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 'A-Mode' 
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Result : Searchterm 'A-Mode' found in 1 term [] and 9 definitions [])
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A-ModeInfoSheet: - Modes - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:<br> - Modes -
 
A-mode (Amplitude-mode) ultrasound is used to judge the depth of an organ, or otherwise assess an organ's dimensions. A-mode technology has been used in midline echoencephalography for rapid screening of intracranial mass lesions and ophthalmologic scanning. A-mode ultrasound imaging is now obsolete in medical imaging. The A-mode scan had also been used for early pregnancy assessment (detection of fetal heart beat), cephalometry and placental localization.
When the ultrasound beam encounters an anatomic boundary, the received sound impulse is processed to appear as a vertical reflection of a point. On the display, it looks like spikes of different heights (the amplitude). The intensity of the returning impulse determined the height of the vertical reflection and the time it took for the impulse to make the round trip would determine the space between verticals. The distance between these spikes can be measured accurately by dividing the speed of sound in tissue (1540 m/sec) by half the sound travel time.
To make an echoencephalography scan, the first A-mode scan is obtained from the right side of the head and the image captured on film. Then the probe is placed at the corresponding point on the left side. The second exposure is made on the same film with inverted spikes. The A-mode ultrasound could be used to identify structures normally located in the midline of the brain such as the third ventricle and falx cerebri. The midline structures would be aligned in normal patients but show displacement in patients with mass lesion such as a subdural, epidural, or intracranial hemorrhage.
See also Ultrasound Biomicroscopy, A-scan, B-mode and the Infosheet about ultrasound modes.
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 Further Reading:
  Basics:
A-Mode EchoencephalographyOpen this link in a new window
   by www.obgyn.net    
A-Mode Area RatioOpen this link in a new window
   by www.wildultrasound.com    
  News & More:
Module 1: Basic A-scan Biometry Section 1: Basic ConceptsOpen this link in a new window
   by www.eyetec.net    
US Resources  
Image Quality - Software - General - Cardiac - Patient Information - Modes
 
A-ScanMRI Resource Directory:<br> - Modes -
 
A-scans are used in ophthalmologic scanning, to detect and monitor pregnancy problems, and screen intracranial mass lesions by using A-modes.
A-scan ultrasound biometry, commonly referred to as an A-scan, is a routine diagnostic test used in ophthalmology. The A-scan provides data on the shape of the eye, which is a major determinant in common sight disorders.
Ultrasound scanners used in this type of test require usually direct contact with the eye.
See also A-Mode, Oculoplethysmography, Ultrasound Biomicroscopy, B-Scan, C-Scan and D-Scan.
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 Further Reading:
  Basics:
Medical Physics: Ultrasound - extended reading exerciseOpen this link in a new window
   by www.cyberphysics.pwp.blueyonder.co.uk    
  News & More:
Evaluation of the validity and reliability of A-scan ultrasound biometry with a single use disposable coverOpen this link in a new window
2002   by bjo.bmjjournals.com    
US Resources  
Supplies and Accessories - Ultrasound Therapy - Ultrasound Guided Interventions - Pelvic - Artifacts - Jobs
 
Artemis 2InfoSheet: - Devices -
Intro, 
TypesMRI Resource Directory:<br> - Devices Machines Scanners Systems -
 
www.arcscan.com/products.html

From Ultralink LLC;
'Artemis is a very high frequency (VHF) ultrasound eye scanner. In use, the patient leans forward placing their head onto an adjustable headrest. The headrest's unique design permits the patient to pull away quickly from the scanner if desired. An eyecup filled with a saline-based interface fluid couples the ultrasound signal to the eye, while a precision mechanism moves the transducer past the front of the eye. During the accurately controlled arc motion of the transducer, which lasts less than one second, many thousands of ultrasound samples are digitized. Following a scan, signal analysis is performed on a PC-compatible microcomputer, and the data are available for immediate viewing on an LCD monitor or disk storage. Artemis is very flexible; many adjustments to the scanning parameters are possible to customize the scan to your clinical needs. Functions are provided for centering the scan about the optical axis of the eye. The starting location of the scans as well as the extent can be varied as desired, to view image planes through the eye at different angles.'

Specifications for this system will be available soon.

See also Ultrasound Biomicroscopy, A-Mode and A-Scan.

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 Further Reading:
  News & More:
Module 1: Basic A-scan Biometry Section 1: Basic ConceptsOpen this link in a new window
   by www.eyetec.net    
ULTRASOUND MEASUREMENT OF THE EFFECT OF TEMPERATURE ON MICROPERFUSION IN THE EYEOpen this link in a new window
Thursday, 25 April 2002   by www.ncbi.nlm.nih.gov    
Searchterm 'A-Mode' was also found in the following service: 
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B-ModeInfoSheet: - Modes - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:<br> - Modes -
 
Also called B-mode echography, B-mode sonography, 2D-mode, and sonogram.
B-mode ultrasound (Brightness-mode) is the display of a 2D-map of B-mode data, currently the most common form of ultrasound imaging.
The development from A-mode to B-mode is that the ultrasound signal is used to produce various points whose brightness depends on the amplitude instead of the spiking vertical movements in the A-mode. Sweeping a narrow ultrasound beam through the area being examined while transmitting pulses and detecting echoes along closely spaced scan lines produces B-scan images. The vertical position of each bright dot is determined by the time delay from pulse transmission to return of the echo, and the horizontal position by the location of the receiving transducer element.
To generate a rapid series of individual 2D images that show motion, the ultrasound beam is swept repeatedly. The returning sound pulses in B-mode have different shades of darkness depending on their intensities. The varying shades of gray reflect variations in the texture of internal organs. This form of display (solid areas appear white and fluid areas appear black) is also called gray scale.

