Fig. 1

Brain abscesses imaging by MRI with contrast, CT with contrast and IOUS and operative specimens. White arrows point to the wall of the abscesses. Case a: Single brain abscess; enhanced wall, hypo-intense content and surrounded by hypo-intense edema in MRIT1 with contrast. Enhanced wall, hypo-dense content, and surrounded by hypo-dense edema in CT with contrast. Spontaneous enhanced wall, heterogeneous hypo-echoic content and surrounded by hyper-echoic edema in IOUS B-Mod. Thick and smooth wall of the operative specimen. Case b, c differ from (a) in the intraoperative specimen as the wall is thin, smooth, and friable. Case d: Two brain abscesses with same characters as (b, c) but less CT delineation of both abscesses especially the anterior one with time lapse less than 48 h between the three types of imaging modalities. Case e: Three abscesses with similar characters as (a) but rough specimen surface. The noted low resolution of ultrasound image can be explained by the use of low frequency 3 MHZ to reach far depth to delineate all of the lesions, but during resection we used step wise high frequencies 5–8 MHZ for superficial abscesses for better resolution, and then, the deepest one was also better delineated through the resection cavity by high frequencies