123I-IMP brain SPECT imaging in a patient with the interval form of CO poisoning.

N-isopropyl-[123I]-p-iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT) brain imaging was repeatedly performed in a 68-year-old man with the interval form of CO poisoning. The initial SPECT under an akinetic-mutism state following the interval period of about 18 days showed high-grade hypoperfusion images in diffuse regions extending to both the gray and white matter in the cerebral cortex. The second SPECT examination performed 328 days after the acute poisoning showed that the diffuse hypoperfusion images had become lighter but remained to a degree consistent with the delay in the recovery from the akinetic-mutism state. The high utility of SPECT brain imaging in determining the diagnosis or prognosis of CO poisoning was discussed in comparison with X-ray or magnetic-resonance imaging findings.