Application of Amyloid PET in Cerebral Amyloid Angiopathy

Intracranial hemorrhage (ICH) consists of about a quarter of stroke subtype. For elderly, cerebral amyloid angiopathy (CAA) is a common etiology of ICH. In patients with CAA, abnormal beta amyloid protein diffusely deposits at cerebral vasculatures, which disrupts the normal vessel structure and increases the risk of bleeding. The standard diagnosis for CAA requires pathological evidences of amyloid deposition at cerebral arteries. Clinically, a diagnosis of CAA-related ICH is usually only made in an elderly developing cortical or subcortical lobar ICH without undergoing biopsy. Brain images using the SWI sequence of MRI study may show several lobar microbleeds in patients with CAA. However, there is still no direct and precise non-invasive diagnostic tool for CAA until now.

Amyloid PET, using 11C-PiB to image amyloid burden, has been used for detecting the cerebral amyloid protein deposition in patients with Alzheimer's dementia (AD) for years. Recently, amyloid PET has also been applied in diagnosis of CAA. CAA patients showed diffusely increased global PiB retention as compared to control subjects and the distribution of PiB retention is also different from that seen in patients with AD in general. Nevertheless, the applications of amyloid PET in CAA diagnosis are still not well established and many important issues still need to be extensively addressed. For example, amyloid PET sometimes is not able to exactly distinguish CAA patients from control and AD subjects. The roles of CAA in patients with drug-related ICH are still unclear. The accuracy of CAA diagnosis using clinical criteria still needs further validation. In addition, the characteristics for long-term progression of amyloid deposition are still unknown in CAA patients.

In this project, we will try to enhance the diagnostic potentials of amyloid PET in CAA by combination of dynamic amyloid PET with MRI SWI and MR perfusion images. We will also try to investigate the roles of CAA in patients with drug-related ICH and validate the accuracy of clinical CAA diagnostic criteria. In addition, we will try to study the characteristics of long-term progression of amyloid deposition in CAA patients. This project will enroll 100 patients with ICH, 30 patients with AD, and 30 control subjects. Each patient will receive the above image studies, followed by data analysis and comparison.