CT in nontraumatic acute thoracic aortic disease: typical and atypical features and complications

Non-A Non-B Acute Aortic Dissection: Is There Some Confusion in the Radiologist's Mind?

BACKGROUND

The aim of this study is to define and determine the rate of acute non-A-non-B aortic dissections, and to evaluate CT angiography findings and possible complications, as well as to discuss management strategies and currently available therapy. Non-A non-B type of aortic dissection is still a grey area in the radiologist's mind, such that it is not entirely clear what should be reported and completed in terms of this disease.

METHODS

A retrospective single-center study including 36 pre-treatment CT angiograms of consecutive patients (mean age: 61 years) between January 2012 and December 2022 with aortic dissection involving the aortic arch with/without the thoracic descending/abdominal aorta (type non-A non-B).

RESULTS

According to the dissection anatomy, we identified three modalities of spontaneous acute non-A-non-B anatomical configurations. Configuration 1 (n = 25) with descending-entry tear and retrograde arch extension (DTA entry). Configuration 2 (n = 4) with Arch entry tear and isolated arch involvement (Arch alone). Configuration 3 (n = 7) with Arch entry and anterograde descending (±abdominal) aorta involvement (Arch entry). CT angiogram findings, management, and treatment options are described.

CONCLUSIONS

Acute non-A non-B dissection represents an infrequent occurrence of aortic arch dissection (with or without involvement of the descending aorta) that does not extend to the ascending aorta. The complete understanding of its natural progression, distinct CT angiography subtypes, optimal management, and treatment strategies remains incomplete. Within our series, patients frequently exhibit a complex clinical course, often necessitating a more assertive approach to treatment compared to type B dissections.

Extended Stanford Type-A Aortic Dissection with Multivessel Coronary and Peripheral Artery Involvement: An Autopsy Case Report

We report the case of a 64-year-old male who died suddenly short after his admission to hospital because of strong chest pain and before any clinical diagnosis was established. His medical history included coronary disease with coronary by-pass surgery at the age of 40 years old, uncontrolled hypertension, diabetes mellitus, and elevated levels of cholesterol. The autopsy revealed quite a rare case of Stanford A aortic dissection with extension to the common and internal carotid arteries; the subclavian, axillary, brachial, and radial arteries; three coronary arteries; the superior mesenteric artery; and the iliac arteries. There was no histological evidence of aortitis or connective tissue disease. The death did not result from the rupture of the aortic dissection, but from myocardial ischemia due to coronary occlusion in combination with hemodynamic disturbance from stress caused by the extended aortic dissection.

Acute aortic dissection complicated with hemorrhagic aortopulmonary artery sheath: a review of the literature

A hemorrhagic aortopulmonary artery sheath (HAPS) is an infrequent and critical complication of aortic dissection (AD), which is caused by a hematoma extending through the ruptured aortic wall into the aortopulmonary artery sheath. The adventitial hematoma might narrow or even occlude the lumen of the pulmonary arteries and extend into the pulmonary interstitium and alveoli. The prompt and accurate recognition of HAPS on computed tomography (CT) is crucial and might assist in the diagnosis of unidentifiable AD. HAPS was manifested as high attenuation areas surrounded the pulmonary arteries without enhancement on CT; even thickened bronchovascular sheath and ground-glass consolidations surrounded bronchovascular distribution, which might be associated with the prognosis. Aggressive and effective surgical treatment is the primary determinant of short-term survival.

Comparative effectiveness and safety of open triple-branched stent graft technique with stented elephant trunk implantation in treating Stanford type A aortic dissection: A trial sequential meta-analysis

BACKGROUND

The optimal surgical intervention for Stanford type A aortic dissection is controversial. The aim of this trial sequential meta-analysis was to investigate the comparative effectiveness and safety of open triple-branched stent graft and stent elephant trunk implantation for total aortic arch reconstruction in Sandford type A aortic dissection.

METHODS

PubMed, Embase, Cochrane library, Chinese Biomedical Literature database (CBM), and China National Knowledge Infrastructure (CNKI) were searched for retrieving relevant studies from inception to February 28, 2022. We evaluated 30-day mortality, procedure-related time including cardiopulmonary bypass (CPB), aortic cross-clamp (ACC), and selective cerebral perfusion (SCP), the incidence of postoperative complications including paralysis, cerebral embolism, and acute renal failure, intensive care unit (ICU) time, and medical expenditure. Statistical analysis was performed by RevMan 5.4 and trial sequential analysis (TSA) software.

RESULTS

Six studies involving 260 dissection cases were included eventually. Total aortic arch reconstruction with open triple-branched stent graft was comparable to the stented elephant trunk implantation in 30-day mortality, incidence of postoperative complications, ICU time, and medical expenditure, but open triple-branched stent graft was related to shorter procedure-related time including CPB (mean difference [MD] = -46.11, 95% confidence interval [CI] = -67.24 to -24.98, p < .001), ACC (MD = -42.82, 95% CI = -66.74 to -18.90, p < .001), and SCP (MD = -17.88, 95% CI = -33.36 to -2.39, p = .02). TSA confirmed robustness of findings.

CONCLUSIONS

Our analysis suggested that total aortic arch reconstruction with open triple-branched stent graft may be an effective and simplified procedure than the stented elephant trunk implantation.

Early Prediction Model of Acute Aortic Syndrome Mortality in Emergency Departments

Purpose

Acute aortic syndrome is a constellation of life-threatening medical conditions for which rapid assessment and targeted intervention are important for the prognosis of patients who are at high risk of in-hospital death. The current study aims to develop and externally validate an early prediction mortality model that can be used to identify high-risk patients with acute aortic syndrome in the emergency department.

