Utility of Thoracolumbar Low-Dose CT With Model-Based Iterative Reconstruction for Measuring Pedicle Diameter Using a Radiation Dose Less Than a One-Time Lumbar X-Ray. Issue 1 (1st January 2020)

• Record Type: Journal Article
• Authors: Masamoto, Kazutaka; Fujibayashi, Shunsuke; Otsuki, Bungo; Hara, Kentaro; Fukushima, Yasuhiro; Koizumi, Koji; Shimizu, Takayoshi; Shimizu, Yu; Morizane, Kazuaki; Murata, Koichi; Matsuda, Shuichi
• Is Part Of: Spine. Volume 45:Issue 1(2020)
• Publication Date: 2020-01-01
• Subjects: computed tomography -- contrast-to-noise -- dose-length product -- effective dose -- hybrid iterative reconstruction -- model-based iterative reconstruction -- pedicle diameter -- pedicle screw -- radiation dose -- thoracolumbar spine; Spine -- Abnormalities -- Periodicals; Spine -- Diseases -- Periodicals; Spine -- Surgery -- Periodicals; 616.73005
• DOI: 10.1097/BRS.0000000000003210
• Languages: English
• ISSNs: 0362-2436

Abstract

Abstract : Study Design: Retrospective. Objective: To evaluate the image quality of low-radiation-dose computed tomography (LD-CT) of the thoracolumbar spine, using model-based iterative reconstruction (MBIR) for measuring pedicle diameter. Summary of Background Data: MBIR can drastically reduce radiation dose but its utility in spine surgery planning is unknown. Methods: We identified patients (mean age, 70.5 ± 13.3 yrs) who incidentally underwent both standard-radiation-dose CT (SD-CT) with hybrid iterative reconstruction and LD-CT with MBIR of the thoracolumbar spine within 2 years. We compared radiation dose, subjective image sharpness, signal-to-noise ratio, and contrast-to-noise ratio for the two tests. Additionally, inner pedicle diameters were measured on SD-CT (DSD ) and LD-CT (DLD ), and statistically compared. Results: We included 24 CT and 84 pedicles for each CT group. The radiation dose of LD-CT estimated by volume CT dose index was 1.21 ± 0.42 mGy, one-sixth the dose of SD-CT. The effective dose of LD-CT was 0.58 ± 0.31 mSv, equivalent to or less than that of a one-time lumbar X-ray in a previous report. LD-CT was significantly inferior in subjective image sharpness for the contour of vertebrae and trabecular structure, but superior for signal-to-noise ratio and contrast-to-noise ratio. The intra-rater reliability (intra-RR) and inter-RR for DLD were 0.985 and 0.892, respectively, comparable to those of DSD . DLD was consistently 0.30 mm smaller than DSD when compared within the same pedicle, regardless of pedicle diameter. Conclusion: LD-CT with MBIR produced a radiation dose equivalent to a one-time lumbar X-ray and provided excellent images for measuring pedicle diameter. LD-CT can be a substitute for SD-CT when planning spine surgery if the relationship between DSD and DLD is sufficiently understood. Level of Evidence: 3 Abstract : Thoracolumbar spinal low-radiation-dose CT, using model-based iterative reconstruction, reduced radiation dose to that of a one-time lumbar X-ray and provided sufficient image quality for measuring inner pedicle diameter. The inner pedicle diameter measured on LD-CT was consistently 0.30 mm shorter than that on SD-CT.