prepulse. A Gd-DTPA bolus was injected into the left atrium and T1-weighted images were acquired with every heart beat. Signal intensity measured from the images in regions of the LAD and left circumflex (LCx) perfusion beds was plotted against time to generate signal intensity versus time curves (SI time curve). Various flow indices were derived according to the indicator dilution theory, and compared with and without volume correction due to vasodilation to the myocardial blood flow (MBF) calculated from radiolabeled microspheres. Correlation of the MR and MBF data demonstrated that different transmural and regional myocardial perfusion levels can be easily visualized in the perfusion images and accurately monitored by the SI time curves. Detection of the impairment of myocardial perfusion improved significantly after administration of DIP. The inverse mean transit time calculated from the SI time curve was found to yield a linear correlation to absolute MBF derived from the microsphere data. These results suggest that with intracardiac injections of exogenous contrast agent, myocardial perfusion can be assessed parametrically with first pass contrast enhanced ultrafast MRI.

Functional images of hepatic perfusion obtained with dynamic CT.

Abstract: A dynamic computed tomographic (CT) technique for separate quantification of arterial and portal components of liver perfusion with functional imaging was developed and used to study 24 livers. A single-location dynamic sequence was performed after intravenous administration of a 50-mL bolus of contrast medium. The time to maximum splenic enhancement was used to differentiate arterial and portal phases, and the maximal slopes of the liver time-density curve in each phase were used to calculate both arterial and portal perfusion. The arterial/total perfusion ratio was also calculated. The values of these parameters for individual pixels were used to create functional images. Arterial perfusion was increased in patients with metastases and cirrhosis. Portal perfusion was reduced in patients with cirrhosis. Functional images were successfully created in all but one case. The technique enables quantification and functional mapping of several perfusion parameters with a spatial resolution greater than that ach...

Cerebral Perfusion and Neuropsychological Consequences of Chronic Cocaine Use

Abstract: Research indicates that cocaine significantly constricts the cerebral vasculature and can lead to ischemic brain infarction. Long-term effects of intermittent or casual cocaine use in patients without symptoms of stroke or transient ischemic attack were investigated. Single-photon emission computed tomography with xenon-133 and [99mTc]hexamethylpropyleneamine oxime, magnetic resonance imaging, and selected neuropsychological measures were used to study cerebral perfusion, brain morphology, and cognitive functioning. Patients were drug free for at least 6 months before evaluation. All showed regions of significant cerebral hypoperfusion in the frontal, periventricular, and/or temporal-parietal areas. Deficits in attention, concentration, new learning, visual and verbal memory, word production, and visuomotor integration were observed. This study indicates that long-term cocaine use may produce sustained brain perfusion deficits and persistent neuropsychological compromise in some subgroups of cocaine-abusing patients.

Imaging Tumor Hypoxia and Tumor Perfusion

Abstract: Tumor perfusion and oxygenation status have been suggested as factors which may influence treatment outcome in cancer patients. Nuclear medicine assays of tumor perfusion [99mTc-hexamethylpropylenamine oxime (HMPAO) and tumor hypoxia [123I-iodoazomycin arabinoside (IAZA)] have recently been developed and described. We report on measurements of perfusion and oxygenation status of 27 tumors in 22 patients using these probes. An inverse correlation between tumor uptake of HMPAO and IAZA was measured (p

Diffusion and perfusion magnetic resonance imaging studies to evaluate a noncompetitive N-methyl-D-aspartate antagonist and reperfusion in experimental stroke in rats.

