Cine-ASL: a new arterial spin labeling method for myocardial perfusion mapping in mice using a Cine-FLASH labeling and r
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Cine-ASL: a new arterial spin labeling method for myocardial perfusion mapping in mice using a Cine-FLASH labeling and readout module Thomas Troalen*, Thibaut Capron, Monique Bernard, Patrick Cozzone, Frank Kober From 15th Annual SCMR Scientific Sessions Orlando, FL, USA. 2-5 February 2012 Summary This study presents a novel arterial spin labeling method to assess myocardial perfusion in small rodents. An ECG-gated pseudo-continuous labeling approach is combined with simultaneous readout over the cardiac cycle using Cine-FLASH. This method allows shorter acquisition times than the previously used Look-Locker FAIR gradient-echo technique while preserving spatial resolution and robustness with respect to cardiac motion. Perfusion measurements were carried out on five mice with both techniques under different anesthetic conditions. Perfusion maps and values show good accordance between both experiments. Background Arterial spin labeling (ASL) has been developed and used to quantitatively map rodent myocardial blood flow (MBF) for more than a decade. There is growing interest in improving sensitivity and measurement strategy, because accurate and motion-robust acquisitions are still time-consuming with typical measurement times of about 20 minutes. Here, we propose to combine continuous Cine-MRI gradient echo readout with a pseudo-continuous arterial labeling approach, which leads to a perfusion-dependent stationary regime. Methods Female C57BL/6 mice (weight = 24-30g, n=5) were anesthetized with 1.5% isoflurane added to 1.2l/min of pure O2. MBF was assessed on a Bruker Biospec 4.7T MR system using an ECG-gated Cine-FLASH sequence repeated over several cardiac cycles in order to reach Centre de Résonance Magnétique Biologique et Médicale, UMR CNRS n° 6612, Faculté de Médecine, Aix-Marseille Université, Marseille, France
the steady-state of a FLASH experiment under the influence of perfusion. As shown in figure 1, one echo in each cine block was substituted by an inversion pulse, labeling the arterial blood in a slice covering the aortic arch and atriums at a precise timing within the cardiac cycle. A control scan was achieved by placing the inversion slab in symmetry to the short-axis imaging plane, compensating for magnetization transfer effects. Interleaved tag and control acquisitions are performed for each k-space line with a total acquisition time of 8 minutes. For comparison, a Look-Locker-FAIR gradient echo ASL (LLFAIRGE) measurement was performed (acquisition time 25 minutes). In two mice, both experiments were performed under two different isoflurane concentrations 1.5% and 2%, the latter inducing strong vasodilation. For both methods, perfusion maps were calculated, and MBF was measured in a region of interest placed into the anterior wall of the myocardium.
Results The results showed good concordance between myocardial perfusion assessed with the new Cine-FLASH ASL technique (8.9 ± 2.5 ml g-1 min-1) and LLFAIRGE (9.8 ± 1.8 ml g-1 min-1), although the new technique had a tend
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