Evaluation of ischemic tissue reversibility by SPECT or DWI/PWI MRI

The potential for application of SPECT and diffusion/perfusion MRI study warrants further evaluation as it may help to improve the assessment of acute ischemic stroke and to choose the most appropriate therapeutic strategy. Since the penumbra is a hypoperfused but viable tissue, it represents an ideal therapeutic target of acute ischemic stroke. The ischemic penumbra is able to regain its function if promptly reperfused. SPECT and diffusion/perfusion MRI have the advantage of giving semiquantitative estimate of CBF as well as various ischemic thresholds. Although the hypoperfused area visualized by SPECT imaging shows not only the ischemic core (irreversible tissue) but also the penumbra (reversible tissue), we are able to know the different CBF thresholds such as penumbra, infarction and hemorrhage. Therefore, SPECT and diffusion/perfusion MRI can provide important information to allow the most appropriate candidate for the thrombolytic therapy and neurointerventional treatment to be selected.