[Cerebral emission computer tomography (SPECT) with 123I-labeled amphetamines]

Comparison of SPECT, EEG, CT, MRI, and pathology in partial epilepsy

Twenty children with partial epilepsy who had surgery between the ages of 4 1/2 months and 18 years were studied preoperatively with electroencephalography (EEG), computed tomography (CT), and technetium-99m hexamethylpropyleneamineoxime 99mTc-HmPAO single photon emission computed tomography (SPECT; 20 interictal, 4 postictal). Fourteen had magnetic resonance imaging (MRI). All had an epileptiform focus (12 unilateral, 8 predominantly unilateral) on EEG. The combination of interictal and postictal regional cerebral blood flow (rCBF) abnormalities alone correlated with EEG foci in 16 of 20 patients. Interictal rCBF abnormalities correlated with EEG foci in 14 of 20. CT findings correlated with EEG foci in 14 of 20. MRI findings correlated with EEG foci in 13 of 14. Pathology demonstrated tumor in 6, cortical dysplasia in 4, mesial temporal sclerosis in 3, Sturge-Weber in 2, cavernous hemangioma in 1, Rasmussen encephalitis in 1, porencephalic cyst and gliosis in 1, and cysts found at surgery (but normal histology) in 2. Interictal and postictal SPECT, EEG foci, and CT findings each correlated with the pathology site in 17, 19, and 15 patients, respectively. MRI correlated with pathology site in 13 of 14 patients. Postictal and interictal abnormalities of rCBF correlated with EEG and pathology as frequently as CT. In 5 patients with normal CT scans and in 1 with a normal MRI, postictal and interictal rCBF correlated with EEG and pathology results; however, these 6 patients all had abnormalities on CT or MRI. SPECT, therefore, may be considered a valuable additional diagnostic procedure in the evaluation of epilepsy surgery candidates in that it adds to the evidence of abnormality at the involved site.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of regional cerebral blood flow and accentuation of the primary auditory cortex with single photon emission computed tomography

Conventional brain scanning uses polar tracers which do not penetrate the normal blood-brain barrier. Radiolabeled amines like 123-iodoamphetamine (IMP) cross the barrier to inhibit serotonin and norepinephrine in synaptosomes. Studies of cerebral perfusion and function seem to be successful with such labeling. We advance the hypothesis for an increased IMP uptake in the stimulated primary auditory cortex. The method of single photon emission computed tomography (SPECT) is described. We have also been able to demonstrate marking of the primary auditory cortex by an increased amphetamine input in 6 out of 15 cases during stimulation by white noise.

Semiquantitative analyses of dynamic single photon emission computed tomography (SPECT) of the primary auditory cortex

To date it has not been possible to work out a standard quantification for single photon emission computed tomography (SPECT). Only one mathematical model has received general recognition, but the theoretical preconditions for this model are not fulfilled by iodine-amphetamine kinetics. A practical solution is offered by semiquantitative analysis. We have developed three computer programs for this analysis for perfusion and cerebral function studies of the symmetrically arranged brain.

99mTc-HM-PAO and 123I-amphetamine cerebral scintigraphy: a new, non invasive method in determination of brain death in children

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.

[Improved diagnosis using deuterated radiopharmaceuticals?--A comparison of the brain affinity of amphetamine analogs]

Ruthenocene amphetamine analogues have the same brain uptake as iodo-labelled amphetamines. This paper compares the organ-distribution of 103Ru labelled ruthenocene- or ferrocene-amphetamine analogues in mice and rats with the same amphetamine in which H-atoms were partly substituted by D-atoms. The uptake in the brain is increased up to 180-200% for deuterium substituted compounds. The pattern of excreted metabolites leads to the conclusion that the deuterated amphetamines are more slowly metabolised than normal (H) compounds.