First-pass Perfusion Disturbance of Coronary Artery Stenosis : An Experimental Study Using MR Imaging withGd-DTPA Enhancement

Abstract

Purpose : In order to determine the value of first-pass MR imaging in the diagnosis of myocardial ischemia,first-pass perfusion abnormality of coronary artery stenosis was observed in MRI after gadopentate dimeglumine(Gd-DTPA) enhancement. Materials and Methods : The left anterior descending (LAD) coronary arteries of six dogswere subjected to approximately 70% stenosis confirmed by coronary angiography. Half an hour after adenosine and99mTc-sestamibi infusion, Gd-DTPA (0.2 mmol/kg) and methylene blue were administered and termination was inducedwith potassium chloride. SE T1-weighted and single-photon emission computed tomography (SPECT) images weresubsequently obtained and the findings of perfusion defect compared with specimen stain. Three dimensionallyreconstructed MR images were used to measure signal intensity (SI) of normal myocardium and perfusion defect fromtheir sectional and total volume. Results : Five of six dogs with LAD artey stenosis ranging from 66% to 73%displayed perfusion defect on MRI, SPECT, and specimen stain, but the remaining dog with stenosis of 58% showed nosuch defect. MRI showed the perfusion defect as distinct low SI, enabling the measurement of percentage perfusiondefect(24.4?.4%), which increased inferiorly. SI of normal myocardium and perfusion defect decreased inferiorly; their difference indicated stenosis-induced perfusion loss according to section location. Volumetric SI ofnormal myocardium and perfusion defect were 3.42?.52 and 2.16?.45, respectively (p < 0.05). Conclusion :Gd-DTPA enhanced MRI displayed first-pass perfusion abnormality of coronary artery stenosis as perfusion defectwith distinct low SI ; this enabled the measurement of its volume and SI changes according to section location,and thus indicated the value of first-pass MR imaging in the diagnosis of myocardial ischemia.