Abstract: Diffusion magnetic resonance imaging (MRI) can quantitatively detect focal ischemic injury within minutes of onset, and perfusion MRI can evaluate the brain's microcirculation. N-Methyl-D-aspartate (NMDA) antagonists and reperfusion can reduce lesion size in stroke models. We used diffusion and perfusion MRI to evaluate the in vivo effects of a noncompetitive NMDA antagonist, CNS 1102, in a temporary ischemia model. Sixteen Sprague-Dawley rats underwent suture occlusion of the middle cerebral artery. Fifteen minutes after occlusion, animals were randomly assigned to treatment with CNS 1102 (n = 10) or placebo (n = 6), receiving a bolus of 1.13 mg/kg at that time and an infusion of 0.785 mg.kg-1.h-1 for the next 165 minutes. The placebo group received a saline bolus and infusion. Diffusion MRI studies by a spin-echo technique were initiated 30 minutes after occlusion and repeated every 30 minutes for the next 3 hours. Perfusion MRI studies were obtained using echo-planar imaging after injection of superparamagnetic iron oxide particles, immediately before and 15 minutes after withdrawal of the occluder at 3 hours after middle cerebral artery occlusion. At 24 hours, the animals were clinically evaluated (scale of 0 to 5) and electively killed, and the brain was stained with triphenyltetrazolium chloride to evaluate infarct size. Diffusion imaging demonstrated markedly reduced ischemic lesion area in the CNS 1102 group during occlusion--10.5 +/- 7.3% (mean +/- SEM) of the ischemic hemisphere (optic chiasm slice) at 30 minutes after occlusion versus 50.0 +/- 2.7% of the hemisphere in controls (P < .02). With reperfusion after 3 hours of temporary ischemia, diffusion imaging documented an additional 29% reduction of the ischemic lesion area in the CNS 1102-treated group (P < .01) compared with the prereperfusion ischemic lesion area, with no change in the placebo group. During occlusion, perfusion imaging demonstrated a relative signal intensity decline of 31.5 +/- 7.7% in controls and 83.4 +/- 7.6% in the CNS 1102 group (P < .005), indicating better perfusion in the latter group. After removal of the occluder, perfusion improved in both groups and was not significantly different. Post mortem infarct volume was 53.8 +/- 20.0 mm3 in the CNS 1102 group and 216.8 +/- 16.1 mm3 in the controls (P < .0001). Clinical outcome at 24 hours was 1.1 +/- 0.4 in the CNS 1102 group and 4.0 +/- 0.5 (scale of 0 to 5) in the controls (P < .005). This study demonstrates that CNS 1102 reduces early postischemic injury as documented by diffusion MRI and improves perfusion as documented by perfusion MRI and that reperfusion confers additional reduction of ischemic lesion size.

Regional Cerebral Blood Flow Improves with Treatment in Chronic Cocaine Polydrug Users

Abstract: Brain perfusion is abnormal in chronic cocaine users. To determine whether these perfusion abnormalities are reversible following treatment, we studied 10 cocaine-dependent polydrug users with 99mTc-HMPAO SPECT 2 to 3 days after admission to an inpatient treatment facility and at 7 to 8 days and 17 to 29 days after abstinence from drugs. The patients also received buprenorphine, an opioid mixed agonist-antagonist, beginning 10 days after admission and continuing to the end of the study. Imaging began 10-15 min after injection of 99mTc-HMPAO (20 mCi) using an annular gamma camera system. MRI was performed during hospitalization using a 1.5 Tesla system. SPECT and MRI were merged and five axial SPECT slices centered at the level of the basal ganglia were selected for analysis. Activity ratios were derived for cortical regions relative to cerebellar activity and were corrected for linearity with respect to regional cerebral blood flow. The cortical regions were classified as abnormal (activity ratio 0.72) based on the results of the first SPECT study. In abnormal zones, regional cerebral blood flow (rCBF) increased 11.0% +/- 9.0% at 7 to 8 days and 23.8% +/- 9.4% at 17 to 29 days after initiation of treatment. The increase in rCBF was 4.8% +/- 7.1% (7 to 8 days) and 11.1% +/- 8.0% (17 to 29 days) in borderline cortex and decreased 2.9% +/- 6.3% (7 to 8 days) and increased only 2.7% +/- 13.4% (17 to 29 days) in normal cortex. The increase in rCBF did not vary significantly by location. The perfusion defects observed in chronic cocaine polydrug users are partially reversible with short-term abstinence and buprenorphine treatment.

