LITMIR.BIZ

Figure 10.5 (a) Sinus venosus ASD with the right upper pulmonary vein draining into the SVC, (b) Bicuspid aortic valve, (c) A distal left main aneurysm.

      Vascular disease

      Aortic disease

      CMR imaging techniques permit the comprehensive assessment of aortic diseases including aortic aneurysms, valve abnormalities, pseudoaneurysms, aortitis, and aortic dissection [53]. They are used to assess disease progression and complications post‐repair [90, 91]. CMR has become the preferred non‐invasive tool for selection for percutaneous intervention in patients with aortic coarctation. It is increasingly being used due to its ability to generate both 3D anatomic and hemodynamic information without radiation exposure [84,92–94].

      Peripheral, carotid, and renal artery disease

      CMR is increasingly being used in the evaluation of stenosis in the peripheral, carotid, and renal arteries. It has better contrast resolution compared to CT and ultrasound in the evaluation of peripheral arterial disease. CE MRA has greater than 95% sensitivity and specificity to detect stenosis with the benefit of avoiding blooming artifact secondary to atherosclerotic calcification as is seen on CTA. It is particularly useful in patients with advanced calcified atherosclerotic disease in the infrageniculate vessels [95]. By utilizing time‐of‐flight MRA, gadolinium can be avoided in patients with diminished renal function. CE MRA techniques now rival CTA and conventional angiography for the assessment of carotid stenosis and aneurysms [96–98]. CE MRA has been shown to be an excellent alternative to CTA without ionizing radiation in patients undergoing evaluation for fibromuscular dysplasia in the renal arteries [99].

      CMR for interventional cardiac procedures

      Transcatheter aortic valve replacement (TAVR)

      CMR has evolved to play a pivotal role in TAVR planning [100]. Direct comparison of CMR and CTA measurements of the aortic root and aortic annulus has shown close agreement [101–103]. CMR is extremely useful in patients with renal insufficiency that are unable to undergo contrast‐enhanced CT. A gated non‐enhanced MRA serves as an alternative for accurate measurements of the aortic root, proximal aorta, LV function and evaluation of the aorto‐iliofemoral system [74,75]. [104, 105] PCVM can be used to quantify the severity of concomitant mitral or aortic regurgitation. The major limitation of CMR is inadequate visualization of aortic calcification [100].

CMR is also important in the evaluation of paravalvular leak (PVL) post‐TAVR. It has much lower interobserver variability in the evaluation of PVL as compared to echocardiography [106, 107] and severity of PVL on CMR has been shown to be associated with increased mortality [108].

      Both MSCT and CVR techniques can be utilized in combination in “no contrast” imaging for certain preprocedure planning in patients with severe renal failure. For example, a non‐contrast gated MSCT of the aortic valve/annulus and the aortoiliac arterial beds can be combined with non contrast cardiac MR and no‐contrast MR‐angiogram of aortoiliac segments to assess sizing and calcification extent in TAVR planning.

      Interventional CMR

      Research in interventional CMR has been ongoing because of its potential to guide procedures with greater accuracy and in a radiation‐free environment. MR‐guided right heart catheterization and interventions such as femoral and popliteal angioplasty have successfully been performed. As interventional CMR rapidly advances, it will play a key role in interventions that are more complex in the future [109].

Conclusions

      Cardiac CT and MRI are excellent imaging modalities with their own unique strengths and limitations. They have found wide application in the assessment of cardiovascular conditions and are an integral part of the multimodality planning of cardiac interventional procedures.

       Interactive multiple choice questions are available for this chapter on www.wiley.com/go/dangas/cardiology

      References