Siemens Aktiengesellschaft

Richard Koellner

Klaus Ludwig

Gerhard Brinker

Frank Rabe

Friedrich Arneth

In a method and apparatus for magnetic resonance imaging with adherence to SAR limit values, a patient is subjected to a radio-frequency pulse sequence via at least one transmission antenna and the magnetic resonance signals that are produced are acquired in a spatially resolved manner via at least one reception antenna and are further-processed for producing magnetic resonance images or spectra, with current SAR values, determined before the implementation of the measurement on the basis of patient data and the position of the patient relative to the transmission antenna for planned parameters of the measurement, being modified as warranted until the current SAR values lie within the SAR limit values. The determination of the current SAR values ensues by comparing the current measurement situation to pre-defined measurement situations stored in a data bank for which pre-calculated SAR values are stored. The stored SAR value of the measurement situation of the data bank coming closest to the current measurement situation is utilized as the current SAR value. A reduction of the calculating outlay for determining the SAR values during the examination is achieved, and the data bank values can be calculated highly detailed, allowing a more exact determination of the current SAR values. The reduction of the safety margins that is achieved allows an enhancement of the system performance for the user, so that the user can implement the measurements in a shorter time and/or simultaneously acquire a number of tomograms.

Magnetic resonance imaging apparatus and method with adherence to SAR limits

In a method and apparatus for magnetic resonance imaging with adherence to SAR limits, a patient is exposed to a radio-frequency pulse sequence via at least one transmission antenna for the implementation of a measurement and the magnetic resonance signals that are generated are acquired in a spatially resolved manner via at least one reception antenna and are further-processed for generating magnetic resonance images or spectra, with current SAR values for planned parameters of the measurement being identified before the implementation of the measurement and the parameters being modified as needed until the current SAR values lie within the SAR limits. The determination of the current SAR values ensues employing stored data that contain the time curve of the RF stressing of the patient during one or more preceding measurements, as well as information from which the temporal spacing of the RF stress of the preceding measurements from the planned measurement can be determined. Better utilization of the performance capability of the magnetic resonance tomography apparatus is achieved by the patient throughput, which is of particular interest for economic feasibility, being increased with adherence to the SAR limit values.

Magnetic resonance imaging method and apparatus with adherence to SAR limits in a scan using data from a previous scan

A magnetic resonance imaging apparatus has a magnet with at least one patient receptacle and at least one support plate, as well as a predetermined number of transmit and/or receive coils. In at least two predetermined exposure positions, at least one exposure respectively takes place using predetermined adjustment parameters. High-contrast exposures can be obtained in a short time, by the required adjustment parameters being determined in a preceding adjustment process, and the exposures are carried out in a subsequent exposure process.

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Weisendorf, Germany

Richard Koellner