Opportunistic Screening Techniques for Analysis of CT Scans

• Published in: Current osteoporosis reports Vol. 21; no. 1; pp. 65 - 76
• Main Authors: Engelke, Klaus, Chaudry, Oliver, Bartenschlager, Stefan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2023
• Subjects: Absorptiometry, Photon - methods; Artificial Intelligence; Bone Density; Epidemiology; Humans; Imaging (H Isaksson and S Boyd; Imaging (H Isaksson and S Boyd, Section Editors); Medicine; Medicine & Public Health; Orthopedics; Osteoporosis - diagnostic imaging; Osteoporotic Fractures; Section Editors; Spinal Fractures - diagnostic imaging; Tomography, X-Ray Computed; Topical Collection on Imaging; Vertebral fracture assessment; Computed tomography; Fracture risk; Opportunistic screening; Internal BMD calibration
• ISSN: 1544-1873; 1544-2241; 1544-2241
• DOI: 10.1007/s11914-022-00764-5

Purpose of Review Opportunistic screening is a combination of techniques to identify subjects of high risk for osteoporotic fracture using routine clinical CT scans prescribed for diagnoses unrelated to osteoporosis. The two main components are automated detection of vertebral fractures and measurement of bone mineral density (BMD) in CT scans, in which a phantom for calibration of CT to BMD values is not used. This review describes the particular challenges of opportunistic screening and provides an overview and comparison of current techniques used for opportunistic screening. The review further outlines the performance of opportunistic screening. Recent Findings A wide range of technologies for the automatic detection of vertebral fractures have been developed and successfully validated. Most of them are based on artificial intelligence algorithms. The automated differentiation of osteoporotic from traumatic fractures and vertebral deformities unrelated to osteoporosis, the grading of vertebral fracture severity, and the detection of mild vertebral fractures is still problematic. The accuracy of automated fracture detection compared to classical radiological semi-quantitative Genant scoring is about 80%. Accuracy errors of alternative BMD calibration methods compared to simultaneous phantom-based calibration used in standard quantitative CT (QCT) range from below 5% to about 10%. The impact of contrast agents, frequently administered in clinical CT on the determination of BMD and on fracture risk determination is still controversial. Summary Opportunistic screening, the identification of vertebral fracture and the measurement of BMD using clinical routine CT scans, is feasible but corresponding techniques still need to be integrated into the clinical workflow and further validated with respect to the prediction of fracture risk.