Comprehensive assessment of the severity and mechanism of aortic regurgitation using multidetector CT and MR

Imaging Methods for Evaluation of Chronic Aortic Regurgitation in Adults: JACC State-of-the-Art Review

A global multidisciplinary workshop was convened to discuss the multimodality diagnostic evaluation of aortic regurgitation (AR). Specifically, the focus was on assessment tools for AR severity and analyzing evolving data on the optimal timing of aortic valve intervention. The key concepts from this expert panel are summarized as: 1) echocardiography is the primary imaging modality for assessment of AR severity; however, when data is incongruent or incomplete, cardiac magnetic resonance may be helpful; 2) assessment of left ventricular size and function is crucial in determining the timing of intervention; 3) recent evidence suggests current cutpoints for intervention in asymptomatic severe AR patients requires further scrutiny; 4) left ventricular end-systolic volume index has emerged as an additional parameter that has promise in guiding timing of intervention; and 5) the role of additional factors (including global longitudinal strain, regurgitant fraction, and myocardial extracellular volume) is worthy of future investigation.

Computed Tomographic Evaluation of Congenital Left Ventricular Outflow Obstruction

Congenital left ventricular outflow obstruction represents a multilevel obstruction with several morphological forms. It can involve the subvalvular, valvar, or supravalvular portion of the aortic valve complex, and may coexist. Computed tomography (CT) plays an important supplementary role in the evaluation of patients with congenital LVOT obstruction. Unlike transthoracic echocardiography and cardiovascular magnetic resonance (CMR) imaging, it is not bounded by a small acoustic window, needs for anaesthesia or sedation, and metallic devices. Current generations of CT scanners with excellent spatial and temporal resolution, high pitch scanning, wide detector system, dose reduction algorithms, and advanced 3-dimensional postprocessing techniques provide a high-quality alternative to CMR or diagnostic cardiac catheterization. Radiologists performing CT in young children should be familiar with the advantages and disadvantages of CT and with the typical morphological imaging features of congenital left ventricular outflow obstruction.

Multimodality Evaluation of Aortic Insufficiency and Aortitis in Rheumatologic Diseases

Aortic insufficiency is commonly observed in rheumatologic diseases such as ankylosing spondylitis, systemic lupus erythematosus, antiphospholipid syndrome, Behçet's disease, granulomatosis with polyangiitis, and Takayasu arteritis. Aortic insufficiency with an underlying rheumatologic disease may be caused by a primary valve pathology (leaflet destruction, prolapse or restriction), annular dilatation due to associated aortitis or a combination of both. Early recognition of characteristic valve and aorta morphology on cardiac imaging has both diagnostic and prognostic importance. Currently, echocardiography remains the primary diagnostic tool for aortic insufficiency. Complementary use of computed tomography, cardiac magnetic resonance imaging and positron emission tomography in these systemic conditions may augment the assessment of underlying mechanism, disease severity and identification of relevant non-valvular/extracardiac pathology. We aim to review common rheumatologic diseases associated with aortic insufficiency and describe their imaging findings that have been reported in the literature.

Multimodality imaging in valvular heart disease: how to use state-of-the-art technology in daily practice

Our understanding of the complexities of valvular heart disease (VHD) has evolved in recent years, primarily because of the increased use of multimodality imaging (MMI). Whilst echocardiography remains the primary imaging technique, the contemporary evaluation of patients with VHD requires comprehensive analysis of the mechanism of valvular dysfunction, accurate quantification of severity, and active exclusion extravalvular consequences. Furthermore, advances in surgical and percutaneous therapies have driven the need for meticulous multimodality imaging to aid in patient and procedural selection. Fundamental decision-making regarding whom, when, and how to treat patients with VHD has become more complex. There has been rapid technological advancement in MMI; many techniques are now available in routine clinical practice, and their integration into has the potential to truly individualize management strategies. This review provides an overview of the current evidence for the use of MMI in VHD, and how various techniques within each modality can be used practically to answer clinical conundrums.

Evaluation of aortic regurgitation with cardiac magnetic resonance imaging: a systematic review

This review summaries the utility, application and data supporting use of cardiac magnetic resonance imaging (CMR) to evaluate and quantitate aortic regurgitation. We systematically searched Medline and PubMed for original research articles published since 2000 that provided data on the quantitation of aortic regurgitation by CMR and identified 11 articles for review. Direct aortic measurements using phase contrast allow quantitation of volumetric flow across the aortic valve and are highly reproducible and accurate compared with echocardiography. However, this technique requires diligence in prescribing the correct imaging planes in the aorta. Volumetric analytic techniques using differences in ventricular volumes are also highly accurate but less than phase contrast techniques and only accurate when concomitant valvular disease is absent. Comparison of both aortic and ventricular data for internal data verification ensures fidelity of aortic regurgitant data. CMR data can be applied to many types of aortic valve regurgitation including combined aortic stenosis with regurgitation, congenital valve diseases and post-transcatheter valve placement. CMR also predicts those patients who progress to surgery with high overall sensitivity and specificity. Future studies of CMR in patients with aortic regurgitation to quantify the incremental benefit over echocardiography as well as prediction of cardiovascular events are warranted.

[Planimetric measurement of the regurgitant orifice area using tridimensional transoesophageal echocardiography for aortic regurgitation, reproducibility and feasibility]

BACKGROUND

Aortic regurgitation is mainly evaluated by trans-thoracic echocardiography using multi-parametric qualitative and semi quantitative tools. All those parameters can fail to meet expectations, resulting in an imperfect diagnostic reliability and assessment of aortic regurgitation severity can be challenging.

