Native T₁ mapping for the diagnosis of cardiac amyloidosis: a pilot research

Objective: To explore the potential role of native cardiac T₁ mapping by cardiac magnetic resonance for detection of cardiac amyloidosis (CA). Methods: Twenty patients with cardiac amyloidosis (with definite cardiac involvement based on standard biomarkers and echo cardiographic criteria) were studied at our hospital from 2012 to 2013. Comparisons were made with 20 healthy volunteers and 40 patients with hypertrophic cardiomyopathy (HCM). All underwent CMR (1.5 T) including native T₁ mapping MOLLI (modified Look-Locker inversion recovery) sequence and LGE (late gadolinium enhancement) imaging. Analysis of variance was performed to analyze the differences between groups regarding native T₁ and LV mass.ROC curve analysis was performed to define a T₁ relaxation time cutoff value that identifies CA with the greatest sum of sensitivity and specificity. Correlation between T₁ and cardiac function indices was assessed using Pearson test. Statistical significance was defined as P<0.05. Results: Cardiac T₁ was significantly elevated in CA patients [(1 124±49) ms] compared to normal subjects [(973±39) ms] and patients with HCM [(1 045±50) ms](F=44.75, P<0.01). The cut off value to diagnose CA was 1 082 ms with specificity 80% and sensitivity 75%. The cut off value to rule out CA was 1 012 ms with sensitivity 100% and specificity 40%).There was significant correlation between native T₁ relaxation times and indices of systolic and diastolic function in the CA cohort. As T₁ relaxation times increased, LV ejection fraction decreased (r= - 0.51, P<0.01) and LV mass index increased (r=0.52, P<0.01).Conclusion Native T₁ mapping may have potential as a valuable method for diagnosing and quantifying CA.