Comparison of I-123 IMP cerebral uptake and MR spectroscopy following experimental carotid occlusion

Evaluation of extracranial-to-intracranial bypass surgery using iodine 123 iodoamphetamine single-photon emission computed tomography

Eleven patients with occlusive cerebrovascular diseases were imaged with N-isopropyl-p-I-123 iodoamphetamine. Preoperative and postoperative single-photon emission computed tomography was performed in 10 patients undergoing extracranial-to-intracranial bypass procedures. New images were reconstructed from the two images obtained on the different days by superimposition and division in each pixel to get the ratio of cerebral perfusion change. All patients with bypass procedures had an increase in cerebral blood flow in the affected areas, and nine of 10 had an increase in cerebral blood flow in the contralateral cortex. There was no increase in cerebral blood flow in one case with no operation. Neither our procedure nor the results in this small series prove that recovery of function is due to an increase in blood flow, but we believe this is the case.

The distribution of N-isopropyl-p-iodoamphetamine in temporary ischemic brain of the mongolian gerbil

We studied the distribution of N-isopropyl-p-[131I]-iodoamphetamine (IMP) in the ischemic brain of 44 mongolian gerbils. The right common carotid artery was temporarily occluded by a clip and recirculated 3 h later. After given time intervals, 50 microCi of IMP was injected into 18 gerbils which had symptoms. One min after injection (or 10 min, 1 h, or 6 h after injection in other gerbils), each gerbil was killed and autoradiography was performed. IMP activity in various parts of the brain was calculated as %Dose/g from each autoradiogram. At one min after recirculation, partial no flow phenomenon was observed in the right cerebral hemisphere. From 10 min to 24 h after recirculation, a high uptake region was observed partially in the right cerebral hemisphere and thalamus. The high activity disappeared rapidly 10 min after injection. It seemed that this high uptake indicated luxury perfusion at the location of severe tissue damage. In the left side, the low perfusion recovered to an almost normal value at one to three days after recirculation. These results suggested the possibility that IMP could demonstrate luxury perfusion and diaschisis.