The number of patients with cerebral ischemia has been increasing recently, and this condition has become an important public health issue. Therefore, diagnosis and medical treatment for it are becoming increasingly important. Evaluation of cerebral perfusion is useful in patients with cerebral ischemia. Conventional methods for evaluation of cerebral hemodynamics currently include angiography, perfusion computed tomography (CT), perfusion magnetic resonance imaging (MRI), transcranial Doppler (TCD), single-photon-emission computed tomography (SPECT), and positron emission tomography (PET). These techniques allow the measurement of cerebral perfusion deficits, but they have several drawbacks. Angiography is invasive, perfusion CT and MRI require injection of a contrast agent, and SPECT and PET require administration of a radioisotope. TCD and arterial spin labeling MRI have been developed as noninvasive, in vivo imaging methods. However, with TCD, the measurement area is limited and the accuracy of the examination depends on the skill of the operator. Arterial spin labeling MRI is still insufficient with regard to diagnostic accuracy. All the aforementioned methods require that the patient be restrained, which makes repeated measurements difficult.1–4 Furthermore, measurements at the bedside cannot be acquired because the equipment required for these examinations (other than TCD) are not easily transportable.