Duplex ultrasonography (duplex scan) consists of two ultrasound modalities to study blood flow and the perivascular tissue. This includes B-mode / gray scale imaging used in combination with spectral Doppler / pulsed-wave Doppler.
The real-time visualization of the vessels and tissue by the B-mode component improves the PW Doppler positioning and the direction of blood flow can be inferred. The angle between the direction of the PW Doppler signal and the estimated direction of blood flow can be measured.
Duplex techniques are available on phased array, linear array, and mechanical scanners. A phased array probe is able to create nearly simultaneous images and flow information. A linear array transducer can also do this if the Doppler probe is attached separately to one end of the scanhead. A mechanical transducer freeze the image; the crystals must be static to produce a Doppler image. The first two transducers are therefore the best choice for Duplex.

See also Compound B-Mode, and Duplex Scanner.

Ultrasound is the ideal tool to examine children of all ages. It is fast, painless, uses no ionizing radiation, and does not require a baby to remain still for long periods. Real-time modes show movement of internal tissues and organs. Advanced ultrasound imaging techniques such as color Doppler, 4D ultrasound, harmonic imaging, and higher resolution, as well as the application of ultrasound contrast agents broaden the potential of ultrasound.
Pediatric [paediatric, Brit.] ultrasound can be used in all body regions and reduce the number of more invasive or radiating examinations that often additionally need sedation or intravenous iodinated contrast agents.

See also Fetal Ultrasound, Reflux Sonography, Ultrasound Safety, Abdominal Ultrasound and Pregnancy Ultrasound.

(AUS) Abdominal ultrasound, also known as abdominal sonography, is a medical imaging technique that focuses on the visualization and assessment of the abdominal organs. While 'abdominal ultrasound' is the commonly used term, there are alternative terms that can be used to refer to this imaging modality: (TAE) transabdominal echography, abdominal ultrasonography, sonogram, FAST (Focused Assessment with Sonography for Trauma).
Abdominal ultrasound imaging is an invaluable clinical tool for identifying the underlying cause of abdominal pain. An abdominal ultrasound examination encompasses a comprehensive evaluation of the liver, gallbladder, biliary tree, pancreas, spleen, kidneys, and abdominal blood vessels. It is a cost-effective, safe, and non-invasive medical imaging modality that is typically utilized as the initial diagnostic investigation.
Advanced ultrasound techniques, such as high-resolution ultrasound, endoscopic ultrasound, and contrast-enhanced Doppler, further enhance the detection of small lesions and provide detailed information for precise diagnosis.
To prepare for an abdominal ultrasound, it is recommended to have nothing to eat or drink for at least 8 hours, starting from midnight the night before the examination.

Indications:
FAST (Focused Assessment with Sonography for Trauma) is a rapid diagnostic test used for trauma patients. It sequentially evaluates the presence of free fluid in the pericardium (hemopericardium) and in four specific views of the abdomen. These views include the right upper quadrant (RUQ), left upper quadrant (LUQ), subcostal, and suprapubic views. They aid in identifying hemoperitoneum in patients with potential truncal injuries. The space between the liver and the right kidney (RUQ), known as Morison's pouch, is a location where intraperitoneal fluid can accumulate.
Emergency abdominal ultrasonography is indicated in cases of suspected aortic aneurysm, appendicitis, biliary and renal colic, as well as blunt or penetrating abdominal trauma. It plays a crucial role in the timely assessment and management of these conditions, providing critical information to guide appropriate treatment decisions.

See also Handheld Ultrasound, Pelvic Ultrasound, Pregnancy Ultrasound, Prostate Ultrasound, Interventional Ultrasound and Pediatric Ultrasound.

Doppler ultrasound is a medical imaging technique for calculating the relative velocity between two points by measuring the frequency shift of a sound wave transmitted from one point to the other, based on the Doppler effect. Continuous or pulsed Doppler is frequently used to examine cardiovascular blood flow. The combination of routine 2D-mode and Doppler ultrasound allows a complete evaluation of the heart's anatomy and function (including the fetal heart). See also Doppler Fluximetry in Pregnancy.
Doppler ultrasound depends on the fact that if a moving object reflects the ultrasound waves, the echo frequencies are changed. A higher frequency is created if the object is moving toward the probe//transducer and a lower frequency if it is moving away from it. How much the frequency is changed depends upon how fast the object is moving. Doppler ultrasound shows the different rates of blood flow in different colors on a monitor in real time.
The major Doppler parameters are the peak systolic velocity and the end-diastolic velocity. The peak systolic velocity ratio compensates the variability between different patients and instrumentations.

Different Doppler and duplex techniques:

Imagent® is an injectable suspension for intravenous administration during a sonogram. This diagnostic contrast agent for enhancement of ultrasound images contains perflexane lipid microspheres. Imagent® US is indicated in the assessment of heart function and perfusion, as well as the detection of tumors and blood flow abnormalities by using gray scale, color Doppler, and harmonic ultrasound imaging techniques.
During the course of its development, the brand name for this product has changed from Imagent to Imavist (between August 2000 and March 2002) back to 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.
Currently the production of Imagent® is discontinued.