Biomedical subjects

W G Stevens

Publications and source records attributed to W G Stevens.

8 recordsLinked to original sources

PubMed1986

In vivo delineation of facial fractures: the application of advanced medical imaging technology.

Advanced medical imaging technology has important advantages over ordinary skull radiography and conventional tomography in the study of facial fractures. Computer-based imaging methods, including computed tomography and magnetic resonance imaging, provide exquisite soft tissue contrast, superior geometrical accuracy, and freedom from overlapping shadows, and permit computer reformating of images. The advantages of computer-based medical imaging for study of facial fractures are identified and illustrated with computed tomographs. Three-dimensional surface reconstruction methods applied to serial high-resolution computed tomography scans of facial fractures are described and evaluated.

Facial Bones↗

PubMed1986

Osseous anatomy of unilateral coronal synostosis.

High resolution, thin slice computerized tomography (CT) scans with paraxial and three-dimensional surface reconstructions were utilized to document the endocranial, exocranial, and orbital anatomy of non-syndromal unicoronal synostosis (UCS). Eighteen patients with UCS were evaluated qualitatively and quantitatively. Of these, 10 were studied both preoperatively and 1 year postoperatively. The endocranial base in UCS is characterized by a 9 degree angulation toward the synostosis of the anterior cranial base with respect to the posterior cranial base. The exocranial base has a 7 degree angulation toward the synostosis between the midpalatal suture and the posterior cranial base. The locus of angulation appears to be posterior to the anterior clinoids endocranially, and between the maxillopalatopterygoid articulations and the mandibular condyle exocranially. The orbital rim height is greater ipsilateral to the synostosis than contralaterally. The analysis documents the normalizing effect of one of two different surgical procedures upon orbital height. Application of computer assisted medical imaging to the study of UCS has allowed in vivo quantitation of cranial base and orbital dysmorphology for both preoperative assessment and postoperative evaluation.

Adult↗

PubMed1985

Three-dimensional imaging of the wrist.

The objective of this study was to determine the diagnostic quality of three-dimensional images of the carpal bones that could be constructed from raw data obtained from a computerized tomography scan. The quality of raw data collected was determined by collimation, slice interval, the number of projections, and x-ray tube operating specifications. The quality of two-dimensional images that were constructed from the raw data was determined by user-specified parameters including zoom or magnification factor, convolution kernels, and centering. The two-dimensional images were modified by erasure, the level of reconstruction, and animation, which permitted isolation of individual carpal bones, the construction of three-dimensional images viewing the external and internal surfaces of the bones, and the rotation of the images to provide multiple views. Representative images are presented.

Carpal Bones↗

PubMed1985

When should nerve gaps be grafted? An experimental study in rats.

In conclusion, animal experiments have shown the following: (1) extensive elevation (mobilization) of a nerve from its bed does not interfere with its capacity to regenerate as long as the longitudinal epineural vessels are preserved, (2) suturing nerve ends under tension has a deleterious effect on the final results, (3) when a segment of nerve has been resected, the remaining nerve and the site of repair can lengthen to accommodate joint extension (within limitations), (4) if there is a segmental loss of nerve and if the nerve ends can be approximated with 10-0 epineural sutures, even if the joints must be fully flexed, the result is better than using a nerve graft, and (5) when a graft is required, it is important to avoid reversing the nerve graft. We believe direct nerve repair is preferred when flexion of the joints and mobilization of the nerve ends permits approximation with 10-0 epineural suture.

Animals↗

PubMed1985

Musculoskeletal applications of three-dimensional surface reconstructions.

We have applied computer programs originally developed for craniofacial surgical planning and evaluation to complex musculoskeletal problems. These computer programs reformat ordinary CT scans into black and white images of the three-dimensional osseous surfaces found in the scanned volume. These reformatted three-dimensional CT scan images increase the utility of CT scan examinations of complex osseous structures, such as the wrist, spine, hip, knee, and shoulder. The software, which operates on an unmodified commercially available CT scanner, can produce high-quality surface reconstructions from CT scan slices without operator intervention. No special knowledge of the principles used in the reconstruction methods is needed to successfully use the programs.

Adolescent↗

PubMed1985

Computerized imaging for soft tissue and osseous reconstruction in the head and neck.

Recent developments in computer-aided medical imaging coupled with the related emergence of computer-aided design and manufacturing technology have had a significant effect on our management of patients with congenital and acquired head and neck deformities. In our institution, plain film skull radiography, cephalometry, and pluridirectional tomography have been largely replaced by high-resolution CT scanning augmented by planar reformations and three-dimensional surface reconstructions. A sophisticated computer-assisted radiologic imaging unit has been established to assist the surgeon and researcher. This marriage of advanced radiographic techniques, industrial computer-aided design technology, and clinical surgery have allowed us to better define aberrant anatomy, design new operative solutions for familiar as well as unusual problems, and quantitate changes of surgery and growth over time.

Adolescent↗

PubMed1984

Surface reconstructions from computerized tomographic scans for evaluation of malignant skull destruction.

The head and neck surgeon is dependent on radiographic technology to diagnose deformity, plan surgery, and evaluate operative results. The development of computerized tomographic scanning has facilitated osseous definition as well as allowed study of intracranial and extracranial soft tissue. Nonetheless, the computerized tomographic image slice format requires an educated interpreter and a fertile imagination for correlation with physical findings. We have created computer software that presents computerized tomographic data as surface images that resemble photographs of the patient or a specimen skull. The program runs on standard computerized tomographic scanners, requires no operator intervention, and is efficient in computation time and space. The surgeon can directly visualize the osseous deformity and mathematically relate it to the overlying soft tissue. The surface images can be viewed from a variety of perspectives, with or without selected structures, such as removing the body of the mandible in the pseudo-Water's projection to demonstrate the palate. The image data can be manipulated to obtain a variety of useful results beyond the images themselves. The addition of this technology to the preoperative evaluation and longitudinal follow-up of patients with head and neck cancer has increased our understanding of the extent of their malignancy.

Aged↗

PubMed1982

Reinsertability after breast prosthesis pocket infection: an experimental study.

We report the development of an animal model for the study of S. aureus infection in silicone gel-filled prosthesis pockets. The purpose of this study was to determine (1) whether successful reinsertion of a prosthesis into a contaminated pocket requires a finite recovery period between implant removal and reinsertion, and (2) whether parenteral antibiotic treatment affects the success of reinsertion. All infected pockets were lavaged with saline and none were drained, either after wound closure or after implant reinsertion. The results indicate that a delay of 2 or more hours between lavage and reinsertion protects against implant exposure. Therapeutic parenteral antibiotic treatment neither prevented implant exposure nor altered the effect of temporal delay on reinsertion. These studies coupled with recent clinical reports suggest that women who develop breast pocket infection need not wait months for restoration of breast symmetry.

Animals↗