title: Osteoporosis imaging: effects of bone preservation on MDCT-based trabecular bone microstructure parameters and finite element models.
abstract: BACKGROUND
  Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength due to a reduction of bone mass and deterioration of bone microstructure predisposing an individual to an increased risk of fracture. Trabecular bone microstructure analysis and finite element models (FEM) have shown to improve the prediction of bone strength beyond bone mineral density (BMD) measurements. These computational methods have been developed and validated in specimens preserved in formalin solution or by freezing. However, little is known about the effects of preservation on trabecular bone microstructure and FEM. The purpose of this observational study was to investigate the effects of preservation on trabecular bone microstructure and FEM in human vertebrae.
  
  
  METHODS
  Four thoracic vertebrae were harvested from each of three fresh human cadavers (n=12). Multi-detector computed tomography (MDCT) images were obtained at baseline, 3 and 6 month follow-up. In the intervals between MDCT imaging, two vertebrae from each donor were formalin-fixed and frozen, respectively. BMD, trabecular bone microstructure parameters (histomorphometry and fractal dimension), and FEM-based apparent compressive modulus (ACM) were determined in the MDCT images and validated by mechanical testing to failure of the vertebrae after 6 months.
  
  
  RESULTS
  Changes of BMD, trabecular bone microstructure parameters, and FEM-based ACM in formalin-fixed and frozen vertebrae over 6 months ranged between 1.0-5.6% and 1.3-6.1%, respectively, and were not statistically significant (p>0.05). BMD, trabecular bone microstructure parameters, and FEM-based ACM as assessed at baseline, 3 and 6 month follow-up correlated significantly with mechanically determined failure load (r=0.89-0.99; p<0.05). The correlation coefficients r were not significantly different for the two preservation methods (p>0.05).
  
  
  CONCLUSIONS
  Formalin fixation and freezing up to six months showed no significant effects on trabecular bone microstructure and FEM-based ACM in human vertebrae and may both be used in corresponding in-vitro experiments in the context of osteoporosis.
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. thbaum@gmx.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. eduardo.grandegarcia@yahoo.es.|Klinik für Orthopädie, Abteilung für Biomechanik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. eduardo.grandegarcia@yahoo.es.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Grande Garcia
authors.affiliation: Klinik für Orthopädie, Abteilung für Biomechanik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. burgkart@tum.de.
authors.forename: Rainer
authors.initials: R
authors.lastname: Burgkart
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. olga.gordijenko@mri.tum.de.
authors.forename: Olga
authors.initials: O
authors.lastname: Gordijenko
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. lieblhans@googlemail.com.
authors.forename: Hans
authors.initials: H
authors.lastname: Liebl
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. pia.jungmann@tum.de.
authors.forename: Pia M
authors.initials: PM
authors.lastname: Jungmann
authors.affiliation: Universitätsklinik für Radiologie und Nuklearmedizin, Abteilung für Neuroradiologie und Muskuloskeletale Radiologie, Medizinischen Universität Wien, Währinger Gürtel 18-20, 1090, Wien, Austria. michael.gruber@meduniwien.ac.at.
authors.forename: Michael
authors.initials: M
authors.lastname: Gruber
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. tinazahel@googlemail.com.
authors.forename: Tina
authors.initials: T
authors.lastname: Zahel
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. ernst.rummeny@tum.de.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.affiliation: Institut für Radiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. simone.waldt@tum.de.
authors.forename: Simone
authors.initials: S
authors.lastname: Waldt
authors.affiliation: Abteilung für Neuroradiologie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, München, Germany. jsb@tum.de.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Bauer
mesh_terms: D000368:Aged; D015519:Bone Density; D002102:Cadaver; D019245:Compressive Strength; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D061330:Multidetector Computed Tomography / Q000379:methods*; D009926:Organ Preservation / Q000379:methods*; D010024:Osteoporosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*