Clinical differentiation of the patient in pain: an introductory guideline for CRNAs

The practical application of colour-coded duplex sonography shows that physico-technical artifacts of colour Doppler imaging may not be obvious in all cases and can lead to misinterpretation. Slice-thickness artifacts are due to restricted transversal resolution, as in the B-mode, and may cause false negative results in vascular occlusions. Specific problems in creating and processing the colour flow image interfere with lateral resolution and lead to errors in the quantification of stenoses from the colour Doppler image. Mirror image artifacts produce phantom pictures that can be easily identified as such in some cases, but may resemble recesses in the arterial wall in other cases. Phenomena of sound shadowing resulting from the same reasons as in B-mode may lead to assume vascular occlusions in cases of long-range stenoses. Artifacts of the sonication angle in case of blood vessel tortuosity may lead to misdiagnosis of a non-existent retrograde flow. The artifacts mentioned do restrict the capacity of colour coded duplex sonography for localising flow in the ultrasound image. Users of the method should therefore be familiar with these artifacts.