Medical Ultrasound Imaging
Friday, 17 May 2024
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(PACS) A system used to communicate and archive medical imaging data, mostly images and associated textural data generated in a radiology department, and disseminated throughout the hospital. A PACS is usually based on the DICOM (Digital Imaging and Communications in Medicine) standard. The main components in the PACS are: acquisition devices where the images are acquired;
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short and longer term archives for storage of digital and textural data;
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a database and database management;
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diagnostic and review workstations;
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software to run the system;
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a communication network linking the system components;
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interfaces with other networks (hospital and radiological information systems).
Acquisition devices, which acquire their data in direct digital format, like a MRI system, are most easily integrated into a PACS. Short term archives need to have rapid access, such as provided by a RAID (redundant array of independent disks), whereas long term archives need not have such rapid access and can be consigned, e.g. to optical disks or a magnetic. High speed networks are necessary for rapid transmission of imaging data from the short term archive to the diagnostic workstations. Optical fibre, ATM (asynchronous transfer mode), fast or switched Ethernet, are examples of high speed transmission networks, whereas demographic textural data may be transmitted along conventional Ethernet. Sophisticated software is a major element in any hospital-wide PACS. The software concepts include: preloading or prefetching of historical images pertinent to current examinations, worklists and folders to subdivide the vast mass of data acquired in a PACS in a form, which is easy and practical to access, default display protocols whereby images are automatically displayed on workstation monitors in a prearranged clinically logical order and format, and protocols radiologists can rapidly report worklists of undictated examinations, using a minimum of computer manipulation. •
The international system for units. Le Systeme international d'Unites officially came into being in October 1960 and has been adopted by nearly all countries, though the amount of actual usage varies considerably. It is based upon 7 principal units: Length - meter (m) Mass - kilogram(kg) Time - second (s) Electric current - ampere (A) Temperature - Kelvin (K) Amount of substance - mole (mol) Luminous intensity - candela (cd) From these basic units many other units are derived and named. See also Ultrasound Physics. •
(TEE) Transesophageal echocardiography provides a superior view of cardiac anatomy compared with transthoracic echocardiography. TEE is performed by the introduction of a probe attached to a fiberoptic endoscope into the esophagus. Caused by the position close to the heart e.g., clot finding and the view of the mitral valve are improved. Indications:
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aortic atherosclerotic disease;
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aortic dissection;
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artificial mitral valves;
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clots inside the left atrium;
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cardiac infections;
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masses or clots in the heart.
The piezoelectric crystal creating the acoustic power is mounted on the gastroscope that must be swallowed by the patient. This endoscopic transducer is miniaturized to approximately the size of a fingernail. Usually the probe is in place for an average of 15 minutes, to numb the surface a topical anesthetic is sprayed into the throat, in addition a conscious sedation is recommended. See also Myocardial Contrast Echocardiography, Stress Echocardiogram, M-Mode Echocardiography, Contrast Enhanced Ultrasound and Vascular Ultrasound Contrast Agents. •
(TVS) The transvaginal sonography (transvaginal echography or endovaginal ultrasound), uses a small vaginal transducer (5-7.5 MHz) that is inserted into the vagina to depict the inner female organs (uterus, ovaries, vessels). As a general rule, ultrasound works better when the probe is close to the area being examined. Compared with a sonogram through the abdominal wall, the transvaginal technique produces a sharper image, not only because of the close proximity to the uterus, but also because the better signal to noise ratio of the used transducer. Indications:
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detection and delineation of pelvic masses;
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ectopic pregnancy;
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ovarian cysts or tumors;
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pelvic inflammatory disease;
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bladder and rectal tumors.
The advantage of transvaginal sonography is being able to get very close to the structures of the pelvis, and thus get better images and a more reliable diagnosis. See also Pelvic Ultrasound, Hysterosalpingo Contrast Sonography.  Further Reading: News & More:
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Ultrasound physics is based on the fact that periodic motion emitted of a vibrating object causes pressure waves. Ultrasonic waves are made of high pressure and low pressure (rarefactional pressure) pulses traveling through a medium. Properties of sound waves: The speed of ultrasound depends on the mass and spacing of the tissue molecules and the attracting force between the particles of the medium. Ultrasonic waves travels faster in dense materials and slower in compressible materials. Ultrasound is reflected at interfaces between tissues of different acoustic impedance e.g., soft tissue - air, bone - air, or soft tissue - bone. The sound waves are produced and received by the piezoelectric crystal of the transducer. The fast Fourier transformation converts the signal into a gray scale ultrasound picture. The ultrasonic transmission and absorption is dependend on: See also Sonographic Features, Doppler Effect and Thermal Effect. Result Pages : | Share This Page     Look Ups |
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[last update: 2023-11-06 01:42:00]