Opportunistic Computed Tomography and Spine Surgery: A Narrative Review

Abstract

Study Design: Narrative review. Objective: This article seeks to provide a narrative review regarding the ability of opportunistic information available from computed tomography (CT) scans to guide decisions in spine surgery related to patient bone quality. Methods: A review of the literature (limited to human and English language) was performed via PubMed and Google Scholar using the search terms; “osteoporosis” AND “opportunistic” AND “computed tomography” AND “spine surgery.” The titles and then abstracts of all identified citations were reviewed for inclusion by 2 of the authors (MS, BAF). Relevant articles were then studied in full text. Results: A review of the literature found 25 articles that were selected for inclusion in this narrative review. These articles were broadly divided into 4 subcategories: (1) opportunistic CT (oCT) and osteoporosis detection, (2) oCT data and the quality of screw fixation, (3) utilization of Hounsfield units to assess clinical and/or radiographic outcomes following spine fusion, and (4) virtual stress testing in spine surgery. Conclusion: The literature on oCT, as well as associated virtual stress-testing techniques, demonstrate the potential to enhance spine surgery outcomes by preoperatively identifying at-risk patients in need of bone health optimization and informing best techniques for performing spinal fusion surgery on patients with diminished bone quality. While our narrative summary of the limited literature to date suggests a promising future for oCT data, significant additional research and/or radiographic workflow standardization is needed to validate these methods for clinical use.

Letter to the Editor concerning “Best Practice Guidelines for Assessment and Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction”

“…1 BCT is reported to provide opportunistic measure of bone density as well as bone strength based on finite element analysis performed on a clinical CT scan. 2 While there are studies correlating BCT results to fracture risk, there are currently no studies correlating BCT results to outcomes of spinal reconstructive surgery. Additionally, there are currently no studies showing the application of BCT in guiding treatment for patients undergoing spinal reconstructive surgery.…”

“…egarding the recent article ''Best Practice Guidelines for Assessment & Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction, 1 spine surgeons may be interested in information not covered in this article concerning an accurate clinical test for diagnosing osteoporosis that is well suited for spinalfusion patients. 2 Given the well-known limitations of dual-energy X-ray absorptiometry (DXA) testing at the spine that are associated with degenerative changes for spinal fusion patients, 3,4 and the weak correlation between T-scores from hip DXA and spine DXA, 5 the guidelines discussed possibly using noncalibrated Hounsfield Unit measurements from an existing computed tomography (CT) scan to assess osteoporosis. While this ''opportunistic'' approach is attractive since it exploits the availability of an already-taken CT scan, that method is investigational, unstandardized, does not account for different scan acquisition settings, and, as noted in the guidelines, is not approved for diagnostic purposes.…”

“…Regarding the recent article “Best Practice Guidelines for Assessment & Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction, 1 spine surgeons may be interested in information not covered in this article concerning an accurate clinical test for diagnosing osteoporosis that is well suited for spinal- fusion patients 2 …”

Clinical use of quantitative computed tomography to evaluate the effect of less paraspinal muscle damage on bone mineral density changes after lumbar interbody fusion

“…Demir et al [4] also found that the Hounsfield unit (HU) values of the vertebrae in stabilized segments consistently decreased postoperatively. Patients with low BMD are at risk of complications such as vertebral compression fractures, cage subsidence, and screw loosening [5][6][7]. Therefore, accurate measurement of vertebral BMD is important in patients who have undergone instrumented spinal fusion for the timely diagnosis of osteoporosis and provision of medical treatment.…”