A COMPARISON OF 2 CEREBRAL PERFUSION TRACERS, N-ISOPROPYL L-123 PARA-IODOAMPHETAMINE AND I-123 HIPDM, IN THE HUMAN

Abstract

Both N-isopropyl l-123 p-iodoamphetamine (IMP) and l-123 HIPDM [iodine-125 labeled N,N,N''-trimethyl-N''-[2-hydroxyl-3-methyl-5-iodobenzyl]-1,3-propanediamine] were advocated as radiotracers for assessing regional cerebral perfusion. The biodistribution of the 2 tracers was compared in 19 patients without evidence of neurological disease. Following i.v. injection, both tracers accumulated initially in the lung. Early after injection the fraction of the total brain uptake was higher for l-123 HIPDM than for l-123 IMP. The peak brain activity for l-123 IMP was higher than for l-123 HIPDM. Brain activity was unchanged with both tracers between 30 and 60 min after injection. Tomographic images were similar in appearance for both tracers. No eye uptake greater than background was observed with either tracer in any patient at 2, 24 and 48 h. l-123 IMP is superior for tomographic imaging because of its higher brain uptake, whereas l-123 HIPDM may be superior for studies performed during rapid changes in blood flow. [The diagnostic advantages of this method in cerebral vascular disease and epilepsy are discussed.].