The use of Cardiac MRI in diagnosis of infective endocarditis: a comparative study with echocardiography

Abstract

Abstract Introduction Echocardiography is a reliable imaging tool in diagnosing infective endocarditis (IE) according to “modified Dukes criteria”; however, it lacks tissue characterization of cardiac masses, transthoracic echocardiography (TTE) has low sensitivity in detection of vegetations, and moreover, transesophageal echo (TEE) is considered semi-invasive and intolerable in some situations. On the other hand, cardiac magnetic resonance (CMR) is a powerful true 3D imaging tool with wide field of view, and superior capability of tissue characterization of cardiac masses; however, modest information is available about utility of CMR in diagnosing IE. Purpose To assess the feasibility of CMR to identify vegetations and complications of IE, and compare obtained findings obtained with those obtained from echocardiography regarding: number and size of vegetations, detection of cardiac complications (e.g. aortic root abscess, periannular abscess, and shunts). Materials and methods Eighty consecutive patients with suspected IE were enrolled in the study. All patients underwent TTE; only those with left-sided lesions underwent TEE. When clinical situation allowed, CMR examination using 1.5 Tesla magnet were performed: SSFP sequence for mobile masses (SSFP), T1W (± fat suppression) and T2W, first-pass perfusion, and delayed hyperenhancement were used. Moreover, chest and abdominal survey was done. Results Sixty-one patients (45 males and 16 females) were able to undergo and complete CMR study. Affection of tricuspid valve was seen in 39.3%, mitral 31.1%, aortic 24.6%, and pulmonary 4.9% of cases. All vegetations visualized by echocardiography were also clearly detected by CMR. The sensitivity, specificity, accuracy and Kappa agreement of CMR with echocardiography in depicting >0.5cm vegetations were all 100%. By tissue characterization, vegetations resemble features of thrombi (with variation in signal intensity according to age of vegetation). However, in some cases, masses have a unique pattern that is different from vegetations of IE, and subsequently other diagnoses were suggested (e.g. fibroelastoma, Libman-Saks endocarditis). In 22 patients, CMR provided more information than echocardiography, and in 6 patients, CMR changed completely the diagnosis. Conclusion Cardiac MRI is a powerful imaging tool in diagnosis of IE and its complications. In comparison with echocardiography, CMR can identify the presence, numbers, and size of vegetations accurately. Moreover, with its unique ability of tissue characterization, CMR helps distinguish vegetations from other masses; therefore changes the diagnosis of IE and subsequent management in some patients. Funding Acknowledgement Type of funding source: None