Search

To investigate cardiac magnetic resonance (MR) imaging measurements of extracellular volume (ECV) and total cell volume in immunoglobulin light-chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) in order to evaluate the amyloid and myocyte volumes.All ethics were approved, and participants provided written informed consent. Of the 257 subjects who were recruited, 92 had AL (mean age, 62 years ± 10), 44 had mutant ATTR (mean age, 68 years ± 10), and 66 had wild-type ATTR (mean age, 75 years ± 7). In addition, eight healthy subjects with ATTR mutations (mean age, 47 years ± 6) and 47 healthy volunteers (mean age, 45 years ± 15) participated. All participants underwent equilibrium contrast material-enhanced cardiac MR imaging. ECV and total cell volume were measured in the heart. T test, χ(2), and one-way analysis of variance with posthoc Bonferroni correction were used.Both the left ventricular indexed mass and ECV were elevated in patients with amyloidosis. For left ventricular indexed mass, mean AL was 107 g/m(2) ± 30; mean mutant ATTR was 137 g/m(2) ± 29; and mean wild-type ATTR was 133 g/m(2) ± 27 versus 65 g/m(2) ± 15 in healthy subjects (P.0001 for all measures). For ECV, mean AL was 0.54 ± 0.07, mean mutant ATTR was 0.60 ± 0.07, and mean wild-type ATTR was 0.57 ± 0.06 versus 0.27 ± 0.03 in healthy subjects (P.0001 for all measures). Patients with ATTR had a higher total cell volume than did healthy subjects (mean, 53 mL/m(2) ± 12 vs 45 mL/m(2) ± 11; P = .001), but in patients with AL, total cell volume was normal (mean, 47 mL/m(2) ± 17 vs 45 mL/m(2) ± 11; P.99). The result is that, in patients with AL, all of the increase in left ventricular indexed mass is extracellular volume, whereas in patients with ATTR, the increase is extracellular, with an additional 18% increase in the intracellular space.Quantification of ECV measures cardiac amyloid deposition in both types of amyloidosis and shows that amyloid deposition is more extensive in patients with ATTR than in those with AL; however, ATTR is associated with higher cell volume, which suggests concomitant cell hypertrophy.

To investigate equilibrium contrast material-enhanced magnetic resonance (MR) imaging measurement of extracellular volume (ECV) fraction within healthy abdominal tissues and to test the hypotheses that tissue ECV in systemic amyloid light-chain (AL) amyloidosis is greater than in healthy patients and show that this increase correlates with organ amyloid burden.A local ethics committee approved the study and all patients gave written informed consent. Forty healthy volunteers (18 men, 22 women; median age, 43 years; age range, 24-88 years) and 67 patients with AL amyloidosis (43 men, 24 women; median age, 65 years; age range, 38-81 years) underwent equilibrium MR imaging of the upper abdomen. ECV was measured in the liver, spleen, and paravertebral muscle. Patients with amyloidosis also underwent serum amyloid P (SAP) component scintigraphy so that specific organ involvement by amyloid could be scored. Variation in ECV between tissues was assessed by using a Friedman Test. Tissue ECV in healthy and amyloidosis groups were compared by using a Mann-Whitney U test. Spearman correlation was used to test for an association between the organ SAP score and ECV.ECV measured at equilibrium MR imaging varied significantly between organs in healthy volunteers (χ(2) = 31.0; P.001). ECV was highest in the spleen (0.34), followed by liver (0.29) and muscle (0.09). ECVs measured within the spleen (0.39; P.001), liver (0.31; P = .005), and muscle (0.16; P.001) were significantly higher in patients with amyloidosis than in healthy control subjects. ECV measured in the liver and spleen showed increasing organ amyloid burden assessed at SAP scintigraphy (liver, rs = 0.54; spleen, rs = 0.57).Equilibrium MR imaging can be used to define ECV within healthy tissues. ECV is increased in amyloidosis compared with healthy tissues, and this increase correlates with rising tissue amyloid burden.