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Pica et al. Vessel Plus 2022;6:10 https://dx.doi.org/10.20517/2574-1209.2021.81 Page 3 of 11

test.

CMR offers accurate information on cardiac structure and function, with the key advantage to provide
information about myocardial tissue substrate. This is promising for crucial earlier diagnosis, better
understanding of disease processes, and potential ability to track disease in response to treatment.

VALUE OF CMR IN AMYLOIDOSIS
Diagnosis
CMR is progressively becoming a standard of care in the diagnosis of CA. Beyond accurate routine
evaluation of volumes, mass, and function, CMR feature tracking (CMR-FT) allowed a precise evaluation of
more subtle functional impairment in CA. CMR confirmed the echocardiographic finding of a global
reduction of LS, with a “relative apical sparing” pattern, also providing mechanistic insights: the
concomitant presence of a base-to-apex gradient of late gadolinium enhancement (LGE) burden suggested
[15]
that the regional strain gradient may be related to the burden of amyloid deposition . This is paralleled by
a recent 99mTc-DPD SPECT study in ATTR, showing less DPD uptake in the LV apex, reinforcing the
[16]
concept of apical sparing from the pathophysiological standpoint .
Newer CMR sequence, i.e., fast strain-encoded magnetic resonance (fast-SENC), is an evolution of tagging
technique, which may perform better than CMR-FT, allowing for a single heartbeat and more
comprehensive evaluation of global myocardial strain, with high reproducibility. Fast-SENC demonstrated
incremental value for the identification of patients with subclinical LV dysfunction due to non-ischemic
[17]
cardiomyopathies, including CA . Furthermore, the combination of atypical LGE and impaired strain,
with a base-to-apex gradient by fast-SENC, demonstrated high accuracy for the differential diagnosis
[18]
between HCM and CA .

However, the most important advantage of CMR is its unique non-invasive tissue characterization, which
offers fundamental information on tissue composition, with histologic validation [19,20] . This is especially
useful in patients with other causes of LV hypertrophy, differentiating CA from hypertensive heart disease,
hypertrophic cardiomyopathy, or other infiltrative cardiomyopathies, which may be challenging by
[21]
echocardiography . Furthermore, CA can coexist with paradoxical low-flow, low-gradient aortic stenosis .
[6]
Two techniques are routinely adopted: LGE and parametric mapping imaging.

LGE imaging
The administration of chelated, gadolinium-based contrast agents, carried within the blood pool into the
extracellular space of the myocardial tissue, allows differentiating between normal and abnormal
myocardium. Gadolinium accumulates in the gaps between cells when the interstitial compartment
increases, mainly as a consequence of cardiomyocytes necrosis with “replacement” fibrosis or primary
abnormal protein deposition, as in CA.

The increased amount of gadolinium can be demonstrated applying the inversion recovery principle to T1-
weighted imaging, with an adequate inversion time to null normal myocardium.

The most relevant feature of CA is the appearance of LGE images, where the blood pool is dark. This is a
consequence of infiltration: myocardial extracellular and plasmatic volume tend to equalize, nulling
approximately at the same time.