A Patel1, S Haleem2, R Rajakulasingam3, S L James1, A M Davies1, R Botchu1. 1. Departments of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham, UK. 2. Departments of Spinal Surgery, Royal Orthopaedic Hospital, Birmingham, UK. 3. Departments of Musculoskeletal Radiology, Royal National Orthopaedic Hospital, Stanmore, London, UK.
Abstract
AIM: To compare the accuracy of the inverted greyscale CT versus the conventional CT in the assessment of post-operative spinal orthopaedic implants and osseous fusion. METHODS: 50 patients who had CT as part of their routine spinal implant follow up were evaluated for the presence of fusion, fracture and loosening with conventional CT and with greyscale inverted CT images. 3 independent observers assessed the images 2 months apart. Diagnostic performance (sensitivity and specificity) of the conventional and greyscale inversion images relative to the reference standard were calculated. Agreement with the reference standard was assessed using Cohen's kappa for conventional and greyscale inversion images. RESULTS: Correct classifications increased when using the greyscale inverted CT images for each reader compared to conventional CT images (40-46, 39 to 42 and 41 to 44 (out of 50)). Inverted images demonstrated better agreement with the reference standard than conventional grayscale images for assessment of fusion (kappa of 0.588 for inverted CT versus 0.484 for conventional CT) and loosening (kappa 0.386 for inverted versus 0.293 for conventional). Sensitivity was increased for assessment of fusion and loosening. McNemar's test performed for assessment of sensitivity differences showed statistical significance (p = 0.038 for fusion and p = 0.0313 for loosening). CONCLUSION: Greyscale inversion CT is a useful adjunct which has advantages (improved sensitivity and better agreement) over conventional CT imaging in cases of fusion and loosening of metallic implants following spinal instrumentation. We recommend the use of both the greyscale inversion CT images and conventional CT imaging when assessing post-operative spinal orthopaedic implants.
AIM: To compare the accuracy of the inverted greyscale CT versus the conventional CT in the assessment of post-operative spinal orthopaedic implants and osseous fusion. METHODS: 50 patients who had CT as part of their routine spinal implant follow up were evaluated for the presence of fusion, fracture and loosening with conventional CT and with greyscale inverted CT images. 3 independent observers assessed the images 2 months apart. Diagnostic performance (sensitivity and specificity) of the conventional and greyscale inversion images relative to the reference standard were calculated. Agreement with the reference standard was assessed using Cohen's kappa for conventional and greyscale inversion images. RESULTS: Correct classifications increased when using the greyscale inverted CT images for each reader compared to conventional CT images (40-46, 39 to 42 and 41 to 44 (out of 50)). Inverted images demonstrated better agreement with the reference standard than conventional grayscale images for assessment of fusion (kappa of 0.588 for inverted CT versus 0.484 for conventional CT) and loosening (kappa 0.386 for inverted versus 0.293 for conventional). Sensitivity was increased for assessment of fusion and loosening. McNemar's test performed for assessment of sensitivity differences showed statistical significance (p = 0.038 for fusion and p = 0.0313 for loosening). CONCLUSION: Greyscale inversion CT is a useful adjunct which has advantages (improved sensitivity and better agreement) over conventional CT imaging in cases of fusion and loosening of metallic implants following spinal instrumentation. We recommend the use of both the greyscale inversion CT images and conventional CT imaging when assessing post-operative spinal orthopaedic implants.
Authors: Diederick W De Boo; Martin Uffmann; Shandra Bipat; Eelco F A Boorsma; Maeke J Scheerder; Michael Weber; Cornelia M Schaefer-Prokop Journal: AJR Am J Roentgenol Date: 2011-11 Impact factor: 3.959
Authors: Sharada Weir; Mihail Samnaliev; Tzu-Chun Kuo; Caitriona Ni Choitir; Travis S Tierney; David Cumming; Julie Bruce; Andrea Manca; Rod S Taylor; Sam Eldabe Journal: BMJ Open Date: 2017-09-11 Impact factor: 2.692