Brain Blood Flow in the Dementias:SPECT with Histopathologic Correlation in 54 Patients Radiology, Vol 202, , Copyright c 1997 by Radiological Society of North America

Purpose to evaluate single photon emission computed tomographic(SPECT) imaging of regional cerebral blood flow in the diagnosis of Alzheimer disease(AD) and the different diagnosis of the dementias

INTRODUCTION The most prevalent of the dementias is Alzheimer disease. AD may account for 3/4 of all demential diseases some of dementias are curable:apathetic hyperthyroidism, myxedema, vitamin B12 deficiency

INTRODUCTION Some may be treatable:neurosyphilis, AIDS, and vascular disease that may eventuate in multiple-infarct dementia DD of these diseases are by means of lab. Test, CT, MRI.But screening results in identification of relatively few patients.

INTRODUCTION During the past 2 decades, SPECT imaging of regional cerebral blood flow has improved rapidly in technical quality and its has become widely available. The most desirable standard is histopathologic diagnosis.

Material and Methods Regional cerebral blood flow SPECT was performed with inhaled xenon-133 in 261 patients and with injected technetium-99m HMPAO in 162 patient with possible demential.In 16 patient, both agents were used in 1 day.SPECT images obtained in elderly heathy control subjects(with Xe-133 in 15, with Tc-99m HMPAO in 14) were avalable.Histopathologic correlation was a available in 54 patients(with autopsy in 51, with biopsy in three)

Material and Methods Xe-133 SPECT: a flow reduction of at least 2 standard deviation below the means of the control group in the at least one posterior region of interest was required for a positive diagnosis of AD Tc-99m HMPAO: a marked regional cerebral blood flow reduction in at least one posterior ROI was required for a diagnosis of AD

RESULTS SPECT diagnoses were true-positive in 37, true- negative in eight, false-positive in three, and false-negative in six patients. Sensitivity was 86% (37 of 43; 95% confidence limits =.72,.95); specificity, 73% (eight of 11; confidence limits =.39,.94); positive predictive value, 92% (37 of 40; confidence limits =.80,.98); and negative predictive value, 57% (eight of 14; confidence limits =.29,.82)

RESULTS

Among 37 true positive diagnosis: marked bilateral posterior regional cerebral blood flow reduction in 22 diagnosis; unilateral changes in 15 diagnosis(left posterior ROI, 12; right posterior ROI, 3)

RESULTS 8 true-negative diagnosis:4 were normal; the other diagnosis were multisystem degeneration, adult polyglucosan body disease, frontal dementia with gliosis, and progressive supranuclear palsy

RESULTS 3 false-positive diagnosis: histopathologic diagnoses were multisystem degeneration, Pick disease, and dysphasic dementia

RESULTS 6 false-negative cases:one was mild AD, 3 were moderate, 2 were severe *Intervals between SPECT imaging and histopathologic diagnosis were months.It is not known whether these intervals contributed to the missed diagnosis.

CONCLUSION Regional cerebral blood flow SPECT may assist in the early and late diagnoses of AD and in the differential- diagnosis of the dementias when there is a complicated or confusing clinical picture The two radiotracer have had similar result