Dual Energy CT Myelography after Lumbar Osteosynthesis

Abstract

Purpose: The purpose of this study was to evaluate the benefits of CT myelography in the DE technique in patients with lumbar osteosynthesis.

Materials and Methods: In 30 patients a DE-CT scan of the spine with tube voltages of 80 kV and 140 kV was performed and a virtual monochromatic series of 120 kV was generated after intrathecal contrast injection. The impact of metal artifacts on the spinal canal and the spinal foramina was evaluated. The visualization of nerve roots was compared between a VRT series of the dural sac and conventional myelography.

Results: With tube voltages of 140 kV, the artifacts were least pronounced. As no overlay disturbance was present, VRT visualization of the nerve roots was more reliable than conventional myelography.

Conclusion: In patients after osteosynthesis, CT in the DE technique provides minimal artifact disturbance using a tube voltage of 140 kV. “Virtual myelography” seems to be superior to conventional myelography for the evaluation of nerve roots. This could reduce additional conventional radiography, may shorten the entire examination and radiation time and diminish unnecessary painful movements for the patient.

Key Points: DE-CT myelography is a promising method in patients after spinal osteosynthesis.

Citation Format:

• Grams AE, Sender J, Moritz R et al. Dual Energy CT Myelography after Lumbar Osteosynthesis. Fortschr Röntgenstr 2014; 186: 670 – 674

Zusammenfassung

Ziel: Das Ziel dieser Studie war es den Nutzen der CT-Myelografie in DE-Technik bei Patienten nach lumbaler Osteosynthese zu untersuchen.

Material und Methoden: Bei 30 Patienten wurde nach intrathekaler Gabe von Kontrastmittel eine DE-CT-Untersuchung der Lendenwirbelsäule mit Röhrenspannungen von 80 kV und 140 kV durchgeführt und eine virtuelle, monochromatische Serie von 120 kV generiert. Es wurde der Einfluss von Metallartefakten auf den Spinalkanal und die Neuroforamina beurteilt und die Darstellung der Wurzeltaschen zwischen einer VRT-Serie und konventionellen Röntgenaufnahmen verglichen.

Ergebnisse: Mit Röhrenspannungen von 140 kV waren die Artefakte am wenigsten stark ausgeprägt. Mit der VRT-Darstellung war es im Gegensatz zu den konventionellen Aufnahmen möglich die Wurzeltaschen ohne Überlagerung durch das Osteosynthesematerial darzustellen.

Schlussfolgerung: Bei Patienten mit lumbaler Osteosynthese erhält man im Rahmen der DE-CT mit 140 kV einen nur minimal durch Artefakte überlagerten Datensatz. Die „virtuelle Myelografie“ mittels VRT-Rekonstruktionen scheint vorteilhaft gegenüber der konventionellen Myelografie bezüglich der Darstellung der spinalen Wurzeltaschen. Dies könnte zusätzliche konventionelle Aufnahmen und somit die Untersuchungs- und Durchleuchtungszeit reduzieren sowie unnötige, schmerzhafte Bewegungen für den Patienten vermeiden.

Kernaussage: Die DE-CT-Myelografie stellt eine vielversprechende Methode bei Patienten nach spinaler Osteosynthese dar.

Key words

spine - CT - surgery

• References:

• 1 Knott PT, Mardjetko SM, Kim RH et al. A comparison of magnetic and radiographic imaging artifact after using three types of metal rods: stainless steel, titanium, and vitallium. The spine journal : official journal of the North American Spine Society 2010; 10: 789-794
• 2 Bauer RW, Kramer S, Renker M et al. Dose and image quality at CT pulmonary angiography-comparison of first and second generation dual-energy CT and 64-slice CT. Eur Radiol 2011; 21: 2139-2147
• 3 Thomas C, Ketelsen D, Tsiflikas I et al. Dual-energy computed tomography: is there a penalty in image quality and radiation dose compared with single-energy computed tomography?. J Comput Assist Tomogr 2010; 34: 309-315
• 4 Flohr TG, McCollough CH, Bruder H et al. First performance evaluation of a dual-source CT (DSCT) system. Eur Radiol 2006; 16: 256-268
• 5 Fahrendorf DM, Goericke SL, Oezkan N et al. The value of dual-energy CTA for control of surgically clipped aneurysms. Eur Radiol 2011; 21: 2193-2201
• 6 Schenzle JC, Sommer WH, Neumaier K et al. Dual energy CT of the chest: how about the dose?. Investigative radiology 2010; 45: 347-353
• 7 Zhou C, Zhao YE, Luo S et al. Monoenergetic imaging of dual-energy CT reduces artifacts from implanted metal orthopedic devices in patients with factures. Acad Radiol 2011; 18: 1252-1257
• 8 Guggenberger R, Winklhofer S, Osterhoff G et al. Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels. European radiology 2012; 22: 2357-2364
• 9 Stolzmann P, Winklhofer S, Schwendener N et al. Monoenergetic computed tomography reconstructions reduce beam hardening artifacts from dental restorations. Forensic science, medicine, and pathology 2013;
• 10 Lell MM, Kramer M, Klotz E et al. Carotid computed tomography angiography with automated bone suppression: a comparative study between dual energy and bone subtraction techniques. Investigative radiology 2009; 44: 322-328
• 11 Thomas C, Korn A, Krauss B et al. Automatic bone and plaque removal using dual energy CT for head and neck angiography: feasibility and initial performance evaluation. Eur J Radiol 2010; 76: 61-67
• 12 Johnson TR, Krauss B, Sedlmair M et al. Material differentiation by dual energy CT: initial experience. Eur Radiol 2007; 17: 1510-1517
• 13 Morhard D, Fink C, Graser A et al. Cervical and cranial computed tomographic angiography with automated bone removal: dual energy computed tomography versus standard computed tomography. Investigative radiology 2009; 44: 293-297
• 14 Wintermark M, Maeder P, Verdun FR et al. Using 80 kVp versus 120 kVp in perfusion CT measurement of regional cerebral blood flow. AJNR Am J Neuroradiol 2000; 21: 1881-1884
• 15 Hwang HJ, Seo JB, Lee JS et al. Radiation dose reduction of chest CT with iterative reconstruction in image space – Part II: assessment of radiologists’ preferences using dual source CT. Korean journal of radiology: official journal of the Korean Radiological Society 2012; 13: 720-727
• 16 Mayo J, Thakur Y. Pulmonary CT angiography as first-line imaging for PE: image quality and radiation dose considerations. Am J Roentgenol American journal of roentgenology 2013; 200: 522-528
• 17 Gervaise A, Teixeira P, Villani N et al. CT dose optimisation and reduction in osteoarticular disease. Diagnostic and interventional imaging 2013; 94: 371-388
• 18 Paul J, Bauer RW, Maentele W et al. Image fusion in dual energy computed tomography for detection of various anatomic structures--effect on contrast enhancement, contrast-to-noise ratio, signal-to-noise ratio and image quality. Eur J Radiol 2011; 80: 612-619
• 19 van der Schaaf I, van Leeuwen M, Vlassenbroek A et al. Minimizing clip artifacts in multi CT angiography of clipped patients. AJNR Am J Neuroradiol 2006; 27: 60-66
• 20 Bamberg F, Dierks A, Nikolaou K et al. Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation. Eur Radiol 2011; 21: 1424-1429