A new tool for 3-D measurement of the aorta may identify fatal heart conditions earlier
The technique has potential to change the way aortic aneurysm is
monitored.

Date:
February 16, 2022
Source:
Michigan Medicine - University of Michigan
Summary:
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.



FULL STORY ========================================================================== Researchers at Michigan Medicine have found a novel method of measuring
growth in the body's largest artery that may help clinicians to identify potentially fatal heart conditions earlier.


==========================================================================
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 RadiologyandMedical 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.



==========================================================================
For these studies, researchers used scans from nearly 50 aortic aneurysm patients and 75 reference models with variable growth of the aortic
wall. They tested the automated program against two expert manual raters
and found the vascular deformation mapping outperformed the humans with
higher accuracy and lower variability in the growth measurements. Vascular deformation mapping achieved an accuracy of less than 1 millimeter in
all cases when even the most experienced human analysts had measurements
with errors of up to 3 millimeters.

"Recent advances in artificial intelligence have generated a lot of
interest in AI in relation to automating radiology tasks," said Charles
Hatt, Ph.D., co- author of the paper and adjunct research assistant
professor of radiology at Michigan Medicine. "It turns out that replacing
human radiologists is not a simple task, and a more realistic goal for
AI is to speed-up workflows and assist radiologists in making object, quantitative measurements that are otherwise cumbersome to perform and inherently subjective. In this regard, vascular deformation mapping is
a perfect, real-world example of how AI and quantitative imaging can
improve clinical care by empowering clinicians rather than attempting to replace them." While these reports show vascular deformation mapping may
be more useful than human rating to inform whether surgery is necessary on
an aortic aneurysm, researchers say the approach must be studied further
in large groups of patients in a clinic. Fortunately, Burris says, the
vascular deformation mapping technique can be performed on routine CT
scans of the aorta, making performing larger research studies easier.

"This is a totally new way of looking at aortic aneurysm growth," he
said. "As this develops, there is a possibility to deploy this across a
larger spectrum of diseases, such as abdominal aortic aneurysm. Moving
from the current one- dimensional measurements to a three-dimensional
approach lets us see patterns of aneurysm growth in a way never
before possible and allows us to ask many new questions and learn how
a highly-accurate tracking tool like this can be used to ultimately
improve care for patients." The first paper's additional authors include Zhangxing Bian, M.S., Michigan Medicine Department of Radiology, Jeffrey Dominic, M.S., Michigan Medicine Department of Radiology, Jianyang Zhong,
M.S., Michigan Medicine Department of Radiology, Ignas B. Houben, M.D., Michigan Medicine Department of Cardiac Surgery, Theodorus M.J. van Bakel, M.D., Michigan Medicine Department of Cardiac Surgery, Himanshu J. Patel,
M.D., Michigan Medicine Department of Cardiac Surgery, Brian Ross, Ph.D., Michigan Medicine Center for Molecular Imaging, and Gary Christiansen,
Ph.D., University of Iowa Department of Electrical and Computer
Engineering The second paper's additional author's include Zhangxing
Bian, M.S., Michigan Medicine Department of Radiology, Jianyang Zhong,
M.S., Michigan Medicine Department of Radiology Jeffrey Dominic, M.S.,
Michigan Medicine Department of Radiology, Gary Christiansen, Ph.D.,
University of Iowa Department of Electrical and Computer Engineering.

Imbio, LLC, has exclusive licensing rights to the intellectual property
the vascular deformation technique described in this post. Hatt is an
Imbio employee with stock in Imbio. Burris is a co-inventor of VDM with royalties related to intellectual property of VDM technology.

Burris supported by Radiological Society of North America Research Scholar Grant (RSCH1801). Burris and Hatt supported by the National Institutes
of Health (R44 HL145953).

========================================================================== Story Source: Materials provided by
Michigan_Medicine_-_University_of_Michigan. Original written by Noah
Fromson. Note: Content may be edited for style and length.


========================================================================== Journal References:
1. Zhangxing Bian, Jiayang Zhong, Jeffrey Dominic, Gary E. Christensen,
Charles R. Hatt, Nicholas S. Burris. Validation of a robust method
for quantification of three‐dimensional growth of the thoracic
aorta using deformable image registration. Medical Physics, 2022;
DOI: 10.1002/ mp.15496
2. Nicholas S. Burris, Zhangxing Bian, Jeffrey Dominic, Jianyang Zhong,
Ignas B. Houben, Theodorus M. J. van Bakel, Himanshu J. Patel,
Brian D.

Ross, Gary E. Christensen, Charles R. Hatt. Vascular Deformation
Mapping for CT Surveillance of Thoracic Aortic Aneurysm
Growth. Radiology, 2022; 302 (1): 218 DOI: 10.1148/radiol.2021210658 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220216112236.htm

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