In the acute encephalitis stage , The CT scan is a lowdensity with unclear boundaries, irregular shapes, and uneven density. Enhanced scan shows patchy, small nodular enhancement, or no enhancement . The lesion shows a low-signal area with unclear border on T1WI. The T2WI shows a flaky high-signal area, which is integrated with the surrounding edema area. The enhanced examination is generally not enhanced or slightly enhanced.
Imaging features
•On the T1WI, the abscess and its surrounding edema are low-signal. On the T2WI, the abscess and its surrounding edema are high signals, and the abscess wall is equal or low signal. After the enhancement, the abscess wall is significantly strengthened, showing a complete, thinwalled, uniform thickness ring intensification; •The abscess cavity shows high signal on DWI and low signal on apparent diffusion coefficient ( ADC)map.
Pathogenesis &Etiology
Brain abscesses are mostly caused by purulent bacteria. The most common pathogens are Staphylococcus, Pneumococci, Streptococcus, Escherichia coli and Proteus. Single pathogen infections are the most common, but there are also many mixed infections.
Pathology
The process of brain abscess usually consists of three stages. •Acute cerebritis stage •Suppurative stage •Capsule formation stage
Imaging features
Brain Abscess
Introduction
•Brain abscess is a kind of abscess cavity formed by the invasion of suppurative bacteria into the brain and the direct destruction of brain tissue. It is a serious intracranial infectious disease. •Brain abscess can occur at any age, with the most common in young adults.
CASE
Case1,Male, 47 years old, headache for two days
2018-2-13
2018-2-22
acute encephalitis stage
Pathogenesis &Etiology
Route of infection •adjacent tissue infection •blood-borne infection •Open craniocerebral injury •Cryptogenic infection
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clinical presentation
Imaging features
During the period of suppuration and capsule formation, CT plain scan shows low density in the center of the lesion and slightly high density in the abscess wall, and enhanced scan shows circular enhancement in the abscess wall.
•Symptoms of systemic infection (fever, chills, headache) •Symptoms and signs of intracranial hypertension (Headache, vomiting, optic papilla edema) •Symptoms and signs of localized neurological impairment(It is related to location, such as hemianopia, aphasia) •Brain abscess is easy to cause brain hernia and abscess rupture crisis, both of which can lead to rapid deterioration or even death.