[Nuclear medicine for general radiologists: clinical application of brain SPECT]

Brain SPECT studies are used to evaluate the cerebral hemodynamic changes in cerebrovascular diseases and other neuro-psychiatric disorders. I-123 and Tc-99m labeled radiopharmaceuticals widely used for brain perfusion SPECT studies include I-123 IMP, Tc-99m HMPAO, and Tc-99m ECD. I-123 IMP is suitable for the quantitative evaluation of cerebral blood flow, while Tc-99m HMPAO and Tc-99m ECD have problems owing to the non-linearity between cerebral radioactivity and cerebral blood flow. In addition, Tc-99m ECD does not show cerebral blood flow in the subacute phase of cerebral infarct or other conditions. Thus, it is important to consider the characteristics of radiopharmaceuticals and the clinical aspect of brain lesions in the interpretation of brain perfusion SPECT images. In this review, some useful information on brain perfusion SPECT is presented mainly as it relates to the cerebrovascular diseases.