Experience with a multichannel system for biomagnetic study

Abstract

The components of the biomagnetic multichannel system Krenikon are described. The combination of biomagnetically yielded localizations with anatomic images gained from MR or CT is discussed as well as the enhancement of the signal-to-noise ratio by using a correlation technique. The overall localization accuracy is tested with technical phantoms. With volunteers measurements of auditory, visual and somatosensory evoked fields are performed to evaluate the system performance in vivo. Clinical studies were performed mainly with partners from the Universities of Erlangen-Nünberg and Ulm. The data acquisition time typically is 2-10 min which is tolerable both for the patient and the clinical staff. Electric potentials even with invasive electrodes can be recorded simultaneously with the magnetic fields. MEG gives important information for the presurgical diagnosis of epileptic patients and for the understanding of the epilepsy genesis. With MCG, centres of biologic excitation such as ventricular ectopies or accessory bundles in WPW syndrome have been successfully localized.

A novel superconducting quantum interference device for biomagnetic measurements

“…From the above results, amplitudes of all the measured signals were smaller than those reported before [8][9][10]. For the MCG and fetal MCG signals, the smaller results attribute to the shorter gradiometer baseline of 50 mm [11], which is also the reason why the maternal MCG signal was not observed during the fetal MCG measurements.…”

Impact of SQUIDs on functional imaging in neuroscience

“…Some of these systems were research prototypes, such as the 28-channel hybrid system in Rome [13], the 24-channel system in Helsinki [14], and the 19-channel system at Twente [15]. At that time, a few commercial systems were also available, such as the 37-channel 'Magnes' from BTi [16] and the 37-channel Siemens Krenikon [17]. These systems were placed in medium quality shielded rooms, made of one to two layers of high magnetic permeability materials and one layer of aluminum.…”

“…Eventually, a mechanism for non-stationarity of RSNs was proposed from MEG investigations [118]. Specifically, one of these RSNs, the default mode network (DMN), has been demonstrated to play a central role (see figure 10, upper right) in a specific frequency band (beta, [13][14][15][16][17][18][19][20][21][22][23][24][25]. This implies that when the DMN is internally connected, parts of other RSNs link to it in a mechanism of time-specific segregation and/or integration.…”