Normal Diastolic and Systolic Myocardial T1 Values at 1.5-T MR Imaging: Correlations and Blood Normalization

Abstract

In normal myocardium, diastolic and systolic myocardial T1 values differ significantly but correlate strongly. Blood normalization eliminates sex differences in myocardial T1 values and reduces their variability.

Native myocardial T1 mapping in pulmonary hypertension: correlations with cardiac function and hemodynamics

“…Twenty healthy subjects (10 women; mean age of all subjects, 33 ± 12 years; age range, 21–54 years) without any history of cardiovascular and/or pulmonary disease and with normal left and right ventricular cardiac function and myocardial mass [14] also underwent MR imaging so that the 3T myocardial T1 blood normalization coefficient could be determined [15]. …”

Myocardial T1 Mapping in Pediatric and Congenital Heart Disease

“…Blood in coronary arteries and capillaries affects myocardial T1 times and ECV as the vessels course through the region of interest. As the coronary blood flow varies with the cardiac cycle, higher ECV values during diastole were found in some studies, 43 albeit not without controversy. 36 One of the most important confounders of T1-derived fibrosis measures arise from partial volume effects at the border between myocardium and blood (inplane and throughplane), 44 and care must be taken to exclude the endocardium/blood interface from the analysis.…”

“…44,48 However, with normalization to blood T1 times, sex differences of native T1 times may disappear, possibly because of sex differences in hematocrit. 43 …”

Cardiac MR Imaging to Probe Tissue Composition of the Heart by Using T1 Mapping

“…T1 mapping data should be stratified by sex or by performing sex-age-adjusted analyses. In addition, this work of Reiter et al (7) emphasizes the need to standardize the reporting of T1 values obtained during diastole versus systole and the expected regional variation that can occur if global values are not reported.…”

“…A key element that is missing in this line of reasoning is that hematocrit values are not reported by Reiter et al (7). In theory, the difference in fluid fraction of the blood (quantified by the hematocrit) could be used to estimate the effect sizes that we might expect in T1 values between men and women, as well as for diastole versus systole.…”