Abstract
Cerebral perfusion single-photon emission computed tomography (SPECT) is a nuclear medicine imaging technique that uses radiopharmaceuticals that selectively accumulate in the brain. However, cerebral perfusion SPECT is typically interpreted through visual assessment, making the results susceptible to observer subjectivity and varying levels of experience. The easy Z-score Imaging System (eZIS) is a software that quantitatively analyzes cerebral perfusion SPECT images obtained using 99mTc-ECD by comparing them with a normal database and applying Z-scores for quantification. The eZIS received regulatory approval in January 2015 and is currently used as an auxiliary tool for clinical diagnosis. The eZIS aids in diagnosing Alzheimer's disease by quantifying the degree of cerebral blood flow reduction in the posterior cingulate gyrus, precuneus, and parietal lobe, which are characteristic regions affected by the disease. Additionally, it can assist in diagnosing Lewy body dementia by evaluating the "cingulate island sign," a characteristic finding in which cerebral blood flow in the posterior cingulate gyrus and precuneus is relatively preserved compared with that in the occipital lobe. eZIS is thus extremely useful for dementia diagnosis.