A Pediatric Radiology Textbook and Pediatric Radiology Digital Library
Pediatric Cerebritis and Pediatric Cerebral Abscess
Etiology: — Immunosuppression is major risk factor — Four routes of innoculation: Hematogenous, trauma, extension from adjacent infection, association with right to left shunts — Four stages of parenchymal infection: Early cerebritis, late cerebritis, early capsular, late capsular
Imaging US: Anechoic fluid collection with peripheral hyperemia in late phase
Imaging CT: — Insensitive to early phases — See subtle hypodensities scattered throughout brain
Imaging MRI Cerebritis: — Primary tool — Often clinically silent during early phase of less than 5 days — Typically imaged when secondary to symptomatic infections such as mastoiditis or subdural empyema — Restricted diffusion early finding — Heterogenous mild peripheral T2WI and SWI hypointensity — Peripheral enhancement mild or absent, with maturation peripheral enhancement becomes more extensive and discrete
Imaging MRI Abscess: — Central cavity – Marked diffusion restriction, T1 hypointense, T2 hyperintense, concentric rings sometimes seen — Capsule – T1 mildly hyperintense, T2 hypointense, susceptibility hypointense, smooth enhancement without nodularity — Peripheral vasogenic edema
Imaging MRI Abscess Evolution: — Early cerebritis 1-5 days: Focal but non-contained area of edema, early necrosis and inflammatory infiltration; polys and macrophages — Late cerebritis 6-12 days: Central area of coalescent necrosis (pus), pseudo-capsule – peripheral hypervascularity with extensive macrophages, no collagenous capsule — Acute abscess 13-28 days: Collagenous true capsule with deep region of macrophage infiltration surrounding central pus containing cavity — Chronic abscess greater than 28 days: Well formed three layer capsule dominated by collagen — Healing abscess 8-12 months
Imaging MRI Abscess Summary: — Central restricted diffusion — Peripheral T2 and SWI hypointensity — Mild peripheral T1 hyperintensity — Concentric rings in abscess cavity — Enhancing rim is not nodular
DDX of cerebral abscess: Metastases, fungal parasitic and granulomatous infection, demyelination
Complications: Delayed development, motor deficits, hemianopsia, hydrocephalus
Treatment: Cerebritis may be treated with antibiotics, abscess requires surgery
Clinical: Prior to antibiotics mortality was 50% but with antibiotics is 10%
Radiology Cases of Cerebritis
Radiology Cases of Cerebral Abscess
Radiology Cases of Cerebral Abscess Due to Mastoiditis
Axial CT with contrast of the brain with bone windows (left) shows opacification and destruction of the right mastoid air cells while axial CT with contrast of the brain with soft tissue windows (right) shows a large low density ring enhancing lesion in the right cerebral hemisphere that is causing midline shift to the left.
Radiology Cases of Cerebral Abscess Due to Maxillary Sinusitis
Axial T2 MRI of the brain (above left) shows a mass in the right front lobe with surrounding vasogenic edema. Axial (above right) and coronal (below right) T1 MRI with contrast shows the mass to have thin rim enhancement and the coronal image also shows left maxillary sinusitis. The mass is shown to demonstrate diffusion restriction on diffusion-weighted imaging (below left).
Radiology Cases of Cerebral Abscess Due to Infective Endocarditis
Coronal T1 MRI with contrast of the brain (above) shows multiple small enhancing lesions in the brain and one large ring enhancing lesion in the right hemisphere of the brain. Coronal CT with contrast of the abdomen (below) shows multiple peripheral low density wedge shaped lesions in the spleen and both kidneys.
Radiology Cases of Cerebral Abscess Due to Pulmonary Arteriovenous Malformation
Axial MRI with contrast of the brain (above) shows multiple ring enhancing lesions in the cerebrum. Axial CT with contrast of the chest (below left) shows multiple necrotic mediastinal lymph nodes. Coronal CT with contrast of the chest (below right) shows a lobulated lesion in the right lower lobe with feeding and draining vessels associated with it.
