Medical Ultrasound Imaging
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The term hyperechogenic or hyperechoic is used if there are many internal echoes. Hyperechoic tissues appear bright in ultrasound imaging. Tendons are hyperechoic because of the fibrillar pattern. Ligaments appear hyperechoic when the beam is perpendicular to the tissue. Peripheral nerves are hyperechoic relative to muscle.
Liver angiomas, tumor cells, blood vessels, fibrosis, and liver steatosis appear diffuse hyperechoic.
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Tissue-specific ultrasound contrast agents improve the image contrast resolution through differential uptake. The concentration of microbubble contrast agents within the vasculature, reticulo-endothelial, or lymphatic systems produces an effective passive targeting of these areas. Other contrast media concepts include targeted drug delivery via contrast microbubbles. Tissue-specific ultrasound contrast agents are injected intravenously and taken up by specific tissues or they adhere to specific targets such as venous thrombosis. These effects may require minutes to several hours to reach maximum effectiveness. By enhancing the acoustic differences between normal and diseased tissues, these tissue-specific agents improve the detectability of abnormalities. Some microbubbles accumulate in normal hepatic tissue; some are phagocytosed by Kupffer cells in the reticuloendothelial system and others may stay in the sinusoids. Liver tumors without normal Kupffer cells can be identified by the lack of the typical mosaic color pattern of the induced acoustic emission. The hepatic parenchymal phase, which may last from less than an hour to several days, depending on the specific contrast medium used, may be imaged by bubble-specific modes such as stimulated acoustic emission (color Doppler using high MI) or pulse inversion imaging.  Further Reading: News & More:
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Ultrasound technology with its advancements is vital for delivering high-quality patient care. Innovations including high-frequency ultrasound, 3D//4D imaging, contrast enhanced ultrasound, elastography, and point-of-care ultrasound, have expanded the capabilities of ultrasound imaging and improved diagnostic accuracy. B-Mode imaging, also known as brightness mode, is the fundamental technique in ultrasound imaging. It produces two-dimensional images based on the echoes received from tissues and organs. Understanding the principles of B-Mode imaging, such as gain adjustment, depth control, and image optimization, is crucial for obtaining diagnostically valuable images. M-Mode imaging, on the other hand, allows for the visualization of motion over time, enabling assessment of cardiac structures and function, as well as fetal heart rate. High-frequency ultrasound refers to the use of ultrasound waves with frequencies greater than 10 MHz. This technology enables improved resolution, allowing for detailed imaging of superficial structures like skin, tendons, and small organs. High-frequency ultrasound has found applications in dermatology, ophthalmology, and musculoskeletal imaging. Traditional 2D ultrasound has been augmented by the advent of 3D ultrasound technology. By acquiring multiple 2D images from different angles, this technique construct a volumetric representation of the imaged area. The addition of 4D ultrasound in real-time motion adds further value by capturing dynamic processes. Doppler imaging employs the Doppler effect to evaluate blood flow within vessels and assess hemodynamics. Color Doppler assigns color to different blood flow velocities, providing a visual representation of blood flow direction and speed. Spectral Doppler displays blood flow velocities as a waveform, allowing for detailed analysis of flow patterns, resistance, and stenosis. Contrast enhanced ultrasound employs microbubble contrast agents to enhance the visualization of blood flow and tissue perfusion. By injecting these agents intravenously, sonographers can differentiate between vascular structures and lesions. Elastography is a technique that measures tissue elasticity or stiffness. It assists in differentiating between normal and abnormal tissues, aiding in the diagnosis of various conditions such as liver fibrosis, breast lesions, and thyroid nodules. Fusion imaging combines ultrasound with other imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). By overlaying or merging ultrasound images with those obtained from other modalities, the user can precisely locate and characterize abnormalities, guide interventions, and improve diagnostic accuracy. Fusion imaging has proven particularly useful in areas such as interventional radiology, oncology, and urology. See also Equipment Preparation, Environmental Protection, Handheld Ultrasound, Portable Ultrasound and Ultrasound Accessories and Supplies. •
Ultrasound waves are created at harmonics of the delivered frequency.
Subharmonic imaging uses the harmonic oscillation of a system at a frequency that is a simple fraction of its fundamental frequency. The subharmonic response frequencies has half of the fundamental frequency.
The second subharmonic has a half fundamental frequency of one half the frequency, and so on.
See also Harmonic Imaging and Superharmonic Imaging. •
(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:
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Abdominal pain
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Gallbladder or kidneys stones
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Inflammation
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Detection of cancer and metastasis
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. Further Reading: Basics: News & More:
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[last update: 2023-11-06 01:42:00]