Which scan is designed to measure the most trabecular bone?

• A. DXA of the hip
• B. QCT of the spine
• C. QUS of the heel
• D. CT scan of the wrist

Answer: (B)

Bone densitometry techniques vary in their ability to assess different types of bone. Trabecular bone, which is also known as cancellous bone, is found predominantly in the axial skeleton, including areas such as the vertebrae.

Quantitative Computed Tomography (QCT) is particularly effective for evaluating trabecular bone because it can differentiate between trabecular and cortical bone components and provides a three-dimensional assessment. Within the options presented, QCT specifically targets the spine, where a significant amount of trabecular bone is located. This method allows for a more precise measurement of bone mineral density in the trabecular regions, making it uniquely suited for assessing conditions like osteoporosis, which often affects trabecular bone density more significantly than cortical bone.

In contrast, Dual-Energy X-ray Absorptiometry (DXA) of the hip primarily focuses on cortical bone, while Quantitative Ultrasound (QUS) of the heel provides a more generalized assessment that doesn't provide the same level of specificity for trabecular bone compared to QCT. CT scans of the wrist similarly do not specifically target regions with a high concentration of trabecular bone. Therefore, QCT of the spine stands out as the method that is designed to measure