Adenosine Stress and Rest T1 Mapping Can Differentiate Between Ischemic, Infarcted, Remote, and Normal Myocardium Without the Need for Gadolinium Contrast Agents

Abstract

ObjectivesThe aim of this study was to evaluate the potential of T1 mapping at rest and during adenosine stress as a novel method for ischemia detection without the use of gadolinium contrast.BackgroundIn chronic coronary artery disease (CAD), accurate detection of ischemia is important because targeted revascularization improves clinical outcomes. Myocardial blood volume (MBV) may be a more comprehensive marker of ischemia than myocardial blood flow. T1 mapping using cardiac magnetic resonance (CMR) is highly sensitive to changes in myocardial water content, including MBV. We propose that T1 mapping at rest and during adenosine vasodilatory stress can detect MBV changes in normal and diseased myocardium in CAD.MethodsTwenty normal controls (10 at 1.5-T; 10 at 3.0-T) and 10 CAD patients (1.5-T) underwent conventional CMR to assess for left ventricular function (cine), infarction (late gadolinium enhancement [LGE]) and ischemia (myocardial perfusion reserve index [MPRI] on first-pass perfusion imaging during adenosine stress). These were compared to novel pre-contrast stress/rest T1 mapping using the Shortened Modified Look-Locker Inversion recovery technique, which is heart rate independent. T1 values were derived for normal myocardium in controls and for infarcted, ischemic, and remote myocardium in CAD patients.ResultsNormal myocardium in controls (normal wall motion, MPRI, no LGE) showed normal resting T1 (954 ± 19 ms at 1.5-T; 1,189 ± 34 ms at 3.0-T) and significant positive T1 reactivity during adenosine stress compared to baseline (6.2 ± 0.5% at 1.5-T; 6.3 ± 1.1% at 3.0-T; all p < 0.0001). Infarcted myocardium showed the highest resting T1 of all tissue classes (1,442 ± 84 ms), without significant T1 reactivity (0.2 ± 1.5%). Ischemic myocardium showed elevated resting T1 compared to normal (987 ± 17 ms; p < 0.001) without significant T1 reactivity (0.2 ± 0.8%). Remote myocardium, although having comparable resting T1 to normal (955 ± 17 ms; p = 0.92), showed blunted T1 reactivity (3.9 ± 0.6%; p < 0.001).ConclusionsT1 mapping at rest and during adenosine stress can differentiate between normal, infarcted, ischemic, and remote myocardium with distinctive T1 profiles. Stress/rest T1 mapping holds promise for ischemia detection without the need for gadolinium contrast.

T1 Mapping in Characterizing Myocardial Disease

“…It is increasingly understood that certain modified Look-Locker imaging variants are considerably influenced by the effects of myocardial water (eg, via wider excitation flip angles 18,19 ), as well as the effect of magnetization transfer and fast water exchange of the unbound tissue water. 16,20,21 This results in a higher and more homogeneous signal, supporting more precise measurements, especially in native T1 acquisition. T1 accuracy and T2 sensitivity seem to be inversely related.…”

“…Finally, native T1 can reflect an increase in myocardial blood volume at rest as a compensatory mechanism for an increased resistance to blood flow because of a stenotic coronary artery, allowing recognition of ischemic areas. 21 These studies highlight the sea of future potential for native T1 in addressing the many pertinent clinical questions in a contrastfree cardiac imaging application.…”

Myocardial Perfusion Is Impaired and Relates to Cardiac Dysfunction in Patients With Atrial Fibrillation Both Before and After Successful Catheter Ablation

“…Images were acquired during end‐expiration to minimize the effects of respiratory motion. The established techniques of cine and adenosine stress/rest perfusion were applied as previously described10, 12 and are detailed below. Strain indices were assessed by the LV tissue‐tracking method 13.…”

T1 and T2 Mapping: The Next Giant Leap in Cardiac Imaging

“…Native T1 mapping provides valuable data in myocarditis [12], hypertrophic cardiomyopathy [13], dilated cardiomyopathy [14], cardiac amyloidosis [15], and others disease states. Noncontrast T1 mapping has recently been shown to reliably elucidate the characteristics of myocardial ischemia, viability, and scarring [16]. Additionally, native T1 mapping of the spleen during adenosine infusion enables the assessment of adequate response during stress protocol (splenic switch-off) without requiring gadolinium [17].…”