Up the creek: truthful imaging in spinal osteoporosis?

Abstract

Up the creek: truthful imaging in spinal osteoporosis? Alan Boyde QMUL, London E1 4NS, UK It is impossible for x-ray computed tomography (CT) or magnetic resonance imaging (MRI) to resolve fine structural details in calcified tissues in large, live bones. This can only be done ex vivo or post mortem. Imaging dead bone, it may be held, does not aid the live patient, but imaging live bone cannot reveal the true situation. The basic principles of stereology demand the use of infinitely thin sections, such as polished surfaces of rock samples. But bone tissue is not a solid, and therefore it has to be embedded – usually in a resin. Backscattered electron SEM of flat block surfaces – best micro-milled, but second best polished – provides very thin electron optical sectioning of vast extent and images selectively the calcified tissues in bones. Earlier difficulties were (1) negative electrostatic charging under the electron beam, solved, even for uncoated samples, by having the sample chamber at “bad” vacuum, when positive gas ions eliminate the problem, and (2) inability to see soft tissue histology, solved by iodine staining of the block surface. In this study, computer controlled digital SEM allowed the stitching (montaging) of large numbers of fields to provide very high resolution re-imaging of entire mid-body, near-midline, vertical sections through PMMA embedded L2 vertebrae (38 male, 31 female, 70±15 years, European Union Concerted Action Biomed 1 “Assessment of bone quality in osteoporosis”). What we learn is how very little and skimpy may be the bone tissue within apparently intact vertebral bodies. Thus parts of cortices are regularly less than one tenth millimetre thickness and trabeculae so fine that they could not possibly be found with clinical imaging. Within and towards the end-plates, calcified cartilage, more densely mineralised than bone, is a major contributor to radio-density. Clinical imaging could never discriminate what is bone, find fine trabeculae or canals within them or show the arrangement of microcallus; all easily achieved with BSE-SEM. This method also shows that the earliest stages of trabecular microfracture healing may employ acellular high density mineralised infill in addition to woven bone. Studies in this field are truly up the creek without BSE-SEM. P075 page 168 Bone Research Society Annual Meeting 29 June- 1 July 2016 Liverpool DOI: 10.3389/978-2-88919-974-7 ISBN: 978-2-88919-974-7 Published in Frontiers in Endocrinology