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Purpose: Caseous calcification is a relatively uncommon variant of calcification of the mitral annulus. The purpose of the study was to assess characteristic radiological features of caseous calcification of the mitral annulus (CCMA) using computed tomography (CT) and compare the usefulness of CT and transthoracic echocardiogram (TTE) in a diagnosis of CCMA. Material and methods: Seventeen patients with CCMA, who underwent TTE and CT, were analysed. The following features of CCMA were evaluated: location, size, attenuation, enhancement after contrast administration, and margins. Results: In all cases TTE visualised an echo-dense structure with an irregular appearance involving the mitral valve annulus. In five cases the acoustic shadowing artefact was visible, and in four cases the mass contained central areas of echolucency. Eleven patients had valve disease. On CT CCMA appeared as a round mass in one case, in 10 cases as an oval mass, and in six patients it had a semilunar shape. In all cases on unenhanced CT, CCMA appeared as a hyperdense mass. On enhanced CT, CCMA in 10 cases (58.8%) had a hypodense centre, and in 7seven (41.2%) it had a hyperdense centre without enhancement after contrast administration. A hyperdense rim was observed in all cases except one patient. Conclusions: In cases of the atypical appearance of CCMA on TTE, CT can lead to a definitive diagnosis. The combination of unenhanced CT and after IV contrast administration scans allows for recognition and distinction of CCMA from other pathologies, while TTE allows for assessment of additional valve dysfunction.