摘要
背景:组织标记M RI及三维应变分析可以定量测定心肌收缩性。作者检验如下假说,即分别于静息及应用低剂量多巴酚丁胺时进行三维应变分析可用于评价缺血性心肌病(ICM)患者的存活和无活力心肌。方法和结果:分别在静息和使用低剂量多巴酚丁胺时,对16例健康志愿者和14例ICM患者行射频组织标记M RI。计算所有受试者在静息和使用多巴酚丁胺时的三维整体和局部周应变(Ecc)。将其结果与心肌存活的常规临床数据相比较。
BACKGROUND -Tissue-tagged magnetic resonance imaging(MRI) with 3-dimensional(3D) myocardial strain analysis allows quantitative assessment of myocardial contractility. We assessed the hypothesis that 3D strain determination at rest and with low-dose dobutamine would discriminate between viable and nonviable myocardium in patients with ischemic cardiomyopathy(ICM). METHODS AND RESULTS -MRI with radiofrequency tissue-tagging at rest and with low-dose dobutamine was performed in 16 normal volunteers and 14 patients with ICM. Three-dimensional global and regional circumferential strains(Ecc) were computed for all subjects at rest and with dobutamine. Results were compared with clinically indicated conventional viability studies. Compared with normal volunteers, global left ventricular Ecc was significantly decreased in patients with ICM at rest(-0.15±0.06 versus-0.27±0.03; P< 0.001) and with dobutamine(-0.17±0.08 versus-0.37±0.10; P< 0.001). Ecc was significantly decreased in nonviable regions compared with viable segments at rest(-0.08±0.06 versus -0.17±0.10; P< 0.001) and with dobutamine(-0.07±0.06 versus -0.21±0.11; P< 0.001). Ecc in viable segments increased significantly in response to dobutamine(P=0.04), whereas Ecc did not change in nonviable segments(P=0.50). Normal controls(96 segments) had increased Ecc at rest(-0.27±0.07) and with dobutamine(-0.37±0.15) compared with both viable and nonviable regions in ICM patients(P< 0.001). CONCLUSIONS -Noninvasive dobutamine tissue-tagged MRI with calculation of 3D strain allows the identification, quantification and display of regionally varying ventricular function. The response of systolic strain to low-dose dobutamine has significant promise in discriminating between viable and nonviable myocardium.
