Biomedical subjects

L J Yuan

Publications and source records attributed to L J Yuan.

3 recordsLinked to original sources

PubMed2000

Vascularized island pedicle iliac bone grafting for avascular necrosis of the femoral head.

BACKGROUND: Nontraumatic avascular necrosis of the femoral head is a common disorder causing disability of the hip joint. The methods for optimally treating this disease in active young patients are still controversial. In this study we investigated the surgical outcome of vascularized pedicle iliac bone grafting for treating nontraumatic avascular necrosis of the femoral head. METHODS: Between 1994 and 1999, we treated 100 cases of avascular necrosis of the femoral head with vascularized pedicle iliac bone grafting. Thirty-nine hips in 33 patients were followed-up longer than 24 months. These patients included 30 men and 3 women, with an average age of 40 years. Steinberg's classification and Ohzono's types were used to categorize the diseased hips. The clinical results were evaluated using Charnley's modification of Merle d'Aubigne and Postel's numeric classification. RESULTS: Of the 33 patients, 82% were satisfied with their decision to have vascularized pedicle iliac bone grafting for avascular necrosis of the femoral head. No serious complications arose during this study. The average operation time for vascularized pedicle iliac bone grafting was 3.5 hours for one team. The rate of conversion to replacement arthroplasty was 10.3% (4 of 39 patients). CONCLUSION: Vascularized pedicle iliac bone grafting is a useful alternative treatment option for patients with avascular necrosis of the femoral head.

Adult↗

PubMed1999

Shape-based grey-level image interpolation.

The three-dimensional (3D) object data obtained from a CT scanner usually have unequal sampling frequencies in the x-, y- and z-directions. Generally, the 3D data are first interpolated between slices to obtain isotropic resolution, reconstructed, then operated on using object extraction and display algorithms. The traditional grey-level interpolation introduces a layer of intermediate substance and is not suitable for objects that are very different from the opposite background. The shape-based interpolation method transfers a pixel location to a parameter related to the object shape and the interpolation is performed on that parameter. This process is able to achieve a better interpolation but its application is limited to binary images only. In this paper, we present an improved shape-based interpolation method for grey-level images. The new method uses a polygon to approximate the object shape and performs the interpolation using polygon vertices as references. The binary images representing the shape of the object were first generated via image segmentation on the source images. The target object binary image was then created using regular shape-based interpolation. The polygon enclosing the object for each slice can be generated from the shape of that slice. We determined the relative location in the source slices of each pixel inside the target polygon using the vertices of a polygon as the reference. The target slice grey-level was interpolated from the corresponding source image pixels. The image quality of this interpolation method is better and the mean squared difference is smaller than with traditional grey-level interpolation.

Image Enhancement↗

PubMed1985

A feasibility study of the in vivo prompt gamma activation analysis using a mobile nuclear reactor.

A facility for in vivo prompt gamma activation analysis using moderated neutron beams from a 0.1 W mobile nuclear reactor is described. The low-power nuclear reactor provides total neutron flux of 3.3 X 10(4)n cm-2 s-1 on the surface of a vertical beam tube to which a liquid phantom is positioned. The capability of such a partial-body irradiation facility is demonstrated by measuring trace amounts of toxic cadmium in kidney. The detection limit of Cd in kidney for a skin dose of 1.66 mSv (166 mrem) is 1.34 mg under 500 s irradiation. This facility therefore combines the advantages of mobility with high sensitivity of detection of a toxic element under low neutron and gamma doses.

Cadmium Poisoning↗