3D image registration is critical to ensure accurate detection of longitudinal changes in trabecular bone density, microstructure, and stiffness measurements in rat tibiae by in vivo microcomputed tomography (μCT)

• Published in: Bone (New York, N.Y.) Vol. 56; no. 1; pp. 83 - 90
• Main Authors: Lan, Shenghui, Luo, Shiming, Huh, Beom Kang, Chandra, Abhishek, Altman, Allison R, Qin, Ling, Liu, X. Sherry
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.09.2013; Elsevier
• Subjects: 3D image registration; Animal models/rodent; Animals; Biological and medical sciences; Biomechanical Phenomena; Bone Density - physiology; Female; Finite Element Analysis; Fundamental and applied biological sciences. Psychology; Imaging, Three-Dimensional; In vivo μCT; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Orthopedics; Osteoarticular system. Muscles; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Tibia - anatomy & histology; Tibia - diagnostic imaging; Tibia - physiology; Time Factors; Trabecular bone microstructure; Vertebrates: anatomy and physiology, studies on body, several organs or systems; X-Ray Microtomography; 3D image registration; Trabecular bone microstructure; Animal models/rodent; Finite element analysis; In vivo μCT; Animal model; Radiodiagnosis; Rat; Image processing; Rodentia; In vivo; Vertebrata; Mammalia; Animal; Morphology; Tomography; Bone mineral density; Tridimensional image; Stiffness; Spongious bone; Microstructure; Finite element
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2013.05.014

Abstract In the recent decade, in vivo μCT scanners have become available to monitor temporal changes in rodent bone in response to diseases and treatments. We investigated short-term and long-term precision of in vivo μCT measurements of trabecular bone density, microstructure and stiffness of rat tibiae and tested whether they can be improved by 3D image registration. Rats in the short-term precision group underwent baseline and follow-up scans within the same day (n = 15) and those in the long-term precision group were scanned at day 0 and day 14 (n = 16) at 10.5 μm voxel size. A 3D image-registration scheme was applied to register the trabecular bone compartments of baseline and follow-up scans. Prior to image registration, short-term precision ranged between 0.85% and 2.65% in bone volume fraction (BV/TV), trabecular number, thickness, and spacing (Tb.N*, Tb.Th*, Tb.Sp*), trabecular bone mineral density and tissue mineral density (Tb.BMD, and Tb.TMD), and was particularly high in structure model index (SMI), connectivity density (Conn.D), and stiffness (4.29%–8.83%). Image registration tended to improve the short-term precision, but the only statistically significant improvement was in Tb.N*, Tb.TMD, and stiffness. On the other hand, unregistered comparisons between day-0 and day-14 scans suggested significant increases in BV/TV, Tb.N*, Tb.Th*, Conn.D, and Tb.BMD and decrease in Tb.Sp* and SMI. However, the percent change in each parameter from registered comparisons was significantly different from unregistered comparisons. Registered results suggested a significant increase in BV/TV, Tb.BMD, and stiffness over 14 days, primarily caused by increased Tb.Th* and Tb.TMD. Due to the continuous growth of rodents, the direct comparisons between the unregistered baseline and follow-up scans were driven by changes due to global bone modeling instead of local remodeling. Our results suggested that 3D image registration is critical for detecting changes due to bone remodeling activities in rodent trabecular bone by in vivo μCT imaging.