Patients and Methods

This retrospective multi-center observational study enrolled 1088 patients with acute aortic syndrome admitted to the emergency departments of two hospitals in China between January 2017 and March 2021 for model development. A total of 210 patients with acute aortic syndrome admitted to the emergency departments of Peking University Third Hospital between January 2007 and December 2021 was enrolled for model validation. Demographics and clinical factors were collected at the time of emergency department admission. The predictive variables were determined by referring to the results of previous studies and the baseline analysis of this study. The study’s endpoint was in-hospital death. To assess internal validity, we used a fivefold cross-validation method. Model performance was validated internally and externally by evaluating model discrimination using the area under the receiver-operating characteristic curve (AUC). A nomogram was developed based on the binary regression results.

Results

In the development cohort, 1088 patients with acute aortic syndromes were included, and 88 (8.1%) patients died during hospitalization. In the validation cohort, 210 patients were included, and 20 (9.5%) patients died during hospitalization. The final model included the following variables: digestive system symptoms (OR=2.25; P=0.024), any pulse deficit (OR=7.78; P<0.001), creatinine (µmol/L)(OR=1.00; P=0.018), lesion extension to iliac vessels (OR=4.49; P<0.001), pericardial effusion (OR=2.67; P=0.008), and Stanford type A (OR=10.46; P<0.001). The model’s AUC was 0.838 (95% CI 0.784–0.892) in the development cohort and 0.821 (95% CI 0.750–0.891) in the validation cohort, and the Hosmer–Lemeshow test showed p=0.597. The fivefold cross-validation demonstrated a mean accuracy of 0.94, a mean precision of 0.67, and a mean recall of 0.13.

Conclusion

This risk prediction tool uses simple variables to provide robust prediction of the risk of in-hospital death from acute aortic syndrome and validated well in an independent cohort. The tool can help emergency clinicians quickly identify high-risk acute aortic syndrome patients, although further studies are needed for verifying the prospective data and the results of our study.

MDCT Imaging of Non-Traumatic Thoracic Aortic Emergencies and Its Impact on Diagnosis and Management—A Reappraisal

Non-traumatic thoracic aorta emergencies are associated with significant morbidity and mortality. Diseases of the intimomedial layers (aortic dissection and variants) have been grouped under the common term of acute aortic syndrome because they are life-threatening conditions clinically indistinguishable on presentation. Patients with aortic dissection may present with a wide variety of symptoms secondary to the pattern of dissection and end organ malperfusion. Other conditions may be seen in patients with acute symptoms, including ruptured and unstable thoracic aortic aneurysm, iatrogenic or infective pseudoaneurysms, aortic fistula, acute aortic thrombus/occlusive disease, and vasculitis. Imaging plays a pivotal role in the patient’s management and care. In the emergency room, chest X-ray is the initial imaging test offering a screening evaluation for alternative common differential diagnoses and a preliminary assessment of the mediastinal dimensions. State-of-the-art multidetector computed tomography angiography (CTA) provides a widely available, rapid, replicable, noninvasive diagnostic imaging with sensitivity approaching 100%. It is an impressive tool in decision-making process with a deep impact on treatment including endovascular or open surgical or conservative treatment. Radiologists must be familiar with the spectrum of these entities to help triage patients appropriately and efficiently. Understanding the imaging findings and proper measurement techniques allow the radiologist to suggest the most appropriate next management step.

CT of the Difficult Acute Aortic Syndrome

Acute aortic syndrome (AAS) is classically attributed to three underlying pathologic conditions-aortic dissection (AD), intramural hematoma (IMH), and penetrating atherosclerotic ulcer (PAU). In the majority of cases, the basics of image interpretation are not difficult and have been extensively reviewed in the literature. In this article, the authors extend existing imaging overviews of AAS by highlighting additional factors related to the diagnosis, classification, and characterization of difficult AAS cases. It has been well documented that AAS is caused not only by an AD but by a spectrum of lesions that often have overlap in imaging features and are not clearly distinguishable. Specifically, phase of contrast enhancement, flow artifacts, and flapless AD equivalents can complicate diagnosis and are discussed. While the A/B dichotomy of the Stanford system is still used, the authors subsequently emphasize the Society for Vascular Surgery's new guidelines for the description of acute aortic pathologic conditions given the expanded use of endovascular techniques used in aortic repair. In the final section, atypical aortic rupture and pitfalls are described. As examples of pericardial and shared sheath rupture become more prevalent in the literature, it is important to recognize contrast material third-spacing and mediastinal blood as potential mimics. By understanding these factors related to difficult cases of AAS, the diagnostic radiologist will be able to accurately refine CT interpretation and thus provide information that is best suited to directing management. Online supplemental material is available for this article. ^©RSNA, 2021.

Potential of unenhanced computed tomography as a screening tool for acute aortic syndromes

AIMS

Contrast-enhanced computed tomography (CE-CT) is the gold standard for diagnosing acute aortic syndromes (AAS). Unenhanced computed tomography (unenhanced-CT) also provides specific findings for AAS; however, its diagnostic ability is not well discussed. This study aims to evaluate the potential of unenhanced-CT as an AAS screening tool.

METHODS AND RESULTS

We retrospectively examined AAS patients who visited our hospital between 2011 and 2021 to validate the diagnostic value of unenhanced-CT alone and along with the aortic dissection detection risk score (ADD-RS) plus D-dimer. Acute aortic syndrome was assessed as detectable using unenhanced-CT with any of the following findings: pericardial haemorrhage, high-attenuation haematoma, and displacement of intimal calcification or a flap. Of the 316 AAS cases, 292 (92%) were detectable with unenhanced-CT. Twenty-four (8%) cases undetectable with unenhanced-CT involved younger patients [median (interquartile range), 45 (42-51) years vs. 72 (63-80) years, P < 0.001] and patients more frequently complicated with a patent false lumen (79% vs. 42%, P < 0.001). Acute aortic syndrome-detection rate with unenhanced-CT increased with age, reaching 98% (276/282) in those ≥50 years of age and 100% (121/121) in those ≥75 years of age. With the ADD-RS plus D-dimer, there was only one AAS case undetectable with unenhanced-CT among patients ≥50 years of age, except for cases with the ADD-RS ≥1 plus D-dimer levels of ≥0.5 μg/mL.

