Aortic valve stenosis: CT contributions to diagnosis and therapy

As populations in Western civilizations are aging, the prevalence of degenerative aortic valve stenosis is increasing. CT imaging provides information on aortic valve pathology in many ways: In nonenhanced scans, aortic valve calcification can be quantified accurately, which helps to understand the pathogenesis and progression of aortic sclerosis and stenosis. After contrast injection, CT allows excellent visualization of aortic valve structure and, through measurement of the aortic valve area, is capable to serve as a "backup method" for the assessment of aortic valve stenosis, especially if other imaging methods are difficult to interpret. Importantly, CT tends to overestimate aortic valve opening areas in comparison to transthoracic echocardiography, which relies on the continuity equation for quantifying aortic stenosis, based on flow velocities and the estimated area of the left ventricular outflow tract. It has recently been shown that the oval rather than round shape of the left ventricular outflow tract is the most likely factor behind this systematic difference between functional compared with anatomic assessment of aortic valve stenosis. In fact, the ability to provide superbly accurate anatomic imaging of the aortic valve and entire aortic root makes CT a uniquely useful tool for the planning of transcatheter aortic valve implantation. Hence, CT imaging spans a wide range of applications in aortic valve disease, from basic research to diagnosis and treatment planning. This review aims to summarize the current state of the art concerning imaging of the aortic valve by CT and the potential clinical applications.     

Endovascular Stent-Graft Repair as a Late Secondary Procedure After Previous Aortic Grafts

Thoracic and abdominal aortic endovascular procedures as alternatives to aortic reoperations were studied in three different cases. An anastomotic aneurysm after previous thoracic aortic graft for coarctation, a second-stage elephant trunk repair (descending thoracic aortic aneurysm), and a secondary aneurysm proximal to a previous abdominal aortic graft were successfully treated with endovascular stent-grafts. During the follow-up period no lethal events or major aortic or graft-related complications were observed, except a type II endoleak in the anastomotic aortic aneurysm case. An endovascular stent-graft can be safely deployed into a previously implanted vascular graft, avoiding repeat surgery.     

Aortic aneurysms: growth rates measured with CT.

Because of a lack of information about the rates of growth of aortic aneurysms, such rates in thoracic and abdominal aortic aneurysms were determined. One hundred seventy-one patients with atherosclerotic aortic aneurysm managed nonoperatively were followed up for more than 6 months with sequential computed tomography (CT). There were 211 aneurysms (thoracic aortic, 82; abdominal aortic, 129). The growth rates of thoracic and abdominal aortic aneurysms were 0.42 and 0.28 cm/y, respectively. Aneurysms at the aortic arch (n = 34) grew at a faster average rate (0.56 cm/y) than aneurysms arising at other levels, even when the rate was corrected for the initial diameter. It is recommended that thoracic aortic aneurysms, especially aortic arch aneurysms, be followed frequently with CT examination of size.     

Aortic valve calcification as a marker for aortic stenosis severity: assessment on 16-MDCT

OBJECTIVE: The degree of valvular calcification in patients with aortic stenosis was determined with retrospectively ECG-gated 16-MDCT and correlated with the severity of stenosis assessed at cardiac catheterization. SUBJECTS AND METHODS: We conducted a prospective study of 72 patients (38 men and 34 women; mean age +/- SD, 69.5 +/- 8.8 years) with aortic stenosis who underwent 16-MDCT and cardiac catheterization. Aortic valve calcification was assessed using the aortic Agatston score, aortic mass score, and aortic volume score. Severity of aortic stenosis was classified at cardiac catheterization. Aortic valve area and peak-to-peak and mean transvalvular gradients were correlated with the degree of calcification determined on MDCT. RESULTS: All measured aortic valve calcification scores were significantly higher in patients with severe aortic stenosis (n = 46) than in patients with moderate (n = 15) or mild (n = 11, p < 0.001) aortic stenosis. Aortic valve calcification scores were inversely related to aortic valve area (r = -0.67, p < 0.001 for aortic mass score) and correlated significantly with peak-to-peak (r = 0.70, p < 0.001) and mean transvalvular (r = 0.72, p < 0.001) gradients. No correlation between the aortic valve calcification and the total coronary calcium scores was observed. CONCLUSION: Aortic valve calcification assessed on 16-MDCT is associated with severity of aortic stenosis. Thus, aortic valve calcification scores should be calculated routinely in all patients undergoing MDCT for assessment of coronary calcification. High aortic valve calcification scores indicate possibly severe aortic stenosis and should prompt a further functional evaluation.     