Magnetic resonance imaging of perfusion in the isolated rat heart using spin inversion of arterial water.

Abstract: Measurement of regional myocardial perfusion is important for the diagnosis and treatment of coronary artery disease. Currently used methods for the measurement of myocardial tissue perfusion are either invasive or not quantitative. Here, we demonstrate a technique for the measurement of myocardial perfusion using magnetic resonance imaging (MRI) with spin tagging of arterial water. In addition, it is shown that changes in perfusion can be quantitated by measuring changes in tissue T1. Perfusion images are obtained in Lan-gondorff-perfused, isolated rat hearts for perfusion rates ranging from 5 to 22 ml/g/min. The MRI-determined perfusion rates are in excellent agreement with perfusion rates determined from measurement of bulk perfusate flow (r = 0.98). The predicted linear dependence of the measured T1 (T1app) on per-fusion is also demonstrated. The ability of perfusion imaging to measure regional variations in flow is demonstrated with hearts in which perfusion defects were created by ligation of a (coronary artery. These results indicate that MRI of perfusion using spin inversion of arterial water gives quantitative maps of cardiac perfusion.

Quantification of regional myocardial perfusion with generator-produced 62Cu-PTSM and positron emission tomography

Abstract: BACKGROUNDNoninvasive assessment of regional myocardial perfusion at rest and after stress is important for the objective evaluation of the effects of coronary artery disease and its response to therapy. Centers that do not have cyclotrons rely on generator-produced radioisotopes for assessment of regional myocardial perfusion with positron emission tomography (PET). The aim of the present study was to develop and implement an approach to quantify regional myocardial perfusion using copper(II) pyruvaldehyde bis-(N4-thiosemicarbazone) (PTSM) labeled with the generator-produced, positron-emitting radionuclide 62Cu (t1/2 = 9.7 minutes).METHODS AND RESULTSRegional perfusion was estimated from dynamic PET scans after intravenous administration of 62Cu-PTSM in 21 studies in 13 intact dogs evaluated over a wide range of myocardial flow values. In 15 interventions in nine dogs, regional perfusion was also estimated with H2(15)O. Regional perfusion with 62Cu-PTSM was estimated from dynamic blood and tissue time-ac...

Clinical Nuclear Cardiology: State of the Art and Future Directions

Abstract: I. Radiopharmaceuticals/Tracer Kinetics Overview of Kinetics and Modeling Kinetics on a Cellular Level Role of Intact Biological Models for Evaluation of Radiotracers II. Instrumentation SPECT Processing, Quantification, and Display SPECT Artifacts Attenuation/Scatter/Resolution Correction: Physics Aspects Attenuation/Scatter Correction: Clinical Aspects Dynamic Cardiac SPECT Using Fast Data Acquisition Systems The New Generation PET/CT Scanners: Implications for Cardiac Imaging State of the Art Instrumentation for PET and SPECT Imaging in Small Animals III. Ventricular Function Cardiac Performance Regional and Global Ventricular Function and Volumes from SPECT Perfusion Imaging IV. Perfusion Imaging Coronary Artery Disease: Exercise Stress Coronary Artery Disease Detection: Pharmacologic Stress Prognosis Applications of Myocardial Perfusion Imaging: Exercise Stress Prognostic Value of Pharmacologic Stress Myocardial Perfusion Scintigraphy And Its Use In Risk Stratification Myocardial Perfusion Imaging Using Non-Radionuclide Techniques Cost Effectiveness of Myocardial Perfusion SPECT V. Disease/Gender Specific Issues Imaging in Women Imaging for Preoperative Risk Stratification Nuclear Imaging in Patients with a History of Coronary Revascularization Stress Myocardial Pefusion Imaging in Patients with Diabetes Mellitus Radionuclide Imaging in Heart Failure and Cardiomyopathies Imaging in Patients Receiving Cardiotoxic Chemotherapy Mechanistic and Methodological Considerations for the Imaging of Mental Stress Ischemia Measurement of Myocardial Blood Flow and Monitoring Therapy VI. Acute Coronary Syndromes Imaging Patients with Chest Pain in the Emergency Department Measuring the Efficacy of Therapy in Acute Myocardial Infarction with Technetium-99m-SESTAMIBI Imaging Risk Stratification After ST Elevation Acute MI Risk Stratification in Acute Coronary Syndromes VII. Viability Physiologic and Metabolic Basis of Myocardial Viability Imaging Assessment of Myocardial Viability with Thallium-201 and Technetium-Based Agents Assessment of Myocardial Viability With PET Comparison with Non-Nuclear Techniques VIII. Tracer Specific Imaging Techniques Fatty Acid Imaging Cardiac Neurotransmitter Imaging: SPECT Cardiac Neurotransmitter Imaging: PET Receptor Imaging IX. New Molecular Approaches New Molecular Approaches For Imaging of Angiogenesis and Hypoxia Noninvasive Detection of Cell Death in Myocardial Disorders Radionuclide Approach to Imaging of Inflammation in Atheroma for the Detection of Lesions Vulnerable to Rupture Molecular Imaging of Gene Products Imaging Myocardial Inflammation Section X: Mini-Atlas of Case Presentations

