123I-N-isopropyl-amphetamine single photon emission computed tomography as a brain imaging technique in dementia

Because of its binding to specific cerebral amine receptor sites 123I-N-isopropyl-amphetamine (IMP) tracer activity can be used as a measure for the regional cerebral blood flow (rCBF) in the human brain. In 21 psychiatric in-patients an IMP perfusion study was performed using a rotating gamma camera system. The findings at single photon emission computed tomography (SPECT) were compared with different clinical parameters including conventional transmission computed tomography. In SPECT, two different patterns of decrease in IMP uptake could be identified. In patients with a history of cerebrovascular disease SPECT showed asymmetrical, multifocal microcirculatory defects without preference for either hemisphere. In patients with suggested Alzheimer type dementia the perfusion deficits involved the gray and white matter of the parieto-occipital lobes in a bilaterally symmetrical mode with variable extension. Thus, by using IMP-SPECT, it was possible to define the underlying pathologic condition in dementia.