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Magnetic Resonance Imaging (MRI)


A single solution for all the production measurement needs

Metrolab’s Magnetic Field Camera is the only instrument able to cover nearly all the magnetic measurement needs of MRI magnet production.

MRI – Production

High precision magnetic measurements in a factory environment represent a tremendous challenge, as even the distant passing of large iron objects such as an overhead crane or a fork-lift cause major field distortions. Only rapid, precise and reliable measurements allow technicians to recognize and avoid such spurious effects.

Mapping and shimming: over 1000 points in a few minutes!

MRI magnets use iron shims and shim coils to compensate for field inhomogeneities. An accurate field map is crucial to compute the exact compensation required. After shimming, the field is remapped to verify the results, and, if needed, the entire process is repeated.

Using a single-point teslameter, shimming is extremely tedious at best. At worst, it will never converge. The Magnetic Field Camera simultaneously measures up to 32 points, and is now standard equipment for nearly all the world’s MRI magnet manufacturers.

Ramping: exactly at the specified field!

When a superconducting magnet is first “turned on,” current is injected until the specified field has been attained. The power supply can then be removed, and the field is maintained by the current that continues to circulate in the superconducting coils. The Magnetic Field Camera allows this point to be determined with great precision.

Decay monitoring: when the field is stable – no sooner, no later!

Due to small shifts of the conductors in the strong magnetic field, a new superconducting magnet needs time to “settle down.” The extreme resolution and stability of the Magnetic Field Camera allows this very slight decay to be observed in real time. Further measurements can be performed only when the field is stable – sooner would invalidate the measurements, and later unnecessarily prolongs the production time.

A full complement of tools

For situations where the field needs to be monitored over a wide range, or if several magnets need to be monitored at the same time, Metrolab recommends the use of one of its single-point NMR teslameters. For quick trouble-shooting, inside and outside the bore, Metrolab’s hand-held three-axis magnetometer is the perfect companion for the high-precision NMR systems.