CT and MR findings of brain abscess: Focus on thickness and signal intensity of abscess wall

To purpose of this study is evaluate the CT and MR findings of brain abscess with emphasis on the thickness and signal intensity of abscess wall. Twenty CT scans and seven MR studied of 23 patients with brain abscess (27 abscess) were retrospectively reviewed with respect to thickness and signal intensity of abscess wall, shape and size of abscess, etc. Thickness of abscess wall was measured in the greatest abscess diameter on the CT scans and MR images obtained after intravenous administration of contrast material. Enhancing abscess wall was 2mm-6mm (average 3mm) thick. The abscess wall was uniform in thickness in 14 cases (52%), thinner in the medial wall than lateral wall in 8 cases (30%), and thicker in the medial wall than lateral wall in 5 cases (18%). Signal intensity of abscess wall was isointense relative to gray matter on T1-weighted MR images and hypointense on both portion- and T2-weighted MR images in 7 out of 8 lesion (88%). The inner margin of the abscess wall was smooth in 14 (52%) and irregular in 13 lesions (48%). The outer margin was smooth in 15 (55%) and irregular in 12 lesion (45%). The size of the abscesses was variable, ranging from 1cm to 6cm in diameter. They were round (16 cases), elliptical (6 cases), or multilobulated (5 cases) in shape. Satellite or daughter abscesses were found in 5 patients. Abscess wall showed variable thickness in the medial and lateral walls with no specific findings. Other CT and MR findings were also nonspecific, although hypointensity of abscess wall on T2-weighted MR images may be helpful in diagnosis of brain abscess