Biomedical subjects

P Anninos

Publications and source records attributed to P Anninos.

At least 19 recordsLinked to original sources

PubMed2006

Transcranial magnetic stimulation. A case report and review of the literature.

OBJECTIVE: Transcranial magnetic stimulation (TMS) is a non-invasive tool for the electrical stimulation of neural tissue. TMS can be applied as single pulses of stimulation, pairs of stimuli separated by variable intervals to the same or different brain areas, or as trains of repetitive stimuli at various frequencies. CASE REPORT: A 2-years-old male infant was referred to our department with a history of Epstein-Barr virus (EBV) encephalitis, treated with foscarnet and steroids, for he developed mutism and ataxia and loss of the ability to eat, walk and talk. Brain imaging revealed loss of white matter around ventricles and progressive global brain atrophy, findings consistent with encephalopathy. Serology for antibodies against EBV infection was positive and the diagnosis of acute and prolonged EBV infection was made. There was an improvement of the clinical findings after the application of TMS with proper field characteristics (intensity: 1-7.5 pT, frequency: 8-13 Hz). CONCLUSIONS: Our case illustrates the possibility of therapeutic applications of TMS (in the order of pT) with proper field characteristics to normalize pathologically decreased levels of brain cortex activity. TMS might provide novel insights into the pathophysiology of the neural circuitry, be developed into clinically useful diagnostic and prognostic tests, and have therapeutic uses in various diseases.

Atrophy↗

PubMed2006

Magnetoencephalography and magnetocardiography in neonates. Our experience in Greece.

This study reports our experience in the application of magnetoencephalography (MEG) and magnetocardiography (MCG) in neonates. Results gained from our studies, lead us to believe that MEG and MCG could provide clinical practice with non-invasive, rapid and easy to perform methods, which could be adjuncts to conventional methods for the evaluation of neonatal brain and heart function.

Adolescent↗

PubMed2005

Low-frequency MEG activity and MRI evaluation in Parkinson's disease.

BACKGROUND: Low - frequency activity has been reported in Parkinson disease (PD). We investigated the magnetoencephalographic (MEG) recordings from PD patients and healthy volunteers in the frequency domain. METHODS: The MEG recordings were carried out in a magnetically shielded room with a whole-head 122-channel gradiometer. Nine patients suffering from PD and 9 age and gender matched healthy subjects were included in the study. MRI with T1-w and T2-w images, was available in patients' records. RESULTS: Frequency analysis may be usefully combined in the analysis of data sets, which contain oscillatory components. Prominent low frequencies can be seen in the spectrum obtained from the PD patients whereas in the control group the frequency range was 6Hz in the majority of channels. MRI did not disclose specific findings in any case. CONCLUSIONS: It is suggested that the MEG could be a complementary method in the diagnostic evaluation of PD using spatial distribution of the raw data in the frequency domain.

Aged↗

PubMed2005

A comparative study of a theoretical neural net model with MEG data from epileptic patients and normal individuals.

OBJECTIVE: The aim of this study was to compare a theoretical neural net model with MEG data from epileptic patients and normal individuals. METHODS: Our experimental study population included 10 epilepsy sufferers and 10 healthy subjects. The recordings were obtained with a one-channel biomagnetometer SQUID in a magnetically shielded room. RESULTS: Using the method of x2-fitting it was found that the MEG amplitudes in epileptic patients and normal subjects had Poisson and Gauss distributions respectively. The Poisson connectivity derived from the theoretical neural model represents the state of epilepsy, whereas the Gauss connectivity represents normal behavior. The MEG data obtained from epileptic areas had higher amplitudes than the MEG from normal regions and were comparable with the theoretical magnetic fields from Poisson and Gauss distributions. Furthermore, the magnetic field derived from the theoretical model had amplitudes in the same order as the recorded MEG from the 20 participants. CONCLUSION: The approximation of the theoretical neural net model with real MEG data provides information about the structure of the brain function in epileptic and normal states encouraging further studies to be conducted.

Epilepsy↗

PubMed2005

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.

Adolescent↗

PubMed2003

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.

Aged↗

PubMed2003

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.

Adult↗

PubMed2003

Chaotic and periodic analysis of fetal magnetocardiogram recordings in growth restriction.

