Interventional Cardiology. Группа авторов

and blood flow [52, 53]. The main limitations of CMR are the inability to image very large or claustrophobic patients, long scan time, contraindications such as certain implanted devices/clips and the risk of nephrogenic systemic fibrosis from gadolinium contrast in patients with impaired renal function. However, the ability of CMR to provide comprehensive evaluations of cardiovascular morphology, function, and pathology makes it an attractive tool for the assessment and planning of patients undergoing cardiac interventional procedures.

      Applications of CMR

      Heart failure

      CMR is useful for the initial evaluation of cardiac structure and function for known or suspected heart failure (HF), patients who are undergoing or are scheduled to begin chemotherapy, patients with familial or genetic dilated cardiomyopathies, suspected pulmonary hypertension, and to determine candidacy for implantation of permanent pacemakers and/or defibrillators [54].

It offers a more accurate assessment of function and morphology than most other imaging modalities. Cine sequences are used to visualize and quantify global atrial and ventricular systolic function relative to reference datasets. The pattern of scarring on late gadolinium enhancement (LGE) allows for accurate discrimination of ischemic from non‐ischemic cardiomyopathies [55]. Ischemic scar is subendocardial or transmural. Non‐ischemic cardiomyopathies either do not have detectable scars or have a non‐subendocardial distribution. In hypertrophic cardiomyopathy (HCM), LGE is patchy and intramyocardial, typically in the hypertrophied regions and in the interventricular septum close to the right ventricular (RV) insertion areas [56, 57] (Figure 10.4a–f). In dilated cardiomyopathy, a mid‐myocardial stripe of septal fibrosis is typical and is of strong prognostic value [58]. T2‐weighted CMR may be useful to detect myocardial inflammation due to acute myocarditis [59, 60]. Quantification of T2* relaxation times have proven useful for estimating intramyocardial iron content [61]. Non‐compaction cardiomyopathy is characterized by a thin compacted myocardium in the mid and apical segments of the LV. An end‐diastolic ratio of the non‐compacted to compacted LV myocardium of ≥2.3 is considered diagnostic [62]. ARVC is characterized by global or regional dilatation of the RV (and in some cases the LV) [63]. Cardiac amyloidosis has the classic appearance of a low signal “dark” blood pool and a very high signal intensity in the myocardium that is difficult to “null” on LGE images [64].

Figure 10.1 (a) Severe stenosis in the proximal RCA on CTA with high‐risk CT features such as positive remodeling and atherosclerotic plaque with low attenuation, (b) Stent in the proximal LAD without in‐stent restenosis. The lumen is well‐visualized, (c) Patent LIMA graft to the distal LAD, (d) Patent LIMA graft to LAD with a stent in the proximal LAD. Lumen of the LAD stent is difficult to visualize due to partial voluming artifact.

Figure 10.2 (a) Post‐TAVR, a bioprosthetic valve is seen in aortic position, (b) TAVR leaflets appear thickened, (c) Right coronary leaflet has restricted motion.

      Coronary artery evaluation

      CMR is evolving as an important diagnostic modality for evaluation of coronary anomalies and coronary artery aneurysms [65, 66]. Segments of anomalous coronaries that course between the aorta and pulmonary artery can cause myocardial ischemia and sudden cardiac death, especially among young adults [67, 68]. Coronary aneurysms, commonly seen in Kawasaki’s disease, are associated with morbidity and mortality [69]. Both are accurately characterized on CMR [70, 71].

      CMR is not commonly used to evaluate coronary stenosis. A focal stenosis appears as signal attenuation. Several studies have evaluated the accuracy of CMR in assessing coronary artery stenosis. A recent article [72] summarized the results of these papers and discussed recent technological innovations, such as advanced motion correction and reconstruction techniques, that have improved MR coronary angiography. Two of the larger studies, with more than 100 patients each, demonstrated high sensitivity and NPV of MR coronary angiography compared to ICA [73, 74]. Coronary bypass grafts are relatively easier to image because of their minimal motion and larger lumens. The assessment of grafts has shown good correlation with quantitative X‐ray angiography for both occlusion and stenosis [75]. Currently, MR coronary angiography is being performed at large academic centers only.

      Ischemic heart disease (IHD)

      The combination of CMR stress perfusion, function, and LGE allows the use of CMR as a primary form of testing for: (i) diagnosing IHD, (ii) determining which patients are candidates for revascularization; and (iii) defining the distribution of CAD prior to revascularization [53].

Figure 10.3 (a) Early and (b) delayed contrast‐enhanced images of the left atrial appendage for evaluation prior to pulmonary vein ablation. There appears to be a filling defect in the early images concerning for thrombus but delayed images confirm that there is no LAA thrombus. Images (c) and (d) delineate the anatomy of the left atrium and the pulmonary veins.

Dobutamine stress CMR relies on wall motion evaluation with increasing doses of dobutamine and vasodilator perfusion stress CMR relies on the perfusion of gadolinium at stress compared to rest for evaluation of ischemia. A recent study [76] evaluated 2349 patients who underwent stress CMR perfusion imaging after presenting with chest pain over a period of 5.4 years and found that patients without ischemia and LGE had a low incidence of cardiac events, need for revascularization and subsequent ischemia testing. This adds to the growing body of evidence that in intermediate‐risk patients with IHD, a normal perfusion stress CMR perfusion can serve as an excellent initial screening test.

      LV systolic function measured on CMR can be used to determine a patient’s eligibility for cardiac resynchronization therapy or for a defibrillator. CMR also plays an important role in evaluating myocardial viability which is defined as transmural scar of 50% or less as characterized by LGE. It has the unique advantage of directly visualizing scar and normal myocardium in the same image and is more sensitive for subendocardial scar than SPECT imaging [77]. Myocardial viability testing is currently recommended as a part of revascularization planning in patients with heart failure [78].

      Pericardial disease

      CMR can provide important information regarding various pericardial diseases [53]. Black blood T1‐ weighted SE CMR is used for morphologic assessment, including measurement of pericardial thickness, and black blood T2‐weighted SE CMR highlights fluid‐rich structures such as pericardial effusion or myocardial edema with concomitant myocarditis. LGE in the pericardium is strongly suggestive of pericarditis. Cine imaging allows visualization of pericardial effusions, paradoxical motion of the interventricular septum in constrictive pericarditis (CP) and RV or RA collapse.[79] Ventricular interdependence, which is the sine qua non of diagnosis of CP, can be evaluated on real‐time cine CMR. Tagged cine can be used to delineate adhesion of the pericardial layers [53, 79].

      Congenital heart disease

CMR