Presentation
Routine inspection.
From the case:
Normal paper clip test of an ultrasound probe

A standard gem type metal paper clip is translated along the surface of the probe after application of a thin layer of US gel. No focal defects in the resultant reverberation artifact can be observed.
Case Discussion
The paper clip test is a sensitive method to look for small piezo element dropouts. Note that due to transducer geometry the standard approach is not suitable for phased array probes, hence a modifed technique utilizing B-mode has been proposed.