Page 21 - Vasoclick emagazine Issue2

New Discovery

Vascular deformation mapping: A new technique to measure thoracic aortic aneurysm growth

Thoracic aortic aneurysm is a common but potentially life-threatening condition. There is a lack of imaging techniques to
assess the three-dimensional (3D) aortic growth accurately which complicates its management. Currently, the growth rate
1
of an aneurysm is measured manually, and the experienced ‘raters’ compare two CT scan images to assess any change in
aortic growth. This makes this method highly prone to variabilities and errors. Additionally, the aneurysm growth rate is just
a fraction of a millimeter every year and thus hard to detect. Hence manual measurements have often proven to be
2,3
inadequate to identify the actual risk with 100% accuracy.

A recent study has optimized a computed tomography-based (CT) medical image analysis technique to measure the
growth rate of thoracic aortic aneurysms for the first time. Vascular deformation mapping (VDM) aims to improve the
1
reliability and accuracy of aortic measurements compared to those of standard methods. It measures all points on the
1
aortic wall for any changes using spatial resolution and CT angiography to capture high-resolution images anywhere in the
thoracic area. Nicholas Burns, the corresponding author of the study, has claimed this technique to be a promising step in
1, 2
vascular surgery. 2

VDM works based on an image analysis technique called image registration. Multiple CT scans are aligned, and any pixel
difference amongst these scans is detected. All the scans align to form a three-dimensional color map of the aorta and
show the real growth and location of the aneurysm. VDM successfully performed 3D growth mapping in 92% of the
1,2
patients involved in the study (Figure 1). It identified growth in six additional areas that were not detected by the standard
method. The accuracy rate of VDM was calculated to be less than 1mm, while the most experienced human analysts have
reported errors up to 3 mm in their assessments.

Based on these promising findings, VDM can be an important tool to plan for surgeries and expand to larger patient
populations by mapping on regular aortic CT scans. Further studies can be designed to confirm the clinical implications of
2
this technique in the long term and other diseases. 1,2
References:
1. Burris N, Bian Z, Dominic J et al. Vascular Deformation Mapping for CT Surveillance of Thoracic Aortic Aneurysm Growth. Radiology.
2022;302(1):218-225. doi:10.1148/radiol.2021210658
2. New technique outperforms manual assessment of thoracic aortic aneurysm growth - Vascular News. Vascular News.
https://vascularnews.com/vascular-deformation-mapping/. Published 2022. Accessed February 25, 2022.
3. A new tool for 3-D measurement of the aorta may identify fatal heart conditions earlier. Science Daily.
https://www.sciencedaily.com/releases/2022/02/220216112236.htm. Published 2022. Accessed February 25, 2022.

Interval 1 (1Y) Interval 2 (2Y) Interval 3 (3Y)

Figure 1: Representative images of ascending aorta in a patient with a 4.7-cm aneurysm by vascular deformation mapping assessment. Patient had
demonstrated stability of the ascending aorta over three surveillance intervals totaling 6 years. No growth of the ascending aorta was detected in the
three-dimensional assessment across all surveillance intervals. But a small focal region of growth was detected in interval 2 (arrowhead). 1