Technetium-99m-HMPAO brain SPECT evaluation of neurotoxicity due to manganese toxicity.

UNLABELLED: We performed initial and follow-up regional cerebral blood flow (rCBF) studies using 99mTc-hexamethylpropyleneamine oxime (HMPAO) SPECT on a patient with manganese-induced central nervous system (CNS) neurotoxicity. METHODS: The patient had a history of long-term exposure to manganese at the time of the first scan, while the follow-up scan was performed 9 mo after removal from the toxic environment. The patient's serum level of manganese was five- to tenfold greater than normal at the time of the initial rCBF brain SPECT scan. RESULTS: The rCBF brain SPECT scan demonstrated significantly decreased rCBF in the right caudate nucleus and both thalami. A MRI scan obtained at the same time was normal. The follow-up rCBF brain SPECT scan was normal. CONCLUSIONS: This report supports the utilization of functional rCBF brain SPECT imaging to provide objective evidence of a function CNS abnormality due to neurotoxicity at an early clinical stage. Our results emphasize that rCBF brain SPECT may provide a confirmational test to support the diagnosis of neurotoxicity in the appropriate clinical setting.

Functional deficits in autistic disorder: characterization by technetium-99m-HMPAO and SPECT.

UNLABELLED: Autistic disorder is an early and severe developmental disorder characterized by deficits in verbal and nonverbal language, social skills, cognitive functioning and an abnormal repertoire of behaviors. Current research, however, has failed to identify the neurobiological mechanisms that underlie autism or those cortical brain regions, if any, that are abnormal. METHODS: We examined regional cerebral blood flow (rCBF) in six young, severely autistic patients. High-resolution brain SPECT with 99mTc-HMPAO was performed while five of the six patients were under general anesthesia. The scans reflected the subjects' rCBF in their usual alert behavioral state, since the tracer was injected at least 15 min prior to anesthesia and is rapidly extracted and fixed in the brain. A computer-automated cortical region of interest (ROI) generator was used to define 12 annular cortical regions (region 1 = left frontal, clockwise to region 12 = right frontal) for count data acquisition. The ratio of average counts in each ROI to whole-slice counts for the autistic patients was compared to age-matched controls using repeated measures (splt-plot) ANOVA statistical analysis for three representative brain levels. RESULTS: In the autistic patients, cortical regions 3, 4, and 10 were abnormally low at the cortical level canthomeatal (CM) + 3.5 cm. At level CM + 5.5 cm, regions 3, 4, 5 and 10 were abnormally low, and at level CM + 7.5 cm, regions 7 and 9 were also abnormally low. These regions correspond to abnormally low rCBF values located predominately in the temporal and parietal lobes, with the left cerebral hemisphere showing greater rCBF abnormalities than the right. CONCLUSION: Our findings suggest that the temporal and parietal lobes have abnormal rCBF in autism. HMPAO brain SPECT in combination with general anesthesia is particularly useful for imaging severely noncompliant patients.

Tc-99m HMPAO brain SPECT scanning in Munchausen syndrome.

Regional cerebral blood flow was studied in a patient with Munchausen syndrome using high resolution Tc-99m HMPAO SPECT. The scan demonstrated marked hyperperfusion of the right hemithalamus. The cranial CT scan was normal. The abnormal right hemithalamic blood flow is discussed in relation to the hypothesized neuropathy of this disorder.