Native Myocardial T1 Mapping, Are We There Yet?

Abstract

SummaryT1 or longitudinal relaxation time is one of the very fundamental magnetic resonance imaging (MRI) time constants and a tissue characterizing parameter. Only during the last decade did it become possible to quantify T1 values of the myocardium through T1 mapping. Evolving from only region of interest analysis and long acquisition times to the pixel-based parametric mapping and short breath-hold sequences, T1 mapping is reaching maturity among cardiac magnetic resonance (CMR) techniques. Both inversion recovery methods such as MOdified Look-Locker Inversion (MOL-LI) and Shortened MOLLI (ShMOLLI) and saturation recovery methods such as Saturation recovery Single-Shot Acquisition (SASHA) are available for T1 quantification with variable degrees of accuracy, precision, and reproducibility. Native (non-contrast) T1 values increase with edema, amyloid deposition, and fibrosis, while they decrease in fat or iron deposition in the myocardium. These features enabled significant expansion of the clinical applications of native T1 mapping where it provides high sensitivity and specificity and even acts as a disease biomarker or a predictor of prognosis. It is of particular usefulness in diffuse myocardial diseases where conventional CMR techniques might be deceiving. A brighter future for the technique is expected if certain challenges are to be faced, examples of which are the need for standardization of normal values, acquisition techniques, and improving analysis tools. (Int Heart J 2016; 57: 400-407)

Native T1 reference values for nonischemic cardiomyopathies and populations with increased cardiovascular risk: A systematic review and meta‐analysis

“…Although there are concerns about the physical accuracy of T 1 mapping, the overall precision and reproducibility are fairly high and of substantial clinical utility . There is, therefore, an increasing demand for normative reference T 1 values . These reference values will be of particular importance for HT, DM, and obese patients because they share cardiac MR characteristics with NICM .…”

“…18 There is, therefore, an increasing demand for normative reference T 1 values. [19][20][21] These reference values will be of particular importance for HT, DM, and obese patients because they share cardiac MR characteristics with NICM. [13][14][15] Because methodological differences can eventually affect the myocardial T 1 values, 18,21 a meta-analysis is a suitable approach to determine the normal myocardial T 1 reference values.…”

Endocardial Fibrotic Lesions Have a Greater Effect on Peak Longitudinal Strain than Epicardial Fibrotic Lesions in Hypertrophic Cardiomyopathy Patients

“…In this study, to evaluate the influence of layerspecific localization of focal MF as confirmed by CMR on regional whole-layer PLS values, we compared wholelayer PLS on TTE in LV segments (1) without MF, (2) with MF only in LVendo, (3) with MF only in LVepi, or (4) with MF both in LVendo and LVepi in HCM patients without myocardial infarction in a site-by-site analysis.…”

“…Furthermore, the T1 mapping method on CMR is the gold standard for quantitative measurement of interstitial volume. 2) In this study, we underwent semiquantitative analysis in which absolute values of global LS (average of 17-segment regional peak LS) on TTE in each patient significantly and negatively correlated with the numbers of segments with MF on CMR (correlation coefficient, -0.61; P < 0.05), and we speculated that there would be a significant relationship between global LS and quantitative volume of MF in HCM patients. Therefore, we hope to evaluate the relationship of global and regional LS and circumferential strain against interstitial volume measured by T1 mapping method.…”

“…M yocardial fibrosis (MF) in the left ventricular (LV) myocardium is observed frequently on cardiac magnetic resonance (CMR) imaging in patients with hypertrophic cardiomyopathy (HCM). [1][2][3] Previously, we reported that regional whole-layer peak longitudinal strain (PLS) of the LV myocardium on two-dimensional (2D) speckle tracking transthoracic echocardiogram (TTE) is useful for the early detection of LV myocardial damage, such as focal MF, at the corresponding sites on CMR in HCM patients. 4) Recent advancements in CMR allow layer-specific differentiation of the location of focal MF such as in the LV endocardial layer (LVendo), in the LV epicardial layer (LVepi), or in both LVendo and LVepi.…”