MRI hardware Superconducting magnet

Magnetic fields greater than 0.5 T can only be generated by extremely heavy electromagnets or by much lighter superconducting magnets. Superconducting magnets are almost universally preferred. Ancillary equipment includes the liquid-helium cooling systems required to keep the temperature low enough (4 K) for superconduction. Cooling consumes the majority of the supplied power. Only a small current is initially required to generate the field, which is then self-sustaining.

Small variations in the homogeneity of the magnetic field give rise to distortions and artefacts. The field is minutely adjusted to improve homogeneity using additional magnets in an automated procedure known as shimming.

Magnetic field gradients are essential to MRI. Rapid switching of gradient coils produces the loud 'knocking' sound associated with magnetic resonance scanners. However, three orthogonal gradients are available which are coupled to generate gradients in any direction.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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