Comparison of human uterine cervical electrical impedance measurements derived using two tetrapolar probes of different sizes

BACKGROUND We sought to compare uterine cervical electrical impedance spectroscopy measurements employing two probes of different sizes, and to employ a finite element model to predict and compare the fraction of electrical current derived from subepithelial stromal tissue. METHODS Cervical impedance was measured in 12 subjects during early pregnancy using 2 different sizes of the probes on each subject. RESULTS Mean cervical resistivity was significantly higher (5.4 vs. 2.8 Ωm; p < 0.001) with the smaller probe in the frequency rage of 4–819 kHz. There was no difference in the short-term intra-observer variability between the two probes. The cervical impedance measurements derived in vivo followed the pattern predicted by the finite element model. CONCLUSION Inter-electrode distance on the probes for measuring cervical impedance influences the tissue resistivity values obtained. Determining the appropriate probe size is necessary when conducting clinical studies of resistivity of the cervix and other human tissues

Biocontrol Potential of Forest Tree Endophytes

Peer reviewe

The Engineering Body Scanner Concept

Residual stress measurements by neutron and synchrotron diffraction have made enormous advances in the last decade. With this has come a desire to examine more demanding component geometries leading to prolonged set-up times and complex scan and reorientation procedures. The Engineering Body Scanner (EBS) project has targeted this problem not only as an issue of physical measurement set-up but also the subsequent need for data storage and co-visualisation. Using a coordinate measurement machine to digitise key features of the sample, measurement plans may be made in advance of the visit to international facilities. This approach also permits the measurements taken at different locations in the sample, perhaps on different instruments, to be located in a single co-ordinate frame of reference — that of the sample. In terms of co-visualisation software, EBS has increased the ease and range of analysis, opening up the possibility of merging different datasets collected from a range of instruments

The role of cervical Electrical Impedance Spectroscopy in the prediction of the course and outcome of induced labour

BACKGROUND: Previous work by us and others had suggested that cervical electrical impedance spectroscopy (EIS) may be predictive of the outcome of induced labour. We sought to determine which probe configuration of the EIS device is predictive of the outcome of induced labour and compare this to digital assessment by the Bishop score. METHODS: In a prospective cohort of 205 women admitted for induction of labour, we used four probes of diameter 3, 6, 9 and 12 mm connected to an impedance meter to measure cervical resistivity (CR) in Ohm.meters at 14 electrical frequencies and compared their values to digital assessment of the cervix by the Bishop score for the prediction of the outcome of induced labour. We tested the association of labour characteristics and outcomes with CR and Bishop score by stepwise multilinear regression analyses, and the accuracy of prediction of categorical clinical outcomes by analysis of the area under the curves (AUC) of derived Receiver Operator Characteristic (ROC) curves.RESULTS:Of the four CR probe dimensions studied, only the 12 mm probe was predictive of any labour indices. In the frequency range 19 - 156 kHz, CR obtained with this probe was higher in women who delivered by caesarean section (CS) than those who delivered vaginally, and in labours lasting > 24 hrs. Cervical resistivity at 78.1 kHz best predicted vaginal delivery [optimal cut-off 24 hrs [optimal cut-off 2.27 O.m, AUC 0.65 (95% CI 0.58, 0.72), sensitivity 71%, specificity 59%, LR+ 1.72, LR- 0.50, P 12 hours and induction-delivery interval < 24 hrs [optimal cut-off = 4, AUC 0.8 (95% CI 0.75, 0.86), sensitivity 77%, specificity 76%, LR+ 3.3, LR- 0.3, P < 0.05] whilst CR did not. CONCLUSION: Cervical resistivity appears predictive of labour duration and delivery mode following induced labour. However the low predictive values obtained suggest that its current design proffers no immediate clinical utility