A standardized CMRI protocol and equipment were used (1.5 T Magnetom Avanto, Siemens Healthcare, Erlangen, Germany). First-pass contrast perfusion imaging was performed using gadolinium contrast of 0.05 mM/kg (Gadodiamide, Omniscan, Amersham, Piscataway, NJ) infused at 4 ml/sec, followed by 20 ml saline at 4 ml/sec. Vasodilator stress was adenosine 140 μg/kg/min infused for two minutes into the arm contralateral to the contrast injection, prior to first-pass perfusion imaging, and continued until completion of the perfusion imaging data acquisition. Resting first-pass perfusion was done 10 minutes later.
Perfusion images were obtained in three left ventricular (LV) short-axis imaging slices (basal, mid and distal LV slice positions) with the following parameters: Gradient echo–EPI hybrid sequence, TR per slice: 148 msec, TE: 1.1 msec, BW: 1420 Hz/pixel, echo train length: 4, readout flip angle: 20°, slice thickness: 8 mm, image matrix: 160 × 70 pixels, in-plane resolution: 2.7 × 2.2 mm2, parallel imaging (GRAPPA) factor: 2, imaging 3 slices every heartbeat. In the event of a peak stress heart rate of >120 bpm, two slices were obtained during stress first-pass imaging with exclusion of the distal LV slice position.
LV function and delayed enhancement imaging were performed using a standardized approach, as previously described13 (link).