Usefulness of quantitative determination of cerebral blood flow by 123I-IMP SPECT reference sample method in various cerebrovascular disorders

Cerebral blood flow (CBF) was quantitatively determined by N-isopropyl-p-[123I] iodo-amphetamine (IMP) single photon emission computed tomography (SPECT) with a rotating gamma camera. A ZLC 7500 unit (SIEMENS Inc.) was used for emission CT, and a SCINTIPAK-2400 (Shimadzu Corp. Ltd.) for data processing. For the quantitative determination of CBF, arterial blood samples were collected for 5 minutes during the intravenous injection of 111 MBq of IMP, and a reference sample method corrected by time-activity curve was used. The determination was carried out in 90 patients with various cerebrovascular diseases and 5 normal volunteers. Mean cerebral blood flow (m-CBF) in the normal cases as determined by the above method was 42.4±6.0 (ml/100g/min). In patients with acute phase subarachnoid hemorrhage (SAH), severity on CT was marked in patients with intracerebral hematomas greater than 45 mm in diameter. Patients with non-hemorrhagic arteriovenous malfomation (AVM) whose nidi were 30 mm or more in diameter showed a decrease in CBF on the afferent side. This decrease was caused by a steal phenomenon affecting CBF around the AVM. The size of cerebral infarction on CT was closely correlated with the decrease in CBF, and CBF in patients with stenosis and obstruction of the main trunks was less than that in patients without them. CBF was increased by 10-20% in patients who underwent carotid endarterectomy or superior temporal artery-middle cerebral artery anastomosis for obstruction or stenosis of the internal carotid artery or the middle cerebral artery. The quantitative determination of CBF by IMP SPECT reference sample method was useful for evaluating the morbid condition and estimating the prognosis of cerebrovascular diseases, and evaluating the effects of therapy. (J.P.N.)