CONCLUSION

Acute aortic syndromes in younger patients and patients with a patent false lumen could be misdiagnosed with unenhanced-CT alone. The combination of the ADD-RS plus D-dimer and unenhanced-CT could minimize AAS misdiagnosis while avoiding over-testing with CE-CT.

Before and after Endovascular Aortic Repair in the Same Patients with Aortic Dissection: A Cohort Study of Four-Dimensional Phase-Contrast Magnetic Resonance Imaging

(1) Background: We used four-dimensional phase-contrast magnetic resonance imaging (4D PC-MRI) to evaluate the impact of an endovascular aortic repair (TEVAR) on aortic dissection. (2) Methods: A total of 10 patients received 4D PC-MRI on a 1.5-T MR both before and after TEVAR. (3) Results: The aortas were repaired with either a GORE TAG Stent (Gore Medical; n = 7) or Zenith Dissection Endovascular Stent (Cook Medical; n = 3). TEVAR increased the forward flow volume of the true lumen (TL) (at the abdominal aorta, p = 0.047). TEVAR also reduced the regurgitant fraction in the TL at the descending aorta but increased it in the false lumen (FL). After TEVAR, the stroke distance increased in the TL (at descending and abdominal aorta, p = 0.018 and 0.015), indicating more effective blood transport per heartbeat. Post-stenting quantitative flow revealed that the reductions in stroke volume, backward flow volume, and absolute stroke volume were greater when covered stents were used than when bare stents were used in the FL of the descending aorta. Bare stents had a higher backward flow volume than covered stents did. (4) Conclusions: TEVAR increased the stroke volume in the TL and increased the regurgitant fraction in the FL in patients with aortic dissection.

Review of Imaging With Focus on New Techniques in Aortic Dissection

The imaging evaluation of a patient with aortic dissection can be undoubtedly complex, requiring that the interpreting physician understands the classification systems and vocabulary used. This can be made all the more challenging by advances in medical imaging that reshape the understanding of aortic dissection. The purpose of this paper is to provide a review of recent advances in the imaging modalities, and select modality-specific technologies, commonly used to study aortic dissection, including computed tomography, magnetic resonance imaging, and ultrasound. This is followed by an overview of imaging findings, including the classification, initial evaluation, and follow up, of aortic dissection.

The effect of postoperative anticoagulation on false lumen patency after surgery for acute type A aortic dissection

Background

Patent false lumen has been shown to have a negative impact on prognosis after surgery for acute type A aortic dissection (ATAAD). We aimed to assess the effect of postoperative anticoagulation on false lumen patency and clinical outcomes in relation to false lumen status.

Methods

Postoperative computed tomographies of 156 patients undergoing ATAAD DeBakey type I surgery were retrospectively evaluated for false lumen patency. The patients were divided into groups determined by anticoagulation treatment at discharge. Uni- and multivariable logistic regression was used for analysing the effect of anticoagulation on the false lumen, and Kaplan–Meier estimates were used to assess the association of a patent false lumen with the incidence of reoperation and long-term survival.

Results

A patent false lumen was present in 81% of the patients. Postoperative anticoagulants were not associated with a patent false lumen (p = 0.48) in univariable analysis. In multivariable analysis, both hemiarch replacement (OR 0.15, CI95% 0.05–0.49, p = 0.001) and the use of betablockers had a protective effect (OR 0.29, CI95% 0.10–0.85, p = 0.023). The Kaplan–Meier estimates for survival and the composite endpoint of survival and freedom from distal reintervention indicated no difference in outcome between patients in regard to anticoagulation treatment (survival p = 0.43, composite p = 0.82) or false lumen status (survival p = 0.21, composite p = 0.09).

Conclusion

This study could not show negative effects from the postoperative use of anticoagulants on false lumen status, nor that false lumen patency was associated with poorer prognosis. A hemiarch procedure was shown to be associated with reduced risk of false lumen patency.

Post-operative computed tomography imaging evaluation of ascending aorta surgery

Ascending thoracic aorta disease is often a life-threatening condition. Aortic aneurysm and aortic dissection are the most frequent ascending aorta diseases requiring surgical intervention. Surgical repair techniques of the ascending aorta are various; they include reconstruction of the ascending aorta by using a graft with or without a prosthetic valve, reconstruction with a composite artificial graft or using a biological graft, and reconstruction of the ascending aorta with a composite graft preserving the native valve and arch repair. The radiologist plays a key role in the identification of post-operative complications; differentiation from normal postoperative findings is fundamental. Our aim is to discuss the main diseases affecting the ascending aorta requiring surgery and the different techniques used to treat them. We also discuss the normal computed tomography (CT) imaging findings and after-surgery complications.

Computed Tomography Angiography Assessment of Acute Aortic Syndromes: Classification, Differentiating Imaging Features, and Imaging Interpretation Pitfalls

An acute aortic syndrome (AAS) is an important life-threatening condition that requires early detection and management. Acute intramural hematoma (IMH), aortic dissection (AD) and penetrating atherosclerotic ulcer (PAU) are included in AAS. ADs can be classified using the well-known Stanford or DeBakey classification systems. However, these classification systems omit description of arch dissections, anatomic variants, and morphologic features that impact outcome. The Society for Vascular Surgery and Society of Thoracic Surgeons (SVS-STS) have recently introduced a classification system that classifies ADs according to the location of the entry tear (primary intimomedial tear, PIT) and the proximal and distal extent of involvement, but does not include description of all morphologic features that may have diagnostic and prognostic significance. This review describes these classification systems for ADs and other AAS entities as well as their limitations. Typical computed tomography angiography (CTA) imaging appearance and differentiating features of ADs, limited intimal tears (LITs), IMHs, intramural blood pools (IBPs), ulcer-like projections (ULPs), and PAUs will be discussed. Furthermore, this review highlights common imaging interpretation pitfalls, what should be included in a comprehensive CTA report, and provides a brief overview of current management options.

