Qualitative and quantitative myocardial perfusion with arterial spin labeling

Introduction A reduction of myocardial blood perfusion is the main physio-pathologic mechanism determining ischemic heart disease. Whilst SPECT and echocardiography are considered the reference standards for imaging perfusion defects, MRI techniques are emerging. Dynamic imaging of the first-pass of a contrast agent is currently the most frequently used of these techniques, however, guidelines on the dose of contrast agent that a patient can receive imposes limitations on the MR protocol. Arterial spin labelling (ASL) in contrast is an alternative to first pass imaging and can be performed without the need for contrast agent. Perfusion imaging using ASL can therefore be repeated several times and requires no timing of a bolus of contrast agent. With standard ASL techniques such as flow-sensitive alternating inversion recovery (FAIR) the signal from arterial blood is measured only at one inversion time and is therefore inefficient and time-consuming. A new ASL method for brain imaging has been previously proposed which combines the FAIR preparation with Look-Locker (LL) readout [1] to allow time resolved perfusion studies by the acquisition at multiple inversion times (TI) with high temporal resolution. In this study, this technique has been modified and implemented for myocardial perfusion in a single breath hold. Furthermore, the combination of T1 mapping and ASL allows quantification of myocardial blood flow [2-4]. Quantification of myocardial blood flow can be used as an indicator of microvascular function and can provide sensitive information about heart function. In this study, the combination of qualitative and quantitative assessment of myocardial perfusion is presented in only two breath holds. First results are shown in 6 healthy volunteers.