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Plain "Cerebral Abscess MRI Protocol"
MR spectroscopy : elevation of a succinate peak is relatively specific but not present in all abscesses ; high lactate, acetate, alanine, valine, leucine, and isoleucine levels peak may be present ; Cho / Crn and NAA peaks are reduced.Magnetic resonance (MR) spectroscopy may be helpful in the differential diagnosis of toxoplasmosis versus CNS lymphoma. CNS lymphoma generally shows a mild pattern of elevated lipid and lactate peaks, with a prominent choline peak with some other normal metabolites. In toxoplasmosis, there are elevated lipid and lactate peaks, while other normal brain metabolites are nearly absent.
Plain "Cerebral Abscess MRI Protocol"
- T1-Sagittal head
- T1 SE-Axial head
- FLAIR Axial head
- T2 FSE Axial head
- DWI/ADC
Post Contrast "Cerebral Abscess MRI Protocol"
- T1 SE-Axial post-gadolinium (This is essentially the same sequence as the pre-gadolinium scan, but can be performed with the addition of a flow compensation (FC) pulse to better delineate the cerebral vessels, and a magnetization transfer (MT) pulse to optimize enhancing lesion detection.)
- T1-coronal post-gadolinium head
- MR perfusion
- MR spectroscopy
Radiology notes:"Cerebral Abscess MRI Protocol"
MR perfusion : rCBV is reduced in the surrounding oedema c.f. to both normal white matter and tumour oedema seen in high grade gliomas .MR spectroscopy : elevation of a succinate peak is relatively specific but not present in all abscesses ; high lactate, acetate, alanine, valine, leucine, and isoleucine levels peak may be present ; Cho / Crn and NAA peaks are reduced.Magnetic resonance (MR) spectroscopy may be helpful in the differential diagnosis of toxoplasmosis versus CNS lymphoma. CNS lymphoma generally shows a mild pattern of elevated lipid and lactate peaks, with a prominent choline peak with some other normal metabolites. In toxoplasmosis, there are elevated lipid and lactate peaks, while other normal brain metabolites are nearly absent.
Diffusion-weighted MRI may be useful in differentiating abscess MRI features from necrotic tumor.
Early cerebritis: swollen, edematous, areas of necrosis, ill-define margins; nonspecific (tumor, infarct)
Late cerebritis: increased central necrosis, thick irregular contrast enhancement, high on FLAIR, T2, and DWI
Early capsule: within 2 weeks, walled off capsule, necrotic center, enhancing rim
Late capsule: more defined rim, multiloculated, capsule is low on T2, markedly high on DWI
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Brain Abscess MRI findings Classification
- Early cerebritis stage-The early cerebritis stage presents as an ill-defined subcortical hyperintense zone that can be noted on T2-weighted imaging. Contrast-enhanced T1-weighted studies demonstrate poorly delineated enhancing areas within the isointense to mildly hypointense edematous region.
- Late cerebritis stage-During the late cerebritis stage, the central necrotic area is hyperintense to brain tissue on proton-density and T2-weighted sequences. Peripheral edema is common. The rim enhances intensely following contrast administration. Satellite lesions may be demonstrated.
- Early and late capsule stages-During the early and late capsule stages, the collagenous abscess capsule is visible prior to contrast as a comparatively thin-walled, isointense to slightly hyperintense ring that becomes hypointense on T2-weighted MRIs.Diffusion-weighted imaging aids in depiction of specific features of a brain abscess. If a cerebral abscess ruptures into the ventricular system, diffusion-weighted images demonstrate specific patterns.Purulent material within the ventricle appears similar to that of the central abscess cavity, with a strongly hyperintense signal on diffusion-weighted images.
MRI Features in different Stages
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