Visualization of 4D Dynamic Pulsatile Flow

The maintenance of cerebral blood flow and pressure is criticalfor normal brain function, and their alteration is associated with a number of diseasestates. However, these properties are not static, rather they fluctuate andpulsate with the systolic increase in blood pressure during the cardiac cycle. Considerabledata have demonstrated that the measurement of pulsatile pressure in the brain isa useful marker for many diseases, particularly hydrocephalus, traumatic braininjury, and other conditions associated with changes in the biomechanicalproperties of the brain and intracranial pressure (ICP). In addition to being a biomarker, pulsatile pressure can stresshighly-perfused organs, including the brain, and cause vascular damage that mayadvance pathological conditions, such as aneurysmal disease. Pulsatile stressincreases with age since vessels stiffen due to a decrease in elastin, whichdampens the pulsations in the brain. This increased stressed is believed to beinvolved in the pathophysiology of lacunar infarcts, mild cognitive impairment,dementia, and other conditions. Three primary techniques have been used to quantifyintracranial pulsatility: continuous ICP monitoring, transcranial Dopplerultrasound (TCD), and magnetic resonance imaging (MRI). ICP monitoring is aninvasive method that measures pressure pulsatility through a pressure sensorplaced within the brain. In comparison, TCD and MRI measure flow pulsatility inexternal, non-invasive manners: TCD measures the velocity of blood flow inlarge arteries using a transducer, while MRI measures the net flow waveformover the cardiac cycle in intracranial arteries or veins, or in cerebral spinalfluid pathways, by imaging. Each of the three techniques has unique benefitsnot available when using alternative methods to measure intracranialpulsatility. Therefore, a non-invasive method that gives continuous measurementsof cerebral blood velocity and flow over time, would greatly enhance thecapability of physicians to diagnose and monitor a number of diseases influencedby cerebral blood flow and pressure. Dr. Moise Danielpour and his colleagues from theCedars-Sinai Medical Center have developed a method to visualize blood flowpulsatility in a four-dimensional fashion, allowing three-dimensional flow tobe visualized over time during the entire cardiac cycle by MRI. Julien Brohan julien.brohan@cshs.org 310.423.0326