What should be clearly visible at the top of a forearm DXA image?

• A. Two rows of carpal bones
• B. One row of carpal bones
• C. The radius
• D. The ulna

Answer: (B)

In a forearm DXA (Dual-Energy X-ray Absorptiometry) image, it is essential for one row of carpal bones to be clearly visible at the top of the image because this indicates that the anatomy being evaluated is correctly positioned and in the appropriate area of interest. The carpal bones, located at the wrist, are the first structural indicators when assessing the forearm; ensuring visibility of at least one row signifies that the region of interest encompasses the distal radius and the surrounding bony structures.

This visibility also aids in accurate assessment and bone density evaluation. If both rows were visible, it might indicate that the image captured too much of the wrist area, potentially diluting the focus on the radius and ulna, which are more significant for assessing bone density in conditions such as osteoporosis. Thus, the presence of one row of carpal bones serves as a guideline to ensure proper technique and relevant anatomical focus during the DXA scan.