Christian Allen Sell BS, Abstract Co-Author: Nothing to Disclose

Jeffrey Neil Masi, Abstract Co-Author: Nothing to Disclose

Andrew Burghardt, Abstract Co-Author: Nothing to Disclose

David Newitt PhD, Abstract Co-Author: Nothing to Disclose

Thomas Marc Link MD, Abstract Co-Author: Nothing to Disclose

Thomas Unil MD, Presenter: Nothing to Disclose

Sharmila Majumdar PhD, Abstract Co-Author: Nothing to Disclose

To use high resolution MR imaging at 3 Tesla to quantify trabecular bone structure in vitro with femoral head specimens and to correlate the calculated structure measures with those determined using MicroCT, the standard of reference. These correlations were compared to correlations previously described for 1.5 Tesla images.

15 cylindrical cores were obtained from fresh femoral heads after total hip arthroplasty. MR images were obtained at 3T using a receive-only wrist coil. High-resolution coronal images were acquired using a 3D fast gradient echo sequence. From these datasets two-dimensional structural (2D) parameters analogous to bone histomorphometry were derived using both mean intercept length (MIL) methods based on the plate model and the more recent model-assumption free 3D distance transformation methods (DT3D). The parameters measured by the 2D plate model-based MIL method and the DT3D method included App. BV/TV (bone volume/total volume), App. Tb.Th (trabecular thickness), App. Tb.Sp (trabecular separation), and App. Tb.N (trabecular number). Identical regions of interest were analyzed in the MR images and the microCT datasets. The means and standard deviations of the parameters over all slices were calculated and MR-derived measures were correlated with those derived from the MicroCT datasets using linear regression analyses.

Due to susceptibility effects and limited spatial resolution structure measures were overestimated with MRI, e.g. App. BV/TV was 0.45 for MRI and 0.20 for microCT, equivalent to an overestimation by a factor of 2.29. App. Tb.Th was overestimated by factor of 1.9 while App. Tb.Sp was underestimated by a factor of 1.6. However, correlations between the individual parameters were excellent (App. BV/TV, r=0.82; App. Tb.Sp, r=0.84; App.Tb.N, r=0.81) except for App.Tb.Th (r=0.665) and substantially higher than those described previously for MRI at 1.5T.

The results of this study show that using MRI at 3T, trabecular bone structure measures may be obtained that show a highly significant correlation with true structure measures obtained by MicroCT, these correlations are higher than those previously described for MR imaging at 1.5T.

Sell, C, Masi, J, Burghardt, A, Newitt, D, Link, T, Unil, T, Majumdar, S, Quantification of Trabecular Bone Structure at 3 Tesla: Initial Calibration Studies Using Micro CT as a Standard of Reference.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4416040.html