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Biomedical subjects

N G Durdle

Publications and source records attributed to N G Durdle.

12 recordsLinked to original sources
PubMed2006

Automatic matching of spine images to assess changes in scoliosis.

This paper presents an image matching approach that can be used to measure changes in scoliotic curves. The proposed approach uses a novel fuzzy logic controller to estimate all open parameters. Using fluoroscopy images of a spine phantom, it was found that, with minimal user interaction, the matching of spine images could be achieved with high accuracy (the average errors were around 0.03 mm) and high computational efficiency (requiring less than 1 minute for matching each vertebra).

Automation↗
PubMed2006

Evaluating similarity metrics in an image matching tool for image guided spine surgery.

This paper presents a comparison study of the effect of three similarity measures (mutual information, normalized mutual information, and mean squared error on the edges of the input image) in an image matching tool that can be used in image guided spine surgery. Using 3D rotational x-rays and magnetic resonance images of a spine phantom, it was found that the similarity measures had similar effect. Therefore, experiments with other datasets are needed before making conclusions about the suitability of these similarity metrics for image guided surgery.

Humans↗
PubMed2002

The daily force pattern of spinal orthoses in subjects with adolescent idiopathic scoliosis.

The efficacy of orthotic treatment for children with abnormal spinal curvature has been hampered by the lack of comprehensive information about wear characteristics. A battery-powered microcomputer system was developed to monitor loads exerted by orthoses used to treat children with spinal deformities during daily living. The system not only records how well the orthosis has been used, but also helps to ensure that the orthosis is being worn as prescribed. Data acquisition is controlled by a microcontroller and can be programmed to have sample intervals ranging from 1 second to 1 hour. Low power control circuitry is designed so that the system can be operated by a battery. In a preliminary study, 16 subjects (3M, 13F) used this system from 1 to 16 days (9.3 +/- 5.0) with the prescribed hours between 16 to 23 hours (22.3 +/- 1.3). This study demonstrated the feasibility of the approach, and that this device may increase the understanding of orthotic mechanics, and may help patients to wear their orthoses in a better way.

Adolescent↗
PubMed2002

Evaluation of a laser scanner for surface topography.

A Minolta VIVID 700 portable non-contact 3D laser scanner was evaluated on 15 subjects with idiopathic scoliosis. The 3D map was compared to two structured light pattern (lines and dots) techniques to determine the reliability, ease of use, speed, and quality. The parameters used for the clinical assessment of scoliosis were measured twice for the Minolta and light projection systems. The edges of the image and areas where occlusion typically occur were examined. The absolute distance in calculated depth between adjacent points was examined to determine errors. The Minolta system and the dot pattern produced regular grids of points. The light projection pattern produced an irregular grid, with more resolution along the video line and less resolution between projected lines, resulted in a somewhat jagged appearance of the surface map. The Minolta system was less sensitive to edge effects, occlusion, and sharp transitions of depth. The comparison of clinical parameters showed good results between repetitions but moderate results between techniques.

Adolescent↗
PubMed2002

Image coding technique for 3-D back reconstruction.

This work investigated the use of coded-line patterns to improve image correspondence and 3D reconstruction. The objective was to define an optimum structured light pattern to facilitate the construction of topographic maps of the trunks of scoliosis patients. The system consisted of stereo CCD television cameras, a slide projector to create the coded-line pattern and a computer with video acquisition card. The optimum pattern in terms of generating correct results with minimum computing time was a line pattern consisting of 6 groupings of 3-level grey lines. This chosen pattern was investigated using known 3D objects to determine the effectiveness, resolution and computational time to correlate stereo images. The selected structured light pattern consisted of a repeated pattern of white (W), grey (G) and black (B) lines. Each line was 4mm wide on the back surface. The pattern consisted of 6 groups of 3 lines, WBG WGB GWB GBW BGW BWG. Using known 3D models of a section of a cylinder, a plate with steps and a ramp-like object; the coded line system was tested under typical clinical lighting conditions. For the 3D test objects, errors in correspondence occurred in 2-4 % of stereo pixels. The processing time varied from 10-12 minutes. The 3D resolution obtained was 4mm.

Back↗
PubMed2002

Local energy as a measure of back symmetry in scoliosis.