Flow density of computed tomography aortography for predicting early unfavorable aortic remodeling after TEVAR in type IIIb aortic dissection

OBJECTIVE

Patients diagnosed of DeBakey type III aortic dissection with partial thrombosis of false lumen (FL) have a higher mortality rate. However, IIIb dissections with full patent FL tend to exhibit a partially thrombosed FL quickly after thoracic endovascular aortic repair (TEVAR); thus, we investigated survival and aortic remodeling in this population.

METHODS

We reviewed computed tomography aortograms (CTAs) of 123 patients with TEVAR-treated IIIb aortic dissections from July 2006 to June 2015; contrast density of CTAs represented intraluminal flow. Patients were selected to fit in 2 groups of FL in term of FL contrast density: low flow (LF) group (non-opacification in the midway of FL) and high flow (HF) group (full patent FL).

RESULTS

Surgical mortality was 10.3% in the HF group and 4.5% in the LF group (n = 61; LF = 22; HF = 39). 3 patients in the HF group suffered from lethal aortic rupture in 10 days postoperatively. The HF group showed significant increase in maximal diameter, and had larger thoracic (+4.00 ± 2.68 vs -1.16 ± 3.42 mm, P < .001) aortic diameter expansion from preoperation to one week postoperation. Both groups exhibited significant favorable thoracic TL expansion and maximal aortic diameter shrinkage in postoperative one week to one year. However, HF group displayed less thoracic aortic FL regression (-70.9 ± 83.5 vs -113.9 ± 95.0 cm³, P = .1) and TL expansion (+14.5 ± 27.2 vs +36.8 ± 28.3 cm³, P = .008) when compared to LF group.

CONCLUSIONS

Preoperative HF in the FL has an unfavorable effect on thoracic aortic diameter in one week post-TEVAR. This might increase the risk of aortic rupture.

Non-contrast CT-based radiomic signature for screening thoracic aortic dissections: a multicenter study

OBJECTIVE

To develop a non-contrast CT-based radiomic signature to effectively screen for thoracic aortic dissections (ADs).

METHODS

We retrospectively enrolled 378 patients who underwent non-contrast chest CT scans along with CT angiography or MRI from 4 medical centers. The training and validation sets were from 3 centers, while the external test set was from a 4th center. Radiomic features were extracted from non-contrast CT images. The radiomic signature was created on the basis of selected features by a logistic regression algorithm. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve, accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were conducted to assess the predictive ability of radiomic signature.

RESULTS

The radiomic signature demonstrated AUCs of 0.91 (95% confidence interval [CI], 0.86-0.95) in the training set, 0.92 (95% CI, 0.86-0.98) in the validation set, and 0.90 (95% CI, 0.82-0.98) in the external test set. The predicted diagnosis was in good agreement with the probability of thoracic AD. In the external test group, the diagnostic accuracy, sensitivity, specificity, PPV, and NPV were 90.5%, 85.7%, 91.7%, 70.6%, and 96.5%, respectively.

CONCLUSIONS

A radiomic signature based on non-contrast CT images can effectively predict thoracic ADs. This method may serve as a potential screening tool for thoracic ADs.

KEY POINTS

• The non-contrast CT-based radiomic signature can effectively predict the thoracic aortic dissections. • This radiomic signature shows better predictive performance compared to the current clinical model. • This prediction method may be a potential tool for screening thoracic aortic dissections.

Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression

Acute aortic dissection is the prototype of acute aortic syndromes (AASs), which include intramural hematoma, limited intimal tear, penetrating atherosclerotic ulcer, traumatic or iatrogenic aortic dissection, and leaking or ruptured aortic aneurysm. The manifestation is usually sudden and catastrophic with acutely severe tearing chest or back pain. However, clinical symptoms do not allow distinction between AAS types and other acute pathologic conditions. Diagnostic imaging is essential to rapidly confirm and accurately diagnose the type, magnitude, and complications of AASs. CT fast acquisition of volumetric datasets has become instrumental in diagnosis, surveillance, and intervention planning. Most critical findings affecting initial intervention and prognosis are obtained at CT, including involvement of the ascending aorta, primary intimal tear location, rupture, malperfusion, size and patency of the false lumen, complexity and extent of the dissection, maximum caliber of the aorta, and progression or postintervention complications. Involvement of the ascending aorta-Stanford type A-has the most rapid lethal complications and requires surgical intervention to affect its morbidity and mortality. Lesions not involving the ascending aorta-Stanford type B-have a lesser rate of complications in the acute phase. During the acute to longitudinal progression, various specific and nonspecific imaging findings are encountered, including pleural and pericardial effusions, fluid collections, progression including aortic enlargement, and postoperative changes that can be discerned at CT. A systematic analysis algorithm is proposed for CT of the entire aorta throughout the continuum of AASs into the chronic and posttreated disease state, which synthesizes and communicates salient findings to all care providers. Online supplemental material is available for this article. ^©RSNA, 2021.

Aortic dissection assessment by 4D phase-contrast MRI with hemodynamic parameters: the impact of stent type

Background

To explore the diagnostic performance of 4-dimensional phase-contrast magnetic resonance imaging (4D PC-MRI) in evaluating aortic dissection in different clinical scenarios.

Methods

The study group comprised 32 patients with a known aortic dissection who each underwent computed tomography angiography (CTA), and then 4D PC-MRI with a 1.5-T MR scanner. The 4D PC-MRI images were compared with the CTA images to evaluate the aortic size, branch identification, and iliac and femoral arterial access.

