Post on 23-Jan-2018
Artifacts
ULTRASOUND
• any record or image obtained in the course of
applying a medical diagnostic technique which is
not representative of the structures under study but
is adventitious”.
• When evaluating anatomic structures, acoustic
artifacts result in added (not real), missing,
improperly located, brightness, shape or size
alterations
Ultrasound
• US waves wavelength and frequency are inversely related
• Low frequency - Better penetration of tissues – good resolution of deeper structures
• High frequency probes used for superficial structures visualization
• Higher frequency waves are more attenuated than lower frequency for a given distance
• 1-20Mhz probes• Atlas of Ultrasound-Guided Procedures in Interventional Pain Manag ement
• Increasing the transducer frequency improves the
spatial resolution at the expense of beam
penetration as a result of sound wave absorption. In
contrast, lower frequency transducers enable
assessment of deeper structures, but the spatial
resolution is lower.
• Angle of insonation
• maximum reflection achieved when the sound wave
is directed perpendicular to the imaged structure
• In addition to reflection, the sound waves also be
absorbed in the examined tissues, and the amount
of absorption increases with greater transducer
frequency and tissue viscosity.
• Acoustic Shadowing: Acoustic shadowing is the
reduction in amplitude of reflected sound caused by
reflectors that lie behind a strongly reflecting or
attenuating structure
Acoustic Reflection and Refraction
Acoustic Enhancement: Acoustic enhancement is a relative
increased echo amplitude caused by an intervening structure
of low attenuation
Ring-down and comet-tail artifacts
Reverbation
• Regional Anesthesia and Pain Medicine Vol. 32 No.
5 September–October 2007
• Ultrasound, Vol. 36, No. 4, 1995, pp 297-306.
• Seminars in Musculoskeletal Radiology Vol. 18 No.
1/2014