The Cobb angle has been the most commonly used method in measuring the severity of scoliosis and its progression. However, in recent years a number of researchers have chosen to monitor scoliosis by examining the severity of the surface deformity resulting from the scoliosis. Each of these approaches has been limited by errors introduced in manual location of landmarks. Scoliosis results in an asymmetry of the back. It would be very desirable to have a computer-based method of measuring this asymmetry. This paper investigates the use of wavelets and the concept of local energy to measure asymmetry associated with scoliosis. The local energy model uses wavelet theory to obtain information about shading and boundaries of objects in an image. Edges and sharp discontinuities are areas of high local energy in an image. Features such as scapular prominence, shoulder edges, waist creases and other anomalies that contribute to the scoliotic back asymmetry have high local energy. A preliminary study was completed to determine if this approach was applicable to measurement of back asymmetry. Two-dimensional local energy images were created from photographs of the backs of patients with scoliosis. The local energy was integrated across each image and a left-to right line of symmetry was calculated. This line of symmetry was then correlated with the scoliotic score developed by our group. This technique shows promise of providing an automatic method of measuring scoliosis progression.

Back↗
PubMed1992

A video digitizer for analysis of trunk deformity in scoliosis.

Scoliosis is a deformity characterized by lateral curvature of the spine and accompanied by axial rotation of the vertebrae; it often causes varying degrees of trunk deformity. Research has indicated that topographic techniques can be used to describe the disorder and monitor its progression. A video image acquisition system has been designed which reduces the time required to quantify topographic details of the trunk and aids in the diagnosis, monitoring and research of scoliosis. This system integrates the capability of large, expensive grey-scale image acquisition equipment into a small, low-cost diagnostic imaging tool using current technologies and design techniques. The video digitizer accepts a standard NTSC monochromatic video signal as input and the unit is connected to a computer via an IEEE-488 bus from which the ditigizer is controlled. The digitizer samples the video signal in real time using a high-speed flash converter controlled by an application-specific integrated circuit; the digital samples are stored in memory until the host computer requests that the information be transferred.

Adolescent↗
PubMed1983

Origin of slow waves in the canine colon.

The objectives of this work were to determine the origin of slow wave activity in the canine colon, to examine the slow wave characteristics in the circular and longitudinal muscle layers, and to examine the roles played by each of these layers in the generation of this activity. Extracellular electrical activity was recorded in vitro from strips of intact muscle wall and from isolated circular and longitudinal muscle using either multiple electrodes applied to one side of the specimen or two electrodes applied simultaneously to opposite sides of the tissue. Intracellular electrical activity was also studied in intact muscle, in isolated circular muscle, and in isolated longitudinal muscle. Slow waves were recorded extracellularly from circular and longitudinal muscle when the two layers formed the intact muscle wall; they were also recorded from isolated circular muscle, but not from isolated longitudinal muscle. Removal of the submucosa from the circular muscle surface abolished slow waves recorded from both isolated circular muscle and the intact specimen. Exposure of the mucosal surface of isolated circular muscle to a hypertonic solution of KCl abolished slow waves, while exposure of the serosal surface to the same concentrations had no effect. Slow waves are not generated in longitudinal muscle. Slow waves in circular muscle are dependent on the integrity of the junction between the submucosa and the innermost circular layer.

Animals↗
PubMedDate not supplied

Trunk distortion in adolescent idiopathic scoliosis.

Trunk images of children with scoliosis were examined to determine features that contribute to the impression of trunk distortion. Twenty subjects with spinal deformity ranging from none to severe were photographed in a relaxed standing position. Seven blinded evaluators subjectively scored their impressions of the trunk appearance, shoulder-height difference, shoulder-angle asymmetry, decompensation, scapula asymmetry, waist crease, waist asymmetry, and pelvic asymmetry. Regression analysis was used with the latter seven features to predict overall impression. The seven measures of the deformity predicted 85% of the overall impression of trunk distortion; scapular asymmetry was the best predictor. Trunk deformity is the most obvious effect of scoliosis to the patients. Objective approaches to the assessment of this important but difficult-to-quantify aspect of idiopathic scoliosis are available and should be used to evaluate treatment outcomes.

Adolescent↗