From the Guidelines
For the evaluation of supravalvular stenosis, a cardiac MRI with contrast enhancement, including gadolinium contrast, cine imaging sequences, and MR angiography (MRA), is the recommended imaging modality. This approach allows for detailed visualization of the ascending aorta, accurate measurement of the stenotic region, assessment of flow dynamics across the narrowed segment, and evaluation of left ventricular function 1. The protocol should include both anatomical and functional assessment components to fully characterize the stenosis severity, extent, and hemodynamic impact.
Some key points to consider when ordering a cardiac MRI for supravalvular stenosis evaluation include:
- The use of gadolinium contrast to enhance visualization of the ascending aorta and surrounding structures
- The inclusion of cine imaging sequences to assess flow dynamics and left ventricular function
- The use of MR angiography (MRA) to provide detailed images of the aortic anatomy and detect any associated cardiac anomalies
- The importance of screening patients for contraindications such as certain metallic implants, severe claustrophobia, or significant renal dysfunction that would preclude gadolinium administration 1.
Cardiac MRI is particularly valuable for supravalvular stenosis evaluation because it provides excellent soft tissue contrast without radiation exposure, allows for multiplanar imaging, and can accurately quantify the degree of narrowing and its physiological consequences 1. Additionally, it can detect associated cardiac anomalies that often accompany supravalvular stenosis, especially in patients with Williams syndrome where multiple cardiovascular abnormalities may coexist. The examination typically takes 45-60 minutes to complete.
It's worth noting that while other imaging modalities such as echocardiography and CT angiography may be useful in the evaluation of supravalvular stenosis, cardiac MRI is generally considered the most comprehensive and accurate imaging modality for this purpose 1.
From the Research
MRI Evaluation for Supravalvular Stenosis
To evaluate supravalvular stenosis, the following MRI techniques can be considered:
- Cardiovascular magnetic resonance (CMR) imaging with steady-state free precession sequences to assess the aortic valve area and planimetry 2
- Contrast-enhanced CMR to evaluate the anatomy of the ascending aorta and detect any associated lesions
Key Considerations
When ordering an MRI for supravalvular stenosis evaluation, consider the following:
- The type of supravalvular stenosis (discrete or diffuse) and its extent
- Associated cardiovascular abnormalities, such as pulmonary involvement or coronary arterial involvement 3
- The need for accurate assessment of the aortic valve area and planimetry 2
Imaging Characteristics
Supravalvular aortic stenosis can be characterized by:
- Discrete or diffuse narrowing of the ascending aorta 3
- Associated pulmonary arterial involvement, coronary arterial involvement, or aortic valvular abnormalities 3
- Presence of associated congenital cardiac defects, such as ventricular septal defect or patent ductus arteriosus 3
Clinical Context
In the clinical context, supravalvular stenosis can present with: