The prevalence of primary heart tumors ranges between 0.001% and 0.030% in the autopsy series . Cardiac metastases are usually found in end-stage disease and their prevalence is 20–40 times higher than primary tumors. It is difficult to define the frequency of thrombi with any accuracy because they develop as the result of an underlying disorder; however for patients whose ejection fraction is below 50% the prevalence of thrombi is assessed at 7% , and at 4% in patients suffering from pulmonary embolism . Thrombi and tumors can both cause serious complications requiring a specific treatment, which, once again, will depend on the etiology of the underlying disorder. Discriminating between variations from the normal anatomy, thrombi and benign or malignant tumors is the basis to set out a therapeutic strategy and make a prognosis. Multidetector computed tomography (MDCT) and cardiac magnetic resonance (CMR) are techniques that yield a functional and morphological analysis of these lesions, giving details of perfusion and enhancement with spatial definition and contrast that no other imaging technology is capable of equaling today. CMR and MDCT have now become the first-line examinations used to explore this type of heart disorder . The goal of this book is (1) to provide a quick overview of the different MRI sequences and CT-scan acquisitions used to explore cardiac masses, (2) to present a collection of clinical cases compiled in cooperation with a number of teams of French-speaking radiologists who are members of SFICV and (3) to provide a series of synoptic tables and decision-making trees for use in the everyday practice of radiology.