• Velasco Forte Mari Nieves MN Division of Imaging Sciences and Biomedical Engineering, King's College London, St Thomas' Hospital, 3rd Floor Lambeth Wing, Westminster Brid, Kuberan Pushparajah, Tobias Schaeffter, Israel Valverde Perez, Kawal Rhode, Bram Ruijsink, Mazen Alhrishy, Nicholas Byrne, Amedeo Chiribiri, Tevfik Ismail, Tarique Hussain, Reza Razavi, and Sébastien Roujol.
• Division of Imaging Sciences and Biomedical Engineering, King's College London, St Thomas' Hospital, 3rd Floor Lambeth Wing, Westminster Bridge Road, London, SE1 7EH, UK.
• J Cardiovasc Magn Reson. 2017 Aug 15; 19 (1): 60.

BackgroundCardiac catheterization is a common procedure in patients with congenital heart disease (CHD). Although cardiovascular magnetic resonance imaging (CMR) represents a promising alternative approach to fluoroscopy guidance, simultaneous high contrast visualization of catheter, soft tissue and the blood pool remains challenging. In this study, a novel passive tracking technique is proposed for enhanced positive contrast visualization of gadolinium-filled balloon catheters using partial saturation (pSAT) magnetization preparation.MethodsThe proposed pSAT sequence uses a single shot acquisition with balanced steady-state free precession (bSSFP) readout preceded by a partial saturation pre-pulse. This technique was initially evaluated in five healthy subjects. The pSAT sequence was compared to conventional bSSFP images acquired with (SAT) and without (Non-SAT) saturation pre-pulse. Signal-to-noise ratio (SNR) of the catheter balloon, blood and myocardium and the corresponding contrast-to-noise ratio (CNR) are reported. Subjective assessment of image suitability for CMR-guidance and ideal pSAT angle was performed by three cardiologists. The feasibility of the pSAT sequence is demonstrated in two adult patients undergoing CMR-guided cardiac catheterization.ResultsThe proposed pSAT approach provided better catheter balloon/blood contrast and catheter balloon/myocardium contrast than conventional Non-SAT sequences. It also resulted in better blood and myocardium SNR than SAT sequences. When averaged over all volunteers, images acquired with a pSAT angle of 20° to 40° enabled simultaneous visualization of the catheter balloon and the cardiovascular anatomy (blood and myocardium) and were found suitable for CMR-guidance in >93% of cases. The pSAT sequence was successfully used in two patients undergoing CMR-guided diagnostic cardiac catheterization.ConclusionsThe proposed pSAT sequence offers real-time, simultaneous, enhanced contrast visualization of the catheter balloon, soft tissues and blood. This technique provides improved passive tracking capabilities during CMR-guided catheterization in patients.

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