Comparison of 3D Free-Breathing Coronary MR Angiography and 64-MDCT Angiography for Detection of Coronary Stenosis in Patients with High Calcium Scores

Abstract

OBJECTIVE-The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (≥ 50%) in patients with high calcium scores. MATERIALS AND METHODS-Eighteenpatients (12 men, six women; mean age, 56 y; age range, 38-77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard.RESULTS-Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 ± 0.62 vs 2.94 ± 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, © American Roentgen Ray Society Address correspondence to J. C. Carr.. Thirty-two eligible patients were recruited for the coronary MRA section of the study within 1-3 days after MDCTA examination. Twenty-seven patients (19 men and eight women; mean age, 58 y; age range, 38-79 y) successfully completed the MRA study. MRA studies could not be completed because of failed respiratory gating in three patients and failed ECG gating in two patients. Eighteen of the 27 patients subsequently underwent conventional CAG 3-10 days (mean, 6 days) after the MRA study. NIH Public AccessThere were no clinical events or medication changes recorded between examinations.Patients who had a heart rate of > 70 beats per minute (bpm) at rest received an oral β-blocker (25-50 mg) or IV metoprolol (5 mg) to decrease their heart rate before both the MDCTA and MRA examinations. The difference in heart rate between the MDCTA and MRA studies was < 5 bpm. Sublingual or IV nitroglycerine (5 mg) was used in both coronary MDCTA and MRA to achieve maximal coronary vasodilation in all patients. Coronary MDCTACoronary MDCTA was performed and calcium scores were obtained using a 64-MDCT scanner (Somatom Sensation Cardiac 64, Siemens Medical Solutions). An initial unenhanced ECG-gated scan was obtained for coronary calcium scoring (collimation, 24 × 0.6 mm; pitch, 0.2;...

Assessment of Coronary Artery Disease Using Magnetic Resonance Coronary Angiography

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