MAGNETIC-RESONANCE-IMAGING DURING DOBUTAMINE STRESS FOR DETECTION ANDLOCALIZATION OF CORONARY-ARTERY DISEASE - QUANTITATIVE WALL-MOTION ANALYSIS USING A MODIFICATION OF THE CENTERLINE METHOD

Background Quantitative measurement of wall motion is essential to ass ess objectively the functional significance of coronary artery disease . We developed a quantitative wall thickening analysis on stress magne tic resonance images. This study was designed to assess the clinical v alue of magnetic resonance imaging (MRI) during dobutamine stress for detection and localization of myocardial ischemia in patients with sus pected coronary artery disease. Methods and Results Thirty-nine consec utive patients with clinically suspected coronary artery disease refer red for coronary arteriography and 10 normal volunteers underwent grad ient-echo MRI at rest and during peak dobutamine stress (infusion rate , 20 mu g.kg(-1).min(-1)). MRI was performed in the short-axis plane a t four adjacent levels. Display in a cine loop provided a qualitative impression of regional wall motion (cine MRI). A modification of the c enterline method was applied for quantitative wall motion analysis by means of calculation of percent systolic wall thickening. Short-axis c ine MRI images were analyzed at 100 equally spaced chords constructed perpendicular to a centerline drawn midway between the end-diastolic a nd end-systolic contours. Dobutamine MRI was considered positive for c oronary artery disease if the percent systolic wall thickening of more than four adjacent chords was <2 SD below the mean values obtained fr om the normal volunteers. The overall sensitivity of dobutamine MRI fo r the detection of significant coronary artery disease (diameter steno sis greater than or equal to 50%) was 91% (30 of 33), specificity was 80% (5 of 6), and accuracy was 90% (35 of 39). The sensitivity for ide ntifying one-vessel disease was 88% (15 of 17), for two-vessel disease 91% (10 of 11), and for three-vessel disease 100% (5 of 5). The sensi tivity for detection of individual coronary artery lesions was 75% for the left anterior descending coronary artery, 87% for the right coron ary artery, and 63% for the left circumflex coronary artery. Conclusio ns Dobutamine MRI clearly identifies wall motion abnormalities by quan titative analysis using a modification of the centerline method. Dobut amine MRI is an accurate method for detection and localization of myoc ardial ischemia and may emerge as a new noninvasive approach for evalu ation of patients with known or suspected coronary artery disease.