Spiral CT angiography of the thoracic aorta

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.

A Comparative Study of Imaging Techniques in Aortic Dissection, DeBakey Type I: Intraoperative Live Three-Dimensional Epicardial Echocardiography, Multiplane Transesophageal Echocardiography, and Multislice Computed Tomography

OBJECTIVE

: To compare the accuracy of intraoperative live 3-dimensional epicardial echocardiography, multiplane transesophageal echocardiography (TEE), and multislice computed tomography (MSCT) imaging in the detection of thoracic aortic dissection, site of intimal tear, and involvement of arch vessel.

METHODS

: Of 24 patients studied from October 2003 to September 2004, 12 had aortic dissection. They were examined preoperatively with contrast material-enhanced MSCT and multiplane TEE. Intraoperative live 3-dimensional epicardial echocardiographic evaluation of the ascending aorta and arch was performed. Imaging results in terms of detection of aortic dissection, site of intimal tear, and involvement of coronary arteries and arch vessels were confirmed at intraoperative exploration by the operating surgeon as the reference standard.

RESULTS

: Sensitivity in the detection of thoracic aortic dissection was 100% for all techniques. Specificity was 92%, 92%, and 100% for live 3-dimensional epicardial echocardiography, multiplane TEE, and MSCT imaging, respectively. In the assessment of aortic arch vessel involvement, sensitivity was 92%, 58%, and 92%, and specificity was 75%, 50%, and 83%, respectively. For the detection of the site of intimal tear, sensitivity was 92%,92%, and 58%, and specificity was 83%,75%, and 50%, respectively.

CONCLUSION

: Intraoperative live 3-dimensional epicardial echocardiography is as valuable as multiplane TEE and MSCT imaging in the detection of thoracic aortic dissection. In the assessment of the aortic arch vessel involvement, MSCT and live 3-dimensional epicardial echocardiography are superior (P < 0.05), whereas live 3-dimensional epicardial echocardiography and TEE are superior in detection of site of intimal tear (P < 0.05).

Reference curves for the aortic area by age

RATIONALE AND OBJECTIVES

The aim of this study was to establish reference curves and formulas for aortic cross-sectional area in patients from infancy to young adulthood.

MATERIALS AND METHODS

Patients (aged 2 days to 18.1 years) who underwent electrocardiographically gated cardiac computed tomography between May 2004 and December 2011 were retrospectively examined. These patients were further divided into a group of normal controls (without aortic disease) and a group with coarctation of aorta. In the group of normal controls, the cross-sectional area of the aorta was measured at six locations: the sinotubular junction, distal ascending aorta, proximal arch, distal arch, aortic isthmus, and descending aorta (DAO). Interobserver and intraobserver variability, gender differences, the relationship between aortic cross-sectional areas and age, and the ratio to the DAO were also examined. The area ratio to the DAO was also examined in the group with coarctation of the aorta.

RESULTS

A total of 65 patients and 365 measurable aortic segments were included in the analysis (55 normal controls and 10 patients with coarctation of aorta). Interobserver and intraobserver variability was limited (aside from measurements of the sinotubular junction). There were no gender differences in age and the cross-sectional areas of the different aortic segments. In the group of normal controls, the cross-sectional area of each aortic segment was highly correlated with age (all >0.90, P < .001). The reference curves and formulas for aortic cross-sectional area by age were also determined for further clinical use. In the normal controls, the <95% confidence intervals of the ratios of aortic isthmus to DAO, distal arch to DAO, and proximal arch to DAO were approximately 0.6, 0.8, and 1.0, respectively. In addition, in the group with coarctation, all area ratios of aortic isthmus to DAO were <0.6, which was significantly different from the group of normal controls (P < .001). The area ratios of distal arch to DAO and proximal arch to DAO were also significantly different between two groups (P < .001 for both).

CONCLUSIONS

Measurement of aortic area was reproducible. The established reference curves and formulas and minimal area ratios were convenient for further clinical use.

