Our article reports a case of a 35-year-old man with cardiac mass, who underwent a wide range of imaging methods, including cardiac magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT). Contrast-enhanced MRI images revealed “sun ray” pattern in the mass. Final histopathological diagnosis of angiosarcoma was confirmed during autopsy. To our knowledge, our case is the second direct observation of this MRI diagnostic pattern and the first one that allows a comparison with PET/CT findings.