technetium-tc-99m-exametazime and 4-iodoamphetamine

Quantitative assessment of regional cerebral blood flow (rCBF) in the bilateral cerebral and cerebellar cortices was performed in 13 epileptic patients receiving long-term high-dose phenytoin (PHT) therapy, using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine 123) p-iodoamphetamine. In 4 of the 13 patients, both the cerebellar to frontal rCBF ratio and cerebellar to cerebral rCBF ratio showed low values as compared with those in 22 normal subjects matched for sex and age, probably reflecting abnormal relative cerebellar hypoperfusion. None of the 4 patients showed any abnormal findings on X-ray computed tomography or magnetic resonance brain imaging. The patients with a history of acute PHT intoxication tended to show the abnormal relative cerebellar hypoperfusion. These results suggest the utility of SPECT scans for early detection of cerebellar abnormalities known to be often present in epileptic patients, and imply a risk of long-term high-dose PHT therapy.

Topics: Adult; Amphetamines; Cerebellar Diseases; Cerebellum; Epilepsies, Partial; Female; Frontal Lobe; Functional Laterality; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Phenytoin; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

In the past 7 years, single photon emission computed tomography (SPECT) has evolved from an interesting nuclear medicine technique rarely performed because of technical difficulties into a valuable clinical tool in the management of cancer cases. The development of stable multidetector instruments with collimators and gantries specifically designed for SPECT and the introduction of new radiopharmaceuticals recently approved by the U.S. Food and Drug Administration have rapidly moved SPECT from the field of clinical investigation to clinical practice. SPECT is a valuable addition to other tomographic modalities capable of displaying the physiology of disease as well as anatomy. In this work the authors describe the role of SPECT in a cancer center and, in particular, how they use it to solve clinical problems. They also review the published literature, when appropriate. The authors have found SPECT of particular value in evaluation of myocardial ischemia, in differentiating tumor recurrence from posttherapy changes in the lymphomas, in tumor diagnosis and surveillance, and in separating hemangioma from malignant lesions in the liver.

Topics: Abdomen; Amphetamines; Antibodies, Monoclonal; Bone Diseases; Brain Diseases; Cardiovascular Diseases; Humans; Neoplasms; Organotechnetium Compounds; Oximes; Quality Control; Technetium Tc 99m Exametazime; Thallium Radioisotopes; Tomography, Emission-Computed, Single-Photon

Functional brain imaging is a powerful tool for examining the central nervous system (CNS) response to pharmacologic challenges. Amphetamine is of interest both because of its role as a stimulant of the dopaminergic system and because of its use to alter mood in mood-disordered patients, particularly in patients suffering from depression. In this study, we report the effects of oral D-amphetamine relative to placebo on regional cerebral blood flow (rCBF) measured by SPECT in healthy volunteers to characterize the normal CNS response to this primarily dopaminergic stimulant.. SPECT was used to assess changes in rCBF induced by amphetamine in 16 healthy volunteers. Subjects received placebo and then 0.4 mg/kg oral amphetamine in a fixed-order single-blind design and were imaged on a triple-head tomograph. Another six healthy volunteers received placebo at both times to assess normal rCBF variability. rCBF changes were assessed with a three-dimensional voxel-based analysis integrated into an automated coregistration system. Data were automatically normalized to whole-brain counts and coregistered. Resultant rCBF changes were evaluated parametrically through the formation of an image whose voxel values were based on the paired t statistic.. Amphetamine increased rCBF in two mesial prefrontal zones (Brodmann's areas 8 and 10), inferior orbital frontal lobe (area 11), brain stem (ventral tegmentum), anteromesial temporal lobe (amygdala), and anterior thalamus. Amphetamine decreased rCBF to motor cortex, visual cortex, fusiform gyrus, posterolateral temporal lobe, and right lateral temporal lobe.. Our data suggest that amphetamine induces focal increases and decreases in rCBF in healthy volunteers in areas primarily innervated by dopamine pathways and in areas with secondary (primarily limbic) affiliations. These data are consistent with glucose metabolic data from autoradiographic studies in animals, in which the largest increases are seen in brain stem, followed by striatum, thalamus, and frontal and sensory cortices. Frontopolar and temporal increases observed in our study appear to be unique to humans.