Iodine-123-IBZM Dopamine D2 Receptor and Technetium-99m-HMPAO Brain Perfusion SPECT in the Evaluation of Patients with and Subjects at Risk for Huntington's Disease

Abstract: Huntington's disease (HD) is pathologically characterized by neuronal loss and neuroreceptor alterations in the striatum, including a reduction in dopamine receptor density. We evaluated the clinical usefulness of 123I-iodobenzamide (IBZM) D2 receptor SPECT imaging and 99mTc-hexamethylpropyleneamineoxime (HMPAO) brain perfusion SPECT imaging by studying four early symptomatic HD patients, 20 asymptomatic subjects at risk for HD and 22 controls. Striatal D2 receptor binding and perfusion were measured semiquantitatively by calculating striatum-to-frontal cortex IBZM and HMPAO uptake ratios, respectively. The control IBZM ratio (1.58 +/- 0.06) declined with age at 1.5% per decade (r = -0.58, p < 0.005), whereas the HMPAO ratio (1.15 +/- 0.05) did not. All four symptomatic patients had decreased IBZM ratios and three patients also had decreased HMPAO ratios. Five of 20 at-risk subjects had decreased IBZM ratios and two subjects also had decreased HMPAO ratios. Three of the five at-risk subjects showed subtle nonchoreic neurological abnormalities. Decreased striatal D2 receptor binding thus may be detected by IBZM-SPECT in the asymptomatic as well as symptomatic groups, and these changes were more marked than perfusion deficits detected by HMPAO-SPECT. IBZM-SPECT thus appears to be a promising method for early diagnosis and preclinical detection of HD.

Perfusion and diffusion MR imaging of thromboembolic stroke.

Abstract: A carotid embolic stroke model in rats was studied with a combination of diffusion- and perfusion-sensitive magnetic resonance (MR) imaging at 47 T Capillary blood deoxygenation changes were monitored during formation of focal ischemia by acquiring multisection magnetic susceptibility-weighted echo-planar images A signal intensity decrease of 7% +/- 3 in ischemic brain (1% +/- 2 in normal brain) was attributable to a T2* decrease due to increased blood deoxygenation, which correlated well with subsequently measured decreases in the apparent diffusion coefficient The same multisection methods were used to track the first-pass transit of a bolus of dysprosium-DTPA-BMA [diethylenetriaminepentaacetic acid-bis(methylamide)] to assess relative tissue perfusion before and after stroke and after treatment with a thrombolytic agent Analysis of contrast agent transit profiles suggested a total perfusion deficit in ischemic tissue and essentially unchanged perfusion in normal brain tissue after stroke

Brain blood flow SPECT in temporary balloon occlusion of carotid and intracerebral arteries

