Technetium-99m-d, 1-HM-PAO: a new radiopharmaceutical for imaging regional brain perfusion using SPECT--a comparison with iodine-123 HIPDM.

A new radiopharmaceutical, technetium-99m hexamethylpropyleneamine oxime (99mTc-d, 1-HM-PAO), has been reported to cross the blood-brain-barrier and to distribute in brain in proportion to regional blood flow. This study reports brain imaging obtained with 99mTc-d,1 HM-PAO in 20 subjects; seven without evidence of cerebral disease and 13 with cerebrovascular disorders. In 16 patients comparative data were available with N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3-propanediamine ([123I]HIPDM). Technetium-99m-d, 1-HM-PAO is retained sufficiently long to allow single photon emission computed tomography (SPECT) with widely available rotating gamma camera systems. The kinetics demonstrated a rapid brain uptake and prolonged retention of activity in cerebral structures. Good tomographic images are obtained with much higher uptake in gray than in white matter. Blood flow maps are comparable to those achieved with [123I]HIPDM and established strokes were clearly seen, with similar details as in HIPDM studies. Delayed studies showed that the distribution in the brain remained virtually unchanged. Technetium-99m-d, 1-HM-PAO imaging appears particularly promising in routine examination of patients with cerebrovascular disorders.