Simultaneous screening for osteoporosis at CT colonography: Bone mineral density assessment using MDCT attenuation techniques compared with the DXA reference standard

Abstract

Purpose To evaluate the utility of lumbar spine attenuation measurement for bone mineral density (BMD) assessment at screening CT colonography (CTC), using central dual-energy x-ray absorptiometry (DXA) as the reference standard. Material and Methods 252 adults (240 women, 12 men; mean age, 58.9 years) underwent CTC screening and central DXA BMD measurement within 2 months (mean interval, 25.0 days). The lowest DXA T-score between the spine and hip served as the reference standard, with low BMD defined per WHO as osteoporosis (DXA T-score ≤-2.5) or osteopenia (DXA T-score between −1.0 and −2.4). Both phantomless QCT and simple non-angled ROI MDCT attenuation measurements were applied to T12-L5 levels. Ability to predict osteoporosis and low BMD (osteoporosis or osteopenia) by DXA was assessed. Results A BMD cut-off of 90 mg/cc at phantomless QCT yielded 100% sensitivity for osteoporosis (29/29) and specificity of 63.8% (143/224); 87.2% (96/110) below this threshold had low BMD and 49.6% (69/139) above this threshold had normal BMD at DXA. At L1, a trabecular ROI attenuation cut-off of 160 HU was 100% sensitive for osteoporosis (29/29), with a specificity of 46.4% (104/224); 83.9% (125/149) below this threshold had low BMD and 57.5% (59/103) above had normal BMD at DXA. ROI performance was similar at all individual T12-L5 levels. At ROC analysis, AUC for osteoporosis was 0.888 for phantomless QCT (95% CI: 0.780–0.946) and ranged from 0.825–0.853 using trabecular ROIs at single lumbar levels (0.864 [0.752–0.930] at multivariate analysis). Supine-prone reproducibility was better with simple ROI method compared with QCT. Conclusion Both phantomless QCT and simple ROI attenuation measurements of the lumbar spine are effective for BMD screening at CTC, with high sensitivity for osteoporosis as defined by the DXA T-score.

Use of computed tomography for assessing bone mineral density

“…18,[25][26][27]30 The proof of concept that HU values can be used be used to estimate regional bone strength and fracture risk was first established using polyurethane foam, where a linear correlation was found between HU value and compressive strength across densities representative of human bone. 30 Estimation of fracture risk is a key variable in determining whether patients should be treated for metabolic bone disease.…”

“…17,25 Using the average of 3 measurements at each vertebra compared with a single measurement appears to offer little advantage in terms of reliability. 26,27 No differences are seen at different levels within the vertebral body (Fig. 2).…”

Biomechanical comparison of vertebral augmentation with silicone and PMMA cement and two filling grades

“…To exclude vertebrae with previous fractures, a qCT was conducted (GE Lightspeed 16, GE Medical Systems, Waukesha, WI, USA), and trabecular BMD was measured. Mean trabecular BMD was 74.4 ± 22.5 mg/cm 3 , osteoporosis was, therefore, present [35].…”

Application of quantitative computed tomography for assessment of trabecular bone mineral density, microarchitecture and mechanical property

“…A phantomless thoracic BMD measurement would be a great advance in clinical practice. To date, three methods were used for the phantomless BMD measurement at spine: 1) Using an individual body tissue as a calibration reference, such as the paraspinal fat and psoas [38,39]; 2) Using a modified calibration factor (calibration curve) [40,41]; 3) Using the CTHU directly [42]. Although the standardization of CTHU was done by individual manufacturers, and the calibration procedure was performed before the row data reconstruction, a significant variation between scanners still exists [36,43].…”

“…Therefore, physicians can assess BMD and evaluate the fracture risk, as an additional evaluation for using these images with or without a calibration phantom using the QCT technique described above. The optimal results were obtained in most studies [33,34,36], including the chest [55,57,66], heart [21,23,36] and abdomen or pelvis CT scan [42,67,68]. A long calibration phantom (at least about 85 cm or longer, developed by Image Analysis, Columbia, KY, USA) is beneficial for the QCT BMD assessment with the whole-body scan [35].…”