Recent advances in diagnostic imaging of vascular dementia

Ken Nagata, Daiki Takano, Takashi Yamazaki, Tetsuya Maeda, Yuichi Satoh, Taizen Nakase

Department of Neurology, Research Institute for Brain and Blood Vessels

Vascular dementia (VaD)is a heterogeneous clinical entity based on the various subtypes of cerebrovascular disease(CVD). Since there used to be a dichotomy in the clinical diagnosis of VaD and Alzheimer’s disease(AD), those who had vascular lesions on neuroimages were automatically diagnosed as VaD. Recent postmortem studies, however, revealed a coexistence of vascular and neurodegenerative lesions in AD patients, the clinical interpretation of AD has been stretched and the AD patients having vascular lesions are now regarded as “AD with CVD”. Structural neuroimagings such as CT and MRI have been applied to the discriminative diagnosis of VaD and AD by detecting ischemic changes in the cortical and white matter areas, and functional neuroimagings including PET and SPECT are used in the evaluation of metabolic and hemodynamic aspects of the brain. Although the retrosplenial hypometabolism or hypoperfusion is known to be a typical pattern in early AD patients, there is no typical pattern on neuroimages in VaD patients. In the evaluation of vascular reactivity VR to carbon dioxide inhalation by PET, the increase in cerebral blood flow was markedly reduced due to the long-lasting brain ischemia in VaD patients, whereas the VR was preserved in AD patients without vascular lesions.

Address correspondence to Dr. Ken Nagata, Department of Neurology, Research Institute for Brain and Blood Vessels (6-10 Senshu-Kubotamachi, Akita 010-0874, Japan)