Identification and typing of cardiac amyloidosis by noninvasive imaging: Two cases for two patterns

Cardiac amyloidosis is a restrictive infiltrative cardiomyopathy burdened by high mortality. The two more common forms are immunoglobulin light-chain amyloidosis and transthyretin-related amyloidosis with different prognoses and treatments. However, distinguishing between them is challenging. Appropriate utilization of the different available imaging techniques in the evaluation of patients with known or suspected cardiac amyloidosis is mandatory. We report two cases with cardiac amyloidosis of different etiology and with distinct imaging patterns. In the first case, the negative ^99mTc-diphosphonate imaging was useful to support the diagnosis of cardiac amyloid light-chain; the second case emphasized the utility of whole-body scintigraphy in recognizing transthyretin-related cardiac amyloidosis and the potential role of cadmium-zinc-telluride SPECT imaging for the evaluation of segmental distribution of cardiac disease. Both cases support the growing interest in looking for noninvasive methods to type cardiac amyloidosis in the place of invasive myocardial biopsy highlighting both possibilities and limitations of available imaging techniques in diagnosis and treatment monitoring.