1.
Försth, Peter, 1966-, et al.
(författare)
Motion Analysis in Lumbar Spinal Stenosis With Degenerative Spondylolisthesis : A Feasibility Study of the 3DCT Technique Comparing Laminectomy Versus Bilateral Laminotomy.
2018
Ingår i: Clinical spine surgery. - : Wolters Kluwer. - 2380-0186 .- 2380-0194. ; 31:8, s. E397-E402
Tidskriftsartikel (refereegranskat) abstract
Study Design: This was a randomized radiologic biomechanical pilot study in vivo. Objective: The objectives of this study was to evaluate if 3-dimensional computed tomography is a feasible tool in motion analyses of the lumbar spine and to study if preservation of segmental midline structures offers less postoperative instability compared with central decompression in patients with lumbar spinal stenosis with degenerative spondylolisthesis. Summary of Background Data: The role of segmental instability after decompression is controversial. Validated techniques for biomechanical evaluation of segmental motion in human live subjects are lacking. Methods: In total, 23 patients (mean age, 68 y) with typical symptoms and magnetic resonance imaging findings of spinal stenosis with degenerative spondylolisthesis (>3 mm) in 1 or 2 adjacent lumbar levels from L3 to L5 were included. They were randomized to either laminectomy (LE) or bilateral laminotomy (LT) (preservation of the midline structures). Documentation of segmental motion was made preoperatively and 6 months postoperatively with CT in provoked flexion and extension. Analyses of movements were performed with validated software. The accuracy for this method is 0.6 mm in translation and 1 degree in rotation. Patient-reported outcome measures were collected from the Swespine register preoperatively and 2-year postoperatively. Results: The mean preoperative values for 3D rotation and translation were 6.2 degrees and 1.8 mm. The mean increase in 3D rotation 6 months after surgery was 0.25 degrees after LT and 0.7 degrees after LE (P=0.79) while the mean increase in 3D translation was 0.15 mm after LT and 1.1 mm after LE (P=0.42). Both surgeries demonstrated significant improvement in patient-reported outcome measures 2 years postoperatively. Conclusions: The 3D computed tomography technique proved to be a feasible tool in the evaluation of segmental motion in this group of older patients. There was negligible increase in segmental motion after decompressive surgery. LE with removal of the midline structures did not create a greater instability compared with when these structures were preserved.
2.
Weidenhielm, Lars, et al.
(författare)
Prosthetic liner wear in total hip replacement : a longitudinal 13-year study with computed tomography.
2018
Ingår i: Skeletal Radiology. - : Springer. - 0364-2348 .- 1432-2161. ; 47:6, s. 883-887
Tidskriftsartikel (refereegranskat) abstract
This case report follows a woman who had a total hip replacement in 1992 when she was 45 years old. Six serial computed tomography (CT) examinations over a period of 13 years provided information that allowed her revision surgery to be limited to liner replacement as opposed to replacement of the entire prosthesis. Additionally, they provided data that ruled out the presence of osteolysis and indeed none was found at surgery. In 2004, when the first CT was performed, the 3D distance the femoral head had penetrated into the cup was determined to be 2.6 mm. By 2017, femoral head penetration had progressed to 5.0 mm. The extracted liner showed wear at the thinnest part to be 5.5 mm, as measured with a micrometer. The use of modern CT techniques can identify problems, while still correctable without major surgery. Furthermore, the ability of CT to assess the direction of wear revealed that the liner wear changed from the cranial to dorsal direction.
3.
Olivecrona, Henrik, et al.
(författare)
A new computed tomography-based radiographic method to detect early loosening of total wrist implants
2007
Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 48:9, s. 997-1003
Tidskriftsartikel (refereegranskat) abstract
Background: Diagnosis of loosening of total wrist implants is usually late using routine radiographs. Switching modality to computed tomography (CT) should aid in early diagnosis. Purpose: To propose and evaluate the accuracy of a new CT method for assessing loosening of the carpal component in total wrist arthroplasty. Material and Methods: A protocol encompassing volume registration of paired CT scans of patients with unexplained pain in a prosthetically replaced wrist (used in clinical routine) is presented. Scans are acquired as a dynamic examination under torsional load. Using volume registration, the carpal component of the prosthesis is brought into spatial alignment. After registration, prosthetic loosening is diagnosed by a shift in position of the bones relative to the prosthesis. This study is a preclinical validation of this method using a human cadaverous arm with a cemented total wrist implant and tantalum markers. Seven CT scans of the arm were acquired. The scans were combined into 21 pairs of CT volumes. The carpal component was registered in each scan pair, and the residual mismatch of the surrounding tantalum markers and bone was analyzed both visually and numerically. Results: The detection limit for prosthetic movement was less than 1 mm. Conclusion: The results of this study demonstrate that CT volume registration holds promise to improve detection of movement of the carpal component at an earlier stage than is obtainable with plain radiography.
