Instructions for performing a TOF MRA
There are three important points to communicate. First, you must decide if you want to use a saturation band and, if so, the direction of the saturation band. A saturation band removes signal from a vessel depending on the direction of its blood flow. For example, if you want the lower extremity arteries not to have signal, apply a superior saturation band to nullify the craniocaudal arterial flow of blood. Conversely, if it is signal in the veins that you want to remove, then apply an inferior saturation band to nullify the caudocranial venous flow of blood. Generally, when assessing the arteries, the signal in the veins is removed, and vice versa. However, you may elect not to use a saturation band.
Second, it is important to specify the plane of the sequence. The image acquisition must be perpendicular to the long axis of the vessel of interest, or as close to the perpendicular as possible. For example, to assess the arteries of the calf, the axial plane is used. To assess the renal arteries, the sagittal plane is used.
Third, decide whether the TOF image acquisition should be gated to the cardiac or respiratory cycle. For assessment of the arteries in the calf and foot, gating may help to improve image quality.
