Biomagnetic Measurement of Gastric Mechanical Motility Using a High-Temperature SQUID Imaging

Nomura, Masahiro; Saijyo, Tetsuya; Haruta, Yasuhiro; Itozaki, Hideo; Toyoda, Haruhisa; Nakaya, Yutaka; Ito, Susumu; Kado, H.

doi:10.1007/978-1-4612-1260-7_152

Cited by 4 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the last decade, fMCG has received increasing attention from scientists working in prenatal medicine because, after appropriate processing, it allows the monitoring of the The development of new acquisition systems working in an unshielded environment and/or suitable for bedside recordings in a hospital setting (Budnyk et al 2004, Nomura et al 2004, Weis et al 2004 implies that the experimental stage, when data acquisition and analysis procedures are developed and tested in research laboratories, evolves to the point when they are assessed for clinical use. Some standardization has already been proposed for fMCG acquisition parameters (Grimm et al 2003a); in a similar way, the homogenization of the techniques used to process fMCG recordings would favour the comparability of fetal cardiac signals obtained with different devices, therefore approaching a larger clinical exploitation of fMCG.…”

Section: Discussionmentioning

confidence: 99%

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

et al. 2005

View full text Add to dashboard Cite

The greatest impediment to extracting high-quality fetal signals from fetal magnetocardiography (fMCG) is environmental magnetic noise, which may have peak-to-peak intensity comparable to fetal QRS amplitude. Being an unstructured Gaussian signal with large disturbances at specific frequencies, ambient field noise can be reduced with hardware-based approaches and/or with software algorithms that digitally filter magnetocardiographic recordings. At present, no systematic evaluation of filters' performances on shielded and unshielded fMCG is available. We designed high-pass and low-pass Chebychev II-type filters with zero-phase and stable impulse response; the most commonly used band-pass filters were implemented combining high-pass and low-pass filters. The achieved ambient noise reduction in shielded and unshielded recordings was quantified, and the corresponding signal-to-noise ratio (SNR) and signal-to-distortion ratio (SDR) of the retrieved fetal signals was evaluated. The study regarded 66 fMCG datasets at different gestational ages (22-37 weeks). Since the spectral structures of shielded and unshielded magnetic noise were very similar, we concluded that the same filter setting might be applied to both conditions. Band-pass filters (1.0-100 Hz) and (2.0-100 Hz) provided the best combinations of fetal signal detection rates, SNR and SDR; however, the former should be preferred in the case of arrhythmic fetuses, which might present spectral components below 2 Hz.

show abstract

Section: Discussionmentioning

confidence: 99%

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Different MCG devices are used in research laboratories and clinical environments, each with a specific sensor configuration and technical characteristics; moreover, a great effort is presently being made to develop new MCG devices dedicated to fetal acquisitions and/or suitable to work in a hospital setting and portable bedside (Lowery et al 2003, Robinson et al 2001, Budnyk et al 2004, Nomura et al 2004, Suzuki et al 2004, Brisinda et al 2005. For this reason, the proposed model was implemented in an open architecture software suitable to process data recorded with different MCG systems.…”

Section: Discussionmentioning

confidence: 99%

A method for the automatic reconstruction of fetal cardiac signals from magnetocardiographic recordings

Mantini¹,

Alleva²,

Comani³

2005

Phys. Med. Biol.

View full text Add to dashboard Cite

Fetal magnetocardiography (fMCG) allows monitoring the fetal heart function through algorithms able to retrieve the fetal cardiac signal, but no standardized automatic model has become available so far. In this paper, we describe an automatic method that restores the fetal cardiac trace from fMCG recordings by means of a weighted summation of fetal components separated with independent component analysis (ICA) and identified through dedicated algorithms that analyse the frequency content and temporal structure of each source signal. Multichannel fMCG datasets of 66 healthy and 4 arrhythmic fetuses were used to validate the automatic method with respect to a classical procedure requiring the manual classification of fetal components by an expert investigator. ICA was run with input clusters of different dimensions to simulate various MCG systems. Detection rates, true negative and false positive component categorization, QRS amplitude, standard deviation and signal-to-noise ratio of reconstructed fetal signals, and real and per cent QRS differences between paired fetal traces retrieved automatically and manually were calculated to quantify the performances of the automatic method. Its robustness and reliability, particularly evident with the use of large input clusters, might increase the diagnostic role of fMCG during the prenatal period.

show abstract

“…During these last years, multi-channel MCG systems have undergone rapid technological developments, their dimensions and costs have been reduced, and successful trials of unshielded fMCG in a hospital setting have already been performed (Brisinda et al 2005). Prototype high-temperature multi-channel systems have recently been produced (Budnyk et al 2004, Nomura et al 2004, Suzuki et al 2004, and the time when these systems will be brought bedside is not too far in the future. In association with instrumentation advances, an analytical model that works on dependable fetal magnetocardiograms and provides a timely quantification of cardiac intervals and their variability might be an effective tool for the clinical use of fMCG in a number of clinical applications.…”

Section: Discussionmentioning

confidence: 99%

Automatic detection of cardiac waves on fetal magnetocardiographic signals

Comani¹,

Mantini²,

Alleva³

et al. 2005

Physiol. Meas.

View full text Add to dashboard Cite

Fetal magnetocardiography (fMCG) provides fetal cardiac traces useful for the prenatal monitoring of fetal heart function. In this paper, we describe an analytical model (ACWD) for the automatic detection of cardiac waves boundaries that works on fetal signals reconstructed from fMCG by means of independent component analysis. ACWD was validated for 45 healthy and 4 arrhythmic fetuses ranging from 22 to 37 weeks; ACWD outcomes were compared with the estimates of three independent investigators. Descriptive statistics were used to assess correspondence between the outcomes of the automatic and manual approaches. The parametric two-tailed Pearson correlation test (alpha=0.01) was employed to quantify, by means of the coefficients of determination, the amount of common variation between the sequences of intervals quantified automatically and manually. ACWD performances on short and long rhythm strips were investigated. ACWD demonstrated to be a robust tool providing dependable estimates of cardiac intervals and their variability during the third gestational trimester also in case of fetal arrhythmias. SNR and stability of fetal traces were the factors limiting ACWD performances. ACWD computation time, which was approximately 1:600 with respect to the manual procedure, was comparable with the time required for fCTI estimation on averaged beats.

show abstract

Biomagnetic Measurement of Gastric Mechanical Motility Using a High-Temperature SQUID Imaging

Cited by 4 publications

References 2 publications

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

A method for the automatic reconstruction of fetal cardiac signals from magnetocardiographic recordings

Automatic detection of cardiac waves on fetal magnetocardiographic signals

Contact Info

Product

Resources

About