Imaging of the Postsurgical Thoracic Aorta: A State-of-the-Art Review

Surgical Strategies in Reoperation of the Proximal Aorta and Arch for Patients with Previous Frozen Elephant Trunk

Background: The frozen elephant trunk (FET) technique is increasingly utilized for aortic arch replacement in cases of aortic dissections and aneurysms. This rise in usage has led to more patients needing redo aortic surgeries due to progression of existing conditions, FET-related complications, or new valvular/coronary diseases. This article aims to evaluate surgical techniques to minimize risks during these reoperations, including a case study of a complex redo surgery. Methods: A comprehensive examination of surgical strategies was conducted, focusing on preoperative preparation, cannulation site identification, cerebral and cardiac protective measures, and pitfalls to avoid. The importance of adapting to the modified anatomical landscape post-FET is emphasized. A detailed case study of a patient undergoing complex redo FET surgery is included. Results: The article identified key surgical strategies for reoperation in patients with prior FET, highlighting the importance of meticulous preoperative planning and execution. Techniques to minimize risks include detailed imaging for planning, strategic cannulation for optimal perfusion, multidisciplinary approaches as well as careful fail-safe measures. The case study demonstrates the practical application of these strategies in a high-risk scenario. The evidence underscores the necessity for individualized patient management and the development of standardized protocols. Conclusions: The FET technique, while effective for initial aortic arch repairs, often necessitates complex reoperations. Adopting advanced surgical strategies and multidisciplinary planning can significantly mitigate risks associated with these procedures. Future research should focus on refining these techniques and establishing standardized protocols to improve patient outcomes.

Utility of structured follow-up imaging after aortic surgery

BACKGROUND

Although postoperative follow-up after aortic surgery is recommended by guidelines, its clinical utility is not well documented. We hypothesized that structured follow-up imaging by an aortic program would improve outcomes. We then documented radiologic findings on asymptomatic postoperative imaging.

METHODS

All patients who survived to discharge after open thoracic aortic surgery between January 2017 and July 2021 were included, excluding endocarditis. Patients who followed at our center and received scheduled imaging were compared with patients who did not. Survival was analyzed by the method of Kaplan-Meier, and reintervention was assessed using the Fine-Gray subhazard function. Routine imaging was reviewed for aortic growth, pseudoaneurysm, and perigraft density.

RESULTS

After aortic surgery, the cumulative incidence of follow-up was 38.6% at 3 years postoperatively. Patients with follow-up were more likely to have a dissection and fewer comorbidities but were similar in regards to socioeconomic factors and distance to hospital. After matching and accounting for immortal time bias, patients with follow-up had a greater reintervention rate (26.0% vs 9.0%) with similar survival (98.7% vs 95.2%, P = .110) at 4 years. The cumulative incidence of pseudoaneurysm, significant perigraft density, and growth ≥3 mm/year on routine imaging was 49.7% at 3 years.

CONCLUSIONS

Implementation of structured follow-up imaging by an aortic program resulted in low clinical compliance. Follow-up was associated with increased rates of aortic reintervention. Clinically relevant radiologic findings were common on asymptomatic imaging and increased throughout 5-year follow-up rather than plateauing in the early postoperative period.

Misdiagnosis of Thoracic Aortic Emergencies Occurs Frequently Among Transfers to Aortic Referral Centers: An Analysis of Over 3700 Patients

