ARDMS (American Registry for Diagnostic Medical Sonography) Practice Test

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Prepare for the ARDMS Sonography Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

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If the sonographer does not see any color flow when applied but could see movement of blood cells within the vessel on grayscale imaging what should the operator assume?

  1. Power Doppler must be used instead.

  2. The angle of incidence is 90 degrees and needs to be changed.

  3. The blood vessel is obstructed.

  4. Maintenance must be called as the color Doppler is not sensitive enough.

The correct answer is: Power Doppler must be used instead.

In this scenario, where the sonographer can visualize the movement of blood cells within the vessel on grayscale imaging but does not see any color flow when color Doppler is applied, the correct assumption for the operator to make is that power Doppler must be used instead. Color Doppler imaging is based on the principle of flow detection towards and away from the transducer, which is influenced by Doppler shifts created by moving blood cells. However, if the angle of incidence is very steep, as in the case where blood flow within the vessel is parallel to the ultrasound beam, color flow may not be detected effectively. In such situations, power Doppler can be more sensitive in detecting slow flow and low-velocity flow because it is not as angle-dependent as color Doppler. Power Doppler is capable of displaying all detected Doppler shifts, providing a qualitative representation of flow strength rather than flow direction. Therefore, the correct course of action for the sonographer in this case would be to switch to power Doppler mode to accurately assess and visualize blood flow within the vessel.