Presentation
Headaches
Patient Data
Multiple peripherally enhancing lesions with central profound restricted diffusion and surrounding vasogenic edema are noted. Also note the presence of a complete thin rim of T2 signal loss. No susceptibility artefact to suggest hemorrhage within these lesions. No evidence of ventriculitis.
Conclusion:
Multiple parenchymal cystic mass lesions with diffusion restriction contents are consistent with cerebral abscesses.
The patient had the posterior fossa abscess drained and the rest were medically treated.
Microbiology:
MICROSCOPY GRAM STAIN:
- Leukocytes +++
- Gram positive bacilli +
CULTURE:
- Nocardia farcinica ++
What follows are a summary of medical management of the remaining lesions, focusing on the changes in diffusion restriction.
D0 study (i.e. same as the complete study above, pre-op)
ADC 529 x 10-6 cm2/s
Day 3 post op.
ADC 600 x 10-6 cm2/s
Day 10 post surgery
ADC 794 x 10-6 cm2/s
Day 20 post op: the morphology of the abscesses remains very similar, as does the degree of edema. ADC have however normalized.
ADC 2,200 x 10-6 cm2/s
Combo image showing how unreliable T1 C+, T2 and FLAIR are at assessing medical response. Note how ADC values progressively increase with successful management.
Case Discussion
When assessing medical management of abscesses it is important to realize that morphology is not a great feature. Rather, measure ADC values which will normalize as treatment is effective.
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