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Methods for improving adaptive filter performance of physiology signals in a MR environment Disclosure Number: IPCOM000007384D
Publication Date: 2002-Mar-20
Document File: 1 page(s) / 74K

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Methods for improving adaptive filter performance of physiology signals in a MR


MR-imaging which is controlled, e.g. triggered, on the basis of physiological

signals, e.g. an ECG. In order to avoid disturbances due to switching of gradient fields

adaptive, i.e. recursive filtering of the physiological signals is applied. The filtering is

adjusted on the basis of gradient reference signals which represent the gradient switching. For

fast MR-imaging strong recursion, i.e. fast adaptation of the filter is desired. However, fast

adaptation caused distortion of the filtered physiological signal. A reference physiological

signal is formed, e.g. by averaging several QRS-complexes of the ECG. This reference

physiological signal is then adapted so as to attain maximum correlation with the adaptively

filtered physiological signal. The difference between the adapted reference physiological

signal and the adaptively filtered physiological signal, indicated as an error signal, is then

used for adjusting the filtering coefficients of the adaptive filter(s).In an other embodiment refiltering

of a pre-set portion of the physiological signal is employed. For example the pre-set

portion is the QRS-complex which is detected by an R-peak detection function. In another

example the pre-set portion has strong gain deviations in the filter settings. Further, the

recursion strength may be gradually decreased to a pre-defined minimum value during

occurrence of gradient reference...