The accuracy and clinical utility of spectral CT bone density measurement in the lumbar spine of unenhanced images: a narrative review

Objectives: To review and evaluate available literature on spectral computed tomography (SCT) bone mineral density (BMD) measurement in adult thoracolumbar vertebrae of unenhanced images compared to quantitative computed tomography (QCT), to understand its current clinical utility.

Key findings: Keyword searches in four databases identified four cross-sectional studies which acquired an SCT BMD measurement in thoracolumbar vertebrae and compared this respectively to QCT, which were then critically appraised using the AXIS tool for cross-sectional studies. 862 vertebrae were measured between T10-S1 in 368 patients. Three studies demonstrated a statistically significant correlation between SCT and QCT for the measurement of Hydroxyapatite (HAP) and calcium (r = 0.86–0.96). One study demonstrated a diagnostic accuracy of 96% using a receiver operating curve. 

Conclusions: SCT measurements of HAP and calcium in the lumbar vertebrae are comparable to QCT for patients with no additional pathology present. However, further research is required to evaluate diagnostic accuracy before clinical application.

Implications for practice: SCT BMD measurement has the potential to be developed as a screening tool for osteoporosis within the fracture liaison service (FLS). This could aid in the identification of patients with osteoporosis and address the current treatment gap. Nonetheless, many factors must be considered for this application including staff training, radiation protection and patient engagement with the screening programme.