Background Acute aortic syndromes may be prone to misdiagnosis by nonreferral aortic centers with less diagnostic experience. We evaluated regional variability in these misdiagnosis trends among patients transferred to different regional quaternary care centers with presumed acute aortic syndromes. Methods and Results Two institutional aortic center databases were retrospectively reviewed for emergency transfers in patients diagnosed with acute aortic dissection, intramural hematoma, penetrating aortic ulcer, thoracic aortic aneurysm, or aortic pseudoaneurysm between 2008 and 2020. Transferring diagnoses versus actual diagnoses were reviewed using physician notes and radiology reports. Misdiagnoses were confirmed by a board-certified cardiothoracic surgeon. A total of 3772 inpatient transfers were identified, of which 1762 patients were classified as emergency transfers. The mean age was 64 years (58% male). Patients were transferred from 203 medical centers by ground (51%) or air (49%). Differences in transfer diagnosis and actual diagnosis were identified in 188 (10.7%) patients. Of those, incorrect classification of Type A versus B dissections was identified among 23%, and 30% of patients with a referring diagnosis of an acute aortic dissection did not have one. In addition, 14% transferred for contained/impending rupture did not have signs of rupture. All misdiagnoses were secondary to misinterpretation of imaging, with motion artifacts (n=32, 17%) and postsurgical changes (n=44, 23%) being common sources of diagnostic error. Conclusions Misdiagnosis of acute aortic syndromes commonly occurred in patients transferred to 2 separate large aortic referral centers. Although diagnostic accuracy may be improving, there are opportunities for improved physician awareness through standardized web-based imaging education.

Quantitative analysis of dynamic computed tomography angiography for the detection of endoleaks after abdominal aorta aneurysm endovascular repair: A feasibility study

Objectives

To assess the feasibility of quantitative analysis of dynamic computed tomography angiography (dCTA) for the detection of endoleaks in patients who underwent endovascular repair of abdominal aortic aneurysms (EVAR).

Material and methods

Twenty patients scheduled for contrast-enhanced CT angiography (CTA) of the abdominal aorta post-EVAR were prospectively enrolled. All patients received a standard triphasic CTA protocol, followed by an additional dCTA. The dCTA acquisition enabled reconstruction of color-coded maps depicting blood perfusion and a dCTA dataset of the aneurysm sac. Observers assessed the dCTA and dynamic CT perfusion (dCTP) images for the detection of endoleaks, establishing diagnostic confidence based on a modified 5-point Likert scale. An index was calculated for the ratio between the endoleak and aneurysm sac using blood flow for dCTP and Hounsfield units (HU) for dCTA. The Wilcoxon test compared the endoleak index and the diagnostic confidence of the observers.

Results

In total, 19 patients (18 males, median age 74 years [70.5–75.7]) were included for analysis. Nine endoleaks were detected in 7 patients using triphasic CTA as the reference standard. There was complete agreement for endoleak detection between the two techniques on a per-patient basis. Both dCTA and dCTP identified an additional endoleak in one patient. The diagnostic confidence using dCTP for detection of endoleaks was not significantly superior to dCTA (5.0 [5–5] vs. 4.5 [4–5], respectively; p = 0.11); however, dCTP demonstrated superior diagnostic confidence for endoleak exclusion compared to dCTA (1.0 [1–1] vs 1.5 [1.5–1.5], respectively; p <0.01). Moreover, the dCTP endoleak index was significantly higher than the dCTA index (18.5 [10.8–20.5] vs. 3.5 [5–2.7], respectively; p = 0.02).

Conclusions

Quantitative analysis of dCTP imaging can aid in the detection of endoleaks and demonstrates a higher endoleak detection rate than triphasic CTA, as well as a strong correlation with visual assessment of dCTA images.

Sinus of Valsalva Aneurysms: Basic Concepts and Imaging Evaluation Using Multidetector Computed Tomography

Sinuses of Valsalva aneurysms are rare cardiac anomalies with a varied clinical spectrum. The presentation may range from silent asymptomatic cases detected incidentally to catastrophic rupture. They are associated with potentially fatal complications; however, the prognosis after treatment is excellent, which mandates prompt and accurate diagnosis. Imaging is of paramount importance in diagnosis, treatment planning, and postsurgical follow-up. Echocardiography remains the initial investigation of choice; however, cardiac magnetic resonance imaging and computed tomography are being increasingly utilized as complementary imaging techniques. The latest generation multidetector computed tomography with its improved spatial and temporal resolution provides high-quality reconstructed images with reduced radiation burden. Moreover, it allows the simultaneous assessment of coronary arteries, thereby helping in mapping the ideal treatment option. Surgical repair remains the treatment of choice with percutaneous closure in selected patients.

Retrospective Comparative Analysis of Computed Tomography Findings of Acute and Chronic Aortic Dissections and Intramural Hematomas

PURPOSE

The objective of this study was to assess the reliability of ancillary imaging findings in distinguishing acute from chronic aortic dissection (AD) and intramural hematoma (IMH) using computed tomography angiography (CTA).

