Using Arterial Spin Labeled Magnetic Resonance Imaging (Asl-Mri) to Evaluate Cerebral Blood Flow Changes in Patients with Chronic Kidney Disease(2/2)

Chronic kidney disease (CKD) is characterized by a progressive loss in kidney function and is associated with cardiovascular effects, brain lesions and cognitive impairment. In Taiwan, CKD affects more than 10% of adults and is associated with an increased risk of stroke. Previous report has indicated that incident rates of stroke are much higher in patients with CKD compared with subjects without kidney disease. Patients with CKD have higher risk of developing cerebrovascular diseases and dementia. Several evidence has suggested that link between impairment in kidney function and cognitive impairment is mediated through vascular mechanisms. It is known that the kidney and brain both show high demand on blood flow and have tightly autoregulated blood flow across a range of perfusion pressures. Intact kidney function is essential for total blood volume regulation and thus impairments in kidney function can lead to disturbances in blood flow regulations in organs such as brain that is critically dependent on constant and adequate blood flow. CKD has been associated with vascular remodeling, which could therefore impair regulation of local cerebral blood flow (CBF). Previous studies have shown that CKD is associated with changes in brain structure and function, including the presence of subcortical ischemic lesions, atrophy, and deficits in cognitive performance. However, the mechanisms and time course by which CKD affects brain structure and function are not yet known. Contrast-enhanced magnetic resonance (MR) perfusion-weighted imaging is the most frequently used MR technique for monitoring CBF changes. However, this technique relies on the injection of a MRI contrast agent such as gadolinium which presents a risk of retention of contrast agent in the brain. Gadolinium-based contrast agent is mainly cleared and excreted along the renal pathway. Nonetheless, substantial evidence has shown that the administration of gadolinium can result in notably varied levels of accumulation of residual gadolinium in the brain even for subjects with normal renal function. Arterial spin labeled magnetic resonance imaging (ASL-MRI) is an endogenous tracer-based perfusion imaging sequence employing radiofrequency and magnetic field gradient pulses to magnetically label the spins of the flowing arterial blood without using extrinsic contrast agents. Its entirely noninvasive nature makes it well suited to studies in a population such as CKD with kidney dysfunction. Functional imaging methods using ASL technique can provide the potential in identifying early changes in neurological diseases such as dementia by imaging regional CBF, thus may improve insights in the pathophysiology of CKD, increase the sensitivity for detecting abnormalities. However, few studies have explored the use of ASL in investigating the physiological change of CBF in CKD. In this study, we will continue our primarily new developed 3D pseudocontinuous ASL-balanced steady state free precession (pCASL-bSSFP) pulse sequence programming and apply this new technique in patients with CKD. This study will investigate the pathophysiological effects of CKD on brain function by correlating CBF, a measure of cerebrovascular function and neural activity, with clinical and behavioral indices in a cohort of CKD patients and age-matched controls. This CBF technique may provide insight into the mechanisms linking CKD with cerebrovascular disease.