Quantitative Computed Tomography, modern data. Review

In the review we discussed about the method of quantitative computed tomography (QCT, quantitative computed tomography). In QCT, X-ray density (HU) is converted to bone mineral density (BMD mg / ml) using linear relationships obtained by scanning calibration standards (phantoms). When compared with the normative age data, it is possible to diagnose osteoporosis (OP). The review presents various QCT techniques and their diagnostic capabilities in accordance with the positions of ISCD 2019 - (International Society for Clinical Densitometry). The results of comparison of QCT and conventional dual-energy X-ray absorptiometry (DXA) are  considered.  It is noted that in the study of the proximal femur (PF), the results of the methods are well comparable, according to the results of both methods, it is possible to diagnose OP by the T-score. However, when examining the spine QCT, the volume BMD of the trabecular bone of the vertebral bodies is assessed, and with DXA, the projection BMD is assessed. The approaches to the interpretation of the results are also different - diagnosis of OP in DXA of the spine based on the T-score, but in QCT, the ACR (American College of Radiology) criteria are used. We describe the phantoms used in QCT, as well as provide data on radiation exposure during QCT and DXA. The article describes an approach to opportunistic screening of osteoporosis by the QCT based on the results of previously performed CT scans, including its automated work-flow using artificial intelligence technologies. These promising techniques are attractive due to the large number of CT examinations performed and the exclusion of additional examinations.