Two-peak alignment method of field shimming
US6064208A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 2, 1998 |
| Grant date | May 16, 2000 |
| Priority date | — |
| Expiry date | Apr 2, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/3875
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for shimming main magnetic field in a magnetic resonance imaging apparatus is provided. The method includes generating a radio frequency pulse sequence (200) while a subject is in an examination region (14) of the magnetic resonance imaging apparatus. A reference signal (EC1) which is immune to shim errors is then acquired. Thereafter, a field echo (EC3a) signal is acquired which is sensitive to shim errors. The field echo (EC3a) signal is acquired at a timed interval (T) equal to a multiple of an amount of time it takes for fat and water signals to become in phase. The temporal position of the maximum of the field echo signal is compared to its predicted temporal position (EC3) relative to the reference signal (EC1). The shim term is calculated based on the preceding comparison and an electrical current is applied to one of a gradient offset and a shim coil such that the main magnetic field is adjusted according to the shim term.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.