用英文对下面的摘要进行评价并提出问题：AbstractObjective：Conventional ultrasound measures the diameter and the velocity of the vein to evaluate early venous tension changes in deep vein thrombosis DVT of lower extremity

This study evaluates the use of the A/C ratio to measure early vein tension changes in DVT of lower extremity. The study compares the cross-sectional area, cross-sectional perimeter, and A/C ratio among normal control group, flow reduced group, and venous thrombosis group. The study concludes that A/C ratio is a more stable measure of vein tension compared to conventional measures, and provides new thinking and reference for early clinical intervention in preventing DVT.

Questions:

• Can the A/C ratio be used as a diagnostic tool for DVT, or is it only useful for measuring early vein tension changes?
• How does the A/C ratio compare to other non-invasive diagnostic tools for DVT, such as D-dimer testing or venous ultrasound imaging?
• Are there any limitations to using the A/C ratio, such as difficulty in obtaining accurate measurements or variability among different patients