Biomedical subjects
Publications and source records attributed to D R Ney.
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.
Thirteen patients with 15 ankle fractures potentially requiring surgical reduction according to plain film criteria were studied with transaxial CT, from which static and animated interactive two-dimensional (2-D) images and animated volumetric three-dimensional (3-D) images were generated. CT criteria believed to parallel well-accepted plain film criteria for triage of ankle fractures were developed and applied. The tibiofibular, talofibular, and tibiotalar articulations were characterized and, where possible (nine cases), compared with the (presumably normal) contralateral ankle. Talocrural angle measurements were made on interactive coronal measurements and compared with standard plain film measurements. Fracture fragment displacement, rotation, and impaction were noted. Posterior tibial lip disruption was quantified. Information derived from the 2-D/3-D CT study led to cancellation of proposed surgery in three of the distal fibular fractures and in two distal tibial fractures. There was far less variation than anticipated between the talocrural angles of the injured and normal ankles, and both injured and normal ankles deviated significantly from the accepted standard of 84 degrees. Displacement at the level of the fibular fracture was a poor predictor of more distal disruption. Two-dimensional CT was found to provide anatomic detail and information superior to either plain film or 3-D CT; 3-D CT was preferred by the surgeons for final surgical planning and for integration of the 2-D data. CT altered management in five of the 13 patients studied, supporting our belief that 2-D/3-D CT can be of significant value in assessing ankle fractures.
Multimedia is a form of computer data presentation that uses multiple formats (text, illustration, sound, and animation) to enhance attention to and retention of presented information. Hypermedia is a nonlinear, branched access version of this that allows the user to pursue information more freely and variably than a linear format does. We used the hypermedia format to create an interactive medical teaching program that we believe holds the user's interest and attention better than a straight-text style does.
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Nonunions involving fractures of the acetabulum are reportedly rare, with few citings and little discussion in the literature. It is possible that acetabular nonunions go undetected because imaging of the acetabulum is difficult by conventional radiography. We report two cases of fracture nonunion involving the weight-bearing surface of the acetabulum diagnosed with the aid of computed tomography (CT) and a newly developed interactive 2D/3D orthotool (copyright and trademark of the Body CT Imaging Laboratory, Department of Radiology, The Johns Hopkins Medical Institutions) that uniquely processes and reformats routine CT data. The interactive 2D/3D orthotool is a sophisticated computer program that allows dynamic viewing of standard multiplanar reconstructions in the axial, coronal, and sagittal planes as well as multiple oblique projections. The 2D/3D orthotool provides on screen correlation of two-dimensional multiplanar images with three-dimensional reconstructions of the pelvis. The authors found this capability ideally suited for studying fractures with off-axis orientation such as those through the acetabular dome, greatly facilitating the diagnosis of nonunion.
A new software program provides the real-time display of high-resolution computed tomographic reformation in the axial, coronal, sagittal, or oblique views. The advantages of this new technique over the standard multiplanar format include (a) larger image display format, (b) reconstruction of entire dataset for each of up to 192 sections, (c) real-time viewing, (d) interactive real-time oblique imaging, and (e) on-screen correlation of multiplanar and three-dimensional images.
Fifty-six patients with musculoskeletal disorders involving the shoulder were examined using two-dimensional computed tomography multiplanar reconstruction and volumetric three-dimensional (3D) image processing. Two- and three-dimensional imaging of the shoulder demonstrated advantages over conventional radiography in clarifying areas of complex anatomy. The techniques were found most beneficial for (1) delineating complex fractures; (2) evaluating joint instability; (3) localizing foreign bodies; (4) detecting lytic lesions; (5) assessing soft tissue pathology; and (6) identifying causes for decreased range of motion. Two-dimensional multiplanar reconstruction provided superior views of the scapula and permitted a better understanding of the orientation of the glenoid. Multiplanar reconstruction displayed deep soft tissue anatomy more clearly, including the course of important neurovascular structures. Volumetric 3D imaging added several unique perspectives, providing a more comprehensive representation of the shoulder and its articulating surfaces. The ability to rotate the shoulder about he vertical and horizontal axes in an animated video loop and to edit away confusing, overlying structures provided a "real-time" 3D model of the shoulder for planning treatment.
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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.
