(US) Also called echography, sonography, ultrasonography, echotomography, ultrasonic tomography.
Diagnostic imaging plays a vital role in modern healthcare, allowing medical professionals to visualize internal structures of the body and assist in the diagnosis and treatment of various conditions. Two terms that are commonly used interchangeably but possess distinct meanings in the field of medical imaging are 'ultrasound' and 'sonography.'
Ultrasound is the imaging technique that utilizes sound waves to create real-time images, while sonography encompasses the entire process of performing ultrasound examinations and interpreting the obtained images. Ultrasonography is a synonymous term for sonography, emphasizing the use of ultrasound technology in diagnostic imaging. A sonogram, on the other hand, refers to the resulting image produced during an ultrasound examination.
Ultrasonic waves, generated by a quartz crystal, cause mechanical perturbation of an elastic medium, resulting in rarefaction and compression of the medium particles. These waves are reflected at the interfaces between different tissues due to differences in their mechanical properties. The transmission and reflection of these high-frequency waves are displayed with different types of ultrasound modes.
By utilizing the speed of wave propagation in tissues, the time of reflection information can be converted into distance of reflection information. The use of higher frequencies in medical ultrasound imaging yields better image resolution. However, higher frequencies also lead to increased absorption of the sound beam by the medium, limiting its penetration depth. For instance, higher frequencies (e.g., 7.5 MHz) are employed to provide detailed imaging of superficial organs like the thyroid gland and breast, while lower frequencies (e.g., 3.5 MHz) are used for abdominal examinations.

Ultrasound in medical imaging offers several advantages including:

Diagnostic ultrasound imaging is generally considered safe, with no adverse effects. As medical ultrasound is extensively used in pregnancy and pediatric imaging, it is crucial for practitioners to ensure its safe usage. Ultrasound can cause mechanical and thermal effects in tissue, which are amplified with increased output power. Consequently, guidelines for the safe use of ultrasound have been issued to address the growing use of color flow imaging, pulsed spectral Doppler, and higher demands on B-mode imaging. Furthermore, recent ultrasound safety regulations have shifted more responsibility to the operator to ensure the safe use of ultrasound.

See also Skinline, Pregnancy Ultrasound, Obstetric and Gynecologic Ultrasound, Musculoskeletal and Joint Ultrasound, Ultrasound Elastography and Prostate Ultrasound.

Ultrasound imaging is excellent for diagnosing cysts and other fluids in soft tissue. For ultrasound imaging or ultrasonography, different modes are used to examine the arterial/venous system, heart, pancreas, urinary system, ovaries, spinal cord, joints and more.
Power levels, frequencies used, amplification, and beamforming determine the clarity of the image. These things are controlled by the sonographer, interacting with the properties of the ultrasound machine.

Various imaging modes:

Ultrasound imaging procedures are widely used in medicine. It is possible to perform diagnostic or therapeutic procedures with the guidance of ultrasonography (interventional ultrasound biopsies or drainage of fluid collections). Sonography or ultrasound scanning involves the application of an ultrasound transducer used to transmit high frequency sound waves, which bounce off internal structures to produce an image that can be displayed and recorded.
Ultrasound imaging procedures include for example:

See also Imagent®.
June 19, 2003
Alliance Pharmaceutical Corporation and Photogen Technologies, Inc. announced that they have closed the previously announced transaction whereby Photogen has acquired all of the assets of Alliance related to medical imaging, including all manufacturing and marketing rights to Imagent (formerly Imavist). Terms of the transaction were not disclosed.

June 03, 2002
Alliance Pharmaceutical Corp. announced that its ultrasound imaging agent, Imagent (perflexane lipid microspheres), has been approved for marketing by the U.S. Food and Drug Administration. The product will be marketed by Alliance in partnership with Cardinal Health, Inc., a provider of products and services to the healthcare industry, and inChord Communications, Inc., an independent healthcare communications company.

March 01, 2002
'Alliance Pharmaceutical Corp. announced that it has entered into a partnership with Bayer Schering Pharma AG, Germany and Cardinal Health Inc. for the marketing of Imavist (perflexane lipid microspheres), an ultrasound contrast agent. Schering licensed worldwide marketing rights for Imavist from Alliance in September 1997. The companies have agreed to modify this agreement to allow Alliance to increase its participation in the marketing of the product. Under the terms of the modified agreement, Alliance will have exclusive marketing rights to Imavist for cardiology indications in the U.S. for five years, and Schering will receive a royalty on product sales. Schering retains marketing rights for other indications in the U.S. and all indications in the rest of the world, subject to Alliance's option to obtain additional indications and territories. Under certain circumstances, Schering would co-market the product at the end of five years. Concurrently, Alliance has entered into a five-year exclusive agreement with Cardinal Health Inc., a provider of products and services to the health-care industry, to assist in the marketing of Imavist.'

