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3.3.1 Brain MRI in an “Easy-to-Site Suite”
ОглавлениеA head–neck focus can still utilize conventional but “shrunk-down” superconducting magnet architectures (perhaps with asymmetric gradients) to provide the “easy-to-site suite” and possibly reduce cost. High-field superconducting head-only scanners include the Siemens Allegra 3-T clinical scanner [29] introduced in the early 2000s but no longer produced, and the more recent GE high-performance 3-T head scanner employing a conduction-cooled magnet with no cryogen vent-pipe [30]. While the magnet and gradients of these high-field head-only systems are more compact, the focus of these two systems was on performance rather than siting alone, which is only modestly simplified. There is renewed interest in making additional changes to provide easier siting of superconducting systems within an ED, ICU, or interventional suite. These approaches all leverage intermediate-field (B0 near 0.5 T) superconducting systems with cryogen-free refrigeration systems such as a conduction-cooled 0.55-T [31] or 0.5-T scanner [32–34], both employing modern, high-performance gradient systems in a standard architecture. Other efforts are underway with an even smaller head-focused 1.5-T high-temperature superconducting magnet [35]. Figure 3.1 shows three “easy-to-site” superconducting approaches recently introduced by manufacturers. Extremely small bore size superconducting magnets have also been introduced as needed for extremity or neonatal imaging.