3.0T cardiac magnetic resonance quantification of native T1 and myocardial extracellular volume for the diagnosis of late gadolinium enhancement-negative cardiac amyloidosis.

Background: Late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) is useful for the detection of cardiac amyloidosis (CA), but characteristic LGE patterns do not always occur or they appear late in the disease. Native T1 and extracellular volume (ECV) by T1 mapping may improve disease detection and quantify myocardial amyloid load. Methods: Thirty patients with definite CA, 10 patients with possible CA, 20 patients with hypertrophic cardiomyopathy (HCM) and 40 healthy volunteers were performed 3.0-T CMR including cine, pre- and postcontrast T1 mapping and LGE. Receiver-operating characteristic (ROC) curves were constructed to assess the diagnostic ability of native T1 and ECV for CA. Correlation analysis between native T1 or ECV and cardiac biomarkers, structure, and function indexes were assessed using Pearson or Spearman correlation, as appropriate. Results: Native T1 values were 1,429±93, 1,290±49, 1,304±42, and 1,225±21 ms, in definite CA, possible CA, HCM, and healthy controls, respectively. ECV values were 44%±9%, 34%±5%, 33%±4%, and 24%±3%, in definite CA, possible CA, HCM, and healthy controls, respectively. Native T1 [area under curve (AUC) =0.89, 95% confidence interval (CI): 0.75-1.00, P<0.001] and ECV (AUC =0.99, 95% CI: 0.98-1.00, P<0.001) showed good ability to differentiate LGE-negative patients with possible CA from healthy controls, especially ECV. Positive correlations were found between native T1 or ECV and New York Heart Association (NYHA) functional class (r=0.673 and r=0.594, respectively; P<0.001), NT-proBNP (r=0.668 and r=0.603, respectively; P<0.001), troponin T (r=0.724 and r=0.591, respectively; P<0.001), left ventricular (LV) mass index (r=0.668 and r=0.579, respectively; P<0.001), and global LV wall thickness (r=0.765 and r=0.629, respectively; P<0.001). Negative correlations were found between native T1 or ECV and left ventricular ejection fraction (LVEF) (r=-0.761 and r=-0.668, respectively; P<0.001) and left ventricular stroke volume (LVSV) (r=-0.777 and r=-0.729, respectively; P<0.001). Conclusions: Native T1 and ECV, which are able to reflect cardiac biochemistry, structure, and function, have high diagnostic accuracy for detecting CA, especially in LGE-negative patients, and thus could be used for early diagnosis of CA.