Non-linear effects at high-speed moving table imaging

Introduction: Continuously moving table imaging [1-4] is an alternative to multi-station techniques, offering enhanced patient through-put and less artefacts along the interfaces between different subimages. Initially developed for MR angiography [2], possible applications might range, e.g., up to obesity-related diagnostics [4]. In the past years, the provided table speed increased from typically 1-2 cm/s [2] up to 5.3 cm/s [4]. Assuming a longterm continuation of this trend of increasing table speed, one has to keep in mind that at table speeds approaching v ≈ 3⋅10 cm/s, non-linear, relativistic effects have to be taken into account [5]. This study investigates possible consequences, particularly on scan time and the Lorentz transformed RF fields. The study is based on simulations due to the current lack of suitable MR systems. Theory: Given a table speed v, the patient length measured in the table frame Ltab and the laboratory frame Llab differs by a factor γ γ / / 1 2 2 tab tab lab L c v L L ≡ − = (1)