Volumetric rendering is a new approach to three-dimensional (3D) imaging that overcomes many of the drawbacks of currently available surface-rendering systems. Its application on the Pixar Imaging System in two cases of acetabular fracture was assessed to illustrate the features of the technique. The fast-computing architecture and large memory of this system allow rapid generation of a series of high-quality 3D images in each plane of rotation (x or spinal axis, z or somersaulting axis) that can be viewed as independent static images or as an animated real-time video loop. Editing to remove the normal contralateral hemipelvis enhances appreciation of acetabular abnormalities. Every pixel of computed tomographic data is preserved, allowing representation of both soft tissue and bone as translucent overlap. The presentation of data also allows detection of subtle abnormalities and features and minimizes the artifact generation common in surface-rendered images.
This paper presents a technique for the multiplanar display and manipulation of standard CT and MRI data. Using this interactive tool one can display axial, coronal, and sagittal plane from standard CT or MRI data sets, as well as selecting arbitrary oblique planes. This system uses a bi-cubic interpolation technique to produce high quality reformatted images. The tool allows interactive roaming of the CT or MRI data volume and facilitates communication between the radiologist and the referring physician.
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.
Three-dimensional volumetric rendering of CT data has proven to be valuable in the evaluation of the hip. Although video loop animation allows review of the anatomy from all perspectives, it does not show the functional range of motion of the femur in the acetabulum. We have developed a technique termed simulated dynamic CT that gives dynamic animated three-dimensional viewing capabilities. This technique incorporates static CT data with gait and movement data to produce a sequence of dynamic images simulating range of motion. Additionally, this technique allows simulation of surgical techniques to visually anticipate the results of reduction and traction and potential limitations in subsequent hip movement. To assess the potential of this technique, two dysplastic hip patients were studied prior to reconstruction. In each case the perspective thus gained led to altered surgical management.
Standard axial CT supplemented by two-dimensional reconstruction in coronal, sagittal, and oblique planes was used to evaluate 35 patients with a history of breast cancer and clinical symptoms suggestive of brachial plexopathy. In five patients, definite tumor recurrence was seen either within the axilla or the neurovascular bundle or near the origin of the brachial plexus at the C5-C7 level. In six patients, there was thickening around the plexus compatible with fibrosis or scarring. In these patients, no mass was seen. In 24 patients, no evidence of abnormality was noted. Reformatted views can supplement transaxial CT and are particularly effective in defining the course of the brachial plexus and detection of tumor recurrence. The oblique views along with orthogonal planes provide optimal visualization of the brachial plexus and are helpful in the detection of tumor involvement.
Of the many steps involved in producing high quality three-dimensional (3D) images of CT data, the data acquisition step is of greatest consequence. The principle of "garbage in, garbage out" applies to 3D imaging--bad scanning technique produces equally bad 3D images. We present a formal study of the effect of two basic scanning parameters, slice thickness and slice spacing, on image quality. Three standard test objects were studied using variable CT scanning parameters. The objects chosen were a bone phantom, a cadaver femur with a simulated 5 mm fracture gap, and a cadaver femur with a simulated 1 mm fracture gap. Each object was scanned at three collimations: 8, 4, and 2 mm. For each collimation, four sets of scans were performed using four slice intervals: 8, 4, 3, and 2 mm. The bone phantom was scanned in two positions: oriented perpendicular to the scanning plane and oriented 45 degrees from the scanning plane. Three-dimensional images of the resulting 48 sets of data were produced using volumetric rendering. Blind review of the resultant 48 data sets was performed by three reviewers rating five factors for each image. The images resulting from scans with thin collimation and small table increments proved to rate the highest in all areas. The data obtained using 2 mm slice intervals proved to rate the highest in perceived image quality. Three millimeter slice spacing with 4 mm collimation, which clinically provides a good compromise between image quality and acquisition time and dose, also produced good perceived image quality. The studies with 8 mm slice intervals provided the least detail and introduced the worst inaccuracies and artifacts and were not suitable for clinical use. Statistical analysis demonstrated that slice interval (i.e., table incrementation) was of primary importance and slice collimation was of secondary, although significant, importance in determining perceived 3D image quality.
Radiologic and imaging findings of parosteal ossifying lipoma along with pathologic correlation are presented in this case report.
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.