Objectives This study assessed changes in myocardial native T1 and T2 values after supine exercise stress in healthy subjects and in patients with suspected ischemia as potential imaging markers of ischemia. Background With emerging data on the long-term retention of gadolinium in the body and brain, there is a need for an alternative noncontrast cardiovascular magnetic resonance (CMR)−based myocardial ischemia assessment. Methods Twenty-eight healthy adult subjects and 14 patients with coronary artery disease (CAD) referred for exercise stress and/or rest single-photon emission computed tomography/myocardial perfusion imaging (SPECT/MPI) for evaluation of chest pain were prospectively enrolled. Free-breathing myocardial native T1 and T2 mapping were performed before and after supine bicycle exercise stress using a CMR-compatible supine ergometer positioned on the MR table. Differences in T1 rest, T2 rest and T1 post-exercise, T2 post-exercise values were calculated as T1 and T2 reactivity, respectively. Results The mean exercise intensity was 104 W, with exercise duration of 6 to 12 min. After exercise, native T1 was increased in healthy subjects (p < 0.001). T1 reactivity, but not T2 reactivity, correlated with the rate−pressure product as the index of myocardial blood flow during exercise (r = 0.62; p < 0.001). In patients with CAD, T1 reactivity was associated with the severity of myocardial perfusion abnormality on SPECT/MPI (normal: 4.9%; quartiles: 3.7% to 6.3%, mild defect: 1.2%, quartiles: 0.08% to 2.5%; moderate defect: 0.45%, quartiles: −0.35% to 1.4%; severe defect: 0.35%, quartiles: −0.44% to 0.8%) and had similar potential as SPECT/MPI to detect significant CAD (>50% diameter stenosis on coronary angiography). The area under the receiver-operating characteristic curve was 0.80 versus 0.72 (p = 0.40). The optimum cutoff value of T1 reactivity for predicting flow-limiting stenosis was 2.5%, with a sensitivity of 83% and a specificity of 92%, a negative predictive value of 96%, a positive predictive value of 71%, and an area under the curve of 0.86. Conclusions Free-breathing stress/rest native T1 mapping, but not T2 mapping, can detect physiological changes in the myocardium during exercise. Our feasibility study in patients shows the potential of this technique as a method for detecting myocardial ischemia in patients with CAD without using a pharmacological stress agent.

中文翻译：

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运动应激后心肌天然T ₁和T _2的变化

非对比CMR试点研究

目的这项研究评估了健康受试者和疑似缺血患者（可能是缺血的影像学指标）在仰卧运动后的心肌天然T1和T2值的变化。背景技术随着emerging和in在人体和大脑中长期保留的新数据的出现，需要进行另一种基于非对比心血管磁共振（CMR）的心肌缺血评估。方法前瞻性招募了28名健康成人受试者和14名患有冠状动脉疾病（CAD）的患者，这些患者因运动压力和/或休息时采用单光子发射计算机断层扫描/心肌灌注显像（SPECT / MPI）评估了胸痛。使用位于MR工作台上的CMR兼容仰卧测力计，在仰卧自行车运动压力前后进行自由呼吸的心肌天然T1和T2定位。T1休息，T2休息和T1运动后，T2运动后的值的差异分别计算为T1和T2反应性。结果平均运动强度为104 W，运动时间为6至12分钟。运动后，健康受试者的天然T1升高（p <0.001）。T1反应性而不是T2反应性与运动过程中心肌血流指数的速率-压力乘积相关（r = 0.62； p <0.001）。在CAD患者中，T1反应性与SPECT / MPI上心肌灌注异常的严重程度有关（正常：4.9％;四分位数：3.7％至6.3％，轻度缺陷：1.2％，四分位数：0.08％至2.5％;中度缺陷：0。45％，四分位数：-0.35％至1.4％；严重缺陷：0.35％，四分位：-0.44％至0.8％），并且具有与SPECT / MPI相似的潜力，可检测出显着的CAD（冠状动脉造影时直径狭窄> 50％）。接收器工作特性曲线下的面积为0.80对0.72（p = 0.40）。预测限流性狭窄的T1反应性的最佳临界值为2.5％，灵敏度为83％，特异性为92％，阴性预测值为96％，阳性预测值为71％，且面积小于曲线为0.86。结论自由呼吸压力/静止的天然T1映射（而非T2映射）可以检测运动过程中心肌的生理变化。