INTERVENTIONAL MRI MAGNETIC FIELD GENERATOR BASED ON PERMANENT MAGNETS

摘要

A magnet assembly primarily for use in MRI Interventional applications is disclosed. The magnet assembly has an array of four main permanent magnets that are spaced-apart and arranged into a ring-like geometry with six easy-access openings. The magnetization direction in each permanent magnet is anti-parallel to any other adjacent permanent magnet in the ring assembly while it is parallel to any other permanent magnet in the array that is oppositely located just as in a quadrupolar system. Such an arrangement has the advantage of concentrating the magnetic field inside the ring enclosure while minimizing magnetic field generated outside. Together, these four spatially spaced-apart permanent magnets create a very homogeneous and strong magnetic field in the central enclosure with two orthogonal access paths with respect to the main magnet axis and one parallel access path to the enclosure. Through one access pathway a patient can be inserted while through the other pathways a doctor can fully access the patient and perform interventional procedures during a real-time MRI scan. For further performance enhancement, the system also has poles and yokes that shape the field and minimize fringe fields. This magnet assembly can achieve 1.0 Tesla or greater magnetic fields for whole-body scanning without saturating the magnet pole and other structures.