Measurement and determinants of infrarenal aortic thrombus volume

Intra-luminal thrombus has been suggested to play a role in the progression of abdominal aortic aneurysm (AAA). The aims of this study were twofold. Firstly, to assess the reproducibility of a computer tomography (CT)-based technique for measurement of aortic thrombus volume. Secondly, to examine the determinants of infrarenal aortic thrombus volume in a cohort of patients with aortic dilatation. A consecutive series of 75 patients assessed by CT angiography with maximum aortic diameter >/=25 mm were recruited. Intra-luminal thrombus volume was measured by a semi-automated workstation protocol based on a previously defined technique to quantitate aortic calcification. Intra- and inter-observer reproducibility were assessed using correlation coefficients, coefficient of variation and Bland-Altman plots. Infrarenal aortic thrombus volume percentage was related to clinical, anatomical and blood characteristics of the patients using univariate and multivariate tests. Infrarenal aortic thrombus volume was related to the severity of aortic dilatation assessed by total aortic volume (r = 0.87, P < 0.0001) or maximum aortic diameter (r = 0.74, P < 0.0001). We therefore examined the clinical determinates of aortic thrombus expressed as a percentage of total aortic volume. Aortic thrombus percentage was negatively correlated with serum high density lipoprotein (HDL, r = -0.31). By ordinal multiple logistic regression analysis serum HDL below median (相似文献   

Aortic valve calcification on computed tomography predicts the severity of aortic stenosis

AIM: Incidental aortic valve calcification is often detected during computed tomography. The aim was to compare the severity of valvular stenosis and calcification in patients with aortic stenosis. MATERIALS AND METHODS: One hundred and fifty-seven patients aged 68+/-11 years (range: 34-85) with aortic valve stenosis underwent multislice helical computed tomography and Doppler echocardiography performed by independent, blinded observers. The aortic valve calcium score was determined using automated computer software calibrated with a phantom. RESULTS: Doppler echocardiography demonstrated a post-valve velocity of 3.45+/-0.66 m/s and a peak gradient of 49+/-11 mmHg. Computed tomography showed excellent reproducibility and the median aortic valve calcium score was 5858 AU (interquartile range, 1555-14,596). The computed tomography aortic valve calcium score positively correlated with the Doppler post-valve velocity and peak gradient (r=0.54, p<0.0001 for both) of the aortic valve. All patients with severe aortic stenosis had a calcium score of >3700 AU. CONCLUSION: Calcification of the aortic valve is closely associated with the severity of aortic stenosis, and heavy calcification suggests the presence of severe aortic stenosis that requires urgent cardiological assessment. Patients with lesser degrees of aortic valve calcification should be screened for aortic stenosis and monitored for disease progression.     

Low-field cine magnetic resonance imaging in aortic valve disease

Cine magnetic resonance imaging (MRI) holds considerable promise as a means of detecting abnormal blood flow patterns with the heart and great vessels. To date, the majority of techniques employed have required moderate to high field strengths. We describe a novel, low-field-strength approach that is technically undemanding and faster than conventional methods, which we have applied to the detection of aortic valve disease. A series of 26 patients with aortic stenosis or aortic regurgitation was compared with 21 normal subjects. All 20 patients with aortic stenosis and 15 of 16 patients with aortic regurgitation were identified. There were four false positives in the aortic stenosis group; all these patients had significant aortic regurgitation. There were no false positives in the aortic regurgitation group. Low-field cine MRI is a practical and useful technique for the detection of aortic valve disease.     

The ascending aorta in aortic stenosis

Dilatation of the ascending aorta, a frequently reported sign of aortic stenosis, was assessed in 47 patients for whom aortic angiograms had been recorded. Twenty-eight of the patients had rheumatic valvar disease and 19 had congenital aortic stenosis. A simple ratio between the maximal width of the mid-ascending aorta and the width of the aortic root was calculated. Patients with congenital aortic stenosis had significantly greater supravalvar aortic dilatation than did those with rheumatic aortic valve involvement. There was no correlation between the pressure difference across the aortic valve and degree of dilatation of the ascending aorta.     