The normal distribution of thoracoabdominal aorta small branch artery ostia

The purpose of this study was to determine the normal distribution of aortic branch artery ostia. CT scans of 100 subjects were retrospectively reviewed. The angular distributions of the aorta with respect to the center of the T3 to L4 vertebral bodies, and of branch artery origins with respect to the center of the aorta were measured. At each vertebral body level the distribution of intercostal/lumbar arteries and other branch arteries were calculated. The proximal descending aorta is posteriorly placed becoming a midline structure, at the thoracolumbar junction, and remains anterior to the vertebral bodies within the abdomen. The intercostal and lumbar artery ostia have a distinct distribution. At each vertebral level from T3 caudally, one intercostal artery originates from the posterior wall of the aorta throughout the thoracic aorta, while the other intercostal artery originates from the medial wall of the descending thoracic aorta high in the chest, posteromedially from the mid-thoracic aorta, and from the posterior wall of the aorta low in the chest. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Lumbar branches originate only from the posterior wall of the abdominal aorta. Aortic branch artery origins arise with a bimodal distribution and have a characteristic location. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Knowing the location of aortic branch artery ostia may help distinguish branch artery pseudoaneurysms from penetrating ulcers.

Stroke severity predicted by aortic atheroma detected by ultra-fast and cardiac-gated chest tomography

Background and Purpose: The presence of aortic atherosclerosis is an independent risk factor for secondary stroke. The present study was designed to have an initial exploration of the correlation between the load and extent of aortic atheroma (AA) and initial stroke severity or clinical outcome 3 months after stroke. Methods: Cardiac-gated chest tomography (CGCT) was used to detect and measure AA in patients with acute ischemic stroke as shown by our group in prior prospective studies and this is part four sub-exploratory study of the same cohort. The National Institute of Health Stroke Scale (NIHSS) was used to assess the initial stroke severity, and the modified Rankin Scale (mRS) was used to assess 3-month outcome. Results: Thirty-two patients underwent CGCT for evaluation of AA, and 21 were found to have AA. AA was more prevalent in patient with NIHSS >6 (14/17 versus 7/15, p-value 0.03). Applying the multiple logistic regression and propensity score adjustment (using the propensity of having AA given the baseline features as covariates) showed a non-significant trend that AA is three times more likely to be associated with NIHSS >6 (p = 0.08, OR 3.08, 95% CI 0.94–13.52). There was no evidence of association of AA with 3-month functional outcome (mRS): 11/14 (78.6%) mRS >1 had AA, and 10/18 (55.5%) of those with mRS ≤1 had AA (p = 0.27). Conclusion: In our current study with limited sample number and exploratory nature, the presence of AA on CGCT with acute ischemic stroke patients may be associated with worse neurological deficit at presentation. There was no evidence of association with 3-month functional outcome using the mRS.

Angiotomografia com múltiplos detectores no diagnóstico de drenagem venosa pulmonar anômala: experiência inicial

OBJETIVO: Demonstrar que a angiotomografia computadorizada com múltiplos detectores é um método efetivo e não invasivo para o diagnóstico de drenagem venosa pulmonar anômala. MATERIAIS E MÉTODOS: Estudo retrospectivo de 2.905 angiotomografias computadorizadas com múltiplos detectores cardíacas realizadas em nosso serviço no período de julho de 2003 a novembro de 2007. Destas, 393 foram destinadas para avaliar cardiopatias congênitas e as 2.512 restantes, para analisar as artérias coronárias. RESULTADOS: Foram encontrados 21 casos de drenagem venosa pulmonar anômala, sendo 7 (33,3%) do tipo total e 14 (66,7%) do tipo parcial. Das drenagens venosas pulmonares anômalas totais, três foram do tipo supracardíaco, três do tipo infracardíaco e uma do tipo cardíaco. CONCLUSÃO: A angiotomografia computadorizada com múltiplos detectores tem demonstrado fundamental importância no diagnóstico destas anomalias, principalmente por se tratar de método não invasivo capaz de analisar estruturas intra e extracardíacas e por permitir um estudo completo da anatomia torácica, contribuindo sobremaneira na conduta cirúrgica e, consequentemente, no prognóstico destes pacientes, especialmente por diagnosticar malformações não suspeitadas clinicamente

Multidetector CT of Aortic Dissection: A Pictorial Review

Aortic dissection is the most common acute emergency condition of the aorta and often has a fatal outcome. Outcome is determined by the type and extent of dissection and the presence of associated complications (eg, cerebral sequelae, aortic branch involvement, pericardial involvement, and visceral involvement), with early diagnosis and treatment being essential for improved prognosis. Aortic dissections are classified on the basis of the site of the intimal tear according to the Stanford classification system. Type A aortic dissection involves the ascending thoracic aorta and may extend into the descending aorta, whereas in a type B dissection the intimal tear is located distal to the left subclavian artery. Type A dissection typically requires urgent surgical intervention, whereas type B dissection can often be treated medically. Modern multidetector computed tomography (CT) is a fast, widely available imaging modality with high sensitivity and specificity. Multidetector CT allows the early recognition and characterization of aortic dissection as well as determination of the presence of any associated complications, findings that are essential for optimizing treatment and improving clinical outcomes.