Results

The patients were divided into three groups: (I) patients diagnosed with Type B aortic dissection but did not undergo intervention (n=8); (II) patients with residual aortic dissection after open repair of Type A dissection (n=7); (III) patients who underwent endovascular aortic repair with or without open surgery (n=17). Without radiation or contrast media injection, 4D PC-MRI provided similar aortic images for patients in Group 1 and most of those in Group 2. In Group 3, stainless steel stents affected image quality in three patients. High-quality 4D PC-MRI images were obtained for the remaining 14 patients in Group 3, who had non-stainless steel stents, and provided major aortic information comparable to that provided by CTA with contrast media. The hemodynamic parameters of true and false lumens were evaluated between three patients with Type B aortic dissections and three patients who underwent thoracic endovascular aortic repair for their aortic dissection. The stroke volume was higher in the true lumen of the patients with stent-grafts than in the patients with Type B aortic dissection without intervention. The regurgitant fraction, an indicator of nonlaminar flow, was higher in the false lumens than in the true lumens. All 32 patients in this study tolerated 4D PC-MRI without adverse events.

Conclusions

4D PC-MRI is radiation- and contrast media-free option for imaging aortic dissection. It not only provided images comparable in quality to those obtained with CTA but also provided information on hemodynamic parameters, including endoleak detection after thoracic endovascular aortic repair. 4D PC-MRI was safe and accurate in evaluating chronic Type B aortic dissection and residual aortic dissection after surgery for acute Type A aortic dissection. Therefore, it could be a potential tool in treating pathology in aortic dissection, especially for patients with malperfusion syndrome of visceral vessels and in young patients with renal function impairment. However, certain endograft materials, especially stainless steel, may prevent the further application of 4D PC-MRI and should be avoided.

Quantification of true lumen helical morphology and chirality in type B aortic dissections

Chirality is a fundamental property in many biological systems. Motivated by previous observations of helical aortic blood flow, aortic tissue fibers, and propagation of aortic dissections, we introduce methods to characterize helical morphology of aortic dissections. After validation on computer-generated phantoms, the methods were applied to patients with type B dissection. For this cohort, there was a distinct bimodal distribution of helical propagation of the dissection with either achiral or exclusively right-handed chirality, with no intermediate cases or left-handed cases. This clear grouping indicates that dissection propagation favors these two modes, which is potentially due to the right-handedness of helical aortic blood flow and cell orientation. The characterization of dissection chirality and quantification of helical morphology advances our understanding of dissection pathology and lays a foundation for applications in clinical research and treatment practice. For example, the chirality and magnitude of helical metrics of dissections may indicate risk of dissection progression, help define treatment and surveillance strategies, and enable development of novel devices that account for various helical morphologies.NEW & NOTEWORTHY A novel definition of helical propagation of type B aortic dissections reveals a distinct bimodality, with the true lumen being either achiral (nonhelical) or exclusively right-handed. This right-handed chirality is consistent with anatomic and physiological phenomena such as right-handed twist during left ventricle contraction, helical blood flow, and tissue fiber direction. The helical character of aortic dissections may be useful for pathology research, diagnostics, treatment selection, therapeutic durability prediction, and aortic device design.

Imaging and Biomarkers in Acute Aortic Syndromes: Diagnostic and Prognostic Implications

Acute aortic syndrome (AAS) is an emergency and life-threatening condition including aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer and iatrogenic-traumatic aortic injury. An integrated multiparametric approach (clinical history and examination, electrocardiogram, biomarkers and imaging techniques) is recommended in order to make timely and accurate diagnosis, delineate the prognosis, choose the most appropriate therapeutic interventions tailored for the individual patient. Nowadays the best imaging strategy for diagnosing AAS and its complications is a combination of transthoracic echocardiography and computed tomography angiography (CTA). Transesophageal echocardiography tends to be carried out in complicated cases prior to surgical or endovascular therapy, often in the operating room and under general anesthesia. In this regard, intravascular ultrasound and intraluminal phase array imaging may be implemented during the endovascular procedures depending on operator expertise and cost issues. On the other hand, owing to its intrinsic characteristics, magnetic resonance imaging is an ideal imaging technique for serial measurements in patients at risk of AAS or with chronic dissection. Among biomarkers, D-dimer is the closest to "golden status" (high sensitivity and low negative likelihood ratio). Interestingly, 18fluorodeoxyglucose positron emission tomography/CT is increasingly being used along with specific serologic biomarkers (white blood cells, C-reactive protein, fibrinogen and D-dimer) to detect and monitor vascular inflammation affecting the aorta and systemic arteries. It is expected, in the near future, the development of serologic and imaging biomarkers able to early detect clinically-silent pathologic changes in the aorta wall before (primary prevention) and after (secondary prevention) the acute index event.

Multidetector Computed Tomography in Traumatic and Nontraumatic Aortic Emergencies: Emphasis on Acute Aortic Syndromes

Aortic emergencies comprise of a list of conditions which are uncommon but are potentially fatal. Prognosis is usually determined by emergent diagnosis and treatment and hence radiology plays a key role in patient management. In this article, we aim to review the various causes of aortic emergencies and the relevant imaging findings placing special emphasis on acute aortic syndromes.

Computed tomography findings and in-hospital mortality in patients with rupture of type B aortic dissection

Background

The relationships between the computed tomography (CT) findings and outcomes of patients with ruptured type B aortic dissection have not been clarified.

Purpose

To evaluate the initial CT findings of patients with ruptured type B aortic dissection and investigate the relationships between the initial CT findings and in-hospital mortality.

Material and Methods

This study was approved by the institutional review board. Thirty-three patients were diagnosed with ruptured Stanford type B aortic dissection at our hospital between 2007 and 2016 (21 men, 12 women; mean age = 76.1±10.7 years). We retrospectively evaluated the initial CT findings of ruptured type B aortic dissection and the relationships between clinical factors and in-hospital mortality using logistic regression analysis.

