UPSC-CMS 2022 — Radiology

Question 1: The most difficult area to visualize using duplex scanning (B-mode ultrasound), especially in an obese patient, is

• A. abdominal aorta above renal vessels
• B. carotid vessels
• C. aortoiliac segment (Correct Answer)
• D. iliofemoral segment

Explanation: ***aortoiliac segment*** - The **aortoiliac segment** is often challenging to visualize due to its deep location within the **pelvis** and the presence of overlying **bowel gas**, which scatters ultrasound waves. - In obese patients, increased **adipose tissue** further attenuates the ultrasound signal, making imaging of this specific segment particularly difficult. *abdominal aorta above renal vessels* - While the **abdominal aorta** can be challenging, particularly the segment above the renal vessels due to the diaphragm and lung bases, it is generally more accessible than the deep pelvic structures. - Visualization can be improved by optimizing patient position and using specific transducer angles. *carotid vessels* - **Carotid vessels** are superficial and easily accessible for duplex scanning, making them one of the easiest vascular beds to image. - There is minimal tissue attenuation, and bowel gas is not a factor. *iliofemoral segment* - The **iliofemoral segment** is more superficial than the aortoiliac segment and is generally well visualized, especially the femoral arteries in the groin. - While obesity can increase the scanning depth, it does not pose the same challenges as the deeper and often gas-obscured pelvic vessels.