Continuous arterial spin labeling using a train of adiabatic inversion pulses

Purpose: To develop a simple and robust magnetic resonance imaging (MRI) pulse sequence for the quantitative measurement of blood flow in the brain and cerebral tumors that has practical implementation advantages over currently used continuous arterial spin labeling (CASL) schemes. Materials and Methods: Presented here is a single-coil protocol that uses a train of hyperbolic secant inversion pulses to produce continuous arterial spin inversion for perfusion weighting of fast spin echo images. Flow maps of normal rat brains and those containing a 9L gliosarcoma orthotopic tumor model conditions were acquired with and without carbogen. Results: The perfusion-weighted images have reduced magnetization transfer signal degradation as compared to the traditional single-coil CASL while avoiding the use of a more complex two-coil CASL technique. Blood flow measurements in tumor and normal brain tissue were consistent with those previously reported by other CASL techniques. Contralateral and normal brain showed increased blood flow with carbogen breathing, while tumor tissue lacked the same CO2 reactivity. Conclusion: This variation of the CASL technique is a quantitative, robust, and practical single-coil method for measuring blood flow. This CASL method does not require specialized radiofrequency coils or amplifiers that are not routinely used for anatomic imaging of the brain, therefore allowing these flow measurements to be easily incorporated into traditional rodent neuroimaging protocols.