Papillary muscle fibrosis on cardiac magnetic resonance imaging: a pictorial review of causes, diagnostic challenges and practical pearls.

Papillary muscle fibrosis (PMF) is being increasingly recognised as a cause of ventricular arrhythmias; therefore, its identification is clinically relevant. PMF has been described in multiple cardiac conditions such as ischaemic cardiomyopathy, mitral valve prolapse and non-ischaemic cardiomyopathies such as hypertrophic cardiomyopathy (HCM), cardiac amyloidosis and cardiac sarcoidosis. Although cardiac magnetic resonance (CMR) imaging is a central tool in its diagnosis, PMF can be overlooked if the papillary muscles are not carefully assessed, especially in cases where the abnormal papillary muscle and the blood pool have the same signal intensity on the late gadolinium enhancement (LGE) phase. In an illustrative fashion, the present review aims to describe the normal anatomy of the papillary muscles, a range of conditions which can cause papillary muscle fibrosis and useful tips for its identification.