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Since the pulse from each transducer is progressively delayed going up the line, each transducer emits its pulse after the one below it. This results in a beam of sound waves emitted at an angle (θ) to the array. By changing the pulse delays, the computer can scan the beam of ultrasound in a raster pattern across the tissue.
Synthetic aperture ultrasound (SAU) imaging is an advanced form of imaging technology used to form high-resolution images in biomedical ultrasound systems. Ultrasound imaging has become an important and popular medical imaging method, as it is safer and more economical than computer tomography (CT) and magnetic resonance imaging (MRI).
This allows for the detection of a pneumothorax with the absence of normal ‘lung-sliding’ and ‘comet-tail’ artifact (seen on the ultrasound screen). Compared with supine chest radiography , with CT or clinical course as the gold standard, bedside sonography has superior sensitivity (49–99% versus 27–75%), similar specificity (95 ...
Intima–media thickness (IMT), also called intimal medial thickness, is a measurement of the thickness of tunica intima and tunica media, the innermost two layers of the wall of an artery. The measurement is usually made by external ultrasound and occasionally by internal, invasive ultrasound catheters .
At 12 weeks of gestational age, an "average" nuchal thickness of 2.18mm has been observed; however, up to 13% of chromosomally normal fetuses present with a nuchal translucency of greater than 2.5mm. Thus for even greater accuracy of predicting risks, the outcome of the nuchal scan may be combined with the results of simultaneous maternal blood ...
The TDTD method uses Doppler ultrasound to translate the pressure balance principle of blood pressure measurement with a sphygmomanometer to the measurement of ICP. The ophthalmic artery (OA), a unique vessel with intracranial and extracranial segments, is used as a pressure sensor and as a natural pair of scales for absolute ICP value in mmHg ...
Spatial resolution of an fMRI study refers to how well it discriminates between nearby locations. It is measured by the size of voxels, as in MRI. A voxel is a three-dimensional rectangular cuboid, whose dimensions are set by the slice thickness, the area of a slice, and the grid imposed on the slice by the scanning process.
Ultrasensitive Doppler has a typical 50-200 μm spatial resolution depending on the ultrasound frequency used. [2] It features temporal resolution ~10 ms, can image the full depth of the brain, and can provide 3D angiography. [10]