A radio-frequency (RF) coil apparatus for magnetic resonance (MR) systems (100, 200, 300, 400, 500, 600, 700, 900, 1000) includes a base (102, 502, 702, 902, 1002) having opposed sides (121), a surface (124) to support an object of interest (OOI) for scanning, and fasteners (127) situated at the opposed sides, A positioner (104, 304A, 304B, 504, 604, 704, 1004) is configured to be releasably attached to the base and has a body (130) extending between opposed ends and fasteners (134,) situated at the opposed ends of the body, The body is configured to form an arch between the opposed ends. An upper section (106, 606, 706, 906, 1006) has at least one RF coil array (142) for acquiring induced MR signals, and is configured to be positioned over the positioner.