Using novel magnetic resonance imaging methods to predict stroke risk in individuals with sickle cell anemia

Sickle cell anemia (SCA) is a well-characterized monogenetic disorder with a high prevalence of cerebral vasculopathy, silent cerebral infarcts, and strokes. A significant mechanism for cerebral infarction in SCA is hemodynamic imbalance. To compensate for reduced oxygen-carrying capacity due to anemia, individuals with SCA have chronically elevated cerebral blood flow to maintain viable oxygen delivery to the brain tissue. Often the oxygen extraction fraction (ratio of oxygen consumed to oxygen delivered) is increased in more severely affected individuals. Subsequently, cerebrovascular reserve capacity, the ability of arterioles to dilate and further increase the cerebral blood volume and flow, will be reduced. These hemodynamic profiles have been associated with prior cerebral infarcts and increased evidence of disease severity. These cerebral hemodynamic parameters can be assessed noninvasively with noncontrast magnetic resonance imaging (MRI) of the brain utilizing specific MRI methods. This review focuses on using advanced neuroimaging methods to assess stroke risk in individuals with SCA, and such methods may be utilized before and after bone marrow or hematopoietic stem cell transplant to assess cerebral hemodynamic response. This manuscript is part of the Proceeding of The European Group for Blood and Marrow Transplantation (EBMT) Congress on Sickle Cell Disease, 16th-17 May 2019, Regensburg, Germany.