Radio-frequency coil selection for MR imaging of the brain and skull base

Radio-frequency coils play a crucial role in the quest for optimal magnetic resonance (MR) image resolution. Given the growing variety of specialized coils available for neuroradiologic imaging applications, it is critical th at radiologists use a coherent strategy for successfully matching these coi ls to specific imaging situations. First, fundamental concepts of coil desi gn are reviewed. Subsequently, a coil-selection algorithm for neuroimaging applications is described. The algorithm uses the patient's clinical histor y to derive a region of interest, a desired spatial resolution, and a desir ed contrast resolution. These factors are then used to impose anatomic cove rage and imaging protocol constraints on the set of available coils. Finall y, coil selection is further refined according to patient tolerance factors . The following coils are considered for use with a 1.5-T superconducting M R imager; namely, quadrature birdcage head, neurovascular phased-array, and dual sing le-circular-element coils, as well as investigational coils that have not yet been approved by the U.S. Food and Drug Administration: reduc ed-volume birdcage end-cap, temporal lobe phased-array, carotid artery phas ed-array, coils. Rationales are discussed regarding appropriate coil select ion for screening whole brain and imaging brainstem, cranial nerves, orbits , cerebral cortex, mesial temporal lobes, and internal auditory canal, and for MR angiography.