Abstract: A method of using a magnetometer system to analyse the magnetic field of a region of a subject's body is disclosed. The method comprises using one or more detectors to detect the time varying magnetic field of a region of a subject's body, filtering a signal or signals from the one or more detectors using a filter or filters, and using the filtered signal or signals to analyse the magnetic field generated by the region of a subject's body. The filter or filters is configured to attenuate noise in the signal or signals that is synchronised with motion of the region of the subject's body such as ballistocardiographic noise.

Abstract: A magnetometer system for medical use comprises one or more induction coils for detecting a time varying magnetic field. Each coil has a maximum outer diameter of 10 cm or less, and a configuration such that the ratio of the coil's length to its outer diameter is 0.9 or more, and the ratio of the coil's inner diameter to its outer diameter is 0.6 or more. Each induction coil comprises a magnetic core. The magnetometer system further comprises a detection circuit coupled to each coil and configured to convert a current or voltage generated in the coil by a time varying magnetic field to an output signal for use to analyse the time varying magnetic field.

Abstract: A method of using a magnetometer system to analyse the magnetic field of a region of a subject's body is disclosed. The method comprises obtaining one or more signals corresponding to the time derivative of the time varying magnetic field of a region of a subject's body, averaging the time derivative signal or signals over plural periods, and using the averaged time derivative signal or signals to analyse the magnetic field generated by the region of the subject's body.

Abstract: A method of using a magnetometer system (30) to analyse the magnetic field of a region of a subject's body is provided. The method comprises using one or more detectors (60) to detect the time varying magnetic field of a region of a subject's body, using a digitiser (42) to digitise a signal or signals from the one or more detectors (60), each signal that is digitised including noise and a periodic signal produced by one or more of the one or more detectors (60) due to the time varying magnetic field of the region of the subject's body, and averaging the digitised signal or signals over plural periods. The magnetometer system (30) is configured such that the noise in each signal provided to the digitiser for digitisation is greater than about 25% of the interval between digitisation levels of the digitiser (42).