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- Open Access
Coronary MRI with induced vasodilation using isosorbide dinitrate
© Hu et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Coronary Image
- Isosorbide Dinitrate
- Sublingual Nitroglycerin
- Healthy Adult Subject
Despite technical progress, coronary magnetic resonance imaging (MRI) still faces multiple challenges. Coronary vasodilators, such as sublingual nitroglycerin (NTG) or longer acting nitrates (e.g., isosorbide dinitrate), are commonly used to study coronary circulation. Terashima et al.  reported use of coronary MRI to evaluate the effect of sublingual NTG. Isosorbide dinitrate (Isordil) has been previously reported in a multi-center clinical coronary MRI trial , however no data has been provided to quantify coronary MRI image quality improvement and time course of Isordil.
To investigate the impact of Isordil administration on SNR, vessel diameter and overall image quality in coronary MRI.
Coronary images were acquired on a cohort of healthy adult subjects before and after Isordil administration. Subjects were divided into four groups to investigate the impact of the imaging sequence and dose. In groups A and B the images were acquired using SSFP imaging sequence with either 2.5 mg or 5 mg Isordil dose. In groups C and D images are acquired using GRE with either 2.5 mg or 5 mg Isordil dose. The impact of vasodilator during a time course was studied by repeated imaging. A free breathing, 3D VCG gated GRE sequence with typical imaging parameters of TR = 7.7 ms, TE = 2.2 ms, FOV = 270 × 270 × 30 mm3, flip angle = 30°, spatial resolution of 0.7 × 1 × 1.5 mm3 reconstructed to 0.52 × 0.52 × 0.75 mm3 was used. The imaging parameters for SSFP imaging included: TR = 4.6 ms, TE = 2.3 ms, FOV = 270 × 270 × 30 mm3, flip angle = 90°, spatial resolution of 1 × 1 × 1.5 mm3 reconstructed to 0.52 × 0.52 × 0.75 mm3 and a half α preparation pulse. T2 prep, fat saturation and navigator sequences were used in both sequences. In order to obtain a more accurate SNR measurement, no parallel imaging was used. SNR was measured with a previously published method . To be consistent, the same noise and signal ROI's were used in all the GRE and balanced-SSFP scans during a study, unless motion is detected between the scans. The coronary cross-sectional diameter in the proximal right coronary artery was measured using the Soap Bubble tool (Philips Healthcare, Best, NL).
Pre-scan Isordil administration improves coronary SNR by 20% for both GRE and SSFP imaging. 5 mg and 2.5 mg doses result in comparable vasodilation. For best SNR enhancement, imaging should be performed later post-Isordil if using 2.5 mg dose than 5 mg.
This article is published under license to BioMed Central Ltd.