A Study of APOE and Cerebral Perfusion in Adult Offspring of Patients with Alzheimer's Dementia using Dynamic Susceptibility Contrast MRI

Blood flow is a candidate marker for detecting early stages of AD because a decrease in cerebral perfusion has already been observed with perfusion MRI in AD using Arterial Spin labeling (ASL) techniques. However, the ASL perfusion method does not provide complementary information on blood volume and transit time that can help distinguish reduced perfusion due to brain atrophy from vasoregulatory changes. The application of DSC perfusion with intravenous gadolinium contrast injection to investigate perfusion changes in AD has the ability to provide cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) perfusion maps. Also this technique can be performed rapidly and is less sensitive to normal age-dependent reductions in blood flow. The purpose of this study is to investigate the ability of DSC MRI to measure CBV, CBF, and MTT changes in non-demented children with increased risk for AD due to one or more risk factors: APOE and/or family history. Materials and Methods Thirty one middle-aged adult children of persons with AD, 19 non-ApoE carriers and 12 ApoE carriers were scanned on a GE Signa 1.5 T MR. The perfusion imaging protocol included two injections, one rapid bolus and one slow infusion of contrast agent (gadolinium). Multiple blocks of single shot EPI images were acquired with TE of 35 msec and 128x64 matrix. The bolus injection was delivered 65 μmol/kg of gadodiamide (Ominscan®, Nycomed, NY) for 3 sec using MR compatible injector (Medrad, Inc., Indiana, PA) with a TR of 1150 msec. The infusion injection is delivered 1.6 μmol/kg/sec with a TR of 3000 msec. The total Gd dose did not exceed the FDA limit of 300 μmol/kg.