Topics: Administration, Oral; Adult; Amphetamine; Amphetamines; Brain; Cerebrovascular Circulation; Female; Humans; Image Processing, Computer-Assisted; Iodine Radioisotopes; Male; Radiopharmaceuticals; Reference Values; Single-Blind Method; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral hyperperfusion syndrome has been increasingly reported as a complication of carotid angioplasty and stent placement. The aim of the present study was to determine significant predictors of hyperperfusion phenomenon after carotid angioplasty and stent placement.. We retrospectively reviewed 30 consecutive patients with unilateral severe carotid stenosis who underwent angioplasty and stent placement. Resting cerebral blood flow (CBF) and cerebral vasoreactivity (CVR) to acetazolamide challenge were quantitatively measured to evaluate cerebral hemodynamic reserve. Split-dose [(123)I] iodoamphetamine single photon emission CT (SPECT) was performed before and 7 days after carotid angioplasty and stent placement. Technetium-99m hexamethylpropyleneamine oxime (HMPAO) SPECT was performed immediately after the procedure.. Three patients had cerebral hyperperfusion phenomenon immediately after angioplasty and stent placement, as shown by HMPAO SPECT: One developed status epilepticus 2 weeks after the procedure. Significant predictors of hyperperfusion included patient age, pretreatment CVR, and pretreatment asymmetry index ([ipsilateral resting CBF/contralateral resting CBF] x 100). Variables determined not to be significant risk factors included pretreatment resting CBF value, degree of carotid stenosis, and interval from the onset of ischemic symptoms.. Significant predictors of hyperperfusion phenomenon after carotid angioplasty and stent placement included patient age, pretreatment CVR, and pretreatment asymmetry index. Pretreatment CBF measurements, including those obtained by quantifying CVR and performing SPECT immediately after the procedure may aid in identifying patients at risk and in initiating careful monitoring and control of blood pressure to prevent hyperperfusion syndrome.

Topics: Acetazolamide; Aged; Aged, 80 and over; Amphetamines; Angioplasty, Balloon; Carotid Stenosis; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Hemodynamics; Humans; Hyperemia; Iodine Radioisotopes; Male; Middle Aged; Predictive Value of Tests; Radiopharmaceuticals; Retrospective Studies; Stents; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vasomotor System

This study was performed to evaluate the role of single photon emission computed tomography (SPECT) perfusion imaging in the evaluation of patients with moyamoya disease.. Five patients (four female, one male) were studied utilizing iodine-123 iodoamphetamine or technetium-99m hexamethylpropyleneamine oxime SPECT. The data were reconstructed into axial, coronal and sagittal sections for review, and compared with CT, MR and/or angiographic images.. All five patients had significant perfusion defects. These areas of vascular compromise were seen to cross normal vascular territories, and were greater in number and extent than seen on anatomic sectional imaging.. Patients with moyamoya disease have a recognizable pattern of scintigraphic perfusion deficits which should be identified by pediatric imaging physicians. SPECT perfusion studies should be performed in conjunction with other imaging modalities (CT, MR or angiography).