OBJECTIVE: We studied how chaotic and periodic heart rate dynamics differ between normal fetuses (n = 19) and intrauterine growth restricted fetuses (n = 11) at 34 to 37 weeks of gestation. We quantified the chaotic dynamics of each heart rate time series obtained by fetal magnetocardiography (FMCG) using correlation dimension. METHODS: The FMCG was recorded digitally by a single-channel biomagnetometer in an electrically shielded room of low magnetic noise. The position of the fetal heart was determined using ultrasonography. RESULTS: The correlation dimension was significantly lower in IUGR than in normal fetuses (p < 0.001, t-test). The periodic dynamics were also obtained by FMCG and measured by power spectrum. The low-frequency components and therefore the periodicity of the low-frequency range were significantly higher in IUGR than in normal fetuses (p < 0.001, t-test). CONCLUSIONS: The analysis of FMCG recordings may offer important perspectives to understand significant features of the heart function of the fetuses. This technique improves the recognition of IUGR fetuses over healthy ones and may help improve perinatal morbidity and mortality.

Adult↗

PubMed2003

Magnelic stimulation can modulate seizures in epileptic patients.

OBJECTIVE: The aim of this study is to investigate the influence of external magnetic stimulation (EMS) in epileptic patients using magnetoencephalographic (MEG) measurements and non-linear analytic techniques. METHODS: The examined group consisted of 15 men aged 19-56 years (mean: 39.5 +/- 11.3) and 15 women aged 15-53 years (mean: 36.7 +/- 11.4). For each one the magnetic activity was recorded from 32 points for each temporal lobe. External magnetic stimulation (EMS) with proper field characteristics (intensity: 1-7.5 pT, frequency: the alpha-rhythm of the patient (8-13 Hz)) was applied in the frontal, occipital and temporal lobes for 2 to 6 minutes and the emitted brain magnetic activity was recorded again. In order to investigate if there is any alteration in the MEG complexity underlying the neural dynamics characterizing the pathologic brain before and after the EMS, chaotic analysis approach was applied for the estimation of the dimensional analysis of the existing strange attractors. RESULTS: The application of EMS resulted in rapid attenuation of the MEG activity of epileptic patients. The obtained results of the dimensionality calculation provide a shift from lower to higher dimensional values. Such a shift is an indication that we are dealing with a chaotic system similar with the one characterizing normal subjects. CONCLUSIONS: The increased values of the dimensional complexity and the lower activity of the MEG after the application of EMS strongly supports the beneficial effects of EMS in epileptic patients.

Adolescent↗

PubMed2003

Pre- and postsurgical biomagnetic activity in malt-type gastric lesions. A case report.

PURPOSE: To evaluate the biomagnetic activity of a low-grade mucosa-associated lymphoid tissue (MALT-) type gastric lymphoma, and to determine if this procedure could be an adjunct to endoscopic ultrasonography (EUS) in the assessment of the disease pre- and postsurgically. MATERIAL AND METHODS: A 47-year-old female with a 2-year clinical history of a low-grade MALT-type gastric lymphoma associated with Helicobacter pylori was examined. The disease showed no histologic remission after eradication of the H. pylori infection and subsequent treatment with chemotherapy and the patient was classified as stage II EA. A decision for surgical resection was made. Biomagnetic waveform recordings were made in the target area before and after surgery and the Fourier analysis of these recordings was performed. RESULTS: The gastric lymphoma biomagnetic waveforms showed high amplitudes (1.8 pT) before and low amplitudes (0.6 pT) after resection. The corresponding Fourier analysis demonstrated that the maximum spectral power of the presurgical measurement was elevated (mean 235 +/- 847 pT2/Hz) compared with that obtained postsurgically (mean 725 +/- 89 pT2/Hz). The difference was of statistical significance ( p < 0.0001, t-test). CONCLUSION: Biomagnetic monitoring of gastric lymphoma, which is an entirely new diagnostic modality, could be a supplement to EUS for assessing remission or persistence of disease with medical treatment during follow up.

Female↗

PubMed2003

Chaotic analysis approach in neonatal magneto-encephalography.