Radiographic manifestations of congenital anomalies of the aortic arch

This article discusses congenital anomalies of the aortic arch. Many malformations of a left, right, or double aortic arch produce tracheal, bronchial, and esophageal compression and can be recognized on chest radiographs or esophagrams and confirmed by angiography, computed tomography, or magnetic resonance imaging. Other congenital lesions of the aortic arch are characterized by aortic obstruction and include supravalvular aortic stenosis, aortic arch interruption or atresia, and coarctation.     

Endovascular stent for use in aortic dissection: an in vitro experiment

Injection of normal saline and contrast material into the walls of aortic specimens from human cadavers created a narrowing of the aortic lumen, simulating aortic dissection. Endovascular stents were applied to expand the aortic lumen. Successful dilatation of the narrowed aortic lumen was demonstrated in all six specimens.     

Bovine aortic arch variant in humans: clarification of a common misnomer

The term "bovine arch" is widely used to describe a common anatomic variant of the human aortic arch branching. This so-called bovine aortic arch has no resemblance to the bovine aortic arch. We describe the most common human aortic arch branching patterns and compare these with the bovine aortic arch.     

Progressive thoracic aortic dilatation after aortic valve replacement

Aneurysms of the ascending aorta developed after aortic valve replacement for chronic aortic insufficiency in four cases. Two of the aneurysms were complicated by dissection; one patient died. Rheumatic disease has become a less common cause of pure aortic regurgitation, and a number of etiologies primarily involving the wall of the aorta are now recognized. Although appropriately timed aortic valve replacement can prevent the irreversible left ventricular depression associated with chronic aortic insufficiency, careful evaluation of the thoracic aorta on serial postoperative chest radiographs is warranted, because the underlying pathologic process may proceed in the aortic wall with eventual aneurysm formation.     

主动脉窦瘤的造影诊断与手术病理对比研究

目的：通过２０便主动脉窦瘤的造影诊断与手术病理对比观察,分析其影像病理基础和漏、误诊原因,以期进一步提高造影的正确诊断率。材料与方法：２０例术前均行主动脉根部造影,４例并行左室造影。２０例均行心内直视手术修复。将造影表现与手术结果进行对比。结果：造影诊断右冠窦瘤１６例,无冠窦瘤破入右房２例,主动脉瓣脱行政区域例,手术证实右冠窦瘤１５例,无冠窦瘤破入右房３例,主动脉右瓣脱行政区域例。造影诊断与手术结     

Automatic determination of aortic compliance with cine-magnetic resonance imaging: an application of fuzzy logic theory

RATIONALE AND OBJECTIVES: Aortic compliance is defined as the relative change in aortic cross-sectional area divided by the change in arterial pressure. Magnetic resonance imaging (MRI) is a useful imaging modality for the noninvasive evaluation of aortic compliance. However, manual tracing of the aortic contour is subject to important interobserver variations. To estimate the aortic compliance from cine-MRI, a method based on fuzzy logic theory was elaborated. MATERIALS AND METHODS: Seven healthy volunteers and eight patients with Marfan syndrome were examined using an ECG gated cine-MRI sequence. The aorta was imaged in the transverse plane at the level of the pulmonary trunk. A method based on fuzzy logic was developed to automatically detect the aortic contour. RESULTS: Through our robust automatic contouring method, the calculation of aortic cross-sectional areas allows an estimation of the aortic compliance. CONCLUSION: The aortic compliance can be obtained from a fuzzy logic based automatic contouring method, thereby avoiding the important interobserver variation often associated with manual tracing.     

Pitfalls in the diagnosis of thoracic aortic dissection at CT angiography.

