This paper presents a comparison of different implementations of 3D anisotropic diffusion speckle noise reduction
technique on ultrasound images. In this project we are developing a novel volumetric calcification assessment metric for
the placenta, and providing a software tool for this purpose. The tool can also automatically segment and visualize (in
3D) ultrasound data. One of the first steps when developing such a tool is to find a fast and efficient way to eliminate
Previous works on this topic by Duan, Q.  and Sun, Q.  have proven that the 3D noise reducing anisotropic
diffusion (3D SRAD) method shows exceptional performance in enhancing ultrasound images for object segmentation.
Therefore we have implemented this method in our software application and performed a comparative study on the
different variants in terms of performance and computation time. To increase processing speed it was necessary to utilize the full potential of current state of the art Graphics Processing Units (GPUs).
Our 3D datasets are represented in a spherical volume format. With the aim of 2D slice visualization and segmentation, a "scan conversion" or "slice-reconstruction" step is needed, which includes coordinate transformation from spherical to Cartesian, re-sampling of the volume and interpolation.
Combining the noise filtering and slice reconstruction in one process on the GPU, we can achieve close to real-time operation on high quality data sets without the need for down-sampling or reducing image quality. For the GPU programming OpenCL language was used. Therefore the presented solution is fully portable.
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