Abstract: It is important to determine preoperatively which patients can tolerate permanent occlusion of a cervical internal carotid or cerebral artery when such a procedure may be necessary to treat cerebrovascular or neoplastic lesions. Here we report our experience in combining temporary intra-arterial balloon occlusion with concomitant cerebral blood flow imaging in preoperative evaluation of such patients. Forty-two patients with a variety of cerebrovascular and neoplastic lesions underwent trial balloon occlusion of an internal carotid or intracerebral artery. Eight patients developed both neurologic symptoms as well as brain perfusion defects during trial occlusion. Nine others developed only perfusion defects. The remainder were asymptomatic and had negative scans. Brain blood flow imaging during intra-arterial balloon occlusion identified 17 patients potentially at risk for developing postsurgical ischemic deficits. Treatment alternatives to acute arterial sacrifice were developed for these patients.

High Resolution Tc-99m HMPAO SPECT in a Patient with Transient Global Amnesia

Abstract: This is a report of a patient who underwent high-resolution brain perfusion SPECT studies during and after an episode of transient global amnesia. During the attack, SPECT imaging showed increased perfusion in the left medial temporal region involving the amygdala and hippocampus. After recovery fro

The value of lung scintigraphy in the diagnosis of pulmonary embolism

Abstract: The role of lung scintigraphy in the diagnostic management of patients with clinically suspected pulmonary embolism is reviewed. Evidence is provided that a normal perfusion scan excludes clinically relevant pulmonary embolism, and that a high probability lung scan, defined as a segmental perfusion defect with locally normal ventilation, sufficiently confirms the presence of pulmonary embolism in the majority of these patients. Furthermore, this review assesses the possibility of non-invasive tests for the diagnosis or exclusion of venous thromboembolic disease as a means of avoiding pulmonary angiography in patients with lung scan outcomes that are neither normal nor high probability.

Quantitative differential pulmonary perfusion: MR imaging versus radionuclide lung scanning.

Abstract: PURPOSE: To compare the results of quantitative analysis of differential pulmonary artery blood flow performed with phase-contrast cine magnetic resonance (MR) images with those of differential radionuclide pulmonary perfusion scanning in preoperative lung transplantation patients. MATERIALS AND METHODS: Forty preoperative lung transplantation patients underwent prospective, quantitative analysis of differential pulmonary artery blood flow performed with MR imaging and radionuclide pulmonary perfusion scanning. MR imaging analysis was performed at 1.5 T with a phase-contrast cine pulse sequence to acquire data perpendicular to each central pulmonary artery. RESULTS: Comparative analysis of differential pulmonary perfusion showed excellent correlation between the two modalities in all patients (P = .0001). MR imaging enabled calculation of the pulmonary artery blood flow to each lung; radionuclide lung scanning enabled only calculation of relative perfusion to each lung. CONCLUSION: MR imaging is as effect...

Postoperative assessment of cerebral blood flow in subarachnoid haemorrhage by means of 99mTc-HMPAO tomography.

Abstract: Regional hypoperfusion is a very frequent complication of subarachnoid haemorrhage (SAH), being related to vasospasm in the majority of cases. Twenty-six patients who were admitted for SAH underwent follow-up with technetium-99m hexamethylpropylene amine oxime single photon emission tomography (SPECT) 3 and 8 days after surgery. Fifteen patients of these had one more examination 15 days after surgery. The degree of hypoperfusion was quantified using an index of asymmetry which allow the comparison of two symmetrical regions of interest (ROIs) on the transaxial slice which presented the greatest perfusion defect. Comparison of CT data, transcranial Doppler data and clinical signs with the perfusion as quantified by99mTc-HMPAO SPECT indicates that a difference in counts of less than 10% between the two symmetrical ROIs is of no diagnostic value. Follow-up of the brain perfusion clearly shows that the most pronounced hypoperfusion was observed just after surgery, with progressive normalization at 8 and 15 days after surgery.99mTc-HMPAO SPECT performed 8 days after surgery allows prediction of the clinical outcome. For these reasons,99mTc-HMPAO SPECT, which is the only method for follow-up of cerebral perfusion in routine clinical practice, should be the first examination to be performed after surgery in patients with SAH.

