The Effect of Quantitative Computed Tomography Acquisition Protocols on Bone Mineral Density Estimation

Area of Science:

• Biomedical Engineering
• Radiology
• Orthopedics

Background:

• Osteoporosis is a condition of bone loss and reduced bone strength, increasing fracture risk.
• Patient-specific quantitative computed tomography (QCT) finite element (FE) models are used to predict fractures under physiological loads.
• Accurate material properties for FE models are derived from CT grayscale values converted to volumetric bone mineral density (vBMD).

Purpose of the Study:

• To investigate the influence of CT acquisition and postprocessing settings on vBMD estimation.
• To determine if variations in scanning parameters affect fracture risk prediction in osteoporosis.

Main Methods:

• A rabbit femur and a calibration phantom were scanned using QCT with varying protocols (voltage, current, reconstruction kernel).
• Cortical and cancellous bone regions were segmented to obtain Hounsfield unit (HU) values.
• HU values were converted to vBMD, and the impact of different scanning parameters was analyzed.

Main Results:

• Estimated vBMD was significantly affected by changes in voltage and reconstruction kernel.
• CT scanning current did not show a significant effect on vBMD estimation.
• Different scanning parameters introduced noise variations, potentially impacting fracture risk assessment in small bone regions.

Conclusions:

• CT acquisition protocols introduce significant variability in vBMD measurements.
• Variations in scanning parameters can negatively affect the accuracy of osteoporosis fracture risk prediction using QCT-FE models.
• Standardization of QCT protocols is crucial for reliable vBMD assessment and fracture risk evaluation.