A morphometric study on cadaveric aortic arch and its major branches in 25 korean adults : the perspective of endovascular surgery

OBJECTIVE

To understand the anatomic characteristics of the aortic arch (AA) and its major branches to build a foundation toward performing endovascular surgery safely.

METHODS

A total of 25 formalin fixed Korean adult cadavers were used. The authors investigated : anatomical variations of the AA and its major branches; curvature of the AA; distance from the mid-vertebrae line to the origin of the major branches; distances from the origin of the major branches of AA to the origin of its distal branches; and the angle of the three major branches, the brachiocephalic trunk (BCT), the left common carotid artery (LCCA) and the left subclavian artery (LSCA) arising from AA.

RESULTS

The three major branches directly originated from AA in 21 (84%) of the cadavers. In two (8%) of remaining four cadavers, orifice of LCCA was slightly above the stem of BCT. In remaining two (8%) cadavers, the left vertebral artery (LVA) was directly originated from AA. Average angle of AA curvature to the coronal plane was 62.2 degrees. BCT originated 0.92 mm on the right of the mid-vertebrae line. LCCA and LSCA originated from 12.3 mm and 22.8 mm on the left of the mid-vertebrae line. Mean distance from the origin of the BCT to the origin of the RCCA was 32.5 mm. Mean distance from the origin of the LSCA to the origin of the LVA was 33.8 mm. Average angles at which the major branches arise from the AA were 65.3, 46.9 and 63.8 degrees.

CONCLUSION

This study may provides a basic anatomical information to catheterize AA and its branches for safely performing endovascular surgery.

Endovascular Repair of Symptomatic Penetrating Atherosclerotic Ulcer of the Thoracic Aorta

BACKGROUND

In this study we evaluate published and personal experience of Endovascular Repair (EVAR) of penetrating atherosclerotic ulcers (PAU).

PATIENTS AND METHOD

In 12 patients (mean 74 years, 58-87 years) PAU was diagnosed with computer tomography (CT). Symptomatic ulcers were treated by vascular surgeons using stentgrafts via a femoral access route. Patients were followed up clinically and with CT for an average of 849 days (186-1968 days).

RESULTS

11 patients had severe acute thoracic pain, one patient presented with hemoptysis. CT showed well outlined ulcer, intramural hematoma, and contrast enhancement of the aortic wall (n=12), pseudoaneurysm (n=11), intimal calcification adjoining the ulcer (n=10), pleural (n=9) and mediastinal fluid (n=4). Mean duration of surgery was 68min (32-120min). Primary technical success was achieved in all patients. There was no perioperative complications except one acute hemorrhage from an intercostal artery and one iliac dissection. 3 months after stentgraft application owing to a severe stenosis of the right common femoral artery, an iliofemoral bypass was performed in one patient. All patients were free of symptoms after the procedure. There was incomplete sealing of PAU in 2 of 12 patients, but no re-intervention was needed. All patients were alive during follow-up.

CONCLUSION

Symptomatic PAU is a potentially fatal lesion. Considering the low morbidity and mortality of EVAR, this option might be first choice.

Nontraumatic Thoracic Emergencies

Acute chest pain is one of the most common complaints of patients who present to an emergency department, and accounts for up to 5% of all visits. It also is one of the most complex issues in an emergency setting because, although clinical signs and symptoms often are nonspecific, rapid diagnosis and therapy are of great importance. The chest radiograph remains an important component of the evaluation of chest pain, and usually is the first examination to be obtained. Nevertheless, cross-sectional imaging has added greatly to the ability to characterize the wide constellation of clinical findings into a distinct etiology. This article reviews how the various entities that can present as nontraumatic chest pain can manifest radiographically.

A Comparative Study of Imaging Techniques in Aortic Dissection, DeBakey Type I: Intraoperative Live Three- Dimensional Epicardial Echocardiography, Multiplane Transesophageal Echocardiography, and Multislice Computed Tomography

Objective

To compare the accuracy of intraoperative live 3-dimensional epicardial echocardiography, multiplane transesophageal echocardiography (TEE), and multislice computed tomography (MSCT) imaging in the detection of thoracic aortic dissection, site of intimal tear, and involvement of arch vessel.