Results

Type B aortic dissections ruptured in the acute and chronic phases in 23 and 10 patients, respectively. The initial CT images showed various findings, including an open false lumen (58%), arch involvement (88%), hematomas in the pleural space (55%), hematomas in the pericardial space (18%), and the extravasation of vascular contrast material (12%). The mean maximum diameter of the affected aorta was 49.5 ± 16.1 mm. Among the 33 patients, 14 died at hospital. Female gender (hazard ratio = 10.284; 95% confidence interval [CI] = 1.61–65.54; P = 0.0136) and the presence of a hematoma in the pleural space (hazard ratio = 6.803; 95% CI = 1.07–43.24; P = 0.0421) were found to be predictors of in-hospital mortality.

Conclusion

Female gender and the presence of a hematoma in the pleural space are significant predictors of in-hospital mortality in patients with ruptured type B aortic dissection.

Significance of an additional unenhanced scan in computed tomography angiography of patients with suspected acute aortic syndrome

AIM

To assess potential benefits of an additional unenhanced acquisition in computed tomography angiography (CTA) in patients with suspected acute aortic syndrome (AAS).

METHODS

A total of 103 aortic CTA (non-electrocardiography-gated, 128 slices) performed due to suspected AAS were retrospectively evaluated for acute aortic dissection (AAD), intramural hematoma (IMH), or penetrating aortic ulcer (PAU). Spiral CTA protocol consisted of an unenhanced acquisition and an arterial phase. If AAS was detected, a venous phase (delay, 90 s) was added. Images were evaluated for the presence and extent of AAD, IMH, PAU, and related complications. The diagnostic benefit of the unenhanced acquisition was evaluated concerning detection of IMH.

RESULTS

Fifty-six (30% women; mean age, 67 years; median, 68 years) of the screened individuals had AAD or IMH. A triphasic CT scan was conducted in 76.8% (n = 43). 56% of the detected AAD were classified as Stanford type A, 44% as Stanford type B. 53.8% of the detected IMH were classified as Stanford type A, 46.2% as Stanford type B. There was no significant difference in the involvement of the ascending aorta between AAD and IMH (P = 1.0) or in the average age between AAD and IMH (P = 0.548), between Stanford type A and Stanford type B in general (P = 0.650) and between Stanford type A and Stanford type B within the entities of AAD and IMH (AAD: P = 0.785; IMH: P = 0.146). Only the unenhanced acquisitions showed a significant density difference between the adjacent lumen and the IMH (P = 0.035). Subadventitial hematoma involving the pulmonary trunk was present in 5 patients (16%) with Stanford A AAD. The difference between the median radiation exposure of a triphasic (2737 mGy*cm) compared to a biphasic CT scan (2135 mGy*cm) was not significant (P = 0.135).

CONCLUSION

IMH is a common and difficult to detect entity of AAS. An additional unenhanced acquisition within an aortic CTA protocol facilitates the detection of IMH.

Hemoptysis

Hemoptysis is a rare complication of acute aortic dissection. A 77-year-old woman was admitted to our department with epigastralgia and hemoptysis. Computed tomography showed Stanford A acute aortic dissection and massive posterior mediastinal hematoma which extended along the right pulmonary artery. Hemoptysis is a lethal sign of aortic dissection, therefore, emergency ascending aortic replacement was performed with a good clinical outcome.

Diagnostic value of multislice computerized tomography angiography for aortic dissection: A comparison with DSA

The aim of the present study was to compare multislice computed tomography angiography (MSCTA) and digital subtraction angiography (DSA) in the diagnosis of aortic dissection. In total, 49 patients with aortic lesions received enhanced computed tomography scanning, and three-dimensional (3D) images were reconstructed by volume rendering (VR), maximum intensity projection (MIP), multiplanar reformation (MPR) and curved planar reconstruction (CPR). The display rate of the entry tear site, intimal flap, true and false lumen from each reconstruction method was calculated. For 30 patients with DeBakey type III aortic dissection, the entry tear site and size of the first intimal flap, aortic maximum diameter at the orifice of left subclavian artery (LSCA), distance between the first entry tear site and the orifice of LSCA, and maximum diameter of aortic true and false lumens were measured prior to implantation of endovascular covered stent-grafts. Data obtained by MSCTA and DSA were then compared. For the entry tear site, MPR, CPR and VR provided a display rate of 95.92, 95.92 and 18.37%, respectively, and the display rate of the intimal flap was 100% in the three methods. MIP did not directly display the entry tear site and intimal flap. For true and false lumens, MPR, CPR, and VR showed a display rate of 100%, while MIP only provided a display rate of 67.35%. When MSCTA was compared with DSA, there was a significant difference in the display of entry site number and position (P<0.05), whereas no significant difference was shown in the measurement of aortic maximum diameter at the orifice of LSCA and the maximum diameter of true and false lumens (P>0.05). In conclusion, among the 3D post-processing reconstruction methods of MSCTA used, MPR and CPR were optimal, followed by VR, and MIP. MSCTA may be the preferable imaging method to diagnose aortic dissection and evaluate treatment of endovascular-covered stent-grafting, preoperatively.

Acute aorta, overview of acute CT findings and endovascular treatment options

Acute aortic pathologies include acute aortic syndrome (aortic dissection, intramural hematoma, penetrating aortic ulcer), impending rupture, aortic aneurysm rupture and aortic trauma. Acute aortic syndrome, aortic aneurysm rupture and aortic trauma are life-threatening conditions requiring prompt diagnosis and treatment. The basic imaging modality for "acute aorta" is CT angiography with typical findings for these aortic pathologies. Based on the CT, it is possible to classify aortic diseases and anatomical classifications are essential for the planning of treatment. Currently, endovascular treatment is the method of choice for acute diseases of the descending thoracic aorta and is increasingly indicated for patients with ruptured abdominal aortic aneurysms.

Type A aortic dissection: Are there CT signs suggestive of valvular involvement?

AIM

To identify the predictive signs of aortic valve involvement on the non-electrocardiogram (ECG)-gated admission computed tomography (CT) of patients with Type A aortic dissection (AD) according to the Stanford classification.

