Pseudoaneurysm of mitral-aortic intervalvular fibrosa in a child: Demonstration by MDCT and MRI
A 10-year-old boy with history of aortic valve disease (bicuspid aortic valve with severe aortic regurgitation) and infective endocarditis 6 months ago was referred for evaluation of echocardiographic finding of a cystic lesion. The lesion was posterior to the aortic root and anterior to left atrium with turbulent flow on color Doppler. The lesion was thought to represent a ruptured myocardial ring abcess; the patient was advised further imaging with MRI. Cardiac MRI was done using ECG gated breath-hold SSFP (TRUFI) sequences in left ventricular short axis and LVOT (3 chamber plane) and transaxial (aortic valve planes). The aneurysm was seen filling during the systole and emptying during the diastole and showed a swirling flow (manifested by hypo intense signal secondary to rapid dephasing due to turbulent flow); the aortic valve was bicuspid with severe aortic regurgitation and thickening of valve margins [ and Videos and ]. The patient was lost to follow-up and turned up after 6 months. A repeat study was requested but the child developed claustrophobia in the MR suite. CT angiography was performed on a 64-slice scanner (Sensation, Siemens Medical Solutions) using a pediatric cardiac CT protocol and retrospective ECG gating. The images were processed on dedicated workstation; reformatted MPR and MIP images in different planes were analyzed. CT angiography revealed an aneurysmal out pouching (measuring 1.9 × 2.9 × 3.0 cm in diastole as compared to previous MRI when the lesion measured 1.7 × 2.5 × 2.7 cm in the same cardiac phase) arising from left ventricular outflow tract below the aortic annulus; the aneurysm was related anteriorly to the aortic root and posteriorly to left atrium [Figures and ]. Multiphasic images revealed that the aortic valve was bicuspid with thickening of the free edges of the valve and dilation of ascending aorta (measuring 3.9 × 3.9 cm). When the size of the pseudo aneurysm was compared to the previous MRI for same cardiac phase a definite increase in the size of lesion was observed and the child was advised surgical repair.