SUMMARY In this study we assessed regional cerebral blood flow in patients with signs and symptoms of acute stroke using single-photon emission computed tomography (SPECT) and N-isopropyl 1-123 p-iodoamphetamine (IMP). Twenty-five patients with acute cerebral infarction had both IMP brain perfusion studies and CT scans performed within one week of each other; 22 had positive and three had negative perfusion studies. Of the 22 patients who had positive perfusion studies, six had negative CT studies initially. In the 16 patients who had abnormal CT studies, eight of the studies depicted areas of edema that were smaller than the perfusion deficits noted on the IMP studies and eight had areas of edema that were approximately equal in size to the perfusion defect. Of the three patients with normal IMP studies, two had normal CT studies and one had a positive CT study showing a 3-ram lacunar infarction.Using eight control patients, mean count rates per tissue volume normalized for the injected dose was calculated. Similarly, the quantitative data from regions of interest in the stroke patients were calculated and compared to the control patients or to a normal region in the uninvolved hemisphere in the same patients. SPECT with IMP was used to assess regional brain perfusion in acute cerebral infarction. Perfusion abnormalities were seen in our patients when the CT scan was normal, and quantitative data could be used to approximate regional cerebral blood flow in these patients when compared to the normal patient population. Stroke Vol 15, No I, 1984 IN STROKE, the brain may appear normal by CT for several days after the acute interruption of cerebral blood flow.1 2 Positron emission computed tomography has graphically demonstrated changes in regional brain physiology in patients whose X-ray CT studies show normal anatomy.3 Although positron studies permit noninvasive measurements of regional cerebral blood flow, glucose metabolism, and oxygen utilization in man, their cost and specialized instrumentation limits their use in routine patient management. If early measurements of regional cerebral blood flow in patients are going to have an impact on the clinical management of stroke, a single-photon approach that is free of the high technology cost of positron tomography needs to be developed so that measurements of regional cerebral blood flow will not be limited to a few centers.Single photon emission computed tomography (SPECT) can be performed with radiolabelled amines, such as N-isopropyl 1-123 p-iodoamphetamine (IMP), which are highly lipophilic, have a high extraction in the brain and are flow limited. SPECT-IMP scanning in this study showed promise as a relatively inexpensive, widely available technique for the measuring of regional cerebral blood flow.
Materials and Methods
RadiopharmaceuticalThe iodine-123 used for the radiolabel is cyclotronproduced by Mediphysics Laboratories (Emeryville, California) by the Te-124 (p,2n) I-123 reaction using a 23 MeV proton. A 2.1 -4 . 6% contamination with I-124 was pre...
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