A method for the automatic measurement of femur length in fetal ultrasound images is presented. Fetal femur length measurements are used to estimate gestational age by comparing the measurement to a typical growth chart. Using a real-time ultrasound system, sonographers currently indicate the femur endpoints on the ultrasound display station with a mouse-like device. The measurements are subjective, and have been proven to be inconsistent. The automatic approach described exploits prior knowledge of the general range of femoral size and shape by using morphological operators, which process images based on shape characteristics. Morphological operators are used first to remove the background (noise) from the image, next to refine the shape of the femur and remove spurious artifacts, and finally to produce a single pixel-wide skeleton of the femur. The skeleton endpoints are assumed to be the femur endpoints. The length of the femur is calculated as the distance between those endpoints. A comparison of the measurements obtained with the manual and with the automated techniques is included.
Stereotactic neurosurgery is a technique in which a rigid frame is applied to the patient's head and pre-operative images acquired. Because the frame and the lesion are visible in the images, the lesion can be located relative to the frame. Devices may then be attached to the frame to direct surgical instruments to the lesion.Conventional stereotactic neurosurgery remains a point by point process, conceptually little changed from the original devices which were designed for use with pneumoencephalograms. The exponential rise in the amount of available imaging information over the past 15 years has not been matched by intrasurgical applications.A new device will be presented which allows the intrasurgical position and trajectory to be displayed on preoperative images. This device has sub-millimetric accuracy and precision and is limited only by the image voxel size. The device can use both CT and MRI image sets concurrently or exclusively. Applications include surgical planning, biopsy, bone flap location and intracranial localization. Both phantom and clinical procedures will be shown.In order to use these devices a frame such as the one shown in Figure 1 is attached to the skull by screws or pins. A set of N-shaped bars formed of a material perceptible on the desired imaging modality. When the images are made, the cross-section of the N-Bars are visible in the image frame. See Figure 2. SPIE Vol. 1444 Image Capture, Formatting, and Display(1991) / 9 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/27/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx
A surgeon typically uses information from a number of tomographic imaging methods (e.g. , CT, MR, PET) during the course of a surgical procedure. These imaging techniques represent three-dimensional information as a set of two-dimensional images. To use this information, the surgeon is required to mentally construct a three-dimensional visualization from the set of two-dimensional images. The formation of the mental image becomes more complicated with the inclusion of multiple imaging modalities and multiple imaging planes.We have developed a technique to enhance the mental three-dimensional visualization process through simultaneous graphics and multislice raster image display. The composite display, capable of displaying up to three raster images along with a patient-specific graphics model, is viewed on a 1280 X 1024 monitor. The raster images, displayed in a 512 X 512 format, may be any combination of imaging methods and imaging planes. The graphics model, determined from the imaging data, may be freely rotated as a depth-cued wireframe or shaded-surface model. Regions-of-interest may be incorporated into the graphics model for additional visual cues. Trajectory information may be obtained by moving a threedimensional cursor in any raster image space or in the graphics model with instantaneous update of the remaining display area.This design allows the surgeon to interactively obtain orientation and visualization information from the images in the operating room. Because the classic imaging planes are used, the surgeon is not required to deal with a new information format or a loss of resolution.
Maximum-Intensity Projection (MIP) algorithms are currently used for construction of Magnetic Resonance (MR) angiograms. In this application, projections calculated at different angles through the image are used to form a cine loop, thus providing a three-dimensional representation from which vascular structure may be deciphered. MIP algorithms cast parallel rays through the MR image volume which has been acquired such that the flow within the vasculature has the highest intensities. The maximum voxel intensity along each ray is placed on the projection plane where the ray meets the plane. Thus, the flow within the vasculature shows up in the projection plane. This research strives to discover methods of reducing the projection calculation time, thus making the technology more accessible to users of less powerful systems.A novel approach was developed for calculating projections in which each image slice was pre-sorted into bins of intensities. By thresholding the intensities used, the background pixels can be ignored and only those intensities that relate to flow are used in the projection. Thresholding reduces the total number of pixels considered for the projection plane, thereby saving calculation time. Additional time savings resulted from precalculating projection 'templates' and filling multiple projection planes at the same time. The algorithms were written in C on a 80386-based system. The new algorithm demonstrated more than a seven-fold increase in projection calculation speed over a bench-mark algorithm..
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