Different types of displayed B-mode images are:
point two-dimensional, 2D-mode;
point gray scale;
point real-time mode;
point compound B-mode.

The probe movement can be performed manual (compound and static B-scanner) or automatic (real-time scanner).
The image reconstruction can be parallel or sector type.
See also B-Scan, 4B-Mode, and Harmonic B-Mode Imaging.
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 Further Reading:
  Basics:
Medical Physics: Ultrasound - extended reading exerciseOpen this link in a new window
   by www.cyberphysics.pwp.blueyonder.co.uk    
  News & More:
Ultrasound anatomy of the neckOpen this link in a new window
   by rad.usuhs.mil    
US Resources  
Services and Supplies - Developers - Rental - Distributors - UltraSound Reimbursement - Gall Bladder
 
History of UltrasoundMRI Resource Directory:<br> - History of UltraSound -
 
point In 1880 the Curie brothers discovered the piezoelectric effect in quartz. Converse piezoelectricity was mathematically deduced from fundamental thermodynamic principles by Lippmann in 1881.
point In 1917, Paul Langevin (France) and his coworkers developed an underwater sonar system (called hydrophone) that uses the piezoelectric effect to detect submarines through echo location.
point In 1935, the first RADAR system was produced by the British physicist Robert Watson-Wat. Also about 1935, developments began with the objective to use ultrasonic power therapeutically, utilizing its heating and disruptive effects on living tissues. In 1936, Siemens markets the first ultrasonic therapeutic machine, the Sonostat.
point Shortly after the World War II, researchers began to explore medical diagnostic capabilities of ultrasound. Karl Theo Dussik (Austria) attempted to locate the cerebral ventricles by measuring the transmission of ultrasound beam through the skull. Other researchers try to use ultrasound to detect gallstones, breast masses, and tumors. These first investigations were performed with A-mode.
point Shortly after the World War II, researchers in Europe, the United States and Japan began to explore medical diagnostic capabilities of ultrasound. Karl Theo Dussik (Austria) attempted to locate the cerebral ventricles by measuring the transmission of ultrasound beam through the skull. Other researchers, e.g. George Ludwig (United States) tried to use ultrasound to detect gallstones, breast masses, and tumors. This first experimentally investigations were performed with A-mode. Ultrasound pioneers contributed innovations and important discoveries, for example the velocity of sound transmission in animal soft tissues with a mean value of 1540 m/sec (still in use today), and determined values of the optimal scanning frequency of the ultrasound transducer.
point In the early 50`s the first B-mode images were obtained. Images were static, without gray-scale information in simple black and white and compound technique. Carl Hellmuth Hertz and Inge Edler (Sweden) made in 1953 the first scan of heart activity. Ian Donald and Colleagues (Scotland) were specialized on obstetric and gynecologic ultrasound research. By continuous development it was possible to study pregnancy and diagnose possible complications.
point After about 1960 two-dimensional compound procedures were developed. The applications in obstetric and gynecologic ultrasound boomed worldwide from the mid 60’s with both, A-scan and B-scan equipment. In the late 60’s B-mode ultrasonography replaced A-mode in wide parts.
point In the 70’s gray scale imaging became available and with progress of computer technique ultrasonic imaging gets better and faster.
point After continuous work, in the 80’s fast realtime B-mode gray-scale imaging was developed. Electronic focusing and duplex flow measurements became popular. A wider range of applications were possible.
point In the 90’s, high resolution scanners with digital beamforming, high transducer frequencies, multi-channel focus and broad-band transducer technology became state of the art. Optimized tissue contrast and improved diagnostic accuracy lead to an important role in breast imaging and cancer detection. Color Doppler and Duplex became available and sensitivity for low flow was continuously improved.
point Actually, machines with advanced ultrasound system performance are equipped with realtime compound imaging, tissue harmonic imaging, contrast harmonic imaging, vascular assessment, matrix array transducers, pulse inversion imaging, 3D and 4D ultrasound with panoramic view.
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 Further Reading:
  News & More:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
A-Mode Area RatioOpen this link in a new window
   by www.wildultrasound.com    
US Resources  
Calculation - Intravascular - Distributors - Breast - Vascular -
 
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 • B-Mode
 • A-Scan
 • Real-Time Mode
 • Oscillation
 • Ultrasound Imaging Procedures
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