CMR in cardiac amyloidosis
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Cardiac MR (CMR) and Cardiac Amyloidosis: An Overview
- The primary method of diagnosing cardiac amyloidosis is myocardial biopsy, which is both invasive and cumbersome
- CMR is a noninvasive imaging modality, offering considerable information which may support or question the diagnosis of cardiac amyloidosis before the necessary (or unnecessary) biopsy[1]
Left and Right Atrial Size
- The 4-chamber cine sequence allows for proper visualization of the atria
- A maximum length is usually taken in an end-systolic frame
- The right atrium can be measured from the annulus of the tricuspid valve back to the right atrial wall, and similarly, the left atrium can be measured from the annulus of the mitral valve back to the left atrial wall
- This is particularly useful in cardiac amyloidosis, as the atria are typically enlarged
Left and Right Ventricular Mass and Volumes
- Using the functional cine sequence known as the Short-Axis (SHAX) Stack, both left and right ventricular volumes and mass can be quantified
- Using Simpson's Rule, and by planimetering the endocardial and epicardial borders of the left and right ventricles (LV and RV, respectively) in both end-diastole (ED) and end-systole (ES), we can easily assess volumes and mass
- This method is extremely beneficial for a differential diagnosis, as patients with cardiac amyloidosis tend to have increased mass and volumes (particularly systolic volumes)
- CMR also allows for sharpened visualization of the RV (as opposed to 2D-echocardiography)
- Cardiac amyloidosis affects both the LV and RV, in that fibrillary protein deposition does not discriminate between ventricles
Regional Myocardial Function
Myocardial Delayed Enhancement
- Delayed enhancement (DE) imaging provides relevant information on both the pathology and morphology of patients with cardiac amyloidosis
- Gadolinium is an inert extracellular contrast agent that cannot penetrate intact sarcomere
- Normal, healthy myocardium is primarily intracellular
- This is why hyperenhancement is absent in normal myocardium
- Amyloid infiltration in cardiac amyloidosis causes gross expansion of the interstitial space
- DE imaging using Gd allows for the Gd to pool or accumulate in these expanded areas of amyloid infiltration, usually causing large, diffuse areas of hyperenhancement[1] (see image)
References
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
