Program Information
Pre-Clinical Investigation of MARS Spectral Molecular Imaging for Use in Bone Quality Assessment
C Leary1*, T Griglock1 , K Tack1 , N Anderson2 , M Ramyar2 , R Aamir2 , (1) Oregon Health & Science University, Portland, OR, (2) University of Otago, Christchurch, NZ
Presentations
SA-B-BRA|B-11 (Saturday, March 18, 2017) 10:30 AM - 12:30 PM Room: Ballroom A|B
Purpose: To investigate utilizing the Medipix All Resolution System Spectral Molecular Imaging (MARS SMI) scanner for osteoporosis imaging, and to compare MARS measurements with currently available and accepted bone strength metrics.
Methods: Four cadaveric femoral necks (female, aged 42-87) were imaged utilizing Dual Energy X-ray Absorptiometry (DXA), High Resolution Peripheral Quantitative Computed Tomography (HRpQCT), and MARS SMI. Areal bone mineral density (BMD) was measured with DXA. Volumetric BMD (vBMD) and microstructural measurements were obtained with HRpQCT. A MARS imaging protocol with energy bin edges 30, 45, 60, 78, and 118 kV was developed to decompose MARS CT data into calcium hydroxyapatite (HA), water, and fat images. Pixel values of the calcium images were transformed into mg HA/cm³ and CT images were analyzed using Fiji and Image J.
Results: MARS produced measurements of vBMD and microstructural properties (trabecular thickness, trabecular spacing, and cortical thickness) comparable to DXA and HRpQCT measurements. MARS and HRpQCT produced similar measurements of cortical-bone vBMD (600-890 mg HA/cm³). All modalities produced measurements of total-bone BMD showing a roughly decreasing trend with age (321-182 mg/cm³), with the second-oldest donor having the lowest BMD. Trabecular thickness measurements were similar for MARS (0.35-0.36 mm) and HRpQCT (0.31-0.36 mm) and relatively constant across all samples, while trabecular spacing showed an increasing trend with age (0.94-2.18 mm). Additionally, measurements of location-specific BMD unique to MARS showed that the two younger donors had a BMD gradient down the femoral neck, while the older two donors had femoral necks with lower BMD and no gradient.
Conclusion: This research shows MARS SMI can provide measurements currently used to investigate bone quality and additional 3D material information. In one scan, MARS produces CT images for microstructural measurements and material images for location-specific BMD measurement which could provide insight into bone quality and fracture risk.
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