MATERIALS AND METHODS

Two radiologists specializing in cardiothoracic and vascular imaging reviewed paired CTAs of patients with AD or IMH who underwent CTA in the acute (within 24 h of presentation) and chronic settings. The radiologists were blinded to the temporal order of the CTAs. Minimum and maximum flap thicknesses and presence or absence of pleural effusion, pericardial effusion, mediastinal hematoma or fat standing, and mediastinal lymphadenopathy were recorded.

RESULTS

Patients included 25 male individuals and 13 female individuals with a mean age of 59 years (range: 34 to 87 y). The group included 29 AD and 9 IMH cases. The median interval between the paired CTs was 542 days (range: 100 to 2533 d). Respectively, the mean minimum flap thicknesses in the acute and chronic AD were 1.3 and 1.4 mm (P=0.3), and the mean maximum flap thicknesses were 2.7 and 2.9 mm (P=0.29). The incidences of ancillary findings in acute and chronic AD and IMH were as follows: pleural effusion (55% vs. 37%, P=0.143), pericardial effusion (8% vs. 11%, P=1.0), lymphadenopathy (47% vs. 47%, P=1.0), and periaortic fat stranding (87% vs. 76%, P=0.344).

CONCLUSIONS

Ancillary CT imaging findings traditionally ascribed to acute AD and IMH are also often found in the chronic setting and are not reliable indicators of acuity. Flap thickness in AD may not be a reliable imaging indicator of acuity of AD.

Spectral Computed Tomography Angiography With a Gadolinium-based Contrast Agent: First Clinical Imaging Results in Cardiovascular Applications

PURPOSE

Computed tomography angiography (CTA) requires IV application of iodine-based contrast agents. There are several medical conditions in which application is not advisable or even feasible, especially for elective examinations. Novel techniques such as monoenergetic reconstructions from dual-energy computed tomographic (CT) data have been shown to increase radiation attenuation of gadolinium (Gd)-based contrast agents in a phantom model. Therefore, the purpose of the present investigation was to evaluate the technical feasibility and image quality of clinical spectral CTA with a Gd-based contrast agent.

MATERIALS AND METHODS

Eleven consecutive patients with common indications for thoracic CTA and contraindications for iodine-based contrast agents were examined using clinical routine doses (0.2 mmol/kg) of Gd-based contrast agent with spectral CT. Monoenergetic reconstructions of the spectral data set were computed.

RESULTS

We performed 11 Gd-enhanced CTAs: 9 aortic angiographies, 1 coronary angiography, and 1 angiography of the pulmonary arteries. Image quality of the monoenergetic reconstructions with 40 keV (monoE40) was considered diagnostic by 2 experienced radiologists in each patient; the conventional CT reconstructions did not reach diagnostic image quality. MonoE40 reconstruction resulted in a substantial, ∼2-fold increase of intravascular Gd attenuation compared with the conventional images (P<0.0001). No relevant change of attenuation was observed for the myocardium or the skeletal muscle.

CONCLUSIONS

With spectral CT and reconstruction of monoenergetic images with extrapolated 40 keV, Gd-based contrast agent thoracic angiography with clinical doses of Gd is technically feasible. Gd-based CTA seems a valuable alternative in patients with contraindications for iodine-based contrast media.

Technological Advancements in Echocardiographic Assessment of Thoracic Aortic Dilatation: Head to Head Comparison Among Multidetector Computed Tomography, 2-Dimensional, and 3-Dimensional Echocardiography Measurements

PURPOSE

The aim of this study was to evaluate the feasibility and accuracy of 2-dimensional (2D) and 3-dimensional (3D) transthoracic echocardiography (2DTTE, 3DTTE) versus multidetector computed tomography (MDCT) in patients with ascending aortic (AA) dilation.