Methods

Of 24 patients studied from October 2003 to September 2004, 12 had aortic dissection. They were examined preoperatively with contrast material-enhanced MSCT and multiplane TEE. Intraoperative live 3-dimensional epicardial echocardiographic evaluation of the ascending aorta and arch was performed. Imaging results in terms of detection of aortic dissection, site of intimal tear, and involvement of coronary arteries and arch vessels were confirmed at intraoperative exploration by the operating surgeon as the reference standard.

Results

Sensitivity in the detection of thoracic aortic dissection was 100% for all techniques. Specificity was 92%, 92%, and 100% for live 3-dimensional epicardial echocardiography, multiplane TEE, and MSCT imaging, respectively. In the assessment of aortic arch vessel involvement, sensitivity was 92%, 58%, and 92%, and specificity was 75%, 50%, and 83%, respectively. For the detection of the site of intimal tear, sensitivity was 92%,92%, and 58%, and specificity was 83%,75%, and 50%, respectively.

Conclusion

Intraoperative live 3-dimensional epicardial echocardiography is as valuable as multiplane TEE and MSCT imaging in the detection of thoracic aortic dissection. In the assessment of the aortic arch vessel involvement, MSCT and live 3-dimensional epicardial echocardiography are superior (P < 0.05), whereas live 3-dimensional epicardial echocardiography and TEE are superior in detection of site of intimal tear (P < 0.05).

Dilatation of the aorta in pure, severe, bicuspid aortic valve stenosis

BACKGROUND

Aortic complications are more frequent after bicuspid aortic valve (BAV) replacement (AVR), than tricuspid aortic valve replacement. We studied the size of the proximal thoracic aorta in patients with BAV undergoing AVR for pure, severe aortic stenosis, looking for dilatation in comparison with patients with a matched tricuspid aortic valve (TAV) and normograms of aortic size.

METHODS

Aortic root and ascending aortic diameter measurements were taken at 3 levels, from electrocardiographic-gated multidetector row computed tomograms, in 28 patients with pure, severe aortic stenosis before AVR. The patients were divided in 2 groups (BAV, n = 10; TAV, n = 18). Patients with greater than mild aortic regurgitation or who were scheduled for aortic root replacement were excluded.

RESULTS

Although patients in the BAV group were younger (P <.0001) and less likely to have hypertension (P <.005), their aortic diameters were larger than those of patients in the TAV group at all levels measured (aortic sinus, 41.1 +/- 8.1 mm vs 33.8 +/- 3.3 mm; sino-tubular junction, 39.0 +/- 7.8 mm vs 31.1 +/- 3.8 mm; right pulmonary artery level, 42.8 +/- 7.1 mm vs 33.7 +/- 4.3 mm; P <.005 for all). Whereas 60% (6/10) of patients in the BAV group had >/=1 aortic diameter measurements greater than the 95th age-adjusted percentile, 0% (0/18) of patients in the TAV group did.

CONCLUSIONS

Patients with BAV undergoing AVR with pure, severe aortic stenosis commonly have moderate dilatation of the thoracic aorta, whereas matched patients with a TAV do not. This finding may contribute to the increased frequency of aortic complications seen in follow up of patients with a BAV after AVR.

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

Thoracic aortic dissection is the most frequent cause of aortic emergency, and unless it is rapidly diagnosed and treated, the result is death. Helical computed tomography (CT) permits the diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. This imaging modality also enables differentiation between proximal aortic dissection (type A in the Stanford classification) and distal aortic dissection (Stanford type B), which are treated differently and have different prognoses. In 70% of patients in whom nontraumatic acute thoracic aortic dissection is diagnosed after evaluation with helical CT, scans show the typical signs of aortic dissection, with rupture and displacement of the intima. CT also can depict other pathologic entities with similar clinical manifestations, such as intramural hematoma and penetrating atherosclerotic ulcer. Awareness of the different radiologic appearances of these disease entities is essential for differential diagnosis. More than one-third of patients with aortic dissection show signs and symptoms indicative of systemic involvement. Because branch-vessel involvement may increase morbidity and mortality, in this group of patients it is important to evaluate the entire aorta so as to determine the distal extent of the dissection and detect any systemic involvement.

