IJCS | Volume 32, Nº2, March/April 2019

182 Figure 3 - Cardiac magnetic resonance from the four-chamber axis view showing (A) increased interventricular septal thickness. (B) Delayed myocardial enhancement in right atrium (white arrow), left atrium (white arrows) and tricuspid valve system (white dashed elliptical circle). Ribeiro et al. CMR and amyloidosis Int J Cardiovasc Sci. 2019;32(2)177-189 Review Article to null the normal myocardial signal after infusion of gadolinium-based contrast (0.02 – 0.04 mmol/kg). Gadolinium does not penetrate intact cell membranes and hence is distributed in the extracellular space; in case of myocyte membrane rupture (e.g., infarction), gadolinium shows a larger volume of distribution. 41,42 In addition, kinetics of the contrast distribution is altered, with a slower washout. 40 Consequently, gadolinium concentrations are much higher in regions of greater extracellular volume, and areas of membrane rupture and communication between intra and extracellular space as compared with normal myocardial tissue approximately 10 minutes after the contrast administration. 39 These areas are white in delayed enhancement images (hypersignal), whereas normal myocardium appears black (low signal - null). Recent technological progresses have allowed acquisition of three-dimensional late gadolinium enhancement, with respiratory navigator during free breathing, one respiratory pause, in real time and without manual adjustment of TI (self-viability or phase sensitivity inversion recovery – PSIR – technique). 7,35 Therefore, in cardiac amyloidosis, tissue definition after contrast administration is obtained fromgadolinium deposition and accumulation in areas with increased myocardial extracellular volume. Such increase in extracellular space results from expansion of amyloid deposits to the extracellular space. Several studies using the delayed enhancement technique have enabled the classification of amyloid deposition patterns – subendocardial (Figure 3), mesocardial (Figure 4) and transmural (Figure 5). 15 The most common patterns of amyloid distribution in immunoglobulin light chain amyloidosis and transthyretin amyloidosis are subendocardial and transmural, respectively. 43 The treatment of amyloidosis depends on the disease subtype; the use of delayed enhancement CMR is hence paramount as it serves as a screening test that lead to other test, such as biopsy, for establishment of disease subtype and definition of therapy. Thus, it is important to reinforce that CMR with late enhancement can be used not only for the diagnosis of cardiac amyloidosis, but also can influence the type of therapy and follow-up of patients, and hence be decisive for the prognosis of these individuals. T1 mapping and extracellular volume (ECV) An important advance in cardiac amyloidosis treatment is the increasing use of quantitative analysis