title: Reduction of Longitudinal Vertebral Blood Perfusion and Its Likely Causes: A Quantitative Dynamic Contrast-enhanced MR Imaging Study of a Rat Osteoporosis Model.
abstract: Purpose To determine the longitudinal relationships among lumbar vertebral blood perfusion, bone mass, and marrow adipose tissue in a rat osteoporosis model after ovariectomy by using quantitative dynamic contrast agent-enhanced (DCE) magnetic resonance (MR) imaging, microcomputed tomography (micro-CT), and proton MR spectroscopy. Materials and Methods In this animal review committee-approved study, lumbar vertebrae were evaluated through MR spectroscopy, quantitative DCE MR imaging, micro-CT, and histopathologic analysis, and blood was examined at 0, 2, 6, 10, 14, 18, and 24 weeks after ovariectomy consisting of exposure of the ovaries but no excision (n = 35) or sham operation, defined as exposure of the ovaries but no excision (n = 35). Differences in the parameters of these examinations between two groups at the same time point were analyzed by an independent-sample t test. Results Significantly reduced volume transfer constant (Ktrans) and volume of extravascular extracellular space per unit volume of tissue (week 2 and 10, respectively; P = .036 and P = .014, respectively), decreased bone mineral density (week 2; P = .014), and increased fat fraction (week 6; P = .036) in the ovariectomy group were observed, compared with those in the sham group. Vascular endothelial growth factor and microvessel density values of the ovariectomy group decreased significantly compared with those of the sham group from weeks 18 (P = .005) and 14 (P = .018), respectively. Transmission electron microscopy revealed tighter gaps among vascular endothelial cells and more marrow fibrosis in the ovariectomy group. Conclusion Quantitative DCE MR imaging can directly reflect marrow perfusion. Ktransis a promising parameter to demonstrate early reduced marrow perfusion. Enhanced vasoconstriction and tightened gaps among vascular endothelial cells may be the likely causes in the initial stage of osteoporosis. Increased marrow adipose tissue, decreased microvessel density, and increased marrow fibrosis may aggravate marrow ischemia in the late stage of osteoporosis.©RSNA, 2016 Online supplemental material is available for this article.
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Jingqi
authors.initials: J
authors.lastname: Zhu
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Wu
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Zuogang
authors.initials: Z
authors.lastname: Xiong
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Yuyou
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Hua
authors.affiliation: From the Department of Radiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Tang
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000098:blood supply* / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000098:blood supply* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D010024:Osteoporosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D003287:Contrast Media