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The dense MCA sign is caused by a fresh thrombus or embolus occluding the lumen of the middle cerebral artery. A thrombus with a high concentration of red blood cells and fibrin has increased density relative to normal flowing blood, leading to its hyperattenuating appearance on a non-contrast CT scan.
An abscess and a THAD (white arrow) on a contrast CT in native, arterial, portal and delayed phase. [1] [predatory publisher]Transient hepatic attenuation differences (THAD) are areas of enhancement during the arterial phase of contrast CT of the liver.
Identification of the dense artery sign is often based on subjective interpretation and false positives may occur. One study aiming to define criteria for the sign determined that measuring Hounsfield units on the CT scan could differentiate between the dense MCA sign associated with ischemic stroke and that caused by false positives. [8]
Unenhanced CT or MRI usually does not show the difference in intensity between the focal nodular hyperplasia and surrounding liver except when there is marked liver steatosis that reduces the attenuation of the liver, causing focal nodular hyperplasia to be hyperattenuating when compared with the surrounding liver.
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]
Meaning h: hr / hours H: histamine or its receptors (if with subscripts) hemagglutinin: H x: history: HA ; H/A hypertonia arterialis headache calcium hydroxyapatite HAA: hepatitis-associated antigen or #History As Above HAART: highly active antiretroviral therapy HACA: human anti-chimeric antibody: HACE: High-altitude cerebral edema: HACEK
MRI scans showing hyperintensities. A hyperintensity or T2 hyperintensity is an area of high intensity on types of magnetic resonance imaging (MRI) scans of the brain of a human or of another mammal that reflect lesions produced largely by demyelination and axonal loss.
This can mean that systolic pressure is abnormally high, but diastolic pressure may be normal or low, a condition termed isolated systolic hypertension. [80] The high pulse pressure in elderly people with hypertension or isolated systolic hypertension is explained by increased arterial stiffness , which typically accompanies aging and may be ...