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The falciform ligament sign is a radiological sign observed on abdominal imaging in cases of pneumoperitoneum, where free intraperitoneal air outlines the falciform ligament. [1] This sign is considered a diagnostic indicator of free air within the abdominal cavity and is most commonly identified on computed tomography (CT) scans and less ...
A CT scan image showing a ruptured abdominal aortic aneurysm. CT Scan of 11 cm Wilms' tumor of right kidney in 13-month-old patient. Computed tomography of the abdomen and pelvis is an application of computed tomography (CT) and is a sensitive method for diagnosis of abdominal diseases. It is used frequently to determine stage of cancer and to ...
CT scanning can perform a virtual colonoscopy with greater accuracy and less discomfort for the patient than a traditional colonoscopy. [143] [144] Virtual colonography is far more accurate than a barium enema for detection of tumors and uses a lower radiation dose. [145] CT is a moderate-to-high radiation diagnostic technique.
A set of many such projections under different angles organized in 2D is called a sinogram (see Fig. 3). In X-ray CT, the line integral represents the total attenuation of the beam of X-rays as it travels in a straight line through the object. As mentioned above, the resulting image is a 2D (or 3D) model of the attenuation coefficient.
The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature is defined as 0 Hounsfield units (HU), while the radiodensity of air at STP is defined as −1000 HU.
High attenuation crescent sign or hyperdense crescent sign is a radiologic sign indicating impending aortic rupture. [1] [2] It is seen as a curvilinear area paralleling the vessel wall of the aorta. [3] The hyperdense area is due to intramural or mural thrombus haemorrhage.
Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, images are created to look for blockages, aneurysms (dilations of walls), dissections (tearing of walls ...
High-resolution CT image showing ground-glass opacities in the periphery of both lungs in a patient with COVID-19 (red arrows). The adjacent normal lung tissue with lower attenuation appears as darker areas. Ground-glass opacity (GGO) is a finding seen on chest x-ray (radiograph) or computed tomography (CT) imaging of the lungs.