4.
Hatherly, Robert, et al.
(författare)
Technical Requirements for Na18F PET Bone Imaging of Patients Being Treated Using a Taylor Spatial Frame.
2014
Ingår i: Journal of nuclear medicine technology. - : Society of Nuclear Medicine. - 1535-5675 .- 0091-4916.
Tidskriftsartikel (refereegranskat) abstract
Diagnosis of new bone growth in patients with compound tibia fractures or deformities treated using a Taylor spatial frame is difficult with conventional radiography because the frame obstructs the images and creates artifacts. The use of Na(18)F PET studies may help to eliminate this difficulty.METHODS: Patients were positioned on the pallet of a clinical PET/CT scanner and made as comfortable as possible with their legs immobilized. One bed position covering the site of the fracture, including the Taylor spatial frame, was chosen for the study. A topogram was performed, as well as diagnostic and attenuation correction CT. The patients were given 2 MBq of Na(18)F per kilogram of body weight. A 45-min list-mode acquisition was performed starting at the time of injection, followed by a 5-min static acquisition 60 min after injection. The patients were examined 6 wk after the Taylor spatial frame had been applied and again at 3 mo to assess new bone growth.RESULTS: A list-mode reconstruction sequence of 1 × 1,800 and 1 × 2,700 s, as well as the 5-min static scan, allowed visualization of regional bone turnover.CONCLUSION: With Na(18)F PET/CT, it was possible to confirm regional bone turnover as a means of visualizing bone remodeling without the interference of artifacts from the Taylor spatial frame. Furthermore, dynamic list-mode acquisition allowed different sequences to be performed, enabling, for example, visualization of tracer transport from blood to the fracture site.
5.
Eriksson, Thomas, et al.
(författare)
Are low-dose CT scans a satisfactory substitute for stereoradiographs for migration studies? A preclinical test of low-dose CT scanning protocols and their application in a pilot patient.
2019
Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455.
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Computed tomography (CT) has the potential to acquire the data needed for migration studies of orthopedic joint implants of patients who have had tantalum beads implanted at the time of joint replacement surgery. This can be accomplished with the same precision as radiostereometric analysis (RSA). Switching to CT would increase availability without the need for the specific facilities required for RSA. However, higher effective dose is a concern.PURPOSE: To investigate if migration measurements can be done with CT with an accuracy and effective dose comparable to that of conventional RSA.MATERIAL AND METHODS: Fourteen scanning protocols were tested in a hip phantom that incorporated tantalum beads and an uncemented femoral stem. The protocols were graded for clinical practice according to the three parameters of image quality, effective dose, and robustness of numerical data. After grading, the two protocols that graded best overall were applied to a pilot patient.RESULTS: All protocols produced scans in which the numerical data were sufficient for a migration analysis at least as precise as would be expected using RSA. A protocol with an effective dose of 0.70 mSv was shown to be applicable in a pilot patient.CONCLUSION: Low-dose CT scans with an effective dose comparable to a set of routine plain radiographs can be used for precise migration measurements.
6.
Maguire Jr., Gerald Q.
(författare)
Looking back at PACS attempts—what has happened since PACS I
1986
Ingår i: Pictorial information systems in medicine : [proceedings of the NATO Advanced Study Inst. on Pictorial Information Systems in Medicine held in Braunlage FRG, August 27 - September 7, 1984]. - 3540139214 - 0387139214 ; , s. 391-399
Konferensbidrag (refereegranskat)
7.
8.
Olivecrona, Lotta, et al.
(författare)
Assessing wear of the acetabular cup using computed tomography : an ex vivo study
2005
Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 46:8, s. 852-857
Tidskriftsartikel (refereegranskat) abstract
Purpose: To validate a clinically useful method for measuring acetabular cup wear using computed tomography (CT). Material and Methods: Eight uncemented acetabular cups were scanned twice ex vivo using CT. The linear penetration depth of the femoral component head into the cup and the thickness of the remaining polyethylene liner were measured in the CT volumes using dedicated software. Two independent examiners twice assessed each volume. The CT measurements were compared to direct measurements using a coordinate measuring device and micrometer measurements. Results: Accuracy of wear measurements expressed as penetration depth was +/- 0.6 and +/- 1.0 mm for the two examiners, respectively, with no significant differences between examiners, trials, and CT scans. Accuracy of measurements of remaining polyethylene was +/- 1.3 and +/- 1.0 mm, respectively, for the two examiners. Systematic differences between examiners were found, but no significant differences between trials and CT scans. These differences were due to different interpretations of metal artifacts in the volumes. Conclusion: The proposed CT method for evaluating wear as head penetration depth allows for reliable wear detection at a clinically relevant level. Measurements of remaining polyethylene on CT volumes are not as reliable as wear measurements owing to metal artifacts.
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