MATERIALS AND METHODS

We retrospectively analyzed the non-ECG-gated CT examinations of patients admitted to the emergency department who underwent surgery for Type A AD over a period of 4 years. The diameter of the following structures was calculated as the mean of the smallest and largest diameters (mm) measured in two different planes: aortic annulus, sinus of Valsalva, sinotubular junction, and proximal ascending aorta. These parameters were compared against operative reports in order to determine whether they were predictive of aortic valve involvement.

RESULTS

In total, 20 patients (13 men and 7 women) of a mean age of 59.5 years (29-80) were included, 55% of patients (11/20) having surgically proven valvular involvement. The mean diameters (inmm) of the aortic annulus, sinus of Valsalva, sinotubular junction and proximal ascending aorta in the group with (and without, respectively) valvular involvement was 27.7 (26.7), 44.3 (38.1), 42.6 (36.6), and 47.8 (45.9). Only the measurement of the mean diameter of the sinuses of Valsalva was significantly predictive (p=0.02) of aortic valve involvement.

CONCLUSION

Our findings suggest that measuring the diameter of the sinuses of Valsalva on non-ECG-gated admission CT examinations allows for predicting aortic valve involvement in Type A AD patients.

CT pulmonary angiography of adult pulmonary vascular diseases: Technical considerations and interpretive pitfalls

Computed tomography pulmonary angiography (CTPA) has become the primary imaging modality for evaluating the pulmonary arteries. Although pulmonary embolism is the primary indication for CTPA, various pulmonary vascular abnormalities can be detected in adults. Knowledge of these disease entities and understanding technical pitfalls that can occur when performing CTPA are essential to enable accurate diagnosis and allow timely management. This review will cover a spectrum of acquired abnormalities including pulmonary embolism due to thrombus and foreign bodies, primary and metastatic tumor involving the pulmonary arteries, pulmonary hypertension, as well as pulmonary artery aneurysms and stenoses. Additionally, methods to overcome technical pitfalls and interventional treatment options will be addressed.

Chest radiography in acute aortic syndrome: pearls and pitfalls

Acute aortic syndrome is a group of life-threatening diseases of the thoracic aorta that usually present to the emergency department. It includes aortic dissection, aortic intramural hematoma, and penetrating aortic ulcer. Rare aortic pathologies of aorto-esophageal fistula and mycotic aneurysm may also be included in this list. All these conditions require urgent treatment with complex clinical care and management. Most patients who present with chest pain are evaluated with a chest radiograph in the emergency department. It is important that maximum diagnostic information is extracted from the chest radiograph as certain signs on the chest radiograph are extremely useful in pointing towards the diagnosis of acute aortic syndrome.

Sudden cardiac death from structural heart diseases in adults: imaging findings with cardiovascular computed tomography and magnetic resonance

Sudden cardiac death (SCD) is defined as the unexpected natural death from a cardiac cause within an hour of the onset of symptoms in the absence of any other cause. Although such a rapid course of death is mainly attributed to a cardiac arrhythmia, identification of structural heart disease by cardiovascular computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging is important to predict the long-term risk of SCD. In adults, SCD most commonly results from coronary artery diseases, coronary artery anomalies, inherited cardiomyopathies, valvular heart diseases, myocarditis, and aortic dissection with coronary artery involvement or acute aortic regurgitation. This review describes the CCT and CMR findings of structural heart diseases related to SCD, which are essential for radiologists to diagnose or predict.

MDCT evaluation of acute aortic syndrome (AAS)

Non-traumatic acute thoracic aortic syndromes (AAS) describe a spectrum of life-threatening aortic pathologies with significant implications on diagnosis, therapy and management. There is a common pathway for the various manifestations of AAS that eventually leads to a breakdown of the aortic intima and media. Improvements in biology and health policy and diffusion of technology into the community resulted in an associated decrease in mortality and morbidity related to aortic therapeutic interventions. Hybrid procedures, branched and fenestrated endografts, and percutaneous aortic valves have emerged as potent and viable alternatives to traditional surgeries. In this context, current state-of-the art multidetector CT (MDCT) is actually the gold standard in the emergency setting because of its intrinsic diagnostic value. Management of acute aortic disease has changed with the increasing realization that endovascular therapies may offer distinct advantages in these situations. This article provides a summary of AAS, focusing especially on the MDCT technique, typical and atypical findings and common pitfalls of AAS, as well as recent concepts regarding the subtypes of AAS, consisting of aortic dissection, intramural haematoma, penetrating atherosclerotic ulcer and unstable aortic aneurysm or contained aortic rupture. MDCT findings will be related to pathophysiology, timing and management options to achieve a definite and timely diagnostic and therapeutic definition. In the present article, we review the aetiology, pathophysiology, clinical presentation, outcomes and therapeutic approaches to acute aortic syndromes.

Lumican as a novel potential clinical indicator for acute aortic dissection: A comparative study, based on multi-slice computed tomography angiography

The aim of the present study was to investigate the association between serum lumican levels and acute aortic dissection (AAD) severity. A total of 82 patients with chest or back pain and 30 healthy volunteers were recruited. Among the patients, there were 70 cases of AAD and 12 cases of intramural hematoma (IMH). AAD severity was determined using multi-slice computed tomography angiography (MSCTA). Serum was collected from the patients upon admission, and lumican levels were detected using an enzyme-linked immunosorbent assay. In addition, correlation analyses were conducted between lumican levels and AAD severity by designing a 'SCORE X, RANGE Y' system to measure the number of affected vital arteries and vertical range of false lumen, based on the MSCTA. Lumican levels differed significantly among the AAD patients (2.32±4.29 ng/ml), IMH patients (0.72±0.32 ng/ml) and healthy volunteers (0.85±0.53 ng/ml; P=0.003). In the AAD patients presenting within 12-72 h of symptom onset, the Spearman's rho correlation coefficient between lumican and SCORE or RANGE was 0.373 (P=0.046) and 0.468 (P=0.010), respectively. The present results suggest that lumican may be a potential marker for aiding the diagnosis and screening for AAD, and may be used to predict the severity of AAD.