MATERIALS AND METHODS

Fifty consecutive patients with AA dilation were evaluated by 2DTTE, X-plane (XP) 3DTTE, and MDCT. Aorta diameters were measured at aortic annulus, aortic root (SIN), sinotubular junction, AA, aortic arch before the prebrachiocephalic artery (PRE), and before left subclavian artery (INTRA). Leading edge-to-leading edge (L-L) and inner-to-inner (I-I) measurements were compared with MDCT data.

RESULTS

Feasibility, quality of imaging, and accuracy was high with all echocardiographic methods. Specifically for MDCT maximum SIN diameter, the best correlation and agreement was obtained using XP maximum diameter at 3DTTE (MDCT: 44.8±7.4 mm vs. XP: 44.4±7.4 mm; r=0.975; bias=-0.4 mm). The same was true for AA maximum diameter at MDCT (MDCT: 46.6±8.1 mm vs. XP: 47.5±8.1 mm; r=0.991; bias=0.1 mm). For aortic arch the best correlation and agreement with MDCT were as follows: 2DTTE L-L diameter for arch PRE (MDCT: 37.9±5.3 mm vs. TTE: 36.6±4.5 mm; r=0.927; bias=-0.9 mm) and MDCT minimum diameter with XP minimum diameter for arch INTRA (MDCT: 28.2±5.0 mm vs. TTE 28.8±4.7 mm; r=0.939; bias=-0.3 mm).

CONCLUSION

In patients with aortic dilatation or aneurysm, new techniques (mainly 2D-3D probes allowing XP views) facilitate accuracy of aortic measurements at different sites of the vessel and allow standardization of analysis to better compare with MDCT.

Association of Aortic Arch Width Assessed by Noncontrast Cardiac Computed Tomography With Cardiac Remodeling, Cardiac Function, and Atherosclerosis in a Japanese Cohort

PURPOSE

Age-related aortic changes are related to adverse cardiac remodeling and reduced cardiac function. Here, we aim to assess the correlations between aortic arch width (AAW) and left ventricular (LV) remodeling and LV function as well as coronary artery calcification (CAC).

MATERIALS AND METHODS

This retrospective study included 194 patients (ages, 67±12 y) who underwent both coronary computed tomography angiography and echocardiography. The AAW is defined as the longest width between the ascending and descending aorta on a transaxial noncontrast coronary computed tomography angiography image at the level of the pulmonary artery bifurcation. Left ventricular mass, relative wall thickness ratio, left ventricular ejection fraction, left atrial volume, and early mitral inflow velocity to mitral annular early diastolic velocity ratio (E/e') were evaluated by echocardiography. CAC was assessed by Agatston score. The relationships between AAW and echocardiography parameters were assessed, and adjusted for demographic data and cardiovascular disease risk factors by multivariate linear regression analysis.

RESULTS

AAW (mean±SD, 11.6±1.4 cm) was positively correlated with left ventricular mass (r=0.28, P<0.0001), left atrial volume (r=0.28, P<0.0001), and E/e' (r=0.21, P<0.01). These correlations remained significant after adjustment for demographic data and cardiovascular disease risk factors. There was no correlation between AAW and left ventricular ejection fraction or relative wall thickness. There was a significant difference of AAW between the groups with Agatston score <100 and those with Agatston score ≥100, and this difference persisted after adjustment for all covariates (P<0.01).

CONCLUSION

Greater AAW was significantly associated with LV remodeling and impaired function as well as advanced CAC.

Postoperative imaging of the aorta

Considerable progress has been made in the management of diseases of the thoracic and abdominal aorta over the past decades, ranging from advances in open repair to the advent of minimally invasive endovascular techniques. Along with this comes an equivalent rise in imaging necessity for these patients, both in preoperative planning and postoperative surveillance. With the growing complexity and diversity of vascular procedures and techniques, it is essential to have a solid understanding of the imaging features and postoperative complications of these procedures to avoid imaging pitfalls. This review is an attempt to define the normal postoperative appearance and important complications of various open and endovascular surgical techniques of the thoracic and abdominal aorta.

Noninvasive aortic imaging

Non-invasive imaging of the aorta has undergone considerable advancements in recent times; largely driven by the technological advances in computed tomography (CT) and magnetic resonance imaging (MRI). This review article highlights these recent advancements and discusses the current role of different imaging tools in the management of aortic diseases.