Congenital pulmonary venolobar syndrome: spectrum of helical CT findings with emphasis on computerized reformatting

The term congenital pulmonary venolobar syndrome refers to a wide spectrum of pulmonary developmental anomalies that may appear singly or in combination. The main components of congenital pulmonary venolobar syndrome are hypogenetic lung (including lobar agenesis, aplasia, or hypoplasia), partial anomalous pulmonary venous return, absence of pulmonary artery, pulmonary sequestration, systemic arterialization of lung, absence of inferior vena cava, and accessory diaphragm. The recent introduction of multisection helical computed tomography (CT), combined with use of advanced postprocessing graphic workstations, allows improved noninvasive delineation of complex congenital anomalies. A single fast (5-15-second) CT scan now enables the radiologist to (a) generate angiogram-like images of the anomalous pulmonary arteries and veins; (b) demonstrate tracheobronchial abnormalities by generating simulated bronchographic or bronchoscopic images; and (c) depict associated parenchymal abnormalities on axial, coronal, or sagittal images, which once represented an important advantage of magnetic resonance imaging over CT. Multisection helical CT is a helpful diagnostic tool in the preoperative evaluation of patients with suspected congenital pulmonary venolobar syndrome.

Thoracic involvement of type A aortic dissection and intramural hematoma: diagnostic accuracy--comparison of emergency helical CT and surgical findings

PURPOSE

To assess the accuracy of various findings at emergency helical computed tomography (CT) for the evaluation of thoracic involvement of type A aortic dissection (AD) and type A intramural hematoma (IMH) and to compare these findings with those at surgical confirmation.

MATERIALS AND METHODS

Fifty-seven patients with acute chest pain underwent emergency helical CT and subsequent surgery for type A AD or IMH. Patients in whom AD or IMH was detected in three segments of the thoracic aorta or those in whom there was a site of any entry tear, arch branch vessel involvement, pericardial effusion, or aortic arch anomaly were examined at helical CT. Sensitivity, specificity, and accuracy of helical CT, along with 95% CIs, were calculated by using surgical confirmation as the reference standard.

RESULTS

For the detection of AD or IMH of the thoracic aorta, the accuracy of helical CT was 100%. The sensitivity, specificity, and accuracy, respectively, were 82%, 100%, and 84% for an entry tear; 95%, 100%, and 98% for arch branch vessel involvement; and 83%, 100%, and 91% for pericardial effusion. These values were all 100% for aortic arch anomalies.

CONCLUSION

Emergency helical CT of the thorax depicts findings that are highly accurate in the evaluation of acute type A AD and IMH.

Endovascular treatment of thoracic aortic pathology: feasibility and mid-term results

OBJECTIVE

to report our experience with 21 consecutive patients treated with a thoracic stent-graft.

DESIGN

retrospective analysis.

MATERIALS AND METHODS

Between October 1998 and February 2002, 21 patients (12 male), mean age 55.6 years (range 19-86 years), were treated for aorticortic pathology localized to the descending aorta (18 patients), the aortic arch (2 patients) and the ascending aorta (1 patient) and comprising true aneurysms (8 patients), false aneurysms (6 patients), traumatic rupture (4 patients), mycotic aneurysms (2 patients), and ruptured aneurysm (1 patient). Plain chest X-rays and computed tomography was performed at 3, 6 and 12 months postoperatively and then annually.

RESULTS

the median (range) operation time was 85min (50-305min), hospital stay 6 days (3-63 days) and follow-up 24 months (5-44 months). Complications occurred in 5 patients and comprised intraoperative migration (1), type I endoleak (1), type II endoleak (1), ischemic myelopathy (1), pneumonia (2), suture granuloma (1) and common femoral artery dissection (1).

CONCLUSIONS

stent-grafting can be successfully employed to treat a wide range of thoracic aortic pathologies with a mortality, morbidity and resource utilization that is considerably less than that associated with conventional surgery. However, long term follow-up on safety and efficacy is needed.

Thoracic aorta imaging with multisclice CT

Multislice CT aortography represents a major advance in the noninvasive evaluation of thoracic aortic disease. MSTCA is rapidly becoming the preferred modality for the initial investigation of acute aortic syndromes. Although scan quality is usually excellent, special attention to various technical parameters is required to optimize image quality. Familiarity with diagnostic pitfalls and the common imaging presentations of various thoracic aortic syndromes is necessary for accurate diagnosis.

