Medical Ultrasound Imaging
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Ultrasound Equipment
The ultrasound equipment includes the ultrasound machine, the coaxial cable, the transducer assembly, different modalities to print out and store the ultrasound pictures, ultrasound gel, and a couch for the patients.
Often, the ultrasound system is connected with the internal radiology information system which allows the takeover of patient data, and a picture archiving and communication system to store images.

See also Ultrasound System Performance.
Endoscopic Ultrasound
(EUS) Endoscopic ultrasound uses a small probe that is inserted in the rectum either through a proctoscope or by itself. During the test biopsies of any suspicious areas are possible. The usual necessary preparation is an enema to empty the rectum. Endoscopic ultrasound provides additional information about rectal polyps, rectal cancer, perianal infection, and sphincter muscle injuries and improves the selection of patients for local excision.
Transrectal echography using a high-frequency transducer is a well established method for preoperative rectal carcinoma assessment.
Endoscopic scanning is limited by the ultrasound physics (depth and axial resolution) of the endocavitary probe. Therefore, the combination of endoscopic and transcutaneous ultrasound is most favorable.
History of Ultrasound
The earliest introduction of vascular ultrasound contrast agents (USCA) was by Gramiak and Shah in 1968, when they injected agitated saline into the ascending aorta and cardiac chambers during echocardiographic to opacify the left heart chamber. Strong echoes were produced within the heart, due to the acoustic mismatch between free air microbubbles in the saline and the surrounding blood.
In 1880 the Curie brothers discovered the piezoelectric effect in quartz. Converse piezoelectricity was mathematically deduced from fundamental thermodynamic principles by Lippmann in 1881.
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.
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.
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.
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.
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.
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.
In the 70's gray scale imaging became available and with progress of computer technique ultrasonic imaging gets better and faster.
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.
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.
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.

Ultrasound Technology
Ultrasound technology with its advancements is vital for delivering high-quality patient care. Innovations including high-frequency ultrasound, 3D//4D imaging, contrast enhanced ultrasound, elastography, and point-of-care ultrasound, have expanded the capabilities of ultrasound imaging and improved diagnostic accuracy.
B-Mode imaging, also known as brightness mode, is the fundamental technique in ultrasound imaging. It produces two-dimensional images based on the echoes received from tissues and organs. Understanding the principles of B-Mode imaging, such as gain adjustment, depth control, and image optimization, is crucial for obtaining diagnostically valuable images. M-Mode imaging, on the other hand, allows for the visualization of motion over time, enabling assessment of cardiac structures and function, as well as fetal heart rate.
High-frequency ultrasound refers to the use of ultrasound waves with frequencies greater than 10 MHz. This technology enables improved resolution, allowing for detailed imaging of superficial structures like skin, tendons, and small organs. High-frequency ultrasound has found applications in dermatology, ophthalmology, and musculoskeletal imaging.
Traditional 2D ultrasound has been augmented by the advent of 3D ultrasound technology. By acquiring multiple 2D images from different angles, this technique construct a volumetric representation of the imaged area. The addition of 4D ultrasound in real-time motion adds further value by capturing dynamic processes.
Doppler imaging employs the Doppler effect to evaluate blood flow within vessels and assess hemodynamics. Color Doppler assigns color to different blood flow velocities, providing a visual representation of blood flow direction and speed. Spectral Doppler displays blood flow velocities as a waveform, allowing for detailed analysis of flow patterns, resistance, and stenosis.
Contrast enhanced ultrasound employs microbubble contrast agents to enhance the visualization of blood flow and tissue perfusion. By injecting these agents intravenously, sonographers can differentiate between vascular structures and lesions. Elastography is a technique that measures tissue elasticity or stiffness. It assists in differentiating between normal and abnormal tissues, aiding in the diagnosis of various conditions such as liver fibrosis, breast lesions, and thyroid nodules.
Fusion imaging combines ultrasound with other imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). By overlaying or merging ultrasound images with those obtained from other modalities, the user can precisely locate and characterize abnormalities, guide interventions, and improve diagnostic accuracy. Fusion imaging has proven particularly useful in areas such as interventional radiology, oncology, and urology.
See also Equipment Preparation, Environmental Protection, Handheld Ultrasound, Portable Ultrasound and Ultrasound Accessories and Supplies.
Veterinary Ultrasound
Conventional, CT and MR imaging technologies are limited in their availability, to depict soft tissue, or to show dynamic activity, like cardiac muscle contractility and blood flow. Easy applicability, real-time sonography and biopsy facilitation are important advantages in veterinarian medicine. Veterinary ultrasound has a very high sensitivity to show the composition of soft tissues, but the low specificity is a disadvantage. High ultrasound system performance includes Doppler techniques, contrast enhanced ultrasound, 3D ultrasound, and tissue harmonic imaging to improve resolution.
Technical and physical requirements of veterinary ultrasound are the same as in human ultrasonography. The higher the sound frequency, the better the possible resolution, but the poorer the tissue penetration. Image quality is depended of the ultrasound equipment. For example, a 10 MHz transducer is excellent for imaging of superficial structures; a 3.5 or 5.0 megahertz transducer allows sufficient penetration to see inner structures like the liver or the heart. In addition, the preparation and performing of the examination is similar to that of humans. The sound beam penetrates soft tissue and fat well, but gas and bone impede the ultrasonic power. Fluid filled organs like the bladder are often used as an acoustic window, and an ultrasound gel is used to conduct the sound beam.
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