The hemodynamics of the umbilical artery in normal and pre-eclamptic pregnancies. A new application of SQUID biomagnetometry

Fetal magnetocardiogram recordings and Fourier spectral analysis

Power spectral analysis of fetal magnetocardiogram (FMCG) data was evaluated in 64 pregnancies, using the non-invasive one channel superconducting quantum interference device (DC-SQUID), in order to investigate the power spectral amplitude distribution in the frequency range between 2 and 3 Hz. In all cases with normal and uncomplicated pregnancies, the data from the fetal heart and specifically the QRS complexes, were identifiable and unaffected by any maternal cardiac activity and furthermore the power spectral amplitudes, which varied between 120 and 350 fT/Hz, were directly related to gestational age.

Differentiation of myomas by means of biomagnetic and doppler findings

Aim

To elucidate the hemodynamics of the uterine artery myomas by use of Doppler ultrasound and biomagnetic measurements.

Method

Twenty-four women were included in the study. Sixteen of them were characterised with large myomas whereas 8 of them with small ones. Biomagnetic signals of uterine arteries myomas were recorded and analyzed with Fourier analysis. The biomagnetic signals were distributed according to spectral amplitudes as high (140–300 ft/√Hz), low (50–110 ft/√Hz) and borderline (111–139 ft/√Hz). Uterine artery waveform measurements were evaluated by use of Pulsatility Index (PI) (normal value PI < 1.45).

Results

There was a statistically significant difference between large and small myomas concerning the waveform amplitudes (P < 0.0005) and the PI index (P < 0.0005). Specifically, we noticed high biomagnetic amplitudes in most large myomas (93.75 %) and low biomagnetic amplitudes in most small ones (87.5 %).

Conclusion

It is suggested that the biomagnetic recordings of uterine artery myomas could be a valuable modality in the estimation of the circulation of blood cells justifying the findings of Doppler velocimetry examination.

Correlation between biomagnetic and Doppler findings of the uterine artery in normal and preeclamptic pregnancies

OBJECTIVES

To elucidate the hemodynamics of the uterine artery in normal and abnormal pregnancies by use of Doppler ultrasound and SQUID biomagnetometry.

METHOD

Two hundred and three women (gestational age 28-42 weeks) were included in the study. Forty-three of them had preeclampsia and/or intrauterine growth restriction and 160 were normal. Uterine artery waveform measurements were evaluated by use of pulsatility index (PI) (normal value PI<1.45). Biomagnetic signals of uterine arteries were recorded and analyzed with Fourier analysis. The biomagnetic signals were distributed according to spectral amplitudes as high (140-300 fT/ radicalHz), low (50-110 fT/ radicalHz) and borderline (111-139 fT/ radicalHz).

RESULTS

There was a statistically significant difference between normal and abnormal pregnancies concerning the waveform amplitudes (p < 0.001) and the PI index (p < 0.001). Specifically, we noticed high biomagnetic amplitudes in most normal pregnancies (92.5%) and low biomagnetic amplitudes in most preeclamptic cases (90.7%).

CONCLUSIONS

Our study results indicated that biomagnetic measurements of uterine artery might prove to be useful in the evaluation of the fetal well being, especially in cases of preeclampsia and intrauterine growth restriction.

The chaos theory for differentiating fetal biomagnetic brain activity in normal and pre-eclamptic pregnancies

In this study we investigated the fetal biomagnetic brain activity obtained in normal and pre-eclamptic pregnancies using a non-linear analysis. Measurements were performed using a single channel biomagnetometer superconducting quantum interference device (SQUID) in an electrically shielded room of low magnetic noise. Using the application of non-linear analysis and dimensionality calculations we have observed a clear saturation for the dimension of the fetal biomagnetic brain activity from pre-eclamptic pregnancies and no saturation for fetal brain activity in normal pregnancies. Thus, the biomagnetic measurements with the SQUID and the application of non-linear analysis, is a promising procedure in assessing and differentiating fetal biomagnetic brain activity in normal and pre-eclamptic pregnancies.

Fetal magnetoencephalogram recordings and Fourier spectral analysis

This study investigates the fetal brain activity in normal and pre-eclamptic pregnancies. Measurements were performed by means of a Superconducting Quantum Interference Device (SQUID) in an electrically shielded room of low magnetic noise. The study was prospective. Eleven pregnant women with pre-eclampsia and 21 normal pregnancies were included. All were at 37-40 weeks of pregnancy. Biomagnetic signals (waveforms), recorded from the fetal brains in the frequency range of 2-7 Hz, were expressed in terms of magnetic power spectral amplitudes. These were low (mean, 376.67; SD, 28.66) in almost all normal pregnancies, and high (mean, 554.91; SD, 149.56) in most pregnancies complicated with preeclampsia. These findings were of statistical significance (Student's t -test, P < 0.005). Biomagnetic measurements of fetal brain activity is a promising screening procedure for assessing the cerebral function, especially in high risk pregnancies.

Correlation between biomagnetic and Doppler findings of umbilical artery in fetal growth restriction

OBJECTIVE

To assess the value of biomagnetic recordings of the umbilical artery over Doppler ultrasound screening in order to predict complications of impaired uteroplacental blood flow in fetuses with intrauterine growth restriction (IUGR).

METHODS

Our study population included 11 IUGR preeclamptic (34-37-weeks gestation; birth weight 1969 +/- 129 g) and 19 normal pregnancies (34-37-weeks gestation; birth weight 3195 +/- 229 g). Umbilical artery Doppler ultrasound waveform measurements were expressed in terms of pulsatility index (PI). Biomagnetic signals (waveforms) recorded from the IUGR umbilical artery were expressed in terms of magnetic power spectral amplitudes.

