Matthew J Middione1, Holden H Wu, Daniel B Ennis. 1. Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, California, USA; Biomedical Physics Interdepartmental Program, University of California, Los Angeles, Los Angeles, California, USA.
Abstract
PURPOSE: To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy for phase-contrast MRI (PC-MRI). METHODS: A conventional flow-compensated and flow-encoded (FCFE) PC-MRI sequence was compared with a CVX PC-MRI sequence using numerical simulations, flow phantom experiments, and in vivo experiments. Flow measurements within the ascending aorta, main pulmonary artery, and right/left pulmonary arteries of normal volunteers (N = 10) were acquired at 3T and analyzed using a conventional FCFE sequence and a CVX sequence with either higher spatial resolution or higher temporal resolution. All sequences mitigated chemical shift-induced phase errors and used equivalent breath-hold durations. RESULTS: Chemical shift-optimized PC-MRI has increased sequence efficiency when using CVX, which can provide either higher spatial or higher temporal resolution compared with conventional FCFE PC-MRI. Numerical simulations, flow phantom experiments, and in vivo experiments indicate that CVX measurements of total flow and peak velocity are increased and more accurate when compared with FCFE. CONCLUSION: CVX PC-MRI increases sequence efficiency while reducing chemical shift-induced phase errors. This can be used to provide either higher spatial or higher temporal resolution than conventional chemical shift-mitigated PC-MRI methods to provide more accurate measurements of blood flow and peak velocity.
PURPOSE: To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy for phase-contrast MRI (PC-MRI). METHODS: A conventional flow-compensated and flow-encoded (FCFE) PC-MRI sequence was compared with a CVX PC-MRI sequence using numerical simulations, flow phantom experiments, and in vivo experiments. Flow measurements within the ascending aorta, main pulmonary artery, and right/left pulmonary arteries of normal volunteers (N = 10) were acquired at 3T and analyzed using a conventional FCFE sequence and a CVX sequence with either higher spatial resolution or higher temporal resolution. All sequences mitigated chemical shift-induced phase errors and used equivalent breath-hold durations. RESULTS: Chemical shift-optimized PC-MRI has increased sequence efficiency when using CVX, which can provide either higher spatial or higher temporal resolution compared with conventional FCFE PC-MRI. Numerical simulations, flow phantom experiments, and in vivo experiments indicate that CVX measurements of total flow and peak velocity are increased and more accurate when compared with FCFE. CONCLUSION: CVX PC-MRI increases sequence efficiency while reducing chemical shift-induced phase errors. This can be used to provide either higher spatial or higher temporal resolution than conventional chemical shift-mitigated PC-MRI methods to provide more accurate measurements of blood flow and peak velocity.
Authors: Krishna S Nayak; Jon-Fredrik Nielsen; Matt A Bernstein; Michael Markl; Peter D Gatehouse; Rene M Botnar; David Saloner; Christine Lorenz; Han Wen; Bob S Hu; Frederick H Epstein; John N Oshinski; Subha V Raman Journal: J Cardiovasc Magn Reson Date: 2015-08-09 Impact factor: 5.364