Items tagged “ultrasound”
506 results found
Article
Ultrasound artifacts
Ultrasound artifacts are commonly encountered and familiarity is necessary to avoid false diagnoses. In some cases, specific artifacts can even offer valuable diagnostic information. For instance, some artifacts may be indicative of certain pathologies. They are not to be confused with ultrasou...
Case
Speed displacement artifact
Published
21 Oct 2014
25% complete
Ultrasound
Article
Speed displacement artifact
Speed displacement artifact, also known as propagation velocity artifact, is a gray scale ultrasound finding that can be identified as an area of focal discontinuity and displacement of an echo deeper than that its actual position in an imaged structure. Depth determination by an ultrasound mach...
Case
Iatrogenic arteriovenous fistula
Published
02 Nov 2014
88% complete
Ultrasound
Article
Beam width artifact
Ultrasound beam width artifact occurs when a reflective object located beyond the widened ultrasound beam, after the focal zone, creates false detectable echoes that are displayed as overlapping the structure of interest.
Features
To understand this artifact, it is important to remember that t...
Article
Anisotropy
Anisotropy is an artifact encountered in ultrasound, notably in muscles and tendons during a musculoskeletal ultrasound. In musculoskeletal applications, the artifact may prompt an incorrect diagnosis of tendinosis or tendon tear.
When the ultrasound beam is incident on a fibrillar structure su...
Case
Anisotropy
Published
30 Oct 2014
91% complete
Ultrasound
Article
Fibrous pseudotumor of the scrotum
Fibrous pseudotumor of the scrotum is a relatively rare, non-neoplastic extratesticular non-epididymal lesion.
Epidemiology
It affects any age. Although rare, it is considered the third most common extra testicular mass after a scrotal lipoma and an epididymal adenomatoid tumor.
Risk factors...
Article
Patent foramen ovale
A patent foramen ovale (PFO) is a normal foetal interatrial connection which can persist into adult life. This can cause stroke due to paradoxical embolus.
Terminology
PFO is an anatomical variant due to persistence of a normal foetal structure rather than a malformation, in contradistinction ...
Article
Reverberation artifact
Reverberation artifact occurs when an ultrasound beam encounters two strong parallel reflectors.
When the ultrasound beam reflects back and forth between the reflectors ("reverberates"), the ultrasound transducer interprets the sound waves returning as deeper structures since it took longer for...
Article
Ultrasound (introduction)
Ultrasound (US) is an imaging technology that uses high-frequency sound waves to characterize tissue. It is a useful and flexible modality in medical imaging and often provides an additional or unique characterization of tissues when compared to other modalities such as conventional radiography ...
Article
Young's modulus
Young's modulus is a relationship between elasticity, strain, and stress:
elasticity x (change in length / original length) = (force / area)
put another way, this is
elasticity x (strain) = stress
or
elasticity = stress / strain
Elasticity is measured in kilopascals (kPa).
This relationsh...
Article
Strain elastography
Strain elastography (also known as tissue strain elastography/static elastography/compression elastography) is a developing form of ultrasound that assesses tissues' macroscopic structure through the strain modulus. This is different from normal B-mode grayscale ultrasound which characterizes a ...
Article
Shear wave elastography
Shear wave elastography is a developing variation of ultrasound imaging.
The concept is similar to strain elastography, but instead of using transducer pressure to compare a shift in an ultrasound A-line (thereby measuring changes in strain), a higher intensity pulse is transmitted to produce s...
Case
Dirofilariasis
Published
14 Nov 2014
88% complete
Ultrasound
Pathology
Article
Acoustic impedance
Acoustic impedance (Z) is a physical property of tissue. It describes how much resistance an ultrasound beam encounters as it passes through a tissue.
Acoustic impedance depends on:
the physical density of the tissue (d, in kg/m3)
the velocity of the soundwave transmitted through the tissue m...
Article
Fine needle aspiration (FNA)
Fine needle aspiration (FNA) is a type of minimally-invasive tissue sampling. It often uses ultrasound as a targeting instrument, although CT and even MRI or fluoroscopy could potentially be used, depending on the situation. Imaging guidance is particularly useful when sampling deep or diffuse l...
Case
Ovarian torsion
Published
20 Nov 2014
75% complete
Ultrasound
Article
Decibel
The decibel (dB) is a unit that measures the relative difference between two sound intensities. The relationship is logarithmic:
dB = 10 log (I2 / I1)
dB = relative intensity of the sounds
I1 = intensity of sound 1
I2 = intensity of sound 2
Informally, decibel is a unit of "loudness", which...
Article
Ultrasound of the elbow
Ultrasound of the elbow allows high-resolution imaging of elbow anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments.
Approach
There are multiple possible approaches to imaging the elbow with ultrasound. A typical protocol is as follows 1:
Anterior elb...
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