Reference values for healthy human myocardium using a T1 mapping methodology: results from the International T1 Multicenter cardiovascular magnetic resonance study

Abstract

BackgroundT1 mapping is a robust and highly reproducible application to quantify myocardial relaxation of longitudinal magnetisation. Available T1 mapping methods are presently site and vendor specific, with variable accuracy and precision of T1 values between the systems and sequences. We assessed the transferability of a T1 mapping method and determined the reference values of healthy human myocardium in a multicenter setting.MethodsHealthy subjects (n = 102; mean age 41 years (range 17–83), male, n = 53 (52%)), with no previous medical history, and normotensive low risk subjects (n=113) referred for clinical cardiovascular magnetic resonance (CMR) were examined. Further inclusion criteria for all were absence of regular medication and subsequently normal findings of routine CMR. All subjects underwent T1 mapping using a uniform imaging set-up (modified Look- Locker inversion recovery, MOLLI, using scheme 3(3)3(3)5)) on 1.5 Tesla (T) and 3 T Philips scanners. Native T1-maps were acquired in a single midventricular short axis slice and repeated 20 minutes following gadobutrol. Reference values were obtained for native T1 and gadolinium-based partition coefficients, λ and extracellular volume fraction (ECV) in a core lab using standardized postprocessing.ResultsIn healthy controls, mean native T1 values were 950 ± 21 msec at 1.5 T and 1052 ± 23 at 3 T. λ and ECV values were 0.44 ± 0.06 and 0.25 ± 0.04 at 1.5 T, and 0.44 ± 0.07 and 0.26 ± 0.04 at 3 T, respectively. There were no significant differences between healthy controls and low risk subjects in routine CMR parameters and T1 values. The entire cohort showed no correlation between age, gender and native T1. Cross-center comparisons of mean values showed no significant difference for any of the T1 indices at any field strength. There were considerable regional differences in segmental T1 values. λ and ECV were found to be dose dependent. There was excellent inter- and intraobserver reproducibility for measurement of native septal T1.ConclusionWe show transferability for a unifying T1 mapping methodology in a multicenter setting. We provide reference ranges for T1 values in healthy human myocardium, which can be applied across participating sites.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-014-0069-x) contains supplementary material, which is available to authorized users.

T1 Mapping in Characterizing Myocardial Disease

“…Of note, septal T1 values are between 50 and 100 ms higher compared with the lateral wall for native T1 acquisitions and mirrored by inverse effects in postcontrast acquisition. 23,[26][27][28] This also creates a difficulty in standardization of segmental values, which hinders accurate registration of regional heterogeneity using native T1 (within the range of noise), although larger differences can be detected, as also shown by visualization of ischemic myocardial scar ( Figure 7). Inclusion of partial (voxel) volume, that is, signal from adjacent tissue, such as low signal from the lungs in the lateral wall or high signal from blood, will contaminate the myocardial measurements, explaining the preference for conservative intramyocardial placement of regions of interest.…”

“…[23][24][25] T1 values in septal segments are highly reproducible, whereas there is high dispersion of values in the lateral segments and thus better suited than averaging the complete short-axis slice to support discrimination between health and disease. The noise of the lateral segments included in short-axis measurement dilutes the physiological meaningful signal and prohibits the detection of interindividual differences, such as between health and mild disease, reducing its diagnostic and prognostic power 11,23,26 ( Figure 6). Of note, septal T1 values are between 50 and 100 ms higher compared with the lateral wall for native T1 acquisitions and mirrored by inverse effects in postcontrast acquisition.…”

The Prognostic Role of T1 Mapping Sequences: Can T1 Mapping Parameters Have a Role in Risk Stratification?

“…With MOLLI sequencing, which is the most popular T1 mapping sequence, normal myocardial native T1 ranges from 950 to 982 ms and thereby ECV is 25.0 to 26.9% in a 1.5 T magnetic field [5,6,14,15]. In a 3 T magnetic field, native T1 is somewhat prolonged to 1052 to 1159 ms [6,16].…”

“…In a 3 T magnetic field, native T1 is somewhat prolonged to 1052 to 1159 ms [6,16]. Although reference values have been published in several studies, the current consensus statement recommends that each center should derive normal values for their specific center [11] Table 1 shows an overview of studies reporting normative ranges for T1-mapping indices.…”

“…T1 mapping data are used in various clinical studies as early detectors of disease or imaging-based biomarkers guiding specific therapies. However, native T1, post-T1 and ECV values vary by equipment manufacturer and according to the magnetic field strength and mapping sequence used [5,6] So, compared to left ventricular (LV) mass, volume and late gadolinium enhancement (LGE) imaging data, multi-vender-based multicenter T1 mapping studies have several limitations. Thus, standardization of T1 mapping is important.…”