Aortic emergencies-diagnosis and treatment: a pictorial review

Objectives

To demonstrate the various presentations of acute aortic pathology and to present diagnostic and therapeutic approaches.

Methods

Diagnostic imaging is the key to the reliable diagnosis of acute aortic pathology with multi-slice computed tomography angiography (CTA) as the fastest and most robust modality. Endovascular aortic repair (EVAR) with stent grafts and open surgical repair are therapeutic approaches for aortic pathology.

Results

CTA is reliable in diagnosing and grading aortic trauma, measuring aortic diameter in aortic aneurysms and detecting vascular wall pathology in acute aortic syndrome and aortic inflammation. CTA enables planning the optimal therapeutic approach. Stent graft implantation and/or an open surgical approach can address vascular wall pathology and exclude aortic aneurysms.

Conclusion

Aortic emergencies have to be detected quickly. CTA is the imaging method of choice and helps to decide whether elective, urgent or emergent treatment is necessary with EVAR and open surgical repair as the main treatment approaches.

Teaching Points

• To present aortic pathology caused by trauma

• To present acute aortic syndrome (aortic dissection, intramural haematoma and penetrating ulcers)

• To present symptomatic and ruptured aortic aneurysm

• To present infection (mycotic aneurysms/aorto-duodenal fistulae) or iatrogenic injury of the aorta

• To understand different presentations for treatment planning (EVAR and open surgery)

CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice.

The role of multidetector-row CT in the diagnosis, classification and management of acute aortic syndrome

The term "acute aortic syndrome" (AAS) encompasses several non-traumatic life-threatening pathologies of the thoracic aorta presenting in patients with a similar clinical profile. These include aortic dissection, intramural haematoma and penetrating atherosclerotic ulcers. These different pathological entities can be indistinguishable on clinical grounds alone and may be confused with other causes of chest pain, including myocardial infarction. Multidetector-row CT (MDCT) is the current modality of choice for imaging AAS with a sensitivity and specificity approaching 100%. Early diagnosis and accurate radiological classification is associated with improved clinical outcomes in AAS. We review the characteristic radiological features of the different pathologies that encompass AAS and highlight the vital role of MDCT in determining the management of these life-threatening conditions.

Multi-detector computed tomography in the diagnosis and management of acute aortic syndromes

Acute aortic syndrome (AAS) is a spectrum of conditions, which may ultimately progress to potentially life-threatening aortic rupture. This syndrome encompasses aortic dissection (AD), intramural haematoma, penetrating atherosclerotic ulcer and unstable thoracic aortic aneurysms. Multi-detector CT (MDCT) is crucial for the diagnosis of AAS, especially in the emergency setting due to its speed, accuracy and ready availability. This review attends to the value of appropriate imaging protocols in obtaining good quality images that can permit a confident diagnosis of AAS. AD is the most commonly encountered AAS and also the one with maximum potential to cause catastrophic outcome if not diagnosed and managed promptly. Hence, this review briefly addresses certain relevant clinical perspectives on this condition. Differentiating the false from the true lumen in AD is often essential; a spectrum of CT findings, e.g., “beak sign”, aortic “cobwebs” that allows such differentiation have been described with explicit illustrations. The value of non enhanced CT scans, especially useful in the diagnosis of an intramural hematoma has also been illustrated. Overlap in the clinical and imaging features of the various conditions presenting as AAS is not unusual. However, on most instances MDCT enables the right diagnosis. On select occasions MRI or trans-esophageal echocardiography may be required as a problem solving tool.

Imaging findings of acute intravascular thrombus on non-enhanced computed tomography

Intravascular thrombosis and thromboembolism are critical diagnoses which are frequently made on contrast-enhanced computed tomography (CECT) or Doppler ultrasound. For a variety of reasons, some patients with acute intravascular pathology are imaged using CT without intravenous contrast. In the acute setting, the increased Hounsfield unit (HU) density of the thrombus compared to the blood pool allows the diagnosis to be made, or at least suggested, on non-enhanced computed tomography (NECT). The increased density of the clot is commonly referred to as the "hyperdense vessel sign." This is a well-known finding in the setting of stroke, but hyperdense vessels can also signal arterial or venous thrombosis in the chest, abdomen, pelvis, and extremities. Once a hyperdense vessel sign is noted on NECT, further exploration with CECT, angiography, or ultrasound may then be performed. Here, we present a pictorial review of the appearance of acute intravascular thrombosis as seen on non-enhanced computed tomography.

The ascending aortic image quality and the whole aortic radiation dose of high-pitch dual-source CT angiography

BACKGROUND

Aortic dissection is a lift-threatening medical emergency associated with high rates of morbidity and mortality. The incidence rate of aortic dissection is estimated at 5 to 30 per 1 million people per year. The prompt and correct diagnosis of aortic dissection is critical. This study was to compare the ascending aortic image quality and the whole aortic radiation dose of high-pitch dual-source CT angiography and conventional dual-source CT angiography.

METHODS

A total of 110 consecutive patients with suspected aortic dissection and other aortic disorders were randomly divided into two groups. Group A underwent traditional scan mode and Group B underwent high-pitch dual-source CT scan mode. The image quality and radiation dose of two groups were compared.

RESULTS

Close interobserver agreement was found for image quality scores (κ = 0.87). The image quality of ascending aorta was significantly better in the high-pitch group than in the conventional group (2.78 ± 0.46 vs 1.57 ± 0.43, P < 0.001). There was no significant difference of the CT attenuation values, the aortic image noise and SNR between two groups. The mean radiation dose of high-pitch group was also significantly lower than that of conventional group (2.7 ± 0.6 mSv vs. 3.9 ± 0.9 mSv, P < 0.001).

CONCLUSIONS

High-pitch dual-source CT angiography of the whole aorta can provide motion-artifact-free imaging of the ascending aorta at a low radiation dose compared to conventional protocol.