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The FONAR 360° Magnetic Resonance Imaging System is indicated for use in producing images of multiple planes in the head and body. These images correspond to the distribution of hydrogen nuclei exhibiting nuclear magnetic resonance (NMR) and depend for their contrast upon NMR parameters [hydrogen nuclei concentration and flow velocity, T1 (spinlattice relaxation time) and T2 (spin-spin relaxation time)]. As a result of the acquisition and processing of the NMR data, these images display the internal structure of the head and body, and when interpreted by a trained physician, can yield diagnostically useful information.

The FONAR 360° magnet follows the same basic design, operating and physical principles, and construction methods and materials of the predicate magnets. The field strength of this magnet is 6000 gauss (0.6T). This magnet configuration is essentially a combination of basic structural elements of Fonar's previously approved magnets. The two pole assemblies of the vertical-field iron-core electromagnet are separated and supported by steel supports that form the "walls", "ceiling" and "floor" of the room-sized magnet. This provides an unimpeded 360° access to the magnet's imaging gap. The electromagnet coil elements are windings of multiple turns of epoxy-insulated copper installed around the poles of the magnet frame, connected to a regulated power source, and chilled via the closed loop chiller system.

During operation, the poles of the magnet establish a vertical magnet field with a limited fringe field. The magnetic field is created by passing a regulated DC current through the coil windings surrounding the magnet poles. The field strength is proportional to the amount of current in the coils. In this magnet the current supplied will result in a magnetic field of 6000 gauss, ± 5% (0.6T ± 5%), operating at frequencies between 24.27 and 26.92 MHz. This magnet functions with all imaging sequences available in the current software releases. All other non-magnet related equipment and procedures used are as previously reviewed by the FDA in PMA 830076, its supplements, and the 510(k) submissions K910839 and K951681.

The transmitter coil for the Fonar 360° is modified from the coil used in the Quad 12000 magnet to accommodate the openness of the gap and the removal of the vertical posts of the Quad magnet construction. The resulting transmitter coil is configured as a quadrature coil instead of the linear coil used in the Quad. While the construction methods are different, the resulting field after application of the RF power produces the same level of excitation as the previously approved coils, and results in images that are equivalent to those produced by the predicate devices.

The provided text describes the FONAR 360° Magnetic Resonance Imaging Scanner and its substantial equivalence to previously approved FONAR MRI magnets. The document focuses on non-clinical and clinical testing to demonstrate safety and effectiveness primarily through comparison to NEMA standards and predicate devices.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the FONAR 360° MRI scanner are primarily based on demonstrating substantial equivalence to predicate devices (Fonar B3000 and Quad 12000) and adherence to NEMA standards. The reported device performance is presented in comparison to these benchmarks.

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