Clinical evaluation of N-isopropyl I-123 p-iodoamphetamine brain scan with SPECT in cerebral infarction

N-isopropyl I-123 p-iodoamphetamine (I-123 IMP) is a radioactive tracer with high lipid solubility and high first pass extraction ratio whose initial distribution has been reported to reflect regional cerebral blood flow at the time of injection. I-123 brain scan with SPECT is of value for the evaluation of the lesion of disturbed CBF when adequate collimator and data processing methods are selected. In this study, the injected dose was 3 mCi and imaging was performed 20 min after intavenous injection with the GE400A/T, a low-energy general-purpose collimator, 3600 of rotation, 64 images, and average total imaging time of 32 min. Ramp filter with additional three dimensional filtering was used for image reconstruction. Twelve cases with cerebral infarction were studied. The region of abnormality turned out to be larger on IMP-SPECT than on X-CT in all cases including three cases in which I-123 IMP-SPECT revealed perfusion deficit area in spite of no abnormality on X-CT. In eight cases, the phenomenon of crossed cerebellar diaschisis was observed. Severe and large decreased perfusion area in parietal lobe proved to be characteristic. In four cases in which this phenomenon was not fonnd, perfusion to the parietal lobe was preserved. In conclusion, I-123 IMP-SPECT is sensitive enough even to detect the remote effect of infraction and the parietal lobe seemed to play an important role in the development of the phenomenon of crossed cerebellar diaschisis. (author)