Two hundred seventy-five computed tomographic (CT) angiograms of the thoracic aorta were obtained over a period of approximately 4 years in patients with suspected or known aortic dissection. In all cases, unenhanced images were initially obtained, followed by contrast material-enhanced images. A variety of pitfalls were encountered that mimicked aortic dissection. These pitfalls were attributable to technical factors (eg, improper timing of contrast material administration relative to image acquisition); streak artifacts generated by high-attenuation material, high-contrast interfaces, or cardiac motion; periaortic structures (eg, aortic arch branches, mediastinal veins, pericardial recess, thymus, atelectasis, pleural thickening or effusion adjacent to the aorta); aortic wall motion and normal aortic sinuses; aortic variations such as congenital ductus diverticulum and acquired aortic aneurysm with thrombus; and penetrating atherosclerotic ulcer. Although several of these pitfalls are easy to recognize and therefore unlikely to present a diagnostic problem, others are potentially confusing. Familiarity with these common pitfalls, coupled with a knowledge of normal intrathoracic anatomy, will facilitate recognition of true aortic dissection and help avoid misdiagnosis at thoracic aortic CT angiography.     

Aortic compliance in patients with aortic regurgitation: evaluation with magnetic resonance imaging

PURPOSE: To assess by means of cine magnetic resonance imaging (MRI) aortic compliance before and after aortic valve replacement (AVR with SJM valve) in patients with aortic regurgitation (AR). MATERIALS AND METHODS: Two groups (healthy controls and patients with severe isolated AR) of 10 subjects each were included in this study. Cine MRI was performed at three locations of the aorta, and aortic compliance was calculated by dividing the maximum change in the aortic area by pulse pressure. RESULTS: Cine MRI is useful to assess abnormalities of aortic compliance in patients with AR. Compared with the control group, aortic compliance in the AR group was significantly less in the ascending aorta (p<0.05), decreasing in order of aortic location. After AVR, aortic compliance improved for all locations. CONCLUSION: Cine MRI enables assessment of aortic biophysical properties such as a compliance for evaluating the progression of AR and the efficacy of treatment.     

CT of aortic aneurysms: the distinction between mural and thrombus calcification

Aortic calcification, either mural or thrombus, is a common finding in patients with abdominal aortic aneurysms. Differentiating between the two sites of calcification is necessary in order to avoid confusing simple thrombus calcification with displaced calcified intima in aortic dissection. The CT scans of 145 cases of abdominal aortic aneurysm and seven cases of abdominal aortic aneurysm with dissection were analyzed with respect to the location of the calcification: mural only or mural and thrombus. Mural calcification was seen in all 152 patients with aneurysms whereas thrombus calcification was identified in only 33 (24%) of the 136 patients with thrombus. Displaced intimal calcification caused by aortic dissection can either appear similar to or, at times, be indistinguishable from thrombus calcification. Thrombus calcification was present in four (57%) of the seven patients with abdominal aortic aneurysms and dissection. To avoid the possibility of a false-positive diagnosis of aortic dissection in patients with abdominal aortic aneurysm, other signs of aortic dissection should be sought such as separation of the true and false lumina by an intimal flap.     

Thoracic aortic disease: Spectrum of multidetector computed tomography imaging findings

The clinical presentation of diseases involving the thoracic aorta ranges from a large number of asymptomatic patients with clinically undetectable thoracic aortic aneurysm to patients with symptoms of severe chest pain as a result of acute aortic dissection. Thoracic aortic disease often remains undiagnosed until a life-threatening complication occurs or the disease is discovered serendipitously on imaging studies performed for other purposes. Multidetector row computed tomography (MDCT) imaging of the aorta is used to diagnose various acute and chronic conditions, including aortic aneurysms, aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer, traumatic injury, rupture, inflammatory disorders, and congenital malformations. This review illustrates the wide range of MDCT imaging findings of thoracic aortic disease.     

主动脉瓣病变的影像学研究进展

随着人口老龄化程度的加剧,主动脉瓣退行性病变导致的狭窄及关闭不全成为老年人主动脉瓣换瓣治疗的主要病因。因此,准确评估主动脉瓣病变患者的瓣环直径、瓣膜和瓣周毗邻病变情况以及冠状动脉和心功能对于该类疾病的临床决策及预后判断具有十分重要的意义。本文拟就目前临床应用最为广泛的超声心动图、计算机断层扫描以及磁共振在主动脉瓣膜置换术前影像学评估中的优缺点以及研究进展作一综述,旨在为换瓣患者的术前评价提供更为丰富和客观的临床资料。     

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.