Fetal magnetocardiography: clinical relevance and feasibility

Brake, ter Hjm Marcel; Rijpma, A.P.; Stinstra, J.G.; Borgmann, J.; Holland, H.J.; Krooshoop, Hendrikus J.G.; Peters, M.J.; Flokstra, Jaap; Quartero, Hwp; Rogalla, Horst

doi:10.1016/s0921-4534(01)01132-7

Cited by 27 publications

(27 citation statements)

References 29 publications

(36 reference statements)

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“…Therefore, the maximum level of the magnetic noise due to the shield that allows realizing an adequate SNR needs to be investigated. In our optimization, we vary this magnetic noise between 0 and 10 fT Hz, which is the worst sensitivity level that is acceptable in fetal magnetocardiography [2]. We optimize the geometry of the gradiometer for all assumed values of and then choose such that the SNR is acceptable.…”

Section: A Measuring Systemmentioning

confidence: 99%

“…The spectral content of the signal is typically in between 1 and 100 Hz. For a successful recording of fMCGs, a resolution better than 10 fT Hz is required [2]. In unshielded environments, this resolution is hard to achieve since the interference from environmental sources can have a spectral density up to 10 nT Hz at the frequency of 1 Hz [3], which is one million times the required sensitivity level.…”

Section: Introductionmentioning

confidence: 99%

“…When operated outside a magnetically shielded room, a fetal magnetocardiograph requires a gradiometer of second or even third order [2], [4]. In this paper, we limit ourselves to the optimization of the third-order gradiometer that is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of a Third-Order Gradiometer for Operation in Unshielded Environments

Uzunbajakau

Rijpma

Brake

et al. 2005

IEEE Trans. Appl. Supercond.

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Abstract-The optimum geometry of a third-order gradiometer for operation in unshielded environments is discussed. The optimization result depends on the specific signal and noise conditions. The fetal heart is considered as an example of the signal source. We optimized the gradiometer such that the signal-to-noise ratio is maximized in an averaged sense for all relevant environmental noise conditions and distances to the signal source. The resulting design consists of two second-order gradiometers that can be combined to form a third-order gradiometer in noisy environments, whereas a single second-order gradiometer can be used in lownoise environments. The gradiometer can provide the signal-tonoise ratio that allows detection of fetal heart signals in all relevant environmental noise conditions.

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Section: A Measuring Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimization of a Third-Order Gradiometer for Operation in Unshielded Environments

Uzunbajakau

Rijpma

Brake

et al. 2005

IEEE Trans. Appl. Supercond.

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“…Today, SQUID-based magnetometers can provide a field sensitivity of the order of 10 fT which is adequate for the recording of fetal heart signals [2]. The ambient sources of magnetic field produce interference that can reach a level of 10nT at a frequency of 1 Hz [3], which is times higher than the intrinsic noise of a SQUID-based magnetometer.…”

Section: Introductionmentioning

confidence: 99%

“…The high costs of such a room are considered to be the major barrier between such a promising diagnostic technique as fetal magnetocardiography and its everyday use in hospitals. As an alternative to a magnetically shielded room, a second-or third-order gradiometer can be used for the suppression of environmental interference [2], [5], [6].…”

Section: Introductionmentioning

confidence: 99%

On Gradiometer Imbalance

Uzunbajakau

Rijpma

Brake

et al. 2006

IEEE Trans. Appl. Supercond.

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We present methods to compute the imbalance in a gradiometer of arbitrary shape due to imperfections in its geometry, eddy currents induced in the radio-frequency interference shield, and screening currents induced in the modules of the superconducting quantum interference devices (SQUIDs). As an example, the methods are applied to evaluate the maximum expected initial imbalance of second-and third-order axial gradiometers in a measuring setup designed for fetal magnetocardiography. Mechanical imperfections in this specific setup appear to have the largest effect: the field imbalance is 2 10 2 ; the first-order gradient imbalance is 10 3 m; the second-order gradient imbalance is 10 4 m 2 . In the example, the imbalance caused by the other effects is one order smaller.

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Multichannel mapping of fetal magnetocardiogram in an unshielded hospital setting

Brisinda

Comani²,

Meloni

et al. 2005

Prenat. Diagn.

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A first demonstration has been given that multichannel mapping of FMCG can be performed in unshielded clinical environments, with resolution good enough for contactless assessment of fetal cardiac electrophysiology. FastICA processing on unshielded FMCG, recorded after the 32nd week, provided beat-to-beat analysis and heart rate variability assessment. Further work is needed to improve signal reconstruction in early pregnancy.

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Fetal magnetocardiography: clinical relevance and feasibility

Cited by 27 publications

References 29 publications

Optimization of a Third-Order Gradiometer for Operation in Unshielded Environments

Optimization of a Third-Order Gradiometer for Operation in Unshielded Environments

On Gradiometer Imbalance

Multichannel mapping of fetal magnetocardiogram in an unshielded hospital setting

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