Magnetic Resonance Imaging in Cardiac Amyloidosis: Unraveling the Stealth Entity

Amyloidosis is a systemic disease involving many organs. Cardiac involvement is a significant cause of morbidity and mortality in these patients. Diagnosis of cardiac amyloidosis is based on endomyocardial biopsy which however is invasive and associated with complications. Noninvasive methods of diagnosis include magnetic resonance imaging (MRI) with various methods and sequences involved. Our study aims at describing MRI features of cardiac amyloidosis including new imaging sequences and to prognosticate the patients based on imaging features. We included 35 patients with suspected cardiac amyloidosis who underwent MRI at our center over 4 years. All images were retrieved from our archive and assessed by an experienced radiologist. Common morphological features in our patients included increased wall thickness of left ventricle (LV) (16. 1 ± 4.1 mm), right ventricle (RV) (6.3 ± 1.1 mm), and interatrial septum (6.2 ± 0.8 mm). Global late gadolinium enhancement (LGE) ( n  = 21 [65%]) including subendocardial or transmural was the most common pattern followed by patchy enhancement. Global transmural LGE was associated with worse prognosis. Four types of myocardial nulling patterns were observed on postcontrast time to invert (TI) scout imaging: normal nulling pattern (myocardium nulls after blood and coincident with spleen) and abnormal nulling pattern (ANP) which is further divided into three types: Type 1-myocardium nulls before blood pool but coincident with spleen, Type 2-myocardium nulling coincident with blood but not coincident with spleen, and Type 3-features of both Type 1 and Type 2. Type 3 ANP was the most common ( n  = 23) nulling pattern in our patients. Cardiac MRI is an essential in noninvasive diagnosis of cardiac amyloidosis. Transmural global LGE serves as a poor prognosticator in these patients. "Three-tier" TI scout imaging is essential to avoid false-negative enhancement results. Type 3 ANP is the most specific nulling pattern in cardiac amyloidosis.