Answer for CoW 02 October 2016
Brain abscess
Findings
Well defined intra-axial T2/FLAIR hyperintense lesion with hypointense rim and surrounding disproportionate edema noted in right parietal lobe measuring 2.8 x 2.6cm causing mass effect and squashing of ipsilateral lateral ventricle and mild midline shift of 6mm to left with subfalcine herniation. Lesion shows diffusion restriction. ARTERIAL SPIN LABELLING IMAGES show reduced blood flow within the lesion and perilesional region. Known case of old pulmonary Tuberculosis/ disseminated TB/ Tuberculoma. Features suggestive of cerebral abscess.
Discussion
Brain abscess is a potentially life threatening condition requiring rapid treatment, and prompt radiological identification. Fortunately MRI is usually able to convincingly make the diagnosis, distinguishing abscesses from other ring enhancing lesions. Four stages are recognized, which distinct pathological and radiological features: early cerebritis late cerebritis early capsule late capsule MRI is more sensitive and especially with the addition MRS and DWI far more specific for the diagnosis of cerebral abscesses. T1 central low intensity (hyperintense to CSF) peripheral low intensity (vasogenic oedema) ring enhancement ventriculitis may be present, in which case hydrocephalus will commonly also be seen T2/FLAIR central high intensity (hypointense to CSF, does not attenuate on FLAIR) peripheral high intensity (vasogenic oedema) the abscess capsule may be visible as a intermediate to slightly low signal thin rim 1 DWI/ADC high DWI signal is usually present centrally 11 represents true restricted diffusion (low signal on ADC, typically ~650 +/- 160 x 10-6 mm2/s 10) peripheral or patchy restricted diffusion may also be seen; this finding is however not as constant as one may think, with up to half of rim enhancing lesions demonstrating some restriction not proving to be abscesses 2 ADC values increase as treatment is successful even if cavity remains 9 SWI low intensity rim 9 complete in 75% smooth in 90% mostly overlaps with contrast enhancing rim dual rim sign: a hyperintense line located inside the low intensity rim 9 MR perfusion: rCBV is reduced in the surrounding oedema cf. to both normal white matter and tumour oedema seen in high grade gliomas 2 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
Please wait till next week.
Findings
Well defined intra-axial T2/FLAIR hyperintense lesion with hypointense rim and surrounding disproportionate edema noted in right parietal lobe measuring 2.8 x 2.6cm causing mass effect and squashing of ipsilateral lateral ventricle and mild midline shift of 6mm to left with subfalcine herniation. Lesion shows diffusion restriction. ARTERIAL SPIN LABELLING IMAGES show reduced blood flow within the lesion and perilesional region. Known case of old pulmonary Tuberculosis/ disseminated TB/ Tuberculoma. Features suggestive of cerebral abscess.
Discussion
Brain abscess is a potentially life threatening condition requiring rapid treatment, and prompt radiological identification. Fortunately MRI is usually able to convincingly make the diagnosis, distinguishing abscesses from other ring enhancing lesions. Four stages are recognized, which distinct pathological and radiological features: early cerebritis late cerebritis early capsule late capsule MRI is more sensitive and especially with the addition MRS and DWI far more specific for the diagnosis of cerebral abscesses. T1 central low intensity (hyperintense to CSF) peripheral low intensity (vasogenic oedema) ring enhancement ventriculitis may be present, in which case hydrocephalus will commonly also be seen T2/FLAIR central high intensity (hypointense to CSF, does not attenuate on FLAIR) peripheral high intensity (vasogenic oedema) the abscess capsule may be visible as a intermediate to slightly low signal thin rim 1 DWI/ADC high DWI signal is usually present centrally 11 represents true restricted diffusion (low signal on ADC, typically ~650 +/- 160 x 10-6 mm2/s 10) peripheral or patchy restricted diffusion may also be seen; this finding is however not as constant as one may think, with up to half of rim enhancing lesions demonstrating some restriction not proving to be abscesses 2 ADC values increase as treatment is successful even if cavity remains 9 SWI low intensity rim 9 complete in 75% smooth in 90% mostly overlaps with contrast enhancing rim dual rim sign: a hyperintense line located inside the low intensity rim 9 MR perfusion: rCBV is reduced in the surrounding oedema cf. to both normal white matter and tumour oedema seen in high grade gliomas 2 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
Please wait till next week.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!