Introduction: Marfan syndrome (MFS) is associated with high aortic growth rate (GR) and incidence of aortic dissection (AD), including delayed type B AD (TBAD) after prophylactic root repair. Elevated aortic stiffness has been investigated as a biomarker in MFS, but it remains uncertain how stiffness relates to GR and risk of AD. Vascular deformation mapping (VDM) is a technique that uses clinical CT angiography (CTA) to yield accurate, 3D maps of aortic growth over surveillance (VDM-G). This technique can also be used to assess aortic stiffness via quantification of cyclic wall stretch between systole and diastole (VDM-D) using multi-phasic dynamic CTA. Research Question: Is distensibility of the descending thoracic aorta associated with aortic GR or development of TBAD in MFS patients? Goal: The aim of this study was to analyze stiffness of the descending thoracic aorta in MFS and its association with aortic GR and occurrence of TBAD. Methods: We identified 36 adult MFS patients with dynamic CTA studies (>1 year interval) between 2004-2020. Growth was quantified by VDM-G, and linearized descending aortic stiffness by VDM-D - via calculation of distensibility - as the ratio of cyclic aortic surface area change (AR) over pulse pressure [(AR-1)/PP]. Results: Patients were 38.9 ± 12.1 years old, 58% were male and 25 (69%) had prior ascending repair. Mean CT follow-up interval was 5.7 ± 3.4 years and 8 developed TBAD during follow-up with pre-dissection diameter of 31.12 ± 6.01 mm at tear location. Age (β -0.4, 95%CI: -0.07, -0.01, p=0.015) and baseline diameter (β 0.10, 95%CI: 0.02, 0.18, p=0.017 ) independently predicted GR on multivariable analysis, but distensibility did not (p=0.38). Both distensibility (OR 0.02, 95% CI: 0.00, 0.68, p=0.03) and GR (OR 8687.05, 95% CI: 1.43, 5x10^7, p=0.04) were independent predictors of TBAD during follow-up, but diameter was not (p=0.49). Conclusion: Aortic stiffness and growth rate are likely predictors of type B aortic dissection in MFS.
Patients with ascending thoracic aortic aneurysm are recommended to undergo routine imaging surveillance. Although maximal diameter is the primary metric of disease severity, recent American College of Cardiology/American Heart Association guidelines emphasize the importance of aortic growth in determining surgical candidacy and risk. As diameter increases, it is assumed that aortic growth rate accelerates because of increased wall tension; however, this relationship is poorly studied. We aim to investigate the relationship between ascending thoracic aortic aneurysm diameter and growth rate using vascular deformation mapping, a validated technique for 3-dimensional growth mapping with submillimeter accuracy.
Abstract Imaging plays a central role in the management of patients with aortic disease. Such imaging can be made particularly complex by changing terminology and definitions, overlapping pathologies, and unfamiliarity with evolving endovascular treatment approaches. This article will review basic principles of aortic imaging that can be applied across a variety of settings and pathologies, with a description of key best practices and potential pitfalls for image acquisition, diagnostic assessment, and reporting. Additionally, the topic of imaging in the setting of endovascular aortic repair will be addressed, as well as a variety of imaging-related diagnostic challenges in the setting of chronic aortic dissection, including surgically repaired type A and uncomplicated type B dissections. Finally, recent developments in advanced aortic imaging will be highlighted with descriptions of several areas of promising research that may yield significant advances in imaging of aortic disease.
