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Redistribution Phenomenon of I-???IMP and a Clinical Value of Delayed SPECT Imaging in Cerebral Ischemia

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Abstract

N - isopropy l- P - [1-123] iodoamphetamine (IMP) has been the most widely studied as a cerebral perfusion tracer, and single photon emission computed tomography (SPECT) using IMP now provides functional information about cerebral perfusion in routine clinical use. From the begining of IMP SPECT studies, temporal changes in the distribution of IMP within the brain was noted as the "Redistribution phenomenon", however the mechanisms and clinical significance of this phenomenon remains uncertain. In this report, we discussed and reviewed about the mechanisms of this phenomenon, the correlation between this phenomenon and the tissue viability, and the factors enhanced to this phenomenon. At the presence, the clinical significances of the delayed image in cerebral ischemia could be estimated as follows: (1) In acute cerebral ischemia, the severity of cerebral ischemia could be indicated by the early and delayed images. The moderate hypoperfusion on the early image with an incomplete redistribution on the delayed image was assessed as a critical perfusion in the affected area. (2) The tissue injury in the hyperperfusion area on the early image followed by reopening of occluded vessels could be estimated by serial changes of the redistribution on the delayed image. Almost complete redistribution was constantly maintained in the hyperperfusion area without severe tissue injury. (3) In patients with occlusive cerebrovascular disease, hemodynamic reserve using IMP SPECT with Diamox-activation could be assessed by the early and delayed images. The moderate hypoperfusion on the early image with an incomplete redistribution on the delayed image under Diamox-activated condition was assessed as a moderate limitation of cerebral vasodilatory capacity in the affected area. Thus, SPECT imaging for cerebral perfusion must appear to offer a more widely available alternative to positron emission tomography (PET) in management of cerebrovascular disease

Topics: cerebral ischemia, delayed imaging, I-123IMP, redistribution, SPECT
Publisher: 中村記念病院
Year: 1989
OAI identifier: oai:ir.cc.sapmed.ac.jp:123456789/717
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