Dirk Mueller MD, Presenter: Nothing to Disclose

Jan Stefan Bauer MD, Abstract Co-Author: Nothing to Disclose

Roberto Adrian Monetti PhD, Abstract Co-Author: Nothing to Disclose

Ernst Josef Rummeny MD, Abstract Co-Author: Nothing to Disclose

Thomas M. Link MD, Abstract Co-Author: Research grant, GlaxoSmithKline plc, Brentford, UK Research grant, Merck & Co, Inc, Whitehouse Station, NJ

Christoph W. Raeth PhD, Abstract Co-Author: Nothing to Disclose

High resolution magnetic resonance imaging (HR-MRI) is used to assess bone structure, which is, in addition to bone mineral density, an important component in determining bone strength and risk of fracture. When applying structure analysis of HR-MRI to longitudinal studies reproducibility considerations become paramount. The purpose of this study was therefore to evaluate the reproducibility of three structure measures: (i) the nonlinear structure measure mp(α), based on the 3D scaling index method (SIM), (ii) the Minkowski-Functionals (MF) and (iii) standard histomorphometric parameters (HM).

HR-MR images of the distal radius were acquired at 1.5 T using a 3D- gradient echo sequence with a voxel size of 500x195x195 µm. Eighteen volunteers were scanned three times; after each MR scan subjects left the scanner table and were repositioned. After semiautomatic segmentation of all the 56 image datasets the nonlinear structure measures mp(α), MF and HM parameters were determined completely automated. Means and standard deviations, repeated measurement percent coefficients of variation (%CV) and standardized CV (%Std.CV) were calculated for all texture measures.

For the nonlinear structure measures mp(α) and MF we obtained for the repeated measurements in the 18 volunteers a %CV of 0.7% and 2.1% and for the %Std.CV 69.2% and 96.4% respectively. The HM parameters performed with comparable %CVs ranging from 1.5% (app.Tb.N) to 3.6% (app.BV/TV). %Std.CVs for the HM analysis were significantly better and varied from 27.8% for app.Tb.N to 39.4% for app.BV/TV.

The results of this study show that the reproducibility of nonlinear structure measures is comparable to histomorphometric parameters for the %CV whereas it is inferior for the %Std.CV. HM measures currently may be more suitable for longitudinal studies, future work will have to show whether higher MR image quality at 3T may improve %Std.CV for the more complex structure measures.

Reproducibility of structure analysis techniques based on HR-MRI is of special interest in longitudinal studies assessing therapy-induced changes of bone architecture in osteoporosis.

Mueller, D, Bauer, J, Monetti, R, Rummeny, E, Link, T, Raeth, C, Reproducibility of 3D Nonlinear and Standard 2D Morphometric Structure Parameters Derived from High Resolution Magnetic Resonance Imaging (HR-MRI) of the Distal Radius.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009603.html