We know that many patients with heart failure exhibit abnormal filling of the heart. This is known as diastolic dysfunction, and is caused to a large degree that the tissue of the heart itself becomes stiffer. Technically, it is very difficult to measure how stiff the heart muscle is. The reference method is to remove a piece of the heart and use a machine to test how stiff it is.
In a recent publication at IEMR, postdoc Lisa Smith has developed a noninvasive high-field magnetic resonance imaging (MRI) technique for measuring the stiffness of the heart. This technique, based on what is known as MR elastography, relies on sending mechanical waves through the object of interest, and visualize them with a specialized MRI scan. Using mathematics and physics, she calculates the stiffness of the object, based on the MRI images.
– It is important to adjust the frequency of the waves to match the object you want to examine. Both too low and too high frequency results in waves that can introduce artifacts in the stiffness measurements, Smith explains.
She has used precisely engineered artificial hearts with different shape and different stiffnesses, known as “phantoms”, to systematically investigate the precise frequencies that results in the most reliable stiffness measurements.
– The new technique will be a valuable research tool, where we aim at better understanding the underlying causes of tissue stiffness and its role in heart failure, Smith concludes.