The retrotracheal space: normal anatomic and pathologic appearances

A variety of diseases can arise from the normal contents of the retrotracheal space or from adjacent structures. Mediastinal diseases in the retrotracheal space typically manifest radiographically as a contour abnormality or an area of increased opacity, although computed tomography (CT) or magnetic resonance (MR) imaging is usually required for diagnosis. The most common aortic arch anomaly, a right subclavian artery that originates from an otherwise normal left-sided aortic arch, appears at posteroanterior chest radiography as an obliquely oriented soft-tissue area of increased opacity that extends superiorly to the right from the superior margin of the aortic arch. CT and MR imaging can reveal associated vascular or mediastinal abnormalities. Aortic aneurysms and pseudoaneurysms can manifest radiographically as fusiform or saccular masslike lesions that protrude into the retrotracheal space. Thoracic MR imaging and spiral CT angiography are the diagnostic procedures of choice for evaluating diverse pathologic conditions of the thoracic aorta. Esophageal diseases can manifest as an abnormality in the retrotracheal space, which may be the initial clue to the diagnosis. At CT, lymphatic malformations in the mediastinum manifest as lobular, multicystic tumors that surround and infiltrate adjacent mediastinal structures. Familiarity with the normal radiologic appearance of the retrotracheal space and with the clinical manifestations of diseases that affect the retrotracheal space and adjacent structures can facilitate detection, diagnosis, and management.

CT angiography of the arterial system

CTA has become an important diagnostic tool in the evaluation of vascular diseases in virtually all parts of the body. Whereas CTA is able to provide images depicting exquisite anatomic detail, careful scanning technique and selection of scan parameters are critical for high quality studies. The choices to be made when prescribing a scan can seem daunting at first, but if one applies the principles outlined previously, CTA can be a relatively easy, fast, and safe diagnostic technique that is effective in the majority of patients with vascular disease.

Diameters of the thoracic aorta throughout life as measured with helical computed tomography

OBJECTIVE

The use of helical computed tomography is well established in the evaluation of the thoracic aorta. Nevertheless, normal diameters and their changes during adult life according to this method are not available. We planned to set up normal diameters for the thoracic aorta of adults obtained by helical computed tomography.

METHODS

Seventy adults, 17 to 89 years old, without any signs of cardiovascular disease were investigated with helical computed tomography. Aortic diameters were measured at seven predefined thoracic levels.

RESULTS

Aortic diameters (mean +/- SD) were 2.98 +/- 0.46 cm at the aortic valve sinus, 3.09 +/- 0.41 cm at the ascending aorta, 2.94 +/- 0.42 cm proximal to the innominate artery, 2.77 +/- 0.37 cm at the proximal transverse arch, 2.61 +/- 0.41 cm at the distal transverse arch, 2.47 +/- 0.40 cm at the isthmus, and 2.43 +/- 0.35 cm at the diaphragm. Men had slightly longer diameters than did women. All diameters increased with age. There was no influence of weight, height, or body surface area. After normalization to the diameter at diaphragmatic level, no statistically significantly influential factor could be detected.

CONCLUSIONS

This study delineates normal intrathoracic aortic diameters for helical computed tomography, including relationships with sex and age. Pathologic dimensions of the aorta should preferably be provided as percentiles or z scores.

Systemic arterial supply to the lungs in adults: spiral CT findings

Systemic arterial supply to the lungs can be congenital or due to acquired disease. Congenital diseases encompass bronchopulmonary sequestration and congenital pulmonary venolobar syndrome, in which the involved lung parenchyma is supplied by the aberrant systemic arteries. An anomalous systemic artery can also supply an area of otherwise normal lung parenchyma. In acquired diseases, hypertrophied normal systemic arteries supply the lungs. Hypertrophied systemic arteries include the bronchial arteries, intercostal arteries, internal mammary arteries, inferior phrenic arteries, branches of the thyrocervical trunk, branches of the hepatic arteries, and branches of the abdominal aorta. Hypertrophy of normal systemic arteries is encountered in patients with bronchiectasis, pulmonary tuberculosis, other pulmonary infections, pulmonary thromboembolism, or chronic obstructive pulmonary disease. These systemic arteries are considered to supply the lungs by means of anastomoses between bronchial and pulmonary arteries within the lung parenchyma or transpleural systemic-pulmonary artery anastomoses. In most cases, the correct diagnosis and treatment plan can be determined by identification of the systemic arteries on computed tomographic scans.

