Myocardial and pericardial involvement in ECD. (A-D) Myocardial lesions. ECD typically affects the myocardium by infiltrating the posterior wall of the right atrium, forming soft tissue density masses with smooth surface, which appear hypointense in b-SSFP sequences (the lesions are framed in A). This b-SSFP hypointense infiltration also develops in the right atrioventricular groove, where it encases the right coronary artery (arrowhead in B). T2w image with signal fat suppression shows that there might be diffuse slight hyperintensity within the soft tissue, which usually corresponds to edema (C). In inversion recovery T1w sequences, late enhancement of the lesional soft tissue likely reflects disease activity/inflammation (dotted lines in D). (E-F) Pericardial lesions. ECD-related infiltration of the pericardium causes soft tissue density nodules arising from the visceral pericardial sheets, in association with pericardial effusion. b-SSFP sequences (E-F) allow optimal visualization of the nodules that appear hypointense as compared with the hyperintense pericardial effusion. Arrowheads indicate soft tissue pericardial nodules in the right ventricle outflow tract (E) and right ventricle free wall (F). The pericardial nodules are associated with conspicuous circumferential pericardial effusion (star in F). (A-D,F) Four-chamber view (a plane that allows comprehensive evaluation of myocardium and pericardium). (E) Sagittal view (the best plane to depict the right ventricle ouflow tract).