Trabecular bone analysis with tomosynthesis in diabetic patients: comparison with CT-based finite-element method

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1 Trabecular bone analysis with tomosynthesis in diabetic patients: comparison with CT-based finite-element method Poster No.: C-1789 Congress: ECR 2015 Type: Scientific Exhibit Authors: M. Fujii, T. Aoki, S. Kinoshita, Y. Hayashida, H. Mori, Y. Okada, Y. Tanaka, Y. Korogi; Kitakyushu/JP Keywords: DOI: Musculoskeletal bone, Digital radiography, Image compression, Osteoporosis /ecr2015/C-1789 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 9

2 Aims and objectives Background Bone mineral density (BMD) accounts for approximately 70% of bone strength, while bone quality, which relates to bone microarchitecture, turnover, microdamage, and mineralization, accounts for the remainder [1]. Although BMD by dual X-ray absorptiometry (DXA) has been used to predict bone strength clinically [2], diabetes mellitus (DM) patients have an elevated fracture risk despite normal BMD [3,4]. Tomosynthesis (TS) is a recent technology that obtains images on arbitrary parallel cross-sections through image reconstruction of multiple projected images taken by a single exposure. It enables us to obtain high resolution cancellous bone tomograms with lower radiation dose than CT [5,6]. Purpose To determine the additional value of trabecular bone analysis using TS images to BMD in bone strength prediction of DM patients. Methods and materials Materials and methods Subjects Thirty-nine women over 50-year-old consecutive patients with an established diagnosis of DM, from March 2014 to August They underwent DXA and TS of the bilateral hip joints and CT covering the vertebral body of Th10 to the hip joints within a week. Fifteen patients showed vertebral compression fracture, and there were no significant differences between fracture and nonfracture groups with regard to age and body mass index. Page 2 of 9

3 Tomosynthesis TS examinations were performed with a commercially available FPD device at a tube voltage of 85 kv and current of 5 mas, and scan time was 1.2 seconds. The mean total radiation dose of TS was 9 mgy. We extracted the trabecular patterns of TS images, and obtained the total strut length (TSL), the bone volume per tissue volume (BV/TV) and the textural features (HOM: homogeneity, ENT: entropy, COR: correlation, CON: contrast, VAR: variance) as the indices of TS images (Fig.1). CT-based finite-element method (FEM) 64-slice CT scanner used for the preparation of the FEM. 3D-FEM was constructed from CT data using Mechanical Finder software with 3 mm tetrahedral element and 3 mm triangular plates (Fig.2). Image analysis Failure load of the femoral neck, determined by the CT- FEM, was used as the gold standard for bone strength. A forward stepwise multiple regression analysis for evaluating the availability of the TS image indices was performed. A logistic model was used with BMD, TSL, BV/TV and the textural features (HOM, ENT, COR, CON, VAR) of TS images. Comparison of the BMD by DXA and the TS image indices between fracture and nonfracture groups was analyzed by using the two-sided paired Student t test. Images for this section: Page 3 of 9

4 Fig. 1: The sequences of the analysis of the microarchitecture of cancellous bone by tomosynthesis. (a) selecting a ROI. (b) removed background non-uniformity image. (c) binarized image. (d) thinned image. (e) co-occurrence matrix. Page 4 of 9

5 Fig. 2: Representative CT-FEM model of 68-year-old diabetic patients with lumbar spine fracture.(a) extraction of outlines. (b) finite-element model. (c) stress evaluation image. Arrow indicates the load direction, and femoral neck fracture (arrowhead) was occurred by 5915N of force. Page 5 of 9

6 Results Results Amongst the combinations of the BMD and each index of TS images, the BMD and the BV/TV showed the highest correlation to the failure load by CT-FEM. The correlation between the failure load and the BMD with the BV/TV (r 2 =0.82) was significantly higher than that between the failure load and the BMD alone (r 2 =0.75; P<.01) (Figs. 3 & 4). The average BV/TV of fracture group (mean; 24.1%) was significantly lower than that of nonfracture group (mean; 20.6%) (p < 0.05). There was no difference between fracture group and nonfracture group in BMD. Images for this section: Page 6 of 9

7 Fig. 3: Correlation between BMD by DXA and failure load by CT-FEM. Fig. 4: Correlation between BMD with BV/TV using TS and failure load by CT-FEM. Page 7 of 9

8 Conclusion Discussion Proximal femur fracture is the most severe complication of osteoporosis and is associated with higher mortality and morbidity than any other fracture [7]. With regard to the correlation to the failure load by CT-FEM, our results demonstrated that the contribution ratio of the combination of the BV/TV using TS and BMD increased by 7% in comparison with BMD alone. Tomosynthesis can provide additional information to BMD in bone strength prediction of proximal femur strength in DM patients. Patients with vertebral compression fractures showed significantly lower BV/ TV of TS in proximal femur than did nonfracture patients, but no differences in BMD. Tomosynthesis can separate overlapping structures in trabecular bones differently than BMD does. Trabecular bone analysis using TS images assessment of proximal femur may provide bone quality information that is not provided by DXA. The CT-FEM is recognized as advanced promising method for measuring bone strength [8-10]. However, CT is not routinely used because of high cost, limited access, and high radiation dose. Tomosynthesis has the advantages of short examination time, low radiation dose, and low cost when compared with CT. Trabecular bone analysis using TS may be practical in bone strength assessment for DM patients. Conclusion The combination of trabecular bone analysis using TS images and BMD is more reliable for predicting bone strength in DM patients than BMD alone. Personal information References Page 8 of 9

9 References 1) Mosekilde L. The effect of modelling and remodelling on human vertebral body architecture. Technol Health Care. 1998; 6: ) Kanis JA. Diagnosis of osteoporosis and assessment of fracture risk. Lancet. 2002; 359: ) Schuit SC, van der Klift M, Weel AE, et al. Fracture incidence and association with bone mineral density in elderly men and women: the Rotterdam Study. Bone 2004; 34: ) Schwartz AV, Vittinghoff E, Bauer DC, et al. Association of BMD and FRAX score with risk of fracture in older adults with type 2 diabetes. JAMA. 2011; 305: ) Geijer M, Borjesson AM, Gothlin JH. Clinical utility of tomosynthesis in suspected scaphoid fracture : a pilot study. Skeletal Radiol 2011; 40: ) Aoki T, Fujii M, Yamashita Y, et al. Tomosynthesis of the wrist and hand in patients with rheumatoid arthritis: comparison with radiography and MRI. AJR 2014; 202: ) Johnell O, Kanis JA, Odén A, et al. Mortality after osteoporotic fractures. Osteoporos Int 2004; 15: ) Ohnishi I, Oikawa K, Tsuji K, et al. A femoral neck fracture model in rabbits. J Biomech. 2003; 36: )Bessho M, Ohnishi I, Matsuyama J, et al. Prediction of strength and strain of the proximal femur by a CT-based finite element method. J Biomech. 2007; 40: ) Wakao N, Harada A, Matsui Y, et al. The effect of impact direction on the fracture load of osteoporotic proximal femurs. Med Eng Phys. 2009; 31: Page 9 of 9