Helical CT angiography and three-dimensional reconstruction of total anomalous pulmonary venous connections in neonates and infants

OBJECTIVE

The objective of this study was to investigate the usefulness of helical CT angiography in the evaluation of total anomalous pulmonary venous connections.

MATERIALS AND METHODS

Fourteen patients with total anomalous pulmonary venous connections underwent helical CT angiography and subsequent three-dimensional (3D) reconstruction. They ranged in age from 3 days to 8 months (median age, 2.3 months) and in weight from 2.3 to 7.1 kg (median weight, 4.3 kg). The types of total anomalous pulmonary venous connections and the number of pulmonary veins were evaluated on axial and 3D images. Qualitative evaluations were performed for extent of pulmonary vascular enhancement and contrast- or motion-induced artifacts.

RESULTS

In all patients, helical CT angiography correctly depicted total anomalous pulmonary venous connections. Seven cases were the supracardiac type, four cases were the cardiac type, one case was the infracardiac type, and two cases were the mixed type. The detection rate of the pulmonary vein in 3D reconstruction images (95-98%) was slightly lower than that of the pulmonary vein in the axial images (100%), but the difference between axial and 3D reconstruction images was not statistically significant (p > 0.1). No statistically significant differences were noted among 3D reconstruction images in the detection rates of the pulmonary vein (p > 0.1). The extent of contrast enhancement of the pulmonary vein was good or excellent in all patients. In five patients, there were contrast-induced artifacts that made some surrounding vascular distortion but did not interfere with the pulmonary vein analysis, except in one patient. Motion-induced artifacts were observed in nine patients. One of them had an obstacle in pulmonary vein analysis.

CONCLUSION

The combination of axial and 3D images in helical CT angiography is helpful in the assessment of a total anomalous pulmonary venous connection containing the individual pulmonary vein, and this combination can be a good diagnostic tool in preoperative evaluation of neonates and infants with a total anomalous pulmonary venous connection.

Helical CT angiography with maximum intensity projection in the assessment of aortic coarctation after surgery

OBJECTIVE

The value of CT angiography and three-dimensional (3D) reconstructions was investigated in the postoperative care after surgical repair of aortic coarctation and compared with conventional angiography.

SUBJECTS AND METHODS

Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients.

RESULTS

The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found.

CONCLUSION

CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.

Penetrating atherosclerotic ulcer of the aorta: imaging features and disease concept

Penetrating atherosclerotic ulcer is an ulcerating atherosclerotic lesion that penetrates the elastic lamina and is associated with hematoma formation within the media of the aortic wall. This pathologic condition is distinct from classic aortic dissection and aortic rupture; however, care should be taken in making the diagnosis, particularly if the disease is discovered incidentally. At computed tomography (CT), penetrating atherosclerotic ulcer manifests as focal involvement with adjacent subintimal hematoma and is often associated with aortic wall thickening or enhancement. Magnetic resonance imaging is superior to conventional CT in differentiating acute intramural hematoma from atherosclerotic plaque and chronic intraluminal thrombus and allows unenhanced multiplanar imaging. Spiral CT involves shorter examination times and allows high-quality two- and three-dimensional image reconstruction. CT angiography can demonstrate complex spatial relationships, mural abnormalities, and extraluminal pathologic conditions. Transesophageal echocardiography has been reported to be highly sensitive and specific in the differentiation of aortic disease, and intravascular ultrasonography may also be useful in this setting. Although rupture or other life-threatening complications are rare, patients with penetrating atherosclerotic ulcer must be followed up, particularly during the 1st month after onset. Surgical treatment may become necessary in cases involving evidence of intramural hematoma expansion, signs of impending rupture, inability to control pain, or blood pressure changes.

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.

Imaging of thoracic aortic disease

Computed tomography, magnetic resonance imaging, and transesophageal echocardiography represent the relatively noninvasive techniques available for imaging thoracic aortic disease, especially in the evaluation of aneurysms and dissections. The article discusses the technique and application of these modalities in the evaluation of thoracic aorta. Imaging appearances of the commonly encountered pathologies of the thoracic aorta are presented and discussed, and potential pitfalls of technique and diagnosis are addressed.

