Introduction: For peripheral QCT usually dedicated scanners like the XtremeCT (ScancoMedical AG, Switzerland) are used. However, scan times are long and only small volumes or single slices can be acquired. In contrast, with widely available clinical whole-body CT scanners, 10 to 20 cm long scans of both distal forearms can be acquired in seconds. We developed a 3D analysis method using 3D segmentation and an automatic placement of analysis volumes of interest (VOIs) for determining bone mineral density (BMD), content (BMC) and cortical thickness.
Methods: 23 datasets of both distal forearms of young professional male climbers (n=11) and age and BMI matched healthy controls (n=12) were acquired on a SIEMENS VolumeZoom (80kV, 122mAs, 24 cm FOV, 15 cm scan, 1.0mm slice thickness, kernel B60s, Siemens Osteo Phantom for BMD calibration). Endosteal and periosteal surfaces of radius and ulna were segmented using a multi-step local adaptive thresholding procedure. Four anatomically adapted VOIs (ultra-distal, distal, mid, proximal) were automatically defined in the radius.
Results: Integral, cortical and trabecular BMD and BMC and cortical thickness were measured in each VOI (results are denoted as: climbers, controls, p-value). Young adult climbers showed significantly increased integral and cortical BMD (ultra-distal: 762±50mg/cm3, 653±48mg/cm3, p<0.001; distal: 1074±35mg/cm3, 1018±59mg/cm3, p<0.05) and BMC as well as cortical thickness (ultra-distal: 0.97±0.08mm, 0.87±0.06mm, p<0.001; distal: 1.2±0.1mm, 1.1±0.1mm, p<0.05) in both distal VOIs. Trabecular BMD (170±18mg/cm3, 142±36 mg/cm3, p<0.05) and BMC was significantly higher in the ultra-distal VOI. Results for mid and proximal VOIs were not significantly different.
Conclusion: A new 3D-QCT analysis program for the distal forearm was developed specifically exploiting advantages of whole-body CT scanners. It can be used to determine BMD, BMC and cortical thickness at any position along the radius included in the scan. The study showed that climbing predominantly affects bone parameters in the most distal regions of the forearm.