OBJECTIVES

We sought to evaluate feasibility and intra- and inter-observer reproducibility of aortic regurgitant orifice area measured by planimetry with tridimensional trans-esophageal echocardiography on patients with at least grade 2/4 aortic regurgitation.

PATIENTS AND METHODS

Consecutive patients with at least grade 2/4 aortic regurgitation measured by trans-thoracic echocardiography and referred for trans-esophageal echocardiography for any reason were included. Planimetric reconstructions of regurgitant orifice area were studied and reproducibility indexes between senior and junior observers were calculated.

RESULTS

Twenty-three patients were included in this study. Intra- and inter-observer reproducibility were excellent with an ICC of 0.95 [0.88-0.98], P<0.0001 and 0.91 [0.79-0.96], P<0.0001, respectively. Mean length of the measurement was 6.6±0.9min [CI95% 6.23-7.01].

CONCLUSION

Planimetric measurement of the aortic regurgitant orifice using tridimensional trans-esophageal echocardiography seems to be feasible and has great intra- and inter-observer reproducibility. Reconstruction durations were compatible with a daily use. There is a need now to investigate the reliability of this measurement as compared with the reference technique.

CT and MR imaging of the aortic valve: radiologic-pathologic correlation

Valvular disease is estimated to account for as many as 20% of cardiac surgical procedures performed in the United States. It may be congenital in origin or secondary to another disease process. One congenital anomaly, bicuspid aortic valve, is associated with increased incidence of stenosis, regurgitation, endocarditis, and aneurysmal dilatation of the aorta. A bicuspid valve has two cusps instead of the normal three; resultant fusion or poor excursion of the valve leaflets may lead to aortic stenosis, the presence of which is signaled by dephasing jets on magnetic resonance (MR) images. Surgery is generally recommended for patients with severe stenosis who are symptomatic or who have significant ventricular dysfunction; transcatheter aortic valve implantation (TAVI) is an emerging therapeutic option for patients who are not eligible for surgical treatment. Computed tomography (CT) is an essential component of preoperative planning for TAVI; it is used to determine the aortic root dimensions, severity of peripheral vascular disease, and status of the coronary arteries. Aortic regurgitation, which is caused by incompetent closure of the aortic valve, likewise leads to the appearance of jets on MR images. The severity of regurgitation is graded on the basis of valvular morphologic parameters; qualitative assessment of dephasing jets at Doppler ultrasonography; or measurements of the regurgitant fraction, volume, and orifice area. Mild regurgitation is managed conservatively, whereas severe or symptomatic regurgitation usually leads to valve replacement surgery, especially in the presence of substantial left ventricular enlargement or dysfunction. Bacterial endocarditis, although less common than aortic stenosis and regurgitation, is associated with substantial morbidity and mortality. Electrocardiographically gated CT reliably demonstrates infectious vegetations and benign excrescences of 1 cm or more on the valve surface, allowing the assessment of any embolic complications.

Evaluation of the aortic and mitral valves with cardiac computed tomography and cardiac magnetic resonance imaging

Cardiac computed tomography (CT) produces high-quality anatomical images of the cardiac valves and associated structures. Cardiac magnetic resonance imaging (MRI) provides images of valve morphology, and allows quantitative evaluation of valvular dysfunction and determination of the impact of valvular lesions on cardiovascular structures. Recent studies have demonstrated that cardiac CT and MRI are important adjuncts to echocardiography for the evaluation of aortic and mitral valvular heart diseases (VHDs). Radiologists should be aware of the technical aspects of cardiac CT and MRI that allow comprehensive assessment of aortic and mitral VHDs, as well as the typical imaging features of common and important aortic and mitral VHDs on cardiac CT and MRI.

Bicuspid aortic valve: spectrum of imaging findings at cardiac MDCT and cardiovascular MRI

OBJECTIVE

Cardiac MDCT and cardiovascular MRI have become widely used for the evaluation of cardiovascular disease, including aortic valve disease. The purpose of this article is to present the cardiac MDCT and cardiovascular MRI findings of bicuspid aortic valve, its various complications, and other congenital cardiovascular malformations.

CONCLUSION

Radiologists should be aware of the clinical significance and the varied appearance of bicuspid aortic valve at cardiac MDCT and cardiovascular MRI.

Planimetric measurement of the regurgitant orifice area using multidetector CT for aortic regurgitation: a comparison with the use of echocardiography

Objective

This study compared the area of the regurgitant orifice, as measured by the use of multidetector-row CT (MDCT), with the severity of aortic regurgitation (AR) as determined by the use of echocardiography for AR.

Materials and Methods

In this study, 45 AR patients underwent electrocardiography-gated 40-slice or 64-slice MDCT and transthoracic or transesophageal echocardiography. We reconstructed CT data sets during mid-systolic to enddiastolic phases in 10% steps (20% and 35-95% of the R-R interval), planimetrically measuring the abnormally opened aortic valve area during diastole on CT reformatted images and comparing the area of the aortic regurgitant orifice (ARO) so measured with the severity of AR, as determined by echocardiography.

Results

In the 14 patients found to have mild AR, the ARO area was 0.18±0.13 cm² (range, 0.04-0.54 cm²). In the 15 moderate AR patients, the ARO area was 0.36 ± 0.23 cm² (range, 0.09-0.81 cm²). In the 16 severe AR patients, the ARO area was 1.00 ± 0.51 cm² (range, 0.23-1.84 cm²). Receiver-operator characteristic curve analysis determined a sensitivity of 85% and a specificity of 82%, for a cutoff of 0.47 cm², to distinguish severe AR from less than severe AR with the use of CT (area under the curve = 0.91; 95% confidence interval, 0.84-1.00; p < 0.001).

Conclusion

Planimetric measurement of the ARO area using MDCT is useful for the quantitative evaluation of the severity of aortic regurgitation.