Liquefaction Necrosis of Mitral Annulus Calcification
Detection and Characterization With Cardiac Magnetic Resonance Imaging
A transthoracic echocardiogram of a 68-year-old man complaining of exercise-related retrosternal chest pain revealed a dense, echogenic, calcified nodular structure at the posterior side of the mitral valve annulus (Figure 1). The patient was referred for cardiac magnetic resonance imaging (MRI). T1-weighted fast spin-echo (FSE) (Figure 2A) showed a well-defined structure (28 mm in diameter) with a homogeneous, slightly hyperintense center and a hypointense rim (Figure 2A, arrows) located between the posterior mitral valve leaflet and adjacent left ventricular myocardium. Fat suppression did not alter signal characteristics (Figure 2B, arrows). On T2 short-τ inversion-recovery FSE, the structure was devoid of signal (Figure 2C, arrows). Dynamic imaging using steady-state free-precession cine MRI in the horizontal long-axis plane (Figure 2D and Movie I) and in the short-axis plane (Figure 3A and Movie II) obtained through the mitral valve plane showed a non- or at most minimally deforming mass moving in synchronicity with the surrounding left ventricular myocardium (arrows) and presence of moderately severe mitral regurgitation (Figure 2D, black arrowheads, and Movie I). Myocardial perfusion MRI in the horizontal long-axis (Movie III) showed a hyperintense appearance of the structure before contrast administration but no evidence of enhancement during the first pass. Although FSE after contrast administration (Figure 2E, arrows) did not show enhancement, strong peripheral enhancement was found 10 minutes after contrast administration with the use of the contrast-enhanced inversion-recovery technique (Figure 2F, arrowhead, and Figure 3B, arrows). On the basis of the above findings, a presumptive diagnosis of a centrally liquefied mass containing a high-protein or hemorrhagic content with a thick inflammatory and/or fibrotic wall that was likely partially calcified was made. A resting ECG was unremarkable (Figure 4), whereas cardiac catheterization confirmed the calcified nature of the lesion (Figure 5). During surgery, a centrally liquefied structure was found posterolaterally in the left ventricle attached to a thickened posterior mitral valve leaflet. Incision into the lesion revealed a dark yellow fluid. The wall was fibrotically thickened, containing areas of either calcification or inflammation, which led to the diagnosis of liquefaction necrosis of mitral annulus calcification. Culture of the fluid was negative. The patient underwent mitral valve replacement and coronary artery bypass graft surgery.
Mitral annulus calcification is a common degenerative disorder in the elderly, particularly in women and in patients with kidney disease.1–2 Liquefaction necrosis of the posterior mitral annulus is a rare and atypical variant of mitral annulus calcification that is usually associated with a benign prognosis and was recently identified as an unusual evolution of mitral annulus calcification.2 The core of liquefaction necrosis comprises amorphous eosinophilic acellular fluid, and the surrounding rim contains macrophages and lymphocytes as well as multiple areas of calcification and necrotic zones.1 Use of a comprehensive MRI approach is helpful to characterize the different components and to rule out other diseases.
The online-only Data Supplement, which contains Movies I through III, is available with this article at http://circ.ahajournals.org/cgi/content/full/ 117/12/e292/DC1.