Comparison of exercise and adenosine technetium-99m sestamibi myocardial scintigraphy for diagnosis of coronary artery disease in patients with left bundle branch block☆

Abstract: False-positive exercise thallium tests occur in approximately 80% of symptomatic patients with left bundle branch block (BBB) and normal coronary arteries. 1 It has been suggested that the low specificity of thallium scintigraphy in patients with left BBB may be due to a heart rate-dependent decrease in coronary blood flow through compression of septal perforator arteries. Adenosine has been proposed as an alternative to exercise stress with thallium-201 perfusion imaging 2–4 for the diagnosis of coronary artery disease (CAD). Adenosine produces maximal or near-maximal coronary vasodilation in 92% of patients, 5 its short half-life obviates the need for theophylline, and it is reported to increase heart rate only slightly. 6 We proposed that combining adenosine, whose diagnostic efficacy is less dependent on increases in heart rate, with technetium (Tc)-99m sestamibi imaging would provide improved specificity for the detection of CAD in patients with left BBB.

Arterial enhancement in acute cerebral ischemia: clinical and angiographic correlation.

Abstract: PURPOSE To investigate the cause and clinical significance of arterial enhancement (AE) in contrast-enhanced T1-weighted MR examinations after acute cerebral ischemia. METHODS Contrast MR examinations and conventional angiograms of 17 patients studied following an acute ischemic event or an internal carotid occlusion were retrospectively reviewed. MR and angiographic studies were performed within 1 day of each other. The presence of AE was correlated with both angiographic findings and patient clinical status. RESULTS AE was not confined to patients with angiographic evidence of complete arterial occlusion. Only 64% of patients demonstrating AE had complete occlusion angiographically. Complete arterial occlusion did not always correlate with AE. In two of nine patients with complete occlusion, no AE was identified. In five of 10 patients with AE, angiographic slow flow was identified. In patients without AE, no angiographic slow flow was identified. In the 64% of patients with AE, significant symptoms were identified. Patients without AE were either asymptomatic or had mild symptoms at the time of the MR study. CONCLUSIONS Our data support the hypothesis that arterial slowing is the cause of AE, which appears to be an indicator of decreased brain perfusion. Such MR findings may add important supplemental information to those provided by conventional angiography.

Brain perfusion imaging in Parkinson's disease and Alzheimer's disease demonstrated by three-dimensional surface display with 123I-iodoamphetamine.

Abstract: We reconstructed three-dimensional (3D) surface images from data from single-photon emission computed tomography (SPECT) with N-isopropyl-p[123I]-iodoamphetamine (123I-IMP) in 29 patients with Parkinson''s disease, 16 patients with Alzheimer''s disease and 11 normal control subjects. In patients with nondementing Parkinson''s disease, perfusion defects were frequently found in the parietal cortical region at a threshold value of 65%. In demented Parkinson''s disease patients, perfusion defects were frequently noted at threshold of 45–65 %, and were more marked in the bilateral temporal and parietal cortices. In Alzheimer''s disease, perfusion defects were similar to those found in dementing Parkinson''s disease. These results suggest that dementia in Parkinson''s disease is related to the perfusion reduction of the temporoparietal cortex, and may support the view that Parkinson''s disease and Alzheimer''s disease overlap in some patients. A 3D display of an 123I-IMP brain tomogram may be useful for detecting cortical lesions in patients with dementia or cognitive impairment.

Considerations of brain death on a SPECT cerebral perfusion study.

Abstract: Brain death imaging is often a diagnostic challenge. Cerebral angioscintigraphy is extensively used for this analysis, but this test does not allow the perfusion evaluation of the posterior fossa. The authors report a case in which a SPECT study showed persistence of blood flow in infratentorial structures with total absence of cerebral (supratentorial) perfusion. This finding excluded the diagnosis of brain death.