THE ROLE OF SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY BRAIN IMAGING WITH TC-99M-BICISATE IN THE LOCALIZATION AND DEFINITION OF MECHANISM OF ISCHEMIC STROKE

Tc-99m-bicisate (Tc-99m-ECD) is a new brain perfusion imaging agent fo rmulated from a radiochemically stable kit (Neurolite). A multicenter trial was conducted to determine the sensitivity and specificity of si ngle photon emission computed tomography (SPECT) imaging with Tc-99m-b icisate in the localization of ischemic stroke; 170 subjects were enro lled, 128 patients with stroke and 42 controls. Imaging results from 1 48 subjects (107 stroke patients and 41 controls) were considered eval uable. In the evaluable subjects, SPECT brain imaging with Tc-99m-bici sate (21.0 +/- 2.5 mCi) was interpreted without clinical information a nd was compared with a final assessment using all clinical, diagnostic , and laboratory procedures except the Tc-99m-bicisate SPECT results. Tc-99m-bicisate was safe and well-tolerated. SPECT imaging with Tc-99m -bicisate demonstrated a specificity of 98% and a sensitivity of 86% f or localization of strokes (kappa, 0.75; 95% confidence interval, 0.64 -0.86). Results were unchanged over time and were similar for all stro ke mechanisms except for lacunar disease (sensitivity, 58%). In a seco ndary analysis, a normal image or small, deep (e.g., subcortical) perf usion defect was highly predictive of a lacunar mechanism. Defects inv olving the cortical surface were strongly associated with nonlacunar m echanisms. SPECT imaging with Tc-99m-bicisate is a sensitive marker in the localization of perfusion defects associated with ischemic stroke and may assist in the determination of the underlying mechanism of a stroke.