What is heterogeneous attenuation?
Heterogeneous refers to a structure with dissimilar components or elements, appearing irregular or variegated. For example, a dermoid cyst has heterogeneous attenuation on CT. It is the antonym for homogeneous, meaning a structure with similar components. Heterogenous refers to a structure having a foreign origin.
What does attenuation in the lungs mean?
A decrease in lung attenuation can be observed when this balance is disturbed by either an abnormal increase in the amount of air, an abnormal decrease in the intravascular blood volume with, as a result, a smaller calibre of the small vessels, and in case of loss of (interstitial) lung tissue.
What causes lung attenuation?
We have observed three categories of disease known to cause a CT mosaic pattern of lung attenuation: small-airway disease, vascular lung disease, and infiltrative disease. Diseases from each of these categories can cause similar patterns of mosaic lung attenuation on CT scans.
What is lung heterogeneity?
Heterogeneity is an intrinsic property of the lungs. Structurally, it is evident in the complex branching of the airways and the spatial distribution of tissue throughout the lung.
What does it mean when a disease is heterogeneous?
A genetic or allelic heterogeneous condition is one where the same disease or condition can be caused, or contributed to, by varying different genes or alleles. In clinical trials and statistics the concepts of homogeneous and heterogeneous populations is important.
What is COPD prognosis?
COPD is a disease with an indeterminate course and variable prognosis. Its prognosis depends on several factors including genetic predisposition, environmental exposures, comorbidities and, to a lesser degree, acute exacerbations.
What does low attenuation on CT mean?
Tissues like air and water have little attenuation and are displayed as low densities (dark), whereas bone has high attenuation and is displayed as high density (bright) on CT. Among pathologic conditions, high density lesions are often seen with freshly clotted blood, hyperemia and with the use of contrast.
What is attenuation on CT?
Terminology. The CT attenuation value is defined as the radiodensity of each material and is expressed in HUs, in which the radiodensity of distilled water at the standard pressure and temperature was defined as 0 HU, whereas that of air was defined as -1000 HU.
What is abnormal attenuation?
High-attenuation pulmonary abnormalities can result from the deposition of calcium or, less commonly, other high-attenuation material such as talc, amiodarone, iron, tin, mercury and barium sulphate.
What are heterogeneous opacities?
Heterogeneous lungs can be caused by varying regional aeration, varying regional perfusion, and ground glass opacities (GGO) representing airspace or interstitial pathology.
Is low attenuation cancerous?
After non-contrast low-dose screening CT reveals a low attenuation lesion, “the radiologist calls it a probable cyst based on low density, and it is never worked up. By our data it could be a renal cancer.” In the study, low unenhanced median attenuation was defined as 20 or fewer HU.
What does attenuation mean in a CT scan?
What does attenuation mean medically?
Weakened or thinned. Attenuated strains of disease-causing bacteria and viruses are often used as vaccines. The weakened strains are used as vaccines because they stimulate a protective immune response while causing no disease or only mild disease in the person receiving the vaccine.
What is the mosaic pattern of lung attenuation?
The terms “mosaic perfusion” or “mosaic oligemia” have also been used to describe this heterogeneous pattern of lung attenuation. We believe that the term “mosaic pattern of lung attenuation” is preferable when describing areas of variable lung attenuation because the term “mosaic perfusion” implies pulmonary vascular pathology.
What causes lung attenuation on CT scan?
Mosaic pattern of lung attenuation on CT scans: frequency among patients with pulmonary artery hypertension of different causes A mosaic pattern of lung attenuation can be seen on CT scans in patients with PAH due to vascular disease, cardiac disease, or lung disease.
What is mosaic attenuation on CT scan?
Mosaic attenuation is a descriptive term used in describing a patchwork of regions of differing pulmonary attenuation on CT imaging. It is a non-specific finding, although is associated with the following: parenchymal disease: most common cause of mosaic attenuation.
What causes attenuation in mosaic perfusion?
parenchymal disease: considered most common cause of mosaic attenuation; high attenuation regions are abnormal and represent ground-glass opacity The term is best used where the differentiation between mosaic perfusion, mosaic oligaemia, and ground-glass opacity cannot be confidently made.