On the fetal magnetocardiogram

Fetal magnetocardiography is a non-invasive technique for studying the electrical activity of the fetal heart. Fetal magnetocardiograms (fMCG) can be used to diagnose and classify fetal cardiac arrhythmias reliably. An averaged fMCG shows a QRS-complex, a P-wave, and a T-wave. However, it is still unknown if the currents in the tissues surrounding the fetal heart disturb these features. Furthermore, the measuring technique is not yet optimised for fMCG registrations. Simulation studies may provide guidelines for the design of an appropriate magnetometer system. Therefore, finite-element and boundary-element models were constructed in order to study the possible influence of the volume conductor. Especially, the influence of the layer of vernix caseosa, a fatty layer that covers the fetus, was investigated. The computations showed that the layer of vernix caseosa will affect the waveform of the fMCG. The signal processing procedure used is also discussed. It turned out to be difficult to deduce the onset and offset of the T-wave from the resulting averaged signals. Possibly, the QRS-complex does not provide a correct trigger to obtain a distinguishable T-wave in the averaged signal, because the RT-interval may be variable

The Use of 3D Power Doppler Ultrasound in the Quantification of Blood Vessels in Uterine Fibroids: Feasibility and Reproducibility

Background: To evaluate the interobserver agreement and discriminating value of three-dimensional power Doppler ultrasound (3D PDUS) in patients with fibroids. Methods: An observational prospective cohort study in 19 patients with fibroids. 3D PDUS was performed by one examiner and evaluated by three independent examiners in order to evaluate various vascular parameters: vascular index (VI), flow index, and vascular flow index of the fibroid, the vascular capsule and of its highest vascular area, using both manual and automatic contour modes. The intraclass correlation coefficient and discriminating values were calculated. The correlation between VI and volume was studied using Kendall's Tau test. Results: In the manual contour mode, the VIs of the fibroid and of the vascular capsule had the highest interobserver agreements (intraclass correlation coefficients of 0.89 and 0.87, respectively). Both parameters seem to have good discriminating values, given the large range of these parameters between different fibroids, independent of their volume. The vascularity of the fibroid and capsule was related. VI was not related to the volume of the fibroid. Conclusions: VI assessed using 3D PDUS is a reproducible parameter in the assessment of fibroid vascularization with discriminating abilities. Additional studies are needed to further evaluate its validity and clinical relevance