Magnetic Resonance Imaging of Neurological Deficits Following Cardiac Surgery

Cardiac surgery may cause a wide spectrum of neurologic injuries, which may cause in cognitive decline. At discharge from hospital, the reported incidence of post-operative cognitive disorder (POCD) is 30–65%. After a few months, the reported incidences are still of the order of 20–40%.The neurological deficits can be induced by embolic particles such as thrombi, fat or gas bubbles originated from the surgical field and the Cardiopulmonary bypass.

Another cause can be an inflammatory response to the cardiac surgery which may induce blood brain barrier disruption.

Magnetic resonance imaging (MRI) allow to non-invasively evaluate brain lesions caused by micro-emboli using diffusion weighted imaging (DWI). Indeed the efficacy of aortic medical devices were evaluated using DWI by reduction in the volume of new brain lesions, and the percentage of patients experiencing new brain lesions.

Blood brain barrier disruption was evaluated using Dynamic contrast enhancement, DCE-MRI and increase in BBB disruption was found 1 day following surgery. Additionally brain integrity was evaluated using diffusion tensor imaging (DTI) and there was a reduction in white matter integrity. Both BBB breakdown and DTI parameters were correlated with cognitive decline following surgery.

MRI is highly sensitive to neurological deficits following cardiac surgery and can evaluate not only micro-emboli but also BBB breakdown and tissue integrity. These methods can enhance development of new therapeutic agents for the prevention of neurological deficits following cardiac surgery.