Items tagged “ultrasound”
506 results found
Case
Subcutaneous abscess (axilla)
Published
09 Jul 2016
91% complete
Ultrasound
Case
Lead zirconate titanate (PZT) diagrams
Published
24 Jul 2016
38% complete
Diagram
Article
Refraction
Refraction of a sound wave occurs if it travels between tissues with different propagation speeds. As the incident pulse or returning echo strikes an interface of different density or elasticity and therefore a different propagation speed, the direction of the wave changes according to Snell’s l...
Article
Refraction artifact
Refraction artifact can occur when a transmitted ultrasound pulse strikes an interface at a non-perpendicular angle. The difference in propagation speeds between the two tissues can cause refraction to occur. Should the refracted incident sound wave strike a reflector and cause an echo to return...
Article
Distance measurement
Ultrasound machines perform distance measurement to synthesize images from returning echoes. To generate images for an ultrasound scan, machines need to determine the distance of reflective interfaces from the transducer. Simply, the formula used is:
distance = (speed x time)/2
Where:
distanc...
Article
Ultrasound-guided peripheral intravenous cannulation
Peripheral intravenous cannulation under ultrasound guidance is the placement of a cannula into a peripherally-located vein under the direct vision of ultrasound. This process allows the cannulation of veins that are unable to be visualized or palpated without ultrasound. In trained individuals ...
Article
Side lobe artifact
Side lobe artifacts occur where side lobes reflect sound from a strong reflector that is outside of the central beam, and where the echoes are displayed as if they originated from within the central beam.
Ultrasound transducer crystals expand and contract to produce primary ultrasound beams in ...
Article
Ring down artifact
Ring down artifact is a special type of resonance artifact. Its appearance is similar to the ladder-like reverberation of comet-tail artifact, but it is produced by a completely different mechanism.
The artifact is only associated with gas bubbles, and occurs when an ultrasound pulse encounters...
Case
Ring down artifact
Published
23 Sep 2016
47% complete
Annotated image
Article
Pulsus bisferiens
Pulsus bisferiens or double pulse refers to a wave pattern where there is the presence of two systolic peaks that can be seen in pressure tracings of the ascending aorta, the aortic arch, and the carotid artery.
It can occur in patients with
aortic valve pathology: aortic regurgitation with or...
Case
Peroneus brevis split tendon syndrome
Published
18 Dec 2016
75% complete
Ultrasound
Case
Fecal peritonitis
Published
23 Dec 2016
91% complete
X-ray
Ultrasound
Article
Temporal tap maneuver
Temporal tap maneuver consists in tapping over the ipsilateral superficial temporal artery while assessing the carotid bifurcation on Doppler ultrasound aiming to produce a reflected flow in the external carotid artery (ECA) and thus helping to distinguish which vessel is being assessed: externa...
Article
Thoracic spine sign (ultrasound)
The thoracic spine sign, or spine sign, on lung ultrasound is an indirect indicator of the presence of a pleural effusion or hemothorax. It represents the visualization of the vertebral bodies in the thoracic cavity above the diaphragm which are usually not seen unless there is a fluid collectio...
Case
Gastric lymphoma
Published
08 Mar 2017
94% complete
Ultrasound
Article
Transrectal ultrasound
Transrectal ultrasound (TRUS) is a technique that is used most commonly to evaluate
the prostate gland, including ultrasound-guided prostate biopsies
depth of invasion of colon/rectal cancer (for staging purposes)
It can also be used for guidance in placing a transrectal drain, or in r...
Article
Vitreous hemorrhage
Vitreous hemorrhage refers to bleeding into the vitreous humor.
Epidemiology
Vitreous hemorrhage has an incidence of approximately 7 in 100,000 1,2.
Clinical presentation
The most common clinical presentation is with sudden, painless visual loss to varying degrees of severity 2. Associated...
Article
Portosystemic shunt ratio
The portosystemic shunt ratio is a measure performed using ultrasound to quantify the abnormal flow of portal venous blood that is shunted away from the hepatic sinusoidal circulation in the context of a congenital portosystemic shunt 1.
Measurement
The ratio is determined on ultrasound using ...
Article
Reflection
Reflection of a sound wave occurs when the wave passes between two tissues of different acoustic impedances and a fraction of the wave 'bounces' back. This forms one of the major principles of ultrasound imaging as the ultrasound probe detects these reflected waves to form the desired image.
An...
Article
Normal hepatic vein Doppler
The hepatic veins have a characteristic spectral Doppler waveform. Alterations in the normal hepatic vein waveform may reveal or confirm abnormalities in the heart or liver.
Terminology
The shape of the hepatic vein spectral Doppler waveform is primarily determined by pressure changes in the r...
Unable to process the form. Check for errors and try again.