RETRACTED: Gadolinium-Free Cardiac MR Stress T1-Mapping to Distinguish Epicardial From Microvascular Coronary Disease

Abstract

BackgroundNovel cardiac magnetic resonance (CMR) stress T1 mapping can detect ischemia and myocardial blood volume changes without contrast agents and may be a more comprehensive ischemia biomarker than myocardial blood flow.ObjectivesThis study describes the performance of the first prospective validation of stress T1 mapping against invasive coronary measurements for detecting obstructive epicardial coronary artery disease (CAD), defined by fractional flow reserve (FFR <0.8), and coronary microvascular dysfunction, defined by FFR ≥0.8 and the index of microcirculatory resistance (IMR ≥25 U), compared with first-pass perfusion imaging.MethodsNinety subjects (60 patients with angina; 30 healthy control subjects) underwent CMR (1.5- and 3-T) to assess left ventricular function (cine), ischemia (adenosine stress/rest T1 mapping and perfusion), and infarction (late gadolinium enhancement). FFR and IMR were assessed ≤7 days post-CMR. Stress and rest images were analyzed blinded to other information.ResultsNormal myocardial T1 reactivity (ΔT1) was 6.2 ± 0.4% (1.5-T) and 6.2 ± 1.3% (3-T). Ischemic viable myocardium downstream of obstructive CAD showed near-abolished T1 reactivity (ΔT1 = 0.7 ± 0.7%). Myocardium downstream of nonobstructive coronary arteries with microvascular dysfunction showed less-blunted T1 reactivity (ΔT1 = 3.0 ± 0.9%). Stress T1 mapping significantly outperformed gadolinium-based first-pass perfusion, including absolute quantification of myocardial blood flow, for detecting obstructive CAD (area under the receiver-operating characteristic curve: 0.97 ± 0.02 vs. 0.91 ± 0.03, respectively; p < 0.001). A ΔT1 of 1.5% accurately detected obstructive CAD (sensitivity: 93%; specificity: 95%; p < 0.001), whereas a less-blunted ΔT1 of 4.0% accurately detected microvascular dysfunction (area under the receiver-operating characteristic curve: 0.95 ± 0.03; sensitivity: 94%; specificity: 94%: p < 0.001).ConclusionsCMR stress T1 mapping accurately detected and differentiated between obstructive epicardial CAD and microvascular dysfunction, without contrast agents or radiation.

Microvascular Disease and Small-Vessel Disease: The Nexus of Multiple Diseases of Women

“…78 CMR perfusion can also distinguish between epicardial stenosis and CMD. 79 In a recent study of 60 patients with angina, the magnitude of change in vasodilator stress T1 mapping could differentiate normals (DT1 * 6%) versus those with CMD (DT1 * 4%) or epicardial stenosis (DT1 < 1.5%). Other novel automated pixel-wide quantification techniques have also shown promise in small studies using adenosine stress MBF and have been validated against an IMR >25 (index of microvascular resistance) in the catheterization laboratory.…”

Cardiac T1 mapping: Techniques and applications

“…This study suggests the potential for classification of normal vs. ischemic or infarcted myocardium using a combination of native and stress T 1 mapping without gadolinium contrast. More recent stress T 1 studies have distinguished microvascular dysfunction and epicardial obstructive CAD in native coronary arteries and identified reduced T 1 stress reactivity in patients with well‐controlled type 2 diabetes mellitus without obstructive CAD, suggestive of early microvascular changes . Other groups have also employed the technique in small samples but the ability to reliably distinguish between normal, ischemic, and infarcted myocardium remains to be definitively proven …”

Cardiac magnetic resonance imaging to detect ischemia in chronic coronary syndromes: state of the art

“…One of the most promising CMR methods is T1 mapping performed during vasodilator stress, which has shown to distinguish obstructive epicardial CAD from microvascular dysfunction. 89 The technique, however, requires carefully designed imaging and processing protocols as effect sizes are relatively small. Changes in T1 can be related to the fact that the microcirculatory arteries in the ischemic myocardium already dilate at rest and are not able to further respond to stress conditions.…”