Bicuspid aortic valve: role of cardiac CT and Cardic MR imaging Poster No.:
477
Congress:
ESCR 2013
Type:
Poster Presentation
Authors:
Y. Arous , S. Bouguerra , M. Aloui , S. KOUKI , H. BOUJEMAA ,
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N. BEN ABDALLAH ; Ariana/TN, Tunis, TU/TN, Tunis/TN Keywords:
MR, CT-Angiography, Cardiac, Defecography, Congenital
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Purpose The purpose of Poster is to present the Computed Tomography and cardiovascular Magnetic Resonance Imaging findings of bicuspid aortic valve.
Methods and Materials Bicuspid aortic valve (BAV) is the most common congenital cardiovascular malformation, affecting approximately 1% of the population. BAV can coexist with other congenital cardiovascular malformations, particularly coarctation of the aorta. Patients with BAV are at increased risk of both valvular and vascular complications. Valvular lesions include aortic stenosis, aortic regurgitation, and infective endocarditis. At our institution, we use a 64 row CT scan (GE VCT). A retrospectively ECGgated MDCT allows reconstruction of images of the aortic valve in any phase of the cardiac cycle. MDCT can yield a high spatial resolution and a good temporal resolution. Multiplanar images can be reconstructed that are analogous to standard echocardiographic views. Images obtained in planes parallel to the aortic valve are useful for assessing the valve leaflets and performing planimetry. Coverage can be extended to include the thoracic aorta. Cardiovascular MRI can be used for assessment of aortic valve structure, left ventricular volume, quantification of the severity of aortic stenosis and aortic regurgitation, and evaluation of the thoracic aorta. In our instituion, we use a 3 Tesla Scan (Siemens Verio).
Results 1. 2.
Aortic Valve anatomy: The aortic valve consists of three cusps with curvilinear or semilunar annular attachments to the aortic ring (fig1) Classification of Bicuspid Aortic Valve (BAV):
BAV refers to a spectrum of congenital abnormalities in which the aortic valve has only two cusps instead of the normal three. The classification system is based on three characteristics: the number of raphes, the spatial position of cusps or raphes, and the functionnal status of the valve. MDCT and Cardiovascular MRI with Cine Images are used for accurate morphologic analysis of BAV.
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BAV is classified into three categories. The main category is termed "type." The subcategories are supplementary. The main category represents the number of raphes, codifying the BAVs into three types: •
type 0: valve with no raphe (fig 2)
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Fig. 2: Cine MR image showing a type 0 BAV References: - Ariana/TN type 1: valves with one raphe (Fig 3)
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•
Fig. 3: Cine MRI image of type 1 BAV with one raphe References: - Ariana/TN type 2: valves with two raphes (fig 4 and 5)
Fig. 5: CT scan MPR images of type 2 BAV References: - Ariana/TN
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Fig. 4: Steady stat Free precession image shows type 3 BAV ( same patient of Figure 4) References: - Ariana/TN The first subcategory relates to the spatial arrangements of the free edge of cusps. The second subcategory is determined by the functional status of the valve. In patients with BAV type 0, diastolic images alone are sufficient for diagnosis. However, to identify BAV with a raphe, both systolic and diastolic data are needed. 3: Associated Congenital Cardiovascular Malformations: the most frequent associated congenital CV malformations is coarctation of the aorta. Approximately 26% of patients with BAV have aortic coactation, but approximately 50-70% of patients with aortic coactation have BAV (fig 6 and7)
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Fig. 6: Volume Rendering MDCT images shows a coarctation of the aorta in a patient with type 2 BAV. References: - Ariana/TN
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Fig. 7: MR angiography , same patient of figure 6 References: - Ariana/TN . Patients with a BAV have also an aortopathy similar to that seen in Marfan syndrome, with an increased propensity for dilatation, aneurysm, dissection, and rupture of the aorta. Dilatation of the ascending aorta is primarily due to an abnormal aortic substrate. 4: Valvular complications The most common complication of BAV is aortic stenosis. Patients with BAV have superimposed calcific changes early in life that progress after the fourth decade. (fig 8)
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Fig. 8: Aortic stenosis in a patient with a type 0 BAV References: - Ariana/TN Assessment of aortic valve structure, motion, and area is possible with ECG-gated MDCT and cardiovascular MRI with good image quality in patients with calcified BAV stenosis. Cardiovascular MRI detects turbulent blood flow through a stenotic aortic valve (Qualitative evaluation) and can be used to quantify blood flow and peak velocity (Quantitative evaluation). The second valvular complication is Aortic Regurgitation. Aortic regurgitation is caused by prolapse of a larger cusp, fibrotic retraction of the cusps, aneurysmal dilatation of the aortic root and valve annulus, and valvular destruction secondary to infective endocarditis.
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Fig. 10: Cine MR steady state free precession 4 chambers view shows a dilated LV with a prolapse of the mitral valve (same patient as figure 9) References: - Ariana/TN
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Fig. 9: Cine MR steady state free precession 3 chambers view shows a regurgitant flow References: - Ariana/TN
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Fig. 11: Phase contrast image in 3 chambers views showing an aortic regurgitation in a patient with BAV References: - Ariana/TN Images for this section:
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Fig. 1: Tricuspid Aortic valve in Cine gradient echo image
Fig. 2: Cine MR image showing a type 0 BAV
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Fig. 5: CT scan MPR images of type 2 BAV
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Fig. 6: Volume Rendering MDCT images shows a coarctation of the aorta in a patient with type 2 BAV.
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Fig. 11: Phase contrast image in 3 chambers views showing an aortic regurgitation in a patient with BAV
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Conclusion Cardiac MDCT and cardiovascular MRI can be used for accurate morphologic assessment of BAV, the related valvular complications, depiction of Coarctation of the aorta and for measurement of the diameter of the ascending aorta Cardiac MDCT can be used to evaluate the morphologic features of the coronary artery, and cardiovascular MRI is a quantitative
References 1.
2.
Sievers HH, Schmidtke C. A classification system for the bicuspid aortic valve from 304 surgical specimens. J Thorac Cardiovasc Surg 2007; 133: 1226-1233. Ko SM, Song MG, Hwang HK. Bicuspid Aortic Valve: Spectrum ofImaging Findings at Cardiac MDCT and Cardiovascular MRI. AJR 2012; 198:89-97.
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