RIDGE NUMBER DENSITY - A NEW PARAMETER FOR IN-VIVO BONE-STRUCTURE ANALYSIS

An advanced analysis of the mechanical properties of bone should inclu de information about the microarchitecture of cancellous bone in addit ion to its density, It has recently been shown that high-resolution qu antitative computed tomography and magnetic resonance imaging have the potential to assess such information in a noninvasive way in patients , Both techniques, however, lark sufficient spatial resolution to imag e the individual trabeculae with true precision, In this work, a new p arameter, Ridge number density (RND), is introduced, RND is a measure for the trabecular number, which can be extracted directly from high-r esolution three-dimensional (3D) images of patients, we applied the RN D technique to a test group of nine healthy, postmenopausal women meas ured repetitively with a high-resolution 3D peripheral quantitative co mputed tomography (3D-pQCT) system with 165 x 165 x 165 mu m(3) voxel size, Simultaneously with the RND determination, the trabecular bone d ensity (TBD) was also assessed in the same volume of interest, The exa mination site was the distal radius, The intersubject variability of t he measured test group was 10.5% for RND and 26.3% for TBD, The root m ean square error between first and second examinations (midterm reprod ucibility) was 1.6% and 1.1%, respectively, RND is determined independ ently front TBD and pertains to the structure of the cancellous bone, As such, it might add crucial information in cases where bone mass or bone density measurements alone give ambiguous results. (C) 1997 by El sevier Science Inc. All rights reserved.