The aim of this study was to investigate the presence of any non-linearity in the magneto-encephalographic recordings (MEG) in neonates born to pre-eclamptic mothers in comparison with the ones born to mothers having uncomplicated pregnancies, in order to find out differences in the mechanisms underlying their brain waves. Our study population consisted of 40 term neonates who were delivered normally, without any clinical signs of brain damage. Thirty of them had a normal pregnancy and labour with normal Apgar scores, umbilical cord pH, and birth weight, while 10 neonates had suffered a pre-eclamptic pregnancy. The above analysis of the MEG in the neonatal pre-eclamptic brain showed a lower dimension complexity as compared with the normal neonatal brain and a lower first Lyapunov exponent which means lower information processing. The non-linear analysis of the MEG activities in neonates may offer important perspectives to understand significant features of their brain function.

Adolescent↗

PubMed2002

Detection of non-linearity in schizophrenic patients using magnetoencephalography.

OBJECTIVE: The aim of this study is to investigate the presence of any non-linearity in the magnetoencephalographic recordings (MEG) from the temporal lobe of schizophrenic patients in comparison with controls, in order to find the differences underlying the brain waves. We calculated the correlation dimension, which is a measure of the complexity of the dynamic system, as well as the first Lyapunov exponent that indicates the system's unpredictability. METHODS: The schizophrenic group consisted of 3 men and 7 women aged 23-32 years (mean 27.2, SD=3.5) and the control group of 3 men and 6 women aged 26-35 years (mean 31.6 +/- 4.1). There were no significant differences between the two groups as far as age and sex were concerned. None of them received any medication. RESULTS: The analysis of the MEG in the schizophrenic group showed lower dimension complexity and moreover the first Lyapunov exponent presented lower values compared with the corresponding ones in the control group, which means lower information processing. CONCLUSION: EEG findings as determined by MEG and non-linear analysis may offer important perspectives to better understand brain function in schizophrenia.

Adult↗

PubMed2001

Linear analysis of fetal magnetocardiogram recordings in normal pregnancies at various gestational ages.

In this study we investigated the fetal magnetocardiogram recordings (FMCG) in 64 women, 21-30 years old, with single normal pregnancies and gestational ages 28-40 weeks. Spectral analysis was used to quantify heart rate variability and to identify the maturation of the autonomic nervous system. According to our results, there was an increase of the ratio LF/HF of the power spectrum, which reflects the maturation of the autonomous nervous system and also an increase in heart rate variability in the course of pregnancies, which was statistically significant (ANOVA test, P < 0.0005) comparing the R-R intervals of the number of cases in the four groups of 28-30, 37-40, 31-33 and 37-40 weeks of gestation. This study highlights some of the advantages of FMCG as a novel, non-invasive technique for obtaining useful clinical information.

Journal Article↗

PubMed2001

Fetal heart rate patterns in normal and ritodrine-treated pregnancies, detected by magnetocardiography.

OBJECTIVE: The aim of the present study was to test the validity of magnetocardiography in the diagnosis of fetal heart rate arrhythmias in normal pregnancies, as compared to the number of arrhythmias reported in other series, which were detected by use of other diagnostic techniques. We also evaluated the influence of ritodrine on the fetal heart rhythm in pregnancies treated for the risk of preterm labor by means of magnetocardiography, in order to provide preliminary results that could be utilized in the future establishment of magnetocardiography as a screening procedure in the diagnosis and management of fetal arrhythmias. METHODS: We performed a prospective study on two subgroups of pregnant women: one of 84 women with normal healthy singleton pregnancies and one of 68 pregnant women treated with ritodrine for the risk of preterm labor. RESULTS: The prevalence of fetal arrhythmias in the first subgroup was 3.5% (3/84), while in the second subgroup the prevalence was 16% (11/68). CONCLUSIONS: The incidence of fetal arrhythmias detected in our population of normal pregnancies was comparable to that reported in previous studies by use of other techniques. Results gained from the second subgroup, although not comparable to others, owing to lack of similar reports, led us to believe that magnetocardiography's advantages over conventional methods of fetal cardiac surveillance could highlight the technique as a useful screening procedure for the detection of preterm fetuses, which should be submitted to closer investigation, because of the arrhythmias caused by ritodrine infusion.

Adult↗

PubMed2001

Biomagnetic activity in the female breast at various physiological states.