RESULTS

In all cases, the frequency band considered was 2 to 7 Hz. The spectral amplitudes were low (mean: 117+/-24 fT/ radical Hz) in most (90.9%) IUGR pregnancies and high (mean: 224+/-37 fT/ radical Hz) in most normal pregnancies (89.5%). There was a statistically significant difference between normal and IUGR pregnancies with respect to spectral amplitudes (p < 0.0001), Doppler PI (p < 0.0005), pH (p < 0.0005) and Apgar score (p < 0.0005). Multiple linear regression analysis revealed an influence of PI, pH and Apgar scores on the biomagnetic values (ANOVA: p < 0.0005).

CONCLUSION

Our data imply that biomagnetic values of the umbilical artery flow could prove to be a helpful method for the evaluation of fetal well being especially in pregnancies complicated with preeclampsia and growth restriction.

Differential diagnosis of prostate lesions with the use of biomagnetic measurements and non-linear analysis

The purpose of this study was to investigate the biomagnetic activity emitted from the prostate gland and to differentiate cancerous from benign prostate lesions with the use of biomagnetic measurement and non-linear analysis. Magnetic recordings were obtained from 47 patients with palpable prostate lesions. Histology revealed 24 prostate cancer patients and 23 benign prostate hyperplasia (BPH) patients. The superconducting quantum interference device (SQUID) biomagnetometer was used to measure the prostate's magnetic field by placing the SQUID detector 3 mm above the symphysis pubis. The magnetic field recorded in the 2-7 Hz frequency range was of high amplitude in most malignant lesions whereas all benign cases were of low amplitude. According to our results, the sensitivity, specificity, positive predictive value and negative predictive value were 83.33%, 100%, 100% and 85.18%, respectively. By applying the Grassberger-Procaccia algorithm to the magnetoprostatogram time series in malignant and benign prostate lesions we found clear saturation in malignant prostate lesions with m>7 whereas in the benign lesions there was not clear saturation. Prostate cancer emits higher biomagnetic activity than the BPH. This confirms a higher angiogenic activity in prostate cancer than the BPH lesions. Furthermore, the saturation value in the estimation of the correlation dimension of the attractor for the cancer lesions confirms the lower complexity of the system in comparison to the BPH, which is characterized by higher complexity.

SQUID biomagnetometry of the uterine arteries in normal and pre-eclamptic pregnancies

AIM

This study was designed to investigate the hemodynamics of the uteroplacental circulation in normal and pre-eclamptic pregnancies using the biomagnetometer SQUID.

METHOD

Twenty-two pregnancies complicated by pre-eclampsia and 49 normal pregnancies were included in this study. All were near term. Biomagnetic signals were recorded from the uterine arteries. After statistical Fourier analysis, the findings were designated in terms of spectral amplitudes as high (140-300 fT/square root of Hz), low (50-110 fT/square root of Hz) and borderline (111-139 fT/square root of Hz).

RESULTS

The uterine artery waveforms and the corresponding spectral densities were of high amplitudes in most (89.7%) normal pregnancies and of low amplitudes in most (81.8%) pregnancies complicated by pre-eclampsia (p < 0.005). These findings were of statistical significance and were correlated with fetal heart rate (FHR) monitoring, pH, Apgar score at 1 and 5 minutes and birth weight percentiles: high amplitude cases were related with normal FHR patterns, pH > 7.25, Apgar score > 7 and birth weight > 75th percentile, while low amplitude recordings were connected with abnormal FHR patterns, pH < 7.25, Apgar score < 7, and birth weight < 10th percentile (8 cases) and < 50th percentile (10 cases).

CONCLUSION

Biomagnetic measurement of the uterine artery flow, is a promising procedure in assessing fetal health, especially in high-risk pregnancies.

Nonlinear analysis of biomagnetic signals recorded from the umbilical artery in normal and pre-eclamptic pregnancies

OBJECTIVE

In this study we investigated the hemodynamics of the feto-placental circulation in normal and pre-eclamptic near term pregnancies using the biomagnetometer SQUID. Thirteen abnormal and 25 normal pregnancies were included in this study.

STUDY DESIGN

The biomagnetic signals were analyzed using nonlinear analysis in order to differentiate these two types of pregnancies.

RESULTS

The application of nonlinear analysis reveal a clear saturation dimension value for pre-eclamptic and non-saturation for normal pregnancies. These findings were statistically significant and were correlated with fetal heart rate monitoring, pH and Apgar score: high biomagnetic cases (140-300 fT/square root Hz) were related with normal patterns, pH>7.25 and Apgar >7, while low biomagnetic recordings (50-110 fT/square root Hz) were connected with abnormal patterns, pH<7.25 and Apgar <7.

CONCLUSIONS

It is suggested that the biomagnetic measurements with SQUID and the application of nonlinear analysis, is a promising procedure in assessing fetal health, especially in high risk pregnancies.

The use of non-linear analysis for differentiating the biomagnetic activity in ovarian lesions

In this study we investigated the biomagnetic activity measured with the superconducting quantum interference device (SQUID) in benign and malignant ovarian lesions using non-linear analysis. We used a single channel biomagnetometer SQUID in order to measure the magnetic field emitted from benign and malignant ovarian lesions. We can differentiate such biomagnetic activities using non-linear analysis. Using the application of non-linear analysis in the ovarian lesions together with the use of dimensional calculations we have observed a clear saturation value for the dimension of malignant ovarian lesions and non-saturation for benign ovarian lesions. The biomagnetic measurements with the SQUID and the application of non-linear analysis in benign and malignant ovarian lesions, is a promising procedure in assessing and differentiating ovarian tumours.