Extended Computed Tomography Scale Images Provide a Detailed Assessment of Metal Screws and Are Superior to Standard Computed Tomography Scale Images and Digital Radiography at Detecting Experimentally Induced Screw Fractures In Vitro

Abstract

Objectives (1) To compare the ability of standard computed tomography (CT) scale (SCTS) and extended CT scale (ECTS) images, produced using conventional CT technology, to provide detailed assessment of metal screws in vitro. (2) To assess how screw size, type, and orientation relative to the Z-axis of the gantry affect implant assessment. (3) To test the ability of SCTS, ECTS, and radiography to diagnose screw failure when there is negligible screw fragment displacement.

Study Design Part 1: 12 screws of different size, type, and composition were scanned in three orientations (parallel or 0°; oblique or 45°; and perpendicular or 90°) relative to the Z-axis of the gantry. SCTS and ECTS reconstructions were made for each screw, in each plane, to assess implant shape, structure, and diameter. Part 2: fatigue-failure was induced in four screws commonly used to stabilize canine humeral intracondylar fissures. Screws were then reassembled achieving grossly perfect apposition and alignment of the fragments. Ability to detect implant failure was tested using SCTS, ECTS, and radiography.

Results ECTS provided better screw assessment compared with SCTS resulting in clear visualization of the structure in 8/12 versus 0/12 screws and shape in 12/12 versus 11/12 screws; however, results were affected by screw size, type, and orientation. ECTS identified all in vitro screw fractures with negligible screw fragment displacement; however, success was affected by screw orientation: 4/4 fractures identified with a 90° angle, 1/4 for 45°, and 0/4 for 0°. SCTS and radiography did not identify any of them.

Conclusion The results indicate that ECTS reconstructions are useful for assessment of metal screws and for detection of nondisplaced screw fractures.

Keywords

extended computed tomography scale - transcondylar screw - fracture - implant failure

Authors' Contributions

All authors provided substantial contribution to this manuscript: J.L. was involved in conception of the study, study design, acquisition of data and data analysis and interpretation, A.H. was involved in conception of the study, study design and data analysis and interpretation, C.I. was involved in conception of the study, study design and data analysis and interpretation. All the authors contrinbuted to drafting and revising the manuscript, approval of submitted manuscript and are publicy accountable for the relevant content of the manuscript.

Animal Care Statement

The authors confirm that this research has been conducted without the use of live animals in a manner likely to be approved by an ethics committee in most countries.

Previous affiliation of authors one and three (J.L. and A.H.) during collection of the data and confection of the manuscript: Southern Counties Veterinary Specialists, Hampshire, BH24 3JW, United Kingdom.

Publikationsverlauf

Eingereicht: 22. Oktober 2021

Angenommen: 23. Februar 2022

Artikel online veröffentlicht:
15. Juni 2022

• References

• 1 Labrador J, Witte PG, Holdsworth A. Use of an extended CT scale reconstruction to diagnose metal implant failure in a canine elbow. Vet Radiol Ultrasound 2021; 62 (06) e63-e66
• 2 Ohashi K, El-Khoury GY, Bennett DL, Restrepo JM, Berbaum KS. Orthopedic hardware complications diagnosed with multi-detector row CT. Radiology 2005; 237 (02) 570-577
• 3 Vande Berg B, Malghem J, Maldague B, Lecouvet F. Multi-detector CT imaging in the postoperative orthopedic patient with metal hardware. Eur J Radiol 2006; 60 (03) 470-479
• 4 Glide-Hurst C, Chen D, Zhong H, Chetty IJ. Changes realized from extended bit-depth and metal artifact reduction in CT. Med Phys 2013; 40 (06) 061711
• 5 Mullins JP, Grams MP, Herman MG, Brinkmann DH, Antolak JA. Treatment planning for metals using an extended CT number scale. J Appl Clin Med Phys 2016; 17 (06) 179-188
• 6 Ese Z, Kressman M, Kreutner J, Schaefers G, Erni D, Zylka W. Influence of conventional and extended CT scale range on quantification of Hounsfield units of medical implants and metallic objects. Technisches Messen. 2018; 85 (05) 343-350
• 7 Jayamani J, Osman N, Tajuddin A, Salehi Z, Ali M, Aziz M. Determination of computed tomography number of high-density materials in 12-bit, 12-bit extended and 16-bit depth for dosimetric calculation inj treatment planning systems. J Radiother Pract 2019; 18 (03) 285-294
• 8 Coolens C, Childs PJ. Calibration of CT Hounsfield units for radiotherapy treatment planning of patients with metallic hip prostheses: the use of the extended CT-scale. Phys Med Biol 2003; 48 (11) 1591-1603
• 9 Gao L, Sun H, Ni X, Fang M, Lin T. Effects of 16-bit CT imaging scanning conditions for metal implants on radiotherapy dose distribution. Oncol Lett 2018; 15 (02) 2373-2379
• 10 Link TM, Berning W, Scherf S. et al. CT of metal implants: reduction of artifacts using an extended CT scale technique. J Comput Assist Tomogr 2000; 24 (01) 165-172
• 11 Klotz E, Kalender W, Sokiransky R, Felsenberg D. Algorithms for the reduction of CT artifacts caused by metallic implants. Proc. SPIE 1234, Medical Imaging IV: PACS Systems Design and Evaluation. 1990
• 12 Ebert MA, Lambert J, Greer PB. CT-ED conversion on a GE Lightspeed-RT scanner: influence of scanner settings. Australas Phys Eng Sci Med 2008; 31 (02) 154-159
• 13 Gascho D, Zoelch N, Deininger-Czermak E. et al. Visualization and material-based differentiation of lodged projectiles by extended CT scale and the dual-energy index. J Forensic Leg Med 2020; 70: 101919
• 14 Fraga-Manteiga E, Shaw DJ, Dennison S, Brownlow A, Schwarz T. An optimized computed tomography protocol for metallic gunshot head trauma in a seal model. Vet Radiol Ultrasound 2014; 55 (04) 393-398
• 15 Charles EA, Ness MG, Yeadon R. Failure mode of transcondylar screws used for treatment of incomplete ossification of the humeral condyle in 5 dogs. Vet Surg 2009; 38 (02) 185-191
• 16 Carrera I, Hammond GJ, Sullivan M. Computed tomographic features of incomplete ossification of the canine humeral condyle. Vet Surg 2008; 37 (03) 226-231
• 17 Kalpakjian S, Schmid S, Musa H. Manufacturing Engineering and Technology. 6th Ed.. London: Pearson; 2009: 74
• 18 Paulis LE, Kroll J, Heijnens L. et al. Is CT bulletproof? On the use of CT for characterization of bullets in forensic radiology. Int J Legal Med 2019; 133 (06) 1869-1877