MRI Assesment of Cerebral Blood Flow in Anesthetized Children

Children undergoing magnetic resonance imaging (MRI) of the brain often need to be sedated to complete the examination, as it is difficult to remain still for a long period, which is required to obtain usable images. During sedation, most patients typically experience a drop in blood pressure, including children. Maintaining an adequate blood pressure under anesthesia is important, as blood pressure is routinely used as a measure to ensure sufficient blood circulation to the body's organs, including the brain. Ensuring adequate blood flow to the brain is one of the cornerstones of all anesthesia, including in children. Therefore, low blood pressure during anesthesia is often treated with standardized interventions, such as blood pressure-raising interventions. These treatments generally restore blood pressure to normal, but how this affects blood flow to the brain in children is not fully known.

With the help of modern MRI technology (so-called Arterial Spin Labeling, ASL), blood flow in the brain can be measured quickly and completely safely with high precision.

In similar situations with adult patients, it has been observed that while blood pressure-raising interventions successfully normalize low blood pressure, MRI scans show that blood flow to the brain paradoxically decreases despite the increase in blood pressure. It is believed that this may be due to the brain's blood vessels constricting.

The investigators now wish to examine this relationship in sedated children undergoing planned brain MRI for certain diagnoses. The investigators hypothesis is that standardized measures intended to raise blood pressure (i.e., the routine treatment used regardless of whether a patient participates in the study or not) normalizes low blood pressure (when deemed necessary to treat according to routine) but does not necessarily lead to improved blood flow to the brain.

Primary research question: How does routine treatment of low blood pressure affect cerebral blood flow in sedated children?