A liver sonography is a diagnostic tool to image the liver and adjoining upper abdominal organs such as the gallbladder, spleen, and pancreas. Deeper structures such as liver and pancreas are imaged at a lower frequency 1-6 MHz with lower axial and lateral resolution but greater penetration. The diagnostic capabilities in this area can be limited by gas in the bowel scattering the sound waves.
The application of microbubbles may be useful for detection of liver lesions and for lesion characterization. Some microbubbles have a liver-specific post vascular phase where they appear to be taken up by the reticuloendothelial system (RES). Dynamic contrast enhanced scans in a similar way as with CT or MRI can be used to studying the arterial, venous and tissue phase.
After a bolus injection, early vascular enhancement is seen at around 30sec in arterialized lesions (e.g., hepatocellular carcinomas (HCC), focal nodular hyperplasia (FNH)). Later enhancement is typical of hemangiomas with gradually filling towards the center. In the late phase at around 90sec, HCCs appear as defects against the liver background. Most metastases are relatively hypovascular and so do not show much enhancement and are seen as signal voids in the different phases.
Either with an intermittent imaging technique or by continuous scanning in a nondestructive, low power mode, characteristic time patterns can be used to differentiate lesions.

See also Medical Imaging, B-Mode, High Intensity Focused Ultrasound, Ultrasound Safety and Contrast Medium.

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.

(CEUS) Contrast agents increase the reflection of ultrasonic energy, improve the signal to noise ratio and caused by that the detection of abnormal microvascular and macrovascular disorders. Contrast enhanced ultrasound is used in abdominal ultrasound (liver sonography) as well as in cerebrovascular examinations e.g., for an accurate grading of carotid stenosis. The used contrast agents are safe and well tolerated.

The quality of the enhancement depends on:
The additional use of ultrasound contrast agents (USCAs) may overcome typical limitations like poor contrast of B-mode imaging or limited sensitivity of Doppler techniques. The development of new ultrasound applications (e.g., blood flow imaging, perfusion quantification) depends also from the development of pulse sequences for bubble specific imaging. In addition, contrast enhanced ultrasound improves the monitoring of ultrasound guided interventions like RF thermal ablation.

See also Contrast Enhanced Doppler Imaging, Contrast Harmonic Imaging, Contrast Imaging Techniques and Contrast Pulse Sequencing.

(TRUS) Transrectal sonography (also called transrectal ultrasonography, transrectal echography (TRE), endorectal ultrasound (ERUS or EUS)) is an ultrasound procedure used to examine the prostate gland, the rectum or bladder.
A small, lubricated transducer placed into the rectum releases sound waves, which create echoes as they enter the region of interest. A computer creates a picture called a sonogram.
TRUS is commonly used for guidance during a prostate needle biopsy and may be used to deliver brachytherapy and monitor cancer treatment. Transrectal ultrasonography detects enlargement, tumors and other abnormalities of the prostate, rectal polyps, rectal cancer, perianal infection, and sphincter muscle injuries. TRUS is also performed on male patients with infertility to view the prostate and surrounding structures and on patients with suspected bladder conditions or disease to view the bladder.

See also Transurethral Sonography, Endoscopic Ultrasound, Pelvic Ultrasound, Rectal Probe, Biplane Probe, Endocavitary Echography and High Intensity Focused 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.