Segmentation and classification in MRI and US fetal imaging: Recent trends and future prospects.

This article focuses on a systems biology approach to studying the pathophysiology of cigarette smoking during pregnancy. Particular emphasis is given to the damaging role of oxidative stress. Cigarette smoking exerts multiple adverse affects but abundant evidence, mostly in adults, suggests that oxidative stress and free radical damage is a major pathophysiological factor. Smoking during pregnancy is known to contribute to numerous poor birth outcomes, such as low birth weight, preterm birth as well as life-long health and developmental problems. It is clinically important to know the separate contributions that cigarette derived-nicotine and smoking-induced free oxidative stress make to these poor outcomes. Surprisingly, the extent to which smoking dependent oxidative stress contributes to these poor outcomes is not well studied but the application of redox proteomics should be useful. Considerable biochemical evidence suggests that antioxidants, such as tocopherols and ascorbate, could be useful in minimizing oxidative stress induced pathology to the developing fetus in those women who, despite medical advice, continue to smoke. Nevertheless, this suggestion has yet to be tested in well-designed clinical studies.

The pathophysiology of smoking during pregnancy: a systems biology approach.

Abnormal placental grading is associated with poor pregnancy outcome. The aim of this study was to measure intra- and interobserver variability in placental grading. Five expert sonographers independently graded 90 images on two occasions, each viewing separated by 1 week. A number of measures were employed to standardise assessment and minimise potential for variation: prior agreement was established between observers on the classifications for placental grading; a controlled viewing laboratory was used for all viewings; ambient lighting was optimal and monitors were calibrated to the GSDF standard. Kappa (κ) analysis was used to measure observer agreement. Substantial variations between individuals' scores were observed. A mean κ-value of 0.34 (range from 0.19 to 0.50) indicated fair interobserver agreement over the two occasions and only nine of the 90 images were graded the same by all five observers. Intraobserver agreement had a moderate mean κ-value of 0.52, with individual comparisons ranging from...

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Poor agreement between operators on grading of the placenta

Objectives

Placental calcification is associated with an increased risk of perinatal morbidity and mortality. The subjectivity of current ultrasound methods of assessment of placental calcification indicates that a more objective method is required. The aim of this study was to correlate the percentage of calcification defined by the clinician using a new software tool for calculating the extent of placental calcification with traditional ultrasound methods and with pregnancy outcome.



Methods

Ninety placental images were individually assessed. An upper threshold was defined, based on high intensity, to quantify calcification within the placenta. Output metrics were then produced including the overall percentage of calcification with respect to the total number of pixels within the region of interest. The results were correlated with traditional ultrasound methods of assessment of placental calcification and with pregnancy outcome.



Results

The results demonstrate a significant correlation between placental calcification, as defined using the software, and traditional methods of Grannum grading of placental calcification. Whilst correlation with perinatal outcome and cord pH was not significant as a result of small numbers, patients with placental calcification assessed using the computerized software at the upper quartile had higher rates of poor perinatal outcome when compared with those at the lower quartile (8/22 (36%) vs 3/23 (13%); P = 0.069).



Conclusion

These results suggest that this computerized software tool has the potential to become an alternative method of assessing placental calcification. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Computerized assessment of placental calcification post-ultrasound: a novel software tool.

Current ultrasound assessment of placental calcification relies on Grannum grading. The aim of this study was to assess
if this method is reproducible by measuring inter- and intra-observer variation in grading placental images, under strictly
controlled viewing conditions. Thirty placental images were acquired and digitally saved. Five experienced sonographers
independently graded the images on two separate occasions. In order to eliminate any technological factors which could
affect data reliability and consistency all observers reviewed images at the same time. To optimise viewing conditions
ambient lighting was maintained between 25-40 lux, with monitors calibrated to the GSDF standard to ensure consistent
brightness and contrast. Kappa (κ) analysis of the grades assigned was used to measure inter- and intra-observer
reliability. Intra-observer agreement had a moderate mean κ-value of 0.55, with individual comparisons ranging from
0.30 to 0.86. Two images saved from the same patient, during the same scan, were each graded as I, II and III by the
same observer. A mean κ-value of 0.30 (range from 0.13 to 0.55) indicated fair inter-observer agreement over the two
occasions and only one image was graded consistently the same by all five observers. The study findings confirmed the
lack of reproducibility associated with Grannum grading of the placenta despite optimal viewing conditions and
highlight the need for new methods of assessing placental health in order to improve neonatal outcomes. Alternative
methods for quantifying placental calcification such as a software based technique and 3D ultrasound assessment need to
be explored.

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Is Grannum grading of the placenta reproducible

In obstetrics, antenatal ultrasound assessment of placental morphology comprises an important part of the estimation of
fetal health. Ultrasound analysis of the placenta may reveal abnormalities such as placental calcification and infarcts.
Current methods of quantification of these abnormalities are subjective and involve a grading system of Grannum stages
I-III. The aim of this project is to develop a software tool that quantifies semi-automatically placental ultrasound images
and facilitates the assessment of placental morphology. We have developed a 2D ultrasound imaging software tool that
allows the obstetrician or sonographer to define the placental region of interest. A secondary reference map is created for
use in our quantification algorithm. Using a slider technique the user can easily define an upper threshold based on high
intensity for calcification classification and a lower threshold to define infarction regions based on low intensity within
the defined region of interest. The percentage of the placental area that is calcified and also the percentage of infarction is
calculated and this is the basis of our new metric. Ultrasound images of abnormal and normal placentas have been
acquired to aid our software development. A full clinical prospective evaluation is currently being performed and we are
currently applying this technology to the three-dimensional ultrasound domain. We have developed a novel software-based
technique for calculating the extent of placental calcification and infarction, providing a new metric in this field.
Our new metric may provide a more accurate measurement of placental calcification and infarction than current
techniques.

Mary Higgins

Papers

A novel software-based technique for quantifying placental calcifications and infarctions from ultrasound