PURPOSE: To investigate the biomagnetic activity produced physiologically by the various normally occurring states of the female breast: puberty, reproductive age, pregnancy, lactation and menopause. METHOD: The mammary glands of 90 healthy women were examined using a Superconducting Quantum Interference Device (SQUID). RESULTS: Biomagnetic activity was low at puberty (105.46+/-3.77 fT/square root(Hz)) and the menopause (111.66+/-25.06 fT/square root(Hz)), but was high during the reproductive years (142.13+/-20.70 fT/square root(Hz)), particularly in the hyperplastic states of late pregnancy (221.86+/-12.14 fT/square root(Hz)) and lactation (252.73+/-54.77 fT/square root(Hz)). The results were statistically significant (p<0.0001 ANOVA test). CONCLUSION: Our observations indicate the importance of SQUID in understanding the biomagnetic activity of the female breast at the various physiological states of life.

Adolescent↗

PubMed2001

Neonatal magnetocardiography and Fourier spectral analysis.

OBJECTIVE: In this study we investigated the relationship between heart rate variability (HRV) and respiration in healthy and probably asphyxiated infants using magnetocardiographic (MCG) recordings. METHODS: Ten healthy and eight infants from pregnancies complicated by preeclampsia with indications of mild perinatal asphyxia were included in the study. All were near term. Maternal age ranged from 16 to 39 years (mean = 29.05, SD = 6.13). Spectral analysis was used to find out any association between respiration and HRV. RESULTS: Respiratory sinus arrhythmia (RSA) was reduced in preeclamptic infants with indications of mild perinatal asphyxia. This difference was statistically significant (p < 0.0002, t-test), whereas the heart rate of the two groups was not statistically significant (p = 0.1, t-test). CONCLUSION: The results suggest that infants with indications of mild preeclampsia differ from controls in respiratory activity and this difference is independent of basal heart rate. Thus, spectral analysis could be useful for the estimation of influence of mild perinatal asphyxia in the RSA rhythm of newborns.

Asphyxia Neonatorum↗

PubMed2001

Neonatal magnetocardiography.

PURPOSE: The aim of the present study was to test the validity of magnetocardiography (MCG) in the estimation of neonatal cardiac rhythm using a single channel superconductive quantum interference device (SQUID). MATERIALS AND METHODS: Our study population consisted of 50 neonates who were delivered normally between 37-41 weeks of gestation from clinically uncomplicated pregnancies. There was also a neonate included in the study in which the diagnosis of "hypoplastic left heart syndrome" was demonstrated by U/S Doppler examination. Maternal age ranged from 18 to 39 years (mean=29.15, SD=6.13). RESULTS: Our study results revealed 44 neonates with normal cardiac rhythm, four with ventricular tachycardia (VT), one with ventricular tachycardia (VT) and extrasystolic beats and one with bradycardia. The neonate with the hypoplastic left heart syndrome presented frequent episodes of ventricular bigeminy in the magnetocardiographic trace. M-mode echocardiography confirmed the diagnosis of the seven cases of arrhythmia in our study group. CONCLUSION: Results gained from the study lead us to believe that MCG could provide clinical practice with a non-invasive, rapid and easy to perform method, which could be used as an adjunct to conventional methods for the evaluation of neonatal cardiac rhythm.

Arrhythmias, Cardiac↗

PubMed2001

Neonatal magnetoencephalography and spectral analysis.

PURPOSE: We performed a prospective study of neonatal brain function on 44 respective term neonates who were delivered normally, without any clinical signs of brain damage. Thirty were associated with a normal pregnancy and labor with normal values of Apgar scores, umbilical cord pH and birth weight, while 14 neonates were the result of pre-eclamptic pregnancy. METHODS-RESULTS: Biomagnetic measurements were performed by means of a Superconducting Quantum Interference Device (SQUID) in an electrically shielded room of low magnetic noise. Biomagnetic signals (waveforms) recorded from neonatal brains in the frequency range of 2-7 Hz were expressed in terms of magnetic power spectral amplitudes. These were low (mean value 163.2, SD 22.57) in almost all neonates from the "normal pregnancy" group, while they were high (mean value 211.6, SD 37.74) in most neonates from the "pre-eclamptic" group. The difference between the two groups was statistically significant (Student's t-test, p < 0.005). CONCLUSION: A statistically significant difference in spectral amplitudes of neonatal brain activity was observed between normal term neonates and the pre-eclamptic neonates. Biomagnetic measurements of neonatal brain activity could provide clinical practice with a promising procedure for assessing brain function.

Adolescent↗