Volume Segmentation and Reconstruction from Freehand Three-Dimensional Ultrasound Data with Application to Ovarian Follicle Measurement – Ultrasound in Medicine and Biology

To view the full text, please login as a subscribed user or purchase a subscription. Click here to view the full text on ScienceDirect. An example ultrasound image of ovarian follicles. The follicles appear as dark homogenous regions. The measurement currently used in clinical practice is the mean diameter of each follicle found from a single 2D B-mode ultrasound image. For the follicle with measurements shown, the measurement recorded in the patient’s notes would be 16 mm. Figure showing the process that most systems have used to reconstruct objects. Segmentation is performed before image reconstruction. Figure showing a process that performs object reconstruction on compounded data. Segmentation is performed after image reconstruction. Graph showing the reconstructed volume measurement and the clinical volume estimate (based on a spherical model) plotted against the aspirated volume for ovarian follicles. The 3D reconstruction can be seen to have lower variation, however, both underestimate the true volume. This figure shows the 3D object reconstruction for the ovary shown in Fig. 1 . The diagonal plane illustrates the position of the image of Fig. 1 . A selection of computer-based segmentation results overlayed on the appropriate image plane. The corresponding 3D reconstruction of all follicle in the ovary is shown adjacent to each image. The position of the delineated boundary can be seen to follow the limit of the antral fluid, which we now believe to represent an under estimation of the follicle volume. This article presents a semi-automatic method for segmentation and reconstruction of freehand three-dimensional (3D) ultrasound data. The method incorporates a number of interesting features within the level-set framework: First, segmentation is carried out using region competition, requiring multiple distinct and competing regions to be encoded within the framework. This region competition uses a simple dot-product based similarity measure to compare intensities within each region. In addition, segmentation and surface reconstruction is performed within the 3D domain to take advantage of the additional spatial information available. This means that the method must interpolate the surface where there are gaps in the data, a feature common to freehand 3D ultrasound reconstruction. Finally, although the level-set method is restricted to a voxel grid, no assumption is made that the data being segmented will conform to this grid and may be segmented in its world-reference position. The volume reconstruction method is demonstrated in vivo for the volume measurement of ovarian follicles. The 3D reconstructions produce a lower error variance than the current clinical measurement based on a mean diameter estimated from two-dimensional (2D) images. However, both the clinical measurement and the semi-automatic method appear to underestimate the true follicular volume. (E-mail: gooding@robots.ox.ac.uk) If you are a current subscriber with Society Membership or an Account Number, claim your access now. Source. Looking for vector maps of Germany (Deutschland Vektorkarten) for Adobe Illustrator?."

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