Spatial and temporal variations in the magnetic fields produced by human gastrointestinal activity

Turnbull, Geoffrey K.; Ritcey, S. P.; Stroink, G.; Brandts, Bodo; Leeuwen, P. van

doi:10.1007/bf02513347

Cited by 11 publications

(6 citation statements)

References 17 publications

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“…23 However, HR mapping is an invasive investigation, requiring direct contact between electrodes and the serosal surface of target organs, and its application in the clinical setting is therefore limited. Research is ongoing into methods that can noninvasively describe GI electropathophysiology, namely electrograstrography (EGG), 24,27 and magnetogastrography (MGG), 4,33 which would have greater clinical utility. However, EGG and MGG presently lack the sensitivity required to adequately describe slow wave electropathophysiology, and the correlation between serosal slow wave activity and EGG and MGG recordings remains incompletely defined.…”

Section: Discussionmentioning

confidence: 99%

High-resolution Mapping of In Vivo Gastrointestinal Slow Wave Activity Using Flexible Printed Circuit Board Electrodes: Methodology and Validation

et al. 2009

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High-resolution, multi-electrode mapping is providing valuable new insights into the origin, propagation, and abnormalities of gastrointestinal (GI) slow wave activity. Construction of high-resolution mapping arrays has previously been a costly and time-consuming endeavor, and existing arrays are not well suited for human research as they cannot be reliably and repeatedly sterilized. The design and fabrication of a new flexible printed circuit board (PCB) multi-electrode array that is suitable for GI mapping is presented, together with its in vivo validation in a porcine model. A modified methodology for characterizing slow waves and forming spatiotemporal activation maps showing slow waves propagation is also demonstrated. The validation study found that flexible PCB electrode arrays are able to reliably record gastric slow wave activity with signal quality near that achieved by traditional epoxy resin-embedded silver electrode arrays. Flexible PCB electrode arrays provide a clinically viable alternative to previously published devices for the high-resolution mapping of GI slow wave activity. PCBs may be mass-produced at low cost, and are easily sterilized and potentially disposable, making them ideally suited to intra-operative human use.

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Section: Discussionmentioning

confidence: 99%

High-resolution Mapping of In Vivo Gastrointestinal Slow Wave Activity Using Flexible Printed Circuit Board Electrodes: Methodology and Validation

et al. 2009

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“…The magnetogastrogram (MGG) measures the same underlying electrical activity as the EGG 22–26 . Superconducting quantum interference device (SQUID) magnetometers have unrivalled sensitivity for detecting the weak magnetic fields associated with the slow wave (fields on the order of picotesla, pT).…”

Section: Introductionmentioning

confidence: 99%

Biomagnetic signatures of uncoupled gastric musculature

Bradshaw

Irimia

Sims

et al. 2009

Neurogastroenterology Motil

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Gastric slow waves propagate in the electrical syncytium of the healthy stomach, being generated at a rate of approximately three times per minute in a pacemaker region along the greater curvature of the antrum and propagating distally towards the pylorus. Disease states are known to alter the normal gastric slow wave. Recent studies have suggested the use of biomagnetic techniques for assessing parameters of the gastric slow wave that have potential diagnostic significance. We present a study in which the gastric syncytium was uncoupled by mechanical division as we recorded serosal electric potentials along with multichannel biomagnetic signals and cutaneous potentials. By computing the surface current density (SCD) from multichannel biomagnetic recordings, we were able to quantify gastric slow wave propagation as well as the frequency and amplitude of the slow wave and to show that these correlate well with similar parameters from serosal electrodes. We found the dominant slow wave frequency to be an unreliable indicator of gastric uncoupling as uncoupling results in the appearance of multiple slow wave sources at various frequencies in external recordings. The percentage of power distributed in specific frequency ranges exhibited significant postdivision changes. Propagation velocity determined from SCD maps was a weak indicator of uncoupling in this work; we believe that the relatively low spatial resolution of our 19-channel biomagnetometer confounds the characterization of spatial variations in slow wave propagation velocities. Nonetheless, the biomagnetic technique represents a non-invasive method for accurate determination of clinically significant parameters of the gastric slow wave.

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“…Our group and others have previously recorded the magnetogastrogram (MGG), the magnetic correlate of the EGG, which measures the transabdominal magnetic fields associated with gastric slow wave activity 13–17 . Human studies of the MGG have demonstrated frequencies that correlate with those detected by EGG and that are consistent with the known frequency of the gastric slow wave, 15 and animal studies have demonstrated good correlation between serosal electrode waveforms and transabdominal MGG 14 …”

Section: Introductionmentioning

confidence: 99%

Biomagnetic characterization of spatiotemporal parameters of the gastric slow wave

Bradshaw

Irimia

Sims

et al. 2006

Neurogastroenterology Motil

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Certain gastric disorders affect spatiotemporal parameters of the gastric slow wave. Whereas the electrogastrogram (EGG) evaluates electric potentials to determine primarily temporal parameters, fundamental physical limitations imposed by the volume conduction properties of the abdomen suggest the evaluation of gastric magnetic fields. We used a multichannel superconducting quantum interference device magnetometer to study the magnetogastrogram (MGG) in 20 normal human subjects before and after a test meal. We computed the frequency and amplitude parameters of the gastric slow wave from MGG. We identified normal gastric slow wave activity with a frequency of 2.6 ± 0.5 cycles per minute (cpm) preprandial and 2.8 ± 0.3 cpm postprandial. In addition to frequency and amplitude, the use of surface current density mapping applied to the multichannel MGG allowed us to visualize the propagating slow wave and compute its propagation velocity (6.6 ± 1.0 mm s )1 preprandial and 7.4 ± 0.4 mm s )1 postprandial). Whereas MGG and EGG signals exhibited strong correlation, there was very little correlation between the MGG and manometry. The MGG not only records frequency dynamics of the gastric slow wave, but also characterizes gastric propagation. The MGG primarily reflects the underlying gastric electrical activity, but not its mechanical activity.

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Spatial and temporal variations in the magnetic fields produced by human gastrointestinal activity

Cited by 11 publications

References 17 publications

High-resolution Mapping of In Vivo Gastrointestinal Slow Wave Activity Using Flexible Printed Circuit Board Electrodes: Methodology and Validation

High-resolution Mapping of In Vivo Gastrointestinal Slow Wave Activity Using Flexible Printed Circuit Board Electrodes: Methodology and Validation

Biomagnetic signatures of uncoupled gastric musculature

Biomagnetic characterization of spatiotemporal parameters of the gastric slow wave

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