Neville Gai PhD, Presenter: Nothing to Disclose

Evrim Bengi Turkbey MD, Abstract Co-Author: Nothing to Disclose

Radwa A. Noureldin MD, MSc, Abstract Co-Author: Nothing to Disclose

Christopher Sibley, Abstract Co-Author: Nothing to Disclose

Songtao Liu, Abstract Co-Author: Nothing to Disclose

Marcelo Souto Nacif MD, PhD, Abstract Co-Author: Nothing to Disclose

David A. Bluemke MD, PhD, Abstract Co-Author: Nothing to Disclose

To determine the limits of sensitivity of T1 mapping to detect different degrees of myocardial fibrosis in the human myocardium.

Healthy volunteers underwent cardiac MRI on 1.5T scanners after administration of gadopentetate dimeglumine. T1 values were determined at five time points. Analytical solution to a two compartment model was used to describe the relation of T1 to physiological and experimental parameters. Perturbation analysis provided information on the relative impact of experimental variables on the T1 value while error propagation analysis (EPA) using measured standard deviations of parameters was used to define the sensitivity of T1 to physiological changes. The results were corroborated with experimentally acquired data in volunteers and 27 non-ischemic cardiomyopathy patients. Probability (P) of detecting a certain amount of fibrosis change was determined from a cumulative error function using EPA model based values.

Error analysis indicates that T1 accuracy increases with post-contrast delay time but levels off after 20min. For time > 10min, perturbation analysis showed that among experimental factors, dose (67%) had the most impact followed by post-contrast delay time (24%) and accuracy of pre-contrast T1 measurement (9%). When experimental variables are constant or corrected for, ve (EES volume fraction) accounts for the most significant variation in T1 value (38%) while those for coefficient corresponding to contrast extraction through glomerular filtration and the rate constant for equilibration between plasma and EES were 27% and 19%, respectively. For patients with fibrosis, ve was determined from T1 and [Hct] and a change of about 0.72% in T1 for 1% change in fibrosis was determined from the sensitivity model. A conservative P of 0.53 for 1% change in fibrosis was determined while a 17% change in fibrosis can be predicted with 95% accuracy. Monte Carlo simulation results also showed excellent agreement with values derived analytically.

We sought to quantify the effect of experimental and physiological variation on the measured post-contrast T1 value in the myocardium. In addition, we also approximately quantified the sensitivity of T1 mapping to fibrosis.

T1 mapping after gadolinium administration is a new MRI technique to detect diffuse myocardial fibrosis. The sensitivity of T1 mapping to detect myocardial fibrosis is currently unknown.

Gai, N, Turkbey, E, Noureldin, R, Sibley, C, Liu, S, Nacif, M, Bluemke, D, Error and Sensitivity Analysis of Factors Affecting T1 Mapping of Myocardium: Implications for Assessment of Myocardial Fibrosis.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002780.html