Table 2.

Comparison of prosthetic heart valve related-masses

	Thrombus	Pannus	Vegetation
Echo predictors	Soft echo density with irregular shape, homogeneous, similar to myocardium	(Semi) circular, bright, and hard echo dense structures, sometimes containing focal calcific deposits	Pedunculated mass initially similar to thrombus, echodensity increases with increasing vegetation age
Localization	Mainly hinges, valve occluder, and/or valve struts	Mitral: Atrial and/or ventricular sides Aortic: Aortic and/or left ventricular outflow tract side	Typically attached on the low pressure side of the prosthesis
Mobility	Fixed or mobile	Immobile	Oscillating or nonoscillating (Mobility usually increases with increasing vegetation size)
3-D echo predictors	Linear, purple- or violet-colored echo density on a bright cream color base of the endothelialized sewing ring surrounding the prosthetic valve suture line or medial to it	(Semi)circular mass narrowing circumferentially the inflow and outflow aspect of the prosthesis by extending into both sides of the prosthesis	Provides the entire morphology of the vegetation and determine its maximum size more accurately, leading to a better prediction of risk of embolism in IE patients compared to 2-D echo
Videointensity ratio	≤0.4	≥0.7	Unavailable data
MDCT	Low attenuation levels (Hounsfield units <90) Favors thrombus	High attenuation levels (Hounsfield units ≥145) Favors pannus formation	Combined with FDG-PET results in high-resolution anatomical and metabolic imaging of the prosthesis and its surrounding anatomy
Associated abnormalities	Pannus, LA and LAA thrombi, strands	Thrombus	Abscess, pseudoaneurysm, perforation, fistula, paravalvular leak, dehiscence

2-D/3-D-dimensional; FDG-PET - 18-fluorine-fluorodesoxyglucose positron emission tomography; IE - infective endocarditis; LA - left atrium; LAA - left atrial appendage; MDCT - multide-tector-row computed tomography