Introduction/Background: The vast majority of type A aortic dissection (TAAD) patients do not meet diameter thresholds for ascending aortic repair before their dissection. Increased ascending aortic length has been suggested to improve risk predictions, but this metric simplifies the aortic shape to a single dimension and doesn’t capture 3D features like tortuosity/torsion. Research Questions/Hypothesis: Are there distinct shape features of the ascending aorta that differentiate patients with TAAD better than aortic diameter? Methods/Approach: We retrospectively identified patients with good quality, pre-dissection CT imaging of the chest at our center prior to surgical repair of acute TAAD, excluding those with pre-existing dissection or prior aortic intervention. This pre-TAAD group was compared to a reference cohort of ‘normal’ patients (no aortic disease), patients with borderline ascending aortic dilation (35-44 mm) and ascending aneurysm (≥45 mm; aTAA). A shape score, based on statical shape modeling (SSM) and cosine similarity was computed (tubular ascending and arch) to quantify the similarity between an individual aortic shape compared to the mean ‘normal’ shape (defined as -1) and mean pre-TAAD shape (defined as +1). Results/Data (descriptive and inferential statistics): We identified 30 spontaneous TAAD patients with CTs at a median of 1.5 (IQR: 0.7-3.8) years pre-dissection. We compared against pre-existing cohorts with normal aortas (n=165), borderline dilation (n=119) and aTAA aneurysm (n=42). Age, sex and hypertension did not significantly differ between TAAD and aTAA groups. Max diameter (47.7 ± 2.0 vs. 40.6 ± 6.0 mm, p<0.01), centerline length (130 ± 11.5 vs. 120 ± 16.7 mm, p<0.01) and tortuosity (1.33 ± 0.08 vs. 1.27 ± 0.07, p<0.01) were higher in aTAA versus TAAD. Median SSM scores were higher in the (TAAD group 1.25, IQR: 0.76-1.46) compared to the aTAA group (-1.25, IQR: -1.60, -0.95; p<0.01) and the borderline dilation group (-1.03, IQR: -1.25, -0.84; p<0.01), Figure 1 . SSM scores for normal, borderline dilated and aTAA did not significantly differ. Conclusion: A novel SSM-based scoring method of assessing ascending aorta and arch geometry reveals clear shape differences among patients prior to TAAD.
Introduction: Methods to define genotype-phenotype correlations are needed to advance precision medicine in heritable thoracic aortic disease (HTAD), particularly for variants of unknown significance (VUS), where evidence is sparse. Vascular deformation mapping (VDM) - an image analysis tool - provides accurate, three-dimensional (3D) aortic growth mapping, to better define disease severity and phenotypes. Research Question: Does the extent of 3D aortic growth mapping vary among patients evaluated for HTAD according to their genetic test results? Methods: We included adults undergoing genetic testing for HTAD with at least 2 CT angiograms spanning ≥2 year interval. VDM quantified the 3D thoracic aortic growth over the longest interval. Results: We analyzed 122 patients (imaging follow-up 5.0 years ± 3.2), a median age of 62.5 years (range: 26-87), 33.6% females, 50% with a history of aneurysm and/or dissection in first-degree relatives, 32% with prior ascending aortic replacement (AAR). Genetic testing results were pathogenic/likely pathogenic (P/LP) in 17%, negative or benign/likely benign (B/LB) in 59%, and VUS in 46%. Among those with negative genetic testing, 80% had no growth by VDM. Among P/LP patients, 65% had at least one affected segment (6% showing growth without AAR; 24% with prior AAR; 35% with growth beyond AAR). Among VUS patients, 44% exhibited no aortic growth and 56% demonstrated aortic growth by VDM (30% with growth and native aorta; 26% with growth beyond the prior AAR). During follow-up, 10 VUS mutations were re-classified as B/LB or P/LP and VDM growth severity assessments were concordant with the re-classified category in 6 (60%). Among those with growth of the native aorta distal to AAR, 50% showed growth at non-dilated (<30 mm) diameters. Conclusion: HTAD presents with variable aortic enlargement patterns that are effectively characterized by VDM, providing an avenue for patient-specific risk assessment and decision-making, especially for VUS cases.
Patients with Marfan syndrome (MFS) are at a high risk of type B dissection (TBAD). Aortic growth and elongation have been suggested as risk factors for TBAD. Vascular deformation mapping (VDM) is an image analysis technique for mapping 3D aortic growth on rouine computed tomography angiography (CTA) scans. We aimed to use VDM to examine the value of aortic growth rate in the descending thoracic aorta (DescAo), among other imaging biomarkers, to identify the factors associated with risk of TBAD in MFS.
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