Researchers have developed a novel method of measuring growth in the aorta that may help clinicians to identify potentially fatal heart conditions earlier. The technique, called vascular deformation mapping, measures changes in the thoracic aorta by using high-resolution CT imaging to calculate three-dimensional changes in the aortic wall. In the study, VDM significantly outperformed the standard manual rating methods performed by experts.
The technique, called vascular deformation mapping, measures changes in the thoracic aorta, which carries blood from the heart to the rest of the body. This new technique uses high-resolution CT imaging to calculate three-dimensional changes in the aortic wall in a manner that significantly outperforms the standard manual rating methods performed by experts, according to results published in Radiology and Medical Physics.
«The technique used in this algorithm has been around for a while, but no one has ever used it to see three-dimensional growth of an aneurysm of the thoracic aorta,» said Nicholas Burris, M.D., corresponding author of the papers, assistant professor of radiology and director of aortic imaging at Michigan Medicine. «This is a promising step towards having technology that pushes the accuracy of measurement past what human raters can achieve, allowing clinicians to have the best possible picture of a patient’s condition.»
Thoracic aortic aneurysm occurs when the largest part of the aorta becomes weakened and grows, or dilates, increasing its risk of a potentially fatal rupture or dissection. For approximately 3% of adult patients over 50 years old with this largely asymptomatic condition, physicians recommend they undergo regular testing, often with CT scans, to measure aortic growth and determine if surgical repair is needed.
Currently, the standard practice to measure growth is done with human «raters» who line up two images and draw a line at two points to find the change. Burris says this process is prone to error, and, in many cases, doctors can’t confidently tell if the thoracic aorta is growing, creating uncertainty regarding the best treatments and follow-up plan.
«The challenge we’re faced with clinically is that a typical aneurysm in the aorta is going to grow only a fraction of a millimeter every year, and the process of manually drawing diameters that precise is very hard to reproduce,» he said. «You have a lot of variability in standard measurements relative to a very small amount of actual aneurysm growth. Basically, you rarely end up getting a confident assessment of growth, which can make it difficult to know what the patient’s actual risk is and how closely they need to be followed with repeat CT scans.»
The vascular deformation mapping technique developed by Burris’ team relies on an image analysis technique known as image registration, which, essentially, aligns the anatomy shown in multiple CT scans by taking any pixel on the first scan and relating its exact position to the pixel on the second scan. When they are all aligned, a three-dimensional color map of the aorta shows how much and where the thoracic aorta has grown.
Story Source: Materials provided by Michigan Medicine — University of Michigan. Original written by Noah Fromson. Note: Content may be edited for style and length.