MRA and phase contrast flow measurements involve the measurement of moving bodies, specifically blood (or in some cases CSF). Motion will produces artifact in MR images. While some of these artifacts are advantageous for the purpose of MRA (TOF) and flow images, unanticipated motion will degrade the quality of the exam. This educational section will discuss the practical considerations and challenges when protocolling MRA and flow measurements.The topics covered will include the discussion of the various challenges associated with the 3 main MRA techniques: time of flight (TOF), contrast enhanced MRA (CE-MRA), and phase contrast MRA. Within each of these topics, intra-voxel dephasing, phase offsets, scan time optimization will be discussed. The use of emerging techniques such as QISS will also be briefly discussed.Beyond the typical considerations, such as partial volume effects, venc selection, and optimization of VNR, we will discuss the challenges associated with eddy currents, phase offset errors, turbulence, and measurement of flow in small vessels. Advanced implementation of 4D flow MRI will also be discussed in detail.