In clinical diagnostic imaging of Alzheimer's disease (AD), MRI and nuclear medicine studies such as cerebral blood flow SPECT are positioned as biomarkers expressing pathological conditions. With understanding its usefulness and limitations, it is important to conduct appropriate application and to utilize the correct evaluation of the result in clinical practice. Although FDG-PET and amyloid PET are still not covered for dementia by health insurance, they are extremely useful for differential diagnosis as well as early diagnosis of AD. As image biomarkers, they may have complementary implications. In addition, tau PET under development not only realizes more accurate evaluation of AD but also is expected to be applied in dementia other than AD. In the future, image biomarkers are indispensable for patient selection (early diagnosis) in mild cognitive impairment (MCI) or earlier stages and for judging the therapeutic effect of interventions in cases when early intervention for AD.
Keywords: Alzheimer’s disease; PET; SPECT; amyloid; tau.