Correlation between bone density measurements on CT or MRI versus DEXA scan: A systematic review

Amer Ahmad; Charles H Crawford 3rd; Steven D Glassman; John R Dimar 2nd; Jeffrey L Gum; Leah Y Carreon

doi:10.1016/j.xnsj.2023.100204

Correlation between bone density measurements on CT or MRI versus DEXA scan: A systematic review

N Am Spine Soc J. 2023 Mar 1:14:100204. doi: 10.1016/j.xnsj.2023.100204. eCollection 2023 Jun.

Authors

Amer Ahmad¹, Charles H Crawford 3rd^{1

2}, Steven D Glassman^{1

2}, John R Dimar 2nd^{1

2}, Jeffrey L Gum^{1

2}, Leah Y Carreon²

Affiliations

¹ Department of Orthopaedic Surgery, University of Louisville School of Medicine, 550 S. Jackson St., 1st Floor ACB, Louisville, KY 40202 USA.
² Norton Leatherman Spine Center, 210 East Gray St, Suite 900, Louisville, KY, 40202 USA.

Abstract

Background: Novel methods of bone density assessment using computed tomography (CT) and magnetic resonance imaging (MRI) have been increasingly reported in the spine surgery literature. Correlations between these newer measurements and traditional Dual-Energy X-ray Absorptiometry (DEXA) is not well known. The purpose of this study is to perform an updated systematic review of correlations between bone mineral density (BMD) from CT or MRI and DEXA.

Methods: Articles published between 2011 and 2021 that reported correlations between the CT-HU or MRI measurements to DEXA t-scores or BMD of lumbar spine or hip were included in this systematic review.

Results: A total of 25 studies (15 CT, 10 MRI) met the inclusion criteria with a total number of 2,745 patients. The pooled correlation coefficient of spine CT-HU versus spine DEXA, spine CT-HU versus hip DEXA and spine CT-HU versus lowest t-score were 0.60, 0.50 and 0.60 respectively. Regarding spine DEXA parameters, the pooled r² for spine CT-HU versus spine t-score was 0.684 and spine CT-HU versus spine BMD was 0.598. Furthermore, in patients undergoing spine surgery in four studies, the pooled correlation between spine CT and spine DEXA was (r²: 0.64). In MRI studies, the pooled r² of spine MRI versus spine DEXA and spine MRI versus hip DEXA were -0.41 and -0.44 respectively.

Conclusions: CT-HU has stronger correlations with DEXA than MRI measurements. Lumbar CT-HU has the highest pooled correlation (r² = 0.6) with both spine DEXA and lowest skeletal t-score followed by lumbar CT-HU with hip DEXA (r² = 0.5) and lumbar MRI with hip (r² = 0.44) and spine (r² = 0.41) DEXA. Both imaging modalities achieved only a moderate correlation with DEXA. Few studies in both modalities have investigated the correlation in spine surgery populations and the available data shows that the correlations are worse in the degenerative spine population. A careful interruption of CT HU and MRI measurement when evaluation of BMD as they only moderately correlated with DEXA scores. At this time, it is unclear which modality is a better predictor of mechanical complications and clinical outcomes in spine surgery patients.

Keywords: Bone mineral density; Computed tomography scan; Correlation; Dual-energy xray absorptiometry; Hounsfield unit; Lumbar spine; Magnetic resonance imaging; Osteoporosis; Quantitative CT scan; T-score.