Abstract
BackgroundPatients with thoracic aortic dilatation who undergo annual computed tomography angiography (CTA) are subject to repeated radiation and contrast exposure. The purpose of this study was to evaluate the feasibility of a non-contrast, respiratory motion-resolved whole-heart cardiovascular magnetic resonance angiography (CMRA) technique against reference standard CTA, for the quantitative assessment of cardiovascular anatomy and monitoring of disease progression in patients with thoracic aortic dilatation. MethodsTwenty-four patients (68.6 ± 9.8 years) with thoracic aortic dilatation prospectively underwent clinical CTA and research 1.5T CMRA between July 2017 and November 2018. Scans were repeated in 15 patients 1 year later. A prototype free-breathing 3D radial balanced steady-state free-precession whole-heart CMRA sequence was used in combination with compressed sensing-based reconstruction. Area, circumference, and diameter measurements were obtained at seven aortic levels by two experienced and two inexperienced readers. In addition, area and diameter measurements of the cardiac chambers, pulmonary arteries and pulmonary veins were also obtained. Agreement between the two modalities was assessed with intraclass correlation coefficient (ICC) analysis, Bland–Altman plots and scatter plots.ResultsArea, circumference and diameter measurements on a per-level analysis showed good or excellent agreement between CTA and CMRA (ICCs > 0.84). Means of differences on Bland–Altman plots were: area 0.0 cm2 [− 1.7; 1.6]; circumference 1.0 mm [− 10.0; 12.0], and diameter 0.6 mm [− 2.6; 3.6]. Area and diameter measurements of the left cardiac chambers showed good agreement (ICCs > 0.80), while moderate to good agreement was observed for the right chambers (all ICCs > 0.56). Similar good to excellent inter-modality agreement was shown for the pulmonary arteries and veins (ICC range 0.79–0.93), with the exception of the left lower pulmonary vein (ICC < 0.51). Inter-reader assessment demonstrated mostly good or excellent agreement for both CTA and CMRA measurements on a per-level analysis (ICCs > 0.64). Difference in maximum aortic diameter measurements at baseline vs follow up showed excellent agreement between CMRA and CTA (ICC = 0.91).ConclusionsThe radial whole-heart CMRA technique combined with respiratory motion-resolved reconstruction provides comparable anatomical measurements of the thoracic aorta and cardiac structures as the reference standard CTA. It could potentially be used to diagnose and monitor patients with thoracic aortic dilatation without exposing them to radiation or contrast media.
Highlights
Patients with thoracic aortic dilatation who undergo annual computed tomography angiography (CTA) are subject to repeated radiation and contrast exposure
Area and diameter measurements of the left cardiac chambers showed good agreement (ICCs > 0.80), while moderate to good agreement was observed for the right chambers
Difference in maximum aortic diameter measurements at baseline vs follow up showed excel‐ lent agreement between cardiovascular magnetic resonance angiography (CMRA) and CTA (ICC = 0.91)
Summary
Patients with thoracic aortic dilatation who undergo annual computed tomography angiography (CTA) are subject to repeated radiation and contrast exposure. Once thoracic aortic dilatation has been diagnosed, a “watch and wait” surveillance program is initiated until the risk of aortic rupture outweighs the potential risks of the surgical repair [3]. During this period, patients are typically examined annually with computed tomography angiography (CTA) of the chest [4]. Patients are typically examined annually with computed tomography angiography (CTA) of the chest [4] This practice raises concerns regarding the administration of multiple doses of iodinated contrast media and repeated exposure to ionizing radiation [5, 6]. Alternative imaging modalities that may reduce or even eliminate cumulative exposure to radiation and repeated contrast administration would be of great benefit to such patients
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