Cardiovascular magnetic resonance stress and rest T1-mapping using regadenoson for detection of ischemic heart disease compared to healthy controls

Abstract

Background: Adenosine stress T1-mapping on cardiovascular magnetic resonance (CMR) can differentiate between normal, ischemic, infarcted, and remote myocardial tissue classes without the need for contrast agents. Regadenoson, a selective coronary vasodilator, is often used in stress perfusion imaging when adenosine is contra-indicated, and has advantages in ease of administration, safety profile, and clinical workflow. We aimed to characterize the regadenoson stress T1-mapping response in healthy individuals, and to investigate its ability to differentiate between myocardial tissue classes in patients with coronary artery disease (CAD).

Methods: Eleven healthy controls and 25 patients with CAD underwent regadenoson stress perfusion CMR, as well as rest and stress ShMOLLI T1-mapping. Native T1 values and stress T1 reactivity were derived for normal myocardium in healthy controls and for different myocardial tissue classes in patients with CAD.

Results: Healthy controls had normal myocardial native T1 values at rest (931 ± 22 ms) with significant global regadenoson stress T1 reactivity (δT1 = 8.2 ± 0.8% relative to baseline; p < 0.0001). Infarcted myocardium had significantly higher resting T1 (1215 ± 115 ms) than ischemic, remote, and normal myocardium (all p < 0.0001) with an abolished stress T1 response (δT1 = -0.8% [IQR: -1.9-0.5]). Ischemic myocardium had elevated resting T1 compared to normal (964 ± 57 ms; p < 0.01) with an abolished stress T1 response (δT1 = 0.5 ± 1.6%). Remote myocardium in patients had comparable resting T1 to normal (949 ms [IQR: 915-973]; p = 0.06) with blunted stress reactivity (δT1 = 4.3% [IQR: 3.1-6.3]; p < 0.0001).

Conclusions: Healthy controls demonstrate significant stress T1 reactivity during regadenoson stress. Regadenoson stress and rest T1-mapping is a viable alternative to adenosine and exercise for the assessment of CAD and can distinguish between normal, ischemic, infarcted, and remote myocardium.

Keywords: Cardiovascular magnetic resonance; Coronary artery disease; Regadenoson; ShMOLLI; T1-mapping.

Fig. 1

Example image of a patient with coronary artery disease. Late gadolinium enhancement image (A) shows evidence of a lateral myocardial infarction (white arrow). On first-pass stress perfusion (B) there is a fixed hypoperfusion defect in the lateral wall corresponding to the area of infarction, as well as inducible hypoperfusion in the septum (red arrows). Regions of interest are placed in the areas of ischemia and infarction and LV blood pool on T1 maps at rest (C) and stress (D). δT1 was significantly abolished in the anteroseptum (1.3%), inferoseptum (−0.8%), and in the lateral infarction (−0.4%). For comparison, the remote myocardium in this case had a δT1 of 3.7%. This participant had severe left anterior descending artery disease on invasive angiography, as well as a chronic total occlusion of the left circumflex artery. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

Normal regadenoson stress T1 responses in healthy controls. Comparison of native myocardial T1 values at rest and during regadenoson stress in healthy controls in standard short-axis slice positions (A) and in the American Heart Association (AHA) 16-segments (B). There are significant increases in T1 values during stress for all slices and myocardial segments. Data presented as mean and standard deviation (error bars). **p < 0.01; ***p < 0.001; ****p < 0.0001; ns = not significant.

Fig. 3

Regadenoson stress T1-mapping distinguishes between different myocardial tissue classes. Myocardial tissue T1 profiles in healthy controls and CAD patients are based on absolute T1 values (A) and the percentage change in T1 between rest and stress (B). Normal and remote myocardium demonstrate significant stress T1 reactivity, whereas areas of myocardial ischemia and infarction have a near-abolished stress T1 response. Data presented as mean and standard deviation or median and IQR (error bars). **p < 0.01; ***p < 0.001; ****p < 0.0001; ns = not significant.