Pediatric Registry Review Flashcards
(621 cards)
Curved Array Transducers
Crystals arranged in the shape of an arc. Provide a wide field of view in the near field.
Linear Array Transducers
Crystals arranged in a line. Rectangular shaped image. Evaluation of Neonatal spine, infant abdomens, bowel wall, brain, MSK, abdominal and superifical parts.
Phased Array Transducers
Crystals arranged in a line. Image produced is pie shaped or vector shaped. Possess a small footprint making them advantageous for intercostal scanning, echocardiography or chest. Also, head imaged.
Narrow bandwidths emit __ frequencies.
Few
Broad bandwidths emit __ frequencies.
Many; multi-hertz transducers have broad bandwidths, which allow the operator to change the frequency; harmonic imaging also results in broad bandwidths.
Frequency and Penetration are ___ proportional.
Inversely
Frequency and Spatial Resolution are __ proportional.
Directly
What is spatial resolution?
Capability of depicting structural detail (axial and lateral resolution)
Axial Resolution
display 2 closely spaced targets parallel to the sound beam as 2 distinct targets.
Dependent on the transducer’s spatial pulse length (SPL)
Spatial pulse length in ultrasound imaging describes the length of time that an ultrasound pulse occupies in space. Mathematically, it is the product of the number of cycles in a pulse and the wavelength. A shorter spatial pulse length results in higher axial resolution.
Lateral Resolution
ability of the transducer to display two targets perpendicular to the path of the sound beam as 2 distinct structures.
Improved with focusing and higher frequency transducers.
Propagation Speed of Soft Tissue
1540 m/s
Propagation Speed of Water
1480 m/s
Propagation Speed of Blood
1575 m/s
Propagation Speed of Bone
4080 m/s
Propagation speed is inversely proportional to:
density, elasticity and compressibility
Propagation speed is directly proportional to:
stiffness
Reflection
return of the sound beam back to the transducer; responsible for CREATING the image
Refraction
change of direction or bending of the sound wave as it passes from one tissue to another
only occurs if there is a change in velocity between 2 media and there is an oblique angle of incidence
Attenuation
weakening of the amplitude or intensity as it travels through a medium
Sources include absorption, reflection, scattering, refraction and interference
Dynamic range controls:
the number of gray shades represented in the display; the higher the dynamic range, the greater amounts of display and the lower the dynamic range, the less gray displayed (more contrasty)
Tissue Harmonic Imaging (THI)
improves the signal to noise ratio, reduces grating lobe artifacts, and improves lateral resolution.
What is the major benefit of Tissue Harmonic Imaging (THI)?
artifact reduction
B-Flow Imaging
displays the blood flow signal throughout an entire gray-scale image
can simultaneously visualize high and low velocities
detailed organ perfusion, such as renal or liver transplants, neonatal heads and superficial masses
Shear Wave Elastography
quantifies tissue stiffness