Derek R. Ney

Volumetric rendering of computed tomography data: principles and techniques

The methods and algorithms used for volumetric rendering of medical computed tomography data are described in detail. Volumetric rendering allows for the use of a mixture paradigm for representation of the volume to be rendered and uses mathematical techniques to reduce or eliminate aliasing. A step-by-step description of the process used to generate two types of images (unshaded and shaded surfaces) is included. The technique generates three-dimensional images of computed tomography data with unprecedented image quality. Images generated with this technique are in routine clinical use.<<ETX>>

Examination of the pathologic anatomy of ankle fractures.

A prospective study of the translational and rotational displacement of the lateral malleolus in ankle fractures was carried out utilizing roentgenographic techniques. Twenty-six ankle fractures in 25 patients were studied using both routine plain films and CT scanning with two- and three-dimensional multiplanar reconstruction. Eighty-one percent were Lauge-Hansen supination-external rotation type injuries. Overall, 21 fractures did not involve the medial malleolus. Initial talar shift was less than or equal to 2 mm in 15 fractures. Although all patients exhibited external rotation deformities of the lateral malleolus on plain films, only one fracture was found to possess any degree of external rotation relative to the talus. The proximal fibula was seen on CT scans to have increased internal rotation with respect to the tibia in 19 cases. One patient had a slightly externally rotated proximal fibula; the remainder appeared normally aligned. The displacements measured by the CT scans at the talofibular articulation were compared with the standard plain film measurements. The displacements at the distal lateral malleolus were consistently overestimated by the plain roentgenograms, presumably because the capsular and ligamentous attachments to the distal fibula limit malleolar displacement. The talocrural angle, determined on both plain films and CT scans, was also not found to be a sensitive measure of fibular shortening nor of the severity of the fracture. The results of this study suggest that, in an isolated lateral malleolar ankle fracture, the apparent external rotation of the fracture fragment is relative only to the proximal fibula and is not associated with derangement of the talofibular articulation. Based on these mechanical considerations, surgical intervention for such fractures may not be necessary. This hypothesis is consistent with previous long-term clinical studies.

Three-dimensional Ct-volumetric Reconstruction and Display of the Bronchial Tree

We applied a refined version of our volumetric rendering technique for three-dimensional (3-D) computed tomographic (CT) imaging to display the cadaveric lung and the major components of the bronchial tree. We report details of the technical aspects of 3-D imaging of the lung, and four representative case studies of lung specimens from our initial experience.

Editing tools for 3D medical imaging

A set of tools called MPR Edit (multiplanar reconstruction editor) is presented. Designed like a paint and drawing program for 3-D data sets, MPR Edit allows the interactive creation of shapes that define volumes of interest in images of medical data. The implementation of MPR Edit is described, and examples of its use are given. Clinical applications are discussed.<<ETX>>

Three-dimensional imaging and display of musculoskeletal anatomy

Conventional three-dimensional imaging uses thresholding, or surface rendering technique, which limits accuracy and detail, and hinders soft tissue definition. Volumetric image rendering preserves all CT data, not just surface boundaries, and therefore overcomes these limitations. Three-dimensional images thus generated can be used for muscular and vascular anatomy as well as skeletal structures, with preservation of subtle detail. Representative cases are used to illustrate this technique and its implications for therapy and plastic and reconstructive surgery.

Complex Shoulder Trauma: Three-Dimensional CT Imaging

Volumetric three-dimensional imaging is a new technique for CT image processing which generates realistic, three-dimensional models of complex musculoskeletal anatomy from routine transaxial CT data. Volumetric three-dimensional imaging is particularly helpful in evaluating complex shoulder trauma, demonstrating significant advantages over plain film radiography. Multipartite fractures involving the shoulder girdle are displayed in a comprehensive fashion with 3D imaging. With volumetric imaging as implemented on a Pixar Imaging Computer, a 3D model of the injured shoulder can be generated with overlapping structures removed from view, and then rotated about the vertical and horizontal axis for better understanding of abnormal anatomy prior to surgical correction.

Acetabular and pelvic fractures in the pediatric patient: value of two- and three-dimensional imaging.

Pediatric trauma is a significant source of morbidity and mortality in pediatric patients. Prompt and accurate assessment of injuries is necessary for the best outcome. Computed tomography (CT) has become a well-accepted, rapid, relatively noninvasive way to assess the trauma patient. In certain cases of pelvic trauma, two- and three-dimensional CT (2D/3D CT) adds detail not otherwise obtainable or appreciated. Although the benefits must be balanced against the slight increase in delivered radiation dose, we believe that 2D/3D CT is often an important part of patient management.

The current state of the art in three dimensional oncologic imaging: An overview

PURPOSE To provide an overview of the methods and clinical applications of three dimensional (3D) medical imaging in the oncologic patient. METHODS AND MATERIALS We briefly outline the techniques currently used to create 3D medical images with an emphasis on their strengths and shortcomings as they relate to oncologic imaging and radiation therapy planning. We then discuss some of the most important and promising oncologic applications of 3D imaging and suggest likely future directions in this rapidly developing field. RESULTS Since the first application of 3D techniques to medical data over a decade ago, 3D medical images have evolved from relatively crude representations of musculoskeletal abnormalities to detailed and accurate representations of a variety of soft tissue, vascular, and oncologic pathology. The rapid development of both computer hardware and software coupled with the application of 3D techniques to a variety of imaging modalities have expanded the clinical applications of this technology dramatically. CONCLUSIONS 3D medical images are clinically practical tools for oncologic evaluation and effective radiation therapy planning.

Parosteal ossifying lipoma : CT and MR findings

Radiologic and imaging findings of parosteal ossifying lipoma along with pathologic correlation are presented in this case report.

Three-dimensional display of hepatic venous anatomy generated from spiral computed tomography data: Preliminary results

A new method is presented for generating three-dimensional images of the hepatic venous anatomy from helical computed tomography (CT) scans using volumetric rendering. The helical CT scans were obtained using peripheral injection of intravenous contrast via a power injector. Five patients with suspected liver tumors were studied from which one sample case was selected for illustration. Surgical planning of hepatic resection from three-dimensional images will soon become a practical part of patient care.