Biomedical subjects

C J Sutherland

Publications and source records attributed to C J Sutherland.

41 records · Page 3Linked to original sources

PubMedDate not supplied

Use of general purpose mechanical computer assisted engineering software in orthopaedic surgical planning: advantages and limitations.

Two surgical plans were developed for an appropriately complex reconstructive orthopaedic surgery case. One plan was developed with customary methods using two-dimensional (2D) radiographs. The second plan was developed with general purpose mechanical computer assisted engineering (MCAE) software using x-ray computed tomography (CT) data. The limitations of each method are identified. To create a surgical plan using three-dimensional (3D) medical datasets and MCAE software, five necessary steps were identified: (a) data reduction; (b) contour extraction; (c) 3D model creation; (d) extraction of mass properties; (e) model idealization. The principal limitation of general purpose MCAE software is the lack of pre-processing modules with which to address the unique requirements of medical image datasets.

Acetabulum↗

PubMedDate not supplied

Depiction of pelvic fractures using 3D volumetric holography: comparison of plain X-ray and CT.

OBJECTIVE: The goal of this study was to demonstrate the feasibility and test the diagnostic performance of a new technology, 3D volumetric holography, for imaging pelvic fractures. The management of pelvic fractures may be complex, and advanced imaging studies such as CT are frequently indicated. Multiplanar CT reformations and 3D renderings provide clinically useful and complementary display of the directly acquired CT data. With the recent availability of volumetric multiple exposure holograms, produced from serial image data, it is now possible to produce true 3D images of the pelvis. In the hologram, one may view the CT data in 3D or as individual planar slices constituting the whole 3D pelvis. The diagnostic performance of the volumetric multiple exposure holograms was tested against routine radiography, CT, and 3D volumetric CT reconstructions. MATERIALS AND METHODS: Routine radiography and CT were performed in 15 patients with suspected pelvic fractures. Volumetric multiple exposure holograms and 3D volumetric CT reconstructions were created from the CT data. Axial and multiplanar reformation CT images were used as the standard for fracture, diastasis, and intraarticular fragment detection. RESULTS: Radiograms detected 39 of 50 of the fractures and diastases and no intraarticular fragments. The 3D CT reconstructions and the holograms viewed as 3D objects alone missed two small fractures of the anterior column and one hip with intraarticular bone fragments. When the volumetric multiple exposure holograms were viewed as a 3D object and as individual planar slices constituting the whole, their results were the same as the standard. CONCLUSION: Volumetric multiple exposure holograms were as sensitive and specific as axial CT and multiplanar reformations in detecting fracture pathology. By containing and making available, from one image, both planar and 3D information, volumetric multiple exposure holograms detected subtle anatomical features that were hidden by overlapping structures in the radiographs and the 3D CT images.

Fractures, Bone↗

PubMedDate not supplied

Artifacts and thresholding in X-ray CT of a cortical bone and titanium composite.

PURPOSE: X-Ray CT has the potential to provide precise and accurate data from which the mechanical properties of bone can be calculated. Such data would be useful in understanding the response of bone tissue to implants. Various artifacts can, however, degrade accuracy of the data. The aim of this study was to measure the artifactual errors produced in CT of a simulated femoral bone-titanium composite and to propose a method to correct for them. METHOD: A composite phantom that simulates cortical bone and a titanium implant was designed and constructed. The phantom was scanned and the image data were analyzed over a range of thresholds with image analysis software developed for this study. The outer (OD) and inner (ID) diameter and the CT number of the cortical bone, with and without titanium, were measured over a range of cortical thicknesses. RESULTS: While ID can be accurately measured by choosing the proper threshold (800 HU), OD, even at optimal threshold, will be underestimated by approximately 2%. If a proper threshold is selected, CT number can also be accurately determined. Errors of up to 5%, however, are produced by titanium unless corrected by proper threshold selection. CONCLUSION: Intramedullary titanium is not a deterrent to obtaining accurate measurements of cortical bone dimensions and properties. Proper choice of thresholds for image analysis of CT scan data can yield accuracy and precision of < or = 2%.

Artifacts↗

PubMedDate not supplied

Preoperative description of severe acetabular defects caused by failed total hip replacement.

PURPOSE: The reconstruction of severe acetabular defects, caused by failed hip prostheses, is difficult and complex. Current radiographic descriptions of the defects are inadequate. We sought to more accurately describe remaining bone and improve surgical planning using 3D physical models based on CT data. METHOD: Nineteen patients (20 hips) with failed total hip replacements and severe acetabular defects were selected. Plain radiography and CT were performed. Solid 3D physical models of each pelvis were constructed using the CT data. Bone loss in structurally important regions was measured from radiographs, models, and intraoperative observation. Comparisons were made of the radiograph-based and model-based bone loss measurements, surgical plans, and interobserver variability. RESULTS: There was no statistical difference between the model-based measurements and the intraoperative measurements. Radiographs statistically underestimated bone loss by at least 20% (p < 0.01). Interobserver bone loss grading was poor for the radiograph-based measurements (kappa = 0.06) but was substantial for the model-based measurements (kappa = 0.73). In only half the cases was prosthesis type correctly selected based on radiographs. Model-based planning selected the correct prosthesis type in all cases. CONCLUSION: The physical models were substantially more accurate than radiographs for measuring acetabular defects and for surgical planning.

Acetabulum↗

PubMedDate not supplied

Volumetric 3-D imaging of computerized tomography scans.

Contiguous transaxial high resolution CT scans of more than 100 patients with craniofacial deformities and orthopedic disorders were obtained. The CT scan examinations were used diagnostically in determining the need for surgery and for planning therapy. The serial section data was reconstructed in a three-dimensional form with surface and transparent volumetric computer graphics processing techniques. Real time sequences showing the presence of internal abnormalities in these patients were produced and recorded on video tape. This study demonstrates the feasibility and technical requirements of three-dimensional volumetric visualization for diagnostic evaluation of patients with craniofacial and orthopedic disorders.

Adult↗