Adjustable permanent magnet assembly for nmr and mri

A magnetic resonance imaging (MRI) method comprising:

• providing an array of permanent magnets to one side an imaging object;
• selecting a target region;
• rotating one or more permanent magnets about one or more axes of rotation to one or more orientations to move a desired magnetic field sensitive volume from a first target region to the selected target region;
• and
• performing an MRI measurement of the imaging object at the selected target region.

A magnetic resonance imaging (MRI) device comprising:

• an array of permanent magnets that are configured to rotate about one or more axes of rotation;
• a processor configured to:
• select a target region;
• command one or more permanent magnets to one or more orientations to move a desired magnetic field sensitive volume from a first target region to the selected target region;
• and
• perform an MRI measurement at the selected target region.

A method of determining permanent magnet (PM) orientations in a PM array for magnetic resonance imaging (MRI), the method comprising:

• selecting a target region and target magnetic fields within the target region;
• finding a minimum of a cost function representing a norm squared of a difference between the target magnetic fields and trial magnetic fields while constraining strengths of magnetizations of the permanent magnets (PMs);
• and
• determining a PM orientation for at least one of the PMs based at least in part on the constrained minimization.