Validation of a robust method for quantification of three‐dimensional growth of the thoracic aorta using deformable image registration

Purpose Accurate assessment of thoracic aortic aneurysm (TAA) growth is important for appropriate clinical management. Maximal aortic diameter is the primary metric that is used to assess growth, but it suffers from substantial measurement variability. A recently proposed technique, termed vascular...

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Bibliographic Details
Published in:Medical physics (Lancaster) 2022-04, Vol.49 (4), p.2514-2530
Main Authors: Bian, Zhangxing, Zhong, Jiayang, Dominic, Jeffrey, Christensen, Gary E., Hatt, Charles R., Burris, Nicholas S.
Format: Article
Language:English
Subjects:
Algorithms
Aorta
Aorta, Thoracic - diagnostic imaging
Computed Tomography Angiography
deformable registration
Humans
Image Processing, Computer-Assisted - methods
Phantoms, Imaging
QUANTITATIVE IMAGING AND IMAGE PROCESSING
thoracic aortic aneurysm
Tomography, X-Ray Computed
vascular deformation mapping
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Summary:Purpose Accurate assessment of thoracic aortic aneurysm (TAA) growth is important for appropriate clinical management. Maximal aortic diameter is the primary metric that is used to assess growth, but it suffers from substantial measurement variability. A recently proposed technique, termed vascular deformation mapping (VDM), is able to quantify three‐dimensional aortic growth using clinical computed tomography angiography (CTA) data using an approach based on deformable image registration (DIR). However, the accuracy and robustness of VDM remains undefined given the lack of ground truth from clinical CTA data, and, furthermore, the performance of VDM relative to standard manual diameter measurements is unknown. Methods To evaluate the performance of the VDM pipeline for quantifying aortic growth, we developed a novel and systematic evaluation process to generate 76 unique synthetic CTA growth phantoms (based on 10 unique cases) with variable degrees and locations of aortic wall deformation. Aortic deformation was quantified using two metrics: area ratio (AR), defined as the ratio of surface area in triangular mesh elements and the magnitude of deformation in the normal direction (DiN) relative to the aortic surface. Using these phantoms, we further investigated the effects on VDM's measurement accuracy resulting from factors that influence the quality of clinical CTA data such as respiratory translations, slice thickness, and image noise. Lastly, we compare the measurement error of VDM TAA growth assessments against two expert raters performing standard diameter measurements of synthetic phantom images. Results Across our population of 76 synthetic growth phantoms, the median absolute error was 0.063 (IQR: 0.073–0.054) for AR and 0.181 mm (interquartile range [IQR]: 0.214–0.143 mm) for DiN. Median relative error was 1.4% for AR and 3.3%$3.3\%$ for DiN at the highest tested noise level (contrast‐to‐noise ratio [CNR] = 2.66). Error in VDM output increased with slice thickness, with the highest median relative error of 1.5% for AR and 4.1% for DiN at a slice thickness of 2.0 mm. Respiratory motion of the aorta resulted in maximal absolute error of 3% AR and 0.6 mm in DiN, but bulk translations in aortic position had a very small effect on measured AR and DiN values (relative errors
ISSN:0094-2405
2473-4209
2473-4209
DOI:10.1002/mp.15496