Ultrasound Scanning

Ultrasound scanning/ultrasonography, also referred to as sonography, is a medical diagnostic technique that employs ultrasound imaging for muscle and organ visualisation.

Through the use of ultrasound scans medical practitioners are able to see internal muscle and organ structure and size, which aid in the identification of lesion and pathology presence.

A more well-known diagnostic ultrasound variation used in pregnancy is obstetric sonography, operating at an energy frequency range of between 2 and 15 megahertz (MHz). Ultrasonic energy frequency is adjusted depending on the use, with lower frequencies for greater internal imaging capacity.

Although imaging resolutions may be less at lower ultrasound frequencies, greater physical depth is achieved. Ultrasound techniques may be used for a range of diagnostic and medical procedures.

Ultrasound Scanning for Diagnostic Purposes

Sonographers perform ultrasound scans for diagnostic purposes such as biopsies and for collecting fluids. Working within a medical team alongside sonologists, the sonographer completes the diagnostic procedures whilst the sonologist reports on the ultrasonic images received.

The ultrasonic diagnostic procedures involve the sonographer placing a transducer or "hand-held probe" over the part of the patient's body being assessed. The probe is moved over the patient's skin using a water-based gel. As the probe moves ultrasound images of internal soft tissues, organs and muscles are visible on a monitor screen.

A higher frequency range of between 7 and 15 MHz are used to see neonatal brain images and images of breasts, testes, muscles and tendons. Lower MHz ranges from 1 to 6 MHz are used to image and view the kidney and liver organs.

Ultrasound scanning features in a wide spectrum of medical applications, including:

• Musculoskeletal muscles, tendons and nerves
• Veins or vascular and arteries
• Intravascular to guide fine needle and fluid aspiration and injections
• Cardiology or echocardiography
• Gastroenterology
• Endocrinology
• Gynaecology
• Urology
• Obstetrics
• Ophthalmology
• Contrast-enhanced and Intervention

Ultrasound is used for diagnosis and treatment within these medical specialities and sub-specialities, such as echocardiography. Ultrasound machines are customised with special features depending on their use and medical purpose.

Where an obstetric ultrasound is needed to monitor the development of a foetus within a pregnant mother, a pelvic ultrasound may be used to view internal organs such as the urinary bladder, uterus and ovaries in women and prostate in men, located within the area of the pelvis.

The application of ultrasound scans may be done externally or internally. For example, a pelvic scan may be applied internally within a woman through transvaginal application and transrectally for men.

With ultrasound scans on the abdominal organs, such as the liver, kidneys, bile ducts, gall bladder, spleen, and pancreas, gas present in the bowel may cause abnormal readings and highlight a potential limitation in the diagnostic procedure.

Therapeutic Purposes

When used as treatment, higher ultrasound energy frequencies are applied or focused for effective recovery or application. Ultrasound is used as a treatment in a range of dental and medical fields, including:

• Professional dental teeth cleaning and scaling.
• Heating of biological tissue for cancer.
• Heating of soft tissue such as tendons and muscles for occupational and physical therapy.
• Ultrasound treatment or phacoemulsification for eye cataracts.
• Focused ultrasound frequency for kidney stone disintegration (lithotripsy).
• Localised frequency and heat treatment of cysts and tumours.

The manner and intensity in which ultrasound frequency is used will differ. In high intensity focused ultrasound (HIFU) or focused ultrasound surgery (FUS), which are used in the treatment of benign and malignant tumours or cancer, ultrasound energy may be higher and frequency lower to achieve treatment success.

Other diagnostic techniques, such as magnetic resonance imaging (MRI), may be used alongside ultrasound techniques to guide accuracy and effectiveness of treatment.