Takayasu's arteritis: a cell-mediated large-vessel vasculitis

Takayasu's arteritis is an idiopathic, systemic inflammatory disease, typically involving the aorta and its main branches. Cell-mediated autoimmunity has been strongly implicated in its pathogenesis. Early or active-stage pathology consists of continuous or patchy granulomatous inflammation, which progresses to intimal and adventitial fibrosis and scarring of the media. Multiple focal or segmental stenoses result and aneurysms may occasionally occur. Clinical presentation is heterogeneous, ranging from asymptomatic to catastrophic. In some patients, constitutional signs and symptoms indicating a systemic inflammatory response are observed, usually in the early stages. Specific features reflect arterial involvement, and result from end-organ or limb ischemia; they include vascular, neurological, cardiac, and pulmonary manifestations. The course of Takayasu's arteritis usually extends for many years with varying degrees of activity. Takayasu's arteritis has a worldwide distribution, with the greatest prevalence in eastern countries. Women of reproductive age are preferentially affected, but the illness is being recognized with increasing frequency in males. Variable phenotypes are recently emerging in different ethnic groups. Diagnosis is based on clinical features and vascular imaging studies that document typical patterns of stenoses or aneurysms of the aorta and its primary branches. Assessment of the activity of Takayasu's arteritis is imprecise, in that clinical features and acute-phase reactants do not accurately reflect active blood vessel inflammation. High-dose corticosteroids alone or a cytotoxic agent in addition to a corticosteroid may be effective in treating active disease. Critical lesions may require correction by surgery or interventional radiology.

Helical (spiral) CT in the evaluation of emergent thoracic aortic syndromes. Traumatic aortic rupture, aortic aneurysm, aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer

For the near future, CT will play the critical and dominant role in the evaluation of patients presenting with emergent aortic syndromes. Its convenience, accuracy, and utility in the rapid evaluation of not just the aorta, but the entire thorax, make it ideally suited for use in emergency settings. Further benefits are likely to be realized in speed and resolution with multislice CT, although it is as yet not widely available.

Aortic dissection: diagnosis and follow-up with helical CT

Acute aortic dissection is a cardiovascular emergency that requires prompt diagnosis and treatment. Helical computed tomography (CT) allows diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. With helical CT, a dissection involving the ascending aorta (type A in the Stanford classification) can be differentiated from one distal to the left subclavian artery (type B). Helical CT can also be used to identify atypical forms of aortic dissection such as intramural hematoma, penetrating atherosclerotic ulcer, ruptured type B dissection, and atypical configurations of the intimal flap. Helical CT is useful in follow-up of aortic dissection by allowing assessment of early and late changes after surgery or medical treatment. Such changes include postoperative complications of type A dissection, healing of intramural hematoma, progression of intramural hematoma, and aneurysms of the true or false lumen. Helical CT can also be used to monitor potentially life-threatening ischemic complications of abdominal branch vessels.

Clinical decision making and operative approaches to thoracic aortic aneurysms

The care of the patient with thoracic aneurysms is quite complicated. The decision to treat an aneurysm must be based on the risk of rupture and the patient's life expectancy. The preoperative evaluation must include detailed imaging to allow proper preoperative planning. This is especially important to determine the need for hypothermic circulatory arrest or the potential to treat a descending aneurysm with an endovascular approach. Thorough preoperative preparation and intraoperative care are as important as surgical decision making and meticulous technique. Although significant advances have been made in operative approaches, cerebral and myocardial preservation, and postoperative care, the management of complicated aneurysms of the thoracic aorta is frequently a humbling experience.

CT angiography of the abdominal and thoracic aorta

Evaluation of the abdominal and thoracic aorta is one of the most common indications for CT angiography (CTA). CTA largely has replaced conventional angiography in the assessment of aortic aneurysms and dissections because it provides all the relevant anatomic information at reduced cost, morbidity, and radiation exposure. This article will focus on the technique, interpretation, and pitfalls in the CTA evaluation of the abdominal and thoracic aorta.

Three-dimensional CT angiography of the thorax: clinical applications

Spiral CT with three-dimensional (3D) display can provide a rapid noninvasive examination of the vascular system and has been shown to have a wide range of clinical applications in the thorax, including imaging of the aorta, pulmonary vasculature, and venous abnormalities. Three-dimensional images can provide views of the imaging volume from innumerable viewing angles for both the radiologist and referring clinician, and potentially obviate invasive procedures such as angiography. In this article, we will review many of these applications of spiral CT angiography with 3D displays. Emphasis is placed on study design, protocol selection, and display of pathology.