title: Use of MR-based trabecular bone microstructure analysis at the distal radius for osteoporosis diagnostics: a study in post-menopausal women with breast cancer and treated with aromatase inhibitor.
abstract: OBJECTIVE
  Treatment with aromatase inhibitor (AI) is recommended for post-menopausal women with hormone-receptor positive breast cancer. However, AI therapy is known to induce bone loss leading to osteoporosis with an increased risk for fragility fractures. The purpose of this study was to investigate whether changes of magnetic resonance (MR)-based trabecular bone microstructure parameters as advanced imaging biomarker can already be detected in subjects with AI intake but still without evidence for osteoporosis according to dual energy X-ray absorptiometry (DXA)-based bone mineral density (BMD) measurements as current clinical gold standard.
  
  
  METHODS
  Twenty-one postmenopausal women (62±6 years of age) with hormone-receptor positive breast cancer, ongoing treatment with aromatase inhibitor for 23±15 months, and no evidence for osteoporosis (current DXA T-score greater than -2.5) were recruited for this study. Eight young, healthy women (24±2 years of age) were included as controls. All subjects underwent 3 Tesla magnetic resonance imaging (MRI) of the distal radius to assess the trabecular bone microstructure.
  
  
  RESULTS
  Trabecular bone microstructure parameters were not significantly (p>0.05) different between subjects with AI intake and controls, including apparent bone fraction (0.42±0.03 vs. 0.42±0.05), trabecular number (1.95±0.10 mm(-1) vs 1.89±0.15 mm(-1)), trabecular separation (0.30±0.03 mm vs 0.31±0.06 mm), trabecular thickness (0.21±0.01 mm vs 0.22±0.02 mm), and fractal dimension (1.70±0.02 vs. 1.70±0.03).
  
  
  CONCLUSIONS
  These findings suggest that the initial deterioration of trabecular bone microstructure as measured by MRI and BMD loss as measured by DXA occur not sequentially but rather simultaneously. Thus, the use of MR-based trabecular bone microstructure assessment is limited as early diagnostic biomarker in this clinical setting.
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Dimitrios C
authors.initials: DC
authors.lastname: Karampinos
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Vanadin
authors.initials: V
authors.lastname: Seifert-Klauss
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Tsvetelina D
authors.initials: TD
authors.lastname: Pencheva
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Pia M
authors.initials: PM
authors.lastname: Jungmann
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Müller
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Bauer
keywords: aromatase inhibitor; magnetic resonance imaging; osteoporosis; trabecular bone microstructure