October 08, 2001
'Alliance Pharmaceutical Corp. announced a clinical study to take place at Thomas Jefferson University Hospital, Philadelphia, using Alliance's Imavist (AF0150) contrast agent with ultrasound imaging to improve detection of prostate cancer. The study, which will involve 300 adult men with suspected prostate cancer, is being funded by the U.S. Department of Defense under a competitive grant awarded to Thomas Jefferson University for investigators at Jefferson's Prostate Center. Imavist is being developed jointly by Alliance and Bayer Schering Pharma AG Germany, and is awaiting final approval from the U.S. Food and Drug Administration.'

August 21, 2000
Alliance Pharmaceutical Corp. announced that it has received a letter from the U.S. Food and Drug Administration (FDA) stating that the FDA has completed its review of the New Drug Application (NDA) for Imagent (AF0150), and found it to be approvable. Imagent, an ultrasound contrast agent, is being developed jointly by Alliance and Bayer Schering Pharma AG, Germany

Notes:
The manufacturer is pursuing additional radiology indications such as ultrasound imaging of the prostate and liver, and clinical trials are currently being conducted to evaluate Imagent in conjunction with ultrasound imaging for use in the detection of prostate cancer. During the course of its development, the brand name for this product has changed from Imagent to Imavist back to Imagent. Initially reported on by the manufacturer as Imagent and then, between August 2000 and March 2002, as 'Imavist (formerly Imagent).' The manufacturer's 06/03/02 press release announcing FDA approval refers to the product as 'Imagent (formerly Imavist),' and the approval notice and monograph posted at the FDA site refers to the product as Imagent. Jointly developed by Alliance Pharmaceutical Corp and Bayer Schering Pharma AG, (Germany). Source: PR Newswire - 10/10/96, 03/31/98, 10/13/99, 03/13/01, 10/08/01; FDA approvals - 05/31/02; Alliance Pharmaceutical press release - 06/03/02.

Interventional ultrasound, also known as ultrasonography, encompasses a range of invasive or surgical procedures guided by ultrasound imaging. While its widest application lies in intravascular ultrasound imaging for measuring atherosclerotic plaque, it has proven valuable in various medical fields.
In urology, ultrasound-guided interventions are employed for treatments like high intensity focused ultrasound (HIFU) in prostate conditions. The precise imaging provided by ultrasound aids in targeting the affected area and delivering therapeutic energy effectively.
In intraabdominal conditions, endoscopic ultrasound is frequently utilized. This technique combines ultrasound imaging with an endoscope to visualize and evaluate structures within the gastrointestinal tract, allowing for precise diagnoses and targeted interventions.
Ultrasound-guided procedures play a significant role in several medical specialties, including liver sonography, obstetric and gynecologic ultrasound, and thyroid ultrasound. These procedures involve interventions such as RF thermal ablation or biopsies, which are guided by real-time ultrasound imaging.
For instance, in liver sonography, ultrasound guidance is crucial for performing biopsies or RF thermal ablation, a technique used to treat liver tumors by delivering localized heat to destroy the abnormal tissue. The real-time imaging allows for precise needle placement and monitoring during the procedure.
In obstetric and gynecologic ultrasound, ultrasound-guided procedures, such as biopsies, can be performed to obtain tissue samples for diagnostic purposes. Additionally, ultrasound guidance is valuable during interventions like amniocentesis or fetal blood sampling, enabling accurate and safe procedures.
Thyroid ultrasound procedures often involve ultrasound-guided fine-needle aspiration biopsy (FNAB), which allows for the sampling of thyroid nodules for cytological examination. The ultrasound image helps guide the needle into the targeted area, ensuring accurate sampling and minimizing potential complications.
Overall, ultrasound-guided interventions provide minimally invasive and precise approaches to diagnosis and treatment. The real-time imaging capabilities of ultrasound contribute to enhanced accuracy, safety, and patient outcomes in procedures like biopsies, injections, and drainage.

See also Transurethral Sonography, Endocavitary Echography, and B-Mode Acquisition and Targeting.