Topics: Adolescent; Adult; Amphetamines; Brain; Cerebral Angiography; Cerebrovascular Circulation; Child; Child, Preschool; Female; Humans; Magnetic Resonance Angiography; Male; Moyamoya Disease; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

To report the development and validation of a technique of dual tracer single-photon emission CT brain imaging using technetium-99m hexamethylpropyleneamine oxime and iodine-123 iodoamphetamine agents and the application of this technique in patients with a variety of diagnoses.. Contamination between the two isotopes' energy windows was calculated by opening both energy windows while scanning a group of patients using a single isotope. To compare uniformity of I-123 down-scatter, Tc-99m studies were performed both before and after the administration of I-123 in five of 24 dual studies. The 24 patients studied with the dual-isotope technique were evaluated during acetazolamide testing, trial balloon occlusion, or embolization of an arteriovenous malformation.. In a dual acquisition, average count contamination of an I-123 study by Tc-99m was less than 1% of the total I-123 counts, and contamination of a Tc-99m study by I-123 was approximately 12% of the total Tc-99m counts. Tc-99m studies performed both before and after the administration of I-123 demonstrated that contaminating counts do not adversely affect scan interpretation. Dual-tracer scans were completed in all 24 patients, 10 of whom showed changes after intervention.. Dual-tracer single-photon emission CT brain scans of adequate diagnostic quality are possible using Tc-99m and I-123.

Topics: Acetazolamide; Adolescent; Adult; Aged; Amphetamines; Brain; Brain Diseases; Cerebrovascular Disorders; Female; Humans; Iodine Radioisotopes; Male; Middle Aged; Models, Structural; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Patients with a clinical diagnosis of Alzheimer's disease were studied using MRI, SPECT, and psychometric tests. Significant correlations between focal perfusion deficits and focal cognitive deficits were found. Significant correlations between regional relaxation time of white matter and psychometric tests of diffuse and focal categories were also found. Pathological examination confirmed Alzheimer's disease as the only diagnosis.

Topics: Aged; Alzheimer Disease; Amphetamines; Blood Flow Velocity; Brain; Cerebral Arteries; Cerebral Cortex; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Neuropsychological Tests; Organotechnetium Compounds; Oximes; Psychometrics; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Brain perfusion was studied in 14 patients with acute encephalitis by use of 123I-iodoamphetamine or 99mTc-hexamethylpropyleneamine oxime and single photon emission computed tomography (SPECT), the first examination being made 4-11 days after onset of encephalitis symptoms. All 6 patients with herpes simplex virus encephalitis (HSVE) had strongly increased accumulation of radiotracer in the affected temporal lobe; in the remaining 8 results were normal. At the time of the first SPECT conventional CT images were normal in all patients. The SPECT abnormality in HSVE gradually converted over 4-10 weeks from increased tracer accumulation to greatly subnormal accumulation. Brain perfusion SPECT may be helpful in the early diagnosis of HSVE.

Topics: Acute Disease; Adult; Amphetamines; Antibodies, Viral; Diagnosis, Differential; Electroencephalography; Encephalitis; Female; Follow-Up Studies; Herpes Simplex; Humans; Iodine Radioisotopes; Male; Middle Aged; Organometallic Compounds; Oximes; Radionuclide Imaging; Simplexvirus; Technetium; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed

Determination of brain death in infants and children is difficult and criteria used in adult brain death are regarded insufficient in pediatric cases. In comatose children, clinical signs of brain death and EEG monitoring may be of limited value, while intercerebral blood flow estimations can provide more direct information. Beside radionuclide bolus angiography of polar radiopharmaceuticals with sequential technique, two radioisotopes are introduced for static brain images. Injection of 123I-amphetamine or the 99mTc labelled lipophilic complex HM-PAO into the peripheral venous circulation enables more precise static imaging of parenchymatous brain perfusion and cellular function in contrast to conventional dynamic imaging because of retention in the intact brain parenchyma. Critical deficits or complete loss of cerebral perfusion can be readily documented. These studies are particularly helpful when clinical signs and EEG alone cannot establish the definite diagnosis of brain death. Their easy application and wide availability renders them especially useful in children.

Topics: Adolescent; Amphetamines; Brain; Brain Death; Cerebrovascular Circulation; Child; Child, Preschool; Humans; Infant; Infant, Newborn; Iodine Radioisotopes; Organometallic Compounds; Oximes; Radionuclide Imaging; Technetium; Technetium Tc 99m Exametazime