Trabecular Bone Architecture in the Distal Radius Using Magnetic Resonance Imaging in Subjects with Fractures of the Proximal Femur

Abstract

To determine whether magnetic resonance (MR)-derived measures of trabecular bone architecture in the distal radius are predictive for prevalent hip fractures, 20 subjects with hip fractures and 19 age-matched postmenopausal controls were studied. Bone mineral density (BMD) measures at the hip (dual-energy X-ray absorptiometry, DXA) and the distal radius (peripheral quantitative computed tomography, pQCT) were also obtained. We compared the MR-based structural measures derived in the radius with those in the calcaneus of the same patients. In the radius, images were acquired at an in-plane resolution of 156 microm and a slice thickness of 0.5 mm. Stereologic measures such as the apparent trabecular thickness (app. Tb.Th), fractional trabecular bone volume (app. BV/TV), trabecular spacing (app. Tb.Sp) and trabecular number (app. Tb.N) were derived from the images. Measures of app. Tb.Sp and app. Tb.N in the distal radius showed significant (p<0.05) differences between the two groups, as did hip BMD measures. However, radial trabecular BMD measures showed only a marginal difference (p = 0.05). Receiver operating curve analysis was used to determine the diagnostic efficacy of BMD, structural measures and a combination of the two. The area under the curve (AUC) for total hip BMD was 0.73, and for radial trabecular BMD was 0.69. AUC for most of the measures of trabecular bone structure at the distal radius was lower than for hip BMD measures; however, AUC for app. Tb.N at the radius was 0.69, comparable to trabecular BMD using pQCT. The AUC for combined BMD (hip) and structure measures was higher (0.87) when radius and calcaneus structure was included. Measures of trabecular architecture derived from MR images combined with BMD measures improve the discrimination between subjects with hip fractures and normal age-matched controls.

Association of larger holes in the trabecular bone at the distal radius in postmenopausal women with type 2 diabetes mellitus compared to controls

“…This study may have been underpowered to accurately assess these other mircoarchitecture outcomes and further investigation is needed. Observational imaging studies in adults with a fracture history have demonstrated that reduced bone strength may be influenced by deficits in the trabecular bone network (10,19,24). In particular, the size of the holes in the trabecular network at appendicular skeletal sites can provide information about bone structural competence (40).…”

“…Hole size analyses do not depend on any stereologic assumptions, whereas the derivation of Tb.Sp, Tb.Th, and Tb.N does indeed depend on sterologic assumptions (i.e., parallel plate model) (35). Moreover, some suggest that comprehensive imaging studies aiming to determine histomorphometric differences between groups should have at least 50 participants per group to provide sufficient power (19). Burghardt and colleagues also found no differences in radius microarchitectural indices, including Tb.N, in a smaller pilot study in women with type 2 DM and age-and height-matched healthy controls using pQCT (47).…”

“…MRI-based measures of trabecular bone microarchitecture may provide insight on alterations in bone quality that occur in adults with type 2 DM. It has been effective in detecting differences in BVTV, Tb.N, Th.Th, and Tb.Sp in groups differing in osteoporosis diagnosis and fracture history, suggesting a relationship between 2-dimensional (2-D) variables of trabecular bone microarchitecture derived from MRIs and fracture (18,19). It has been argued, however, that the resolution of MRIs limits the accurate assessment of such 2-D variables because the images are acquired at the current limits of clinical spatial resolution and can be confounded by partial volume effects (20).…”

Quantitative MRI for the assessment of bone structure and function

“…A further potential motivation is the study of the structural manifestations of metabolic bone disease such as renal osteodystropy (166). Evidence for these developments is the rapid growth of the clinical literature (8,83,84,127,145,165,(167)(168)(169)(170)(171)(172) and also, to a lesser extent, the increased use of CT to characterize TB (14)(15)(16)(173)(174)(175)(176)(177).…”

“…There is now clear evidence that the findings from histomorphometry, suggesting that inclusion of structural parameters substantially improves the discrimination of patients with osteoporotic fractures from their unfractured peers, is equally true for measurements obtained in vivo at much lower resolution (83,127,168,169). At least three studies provide compelling evidence for the independent role of architecture as a predictor of bone strength.…”