A fatty falx cerebri is a common finding, seen (according to one study) 7.3% of patients, and is explained by fat being a normal feature of the extradural neural axis compartment located between the two visceral layers of the falx.
A fatty falx is an incidental finding and should not be mistaken for:
- ruptured intracranial dermoid: multiple droplets of fat in the subarachnoid space
- intracranial lipoma: frequently inter-hemispheric and associated agenesis of the corpus callosum
- osseous metaplasia of the falx cerebri: fat within the medullary space of an ossified falx (also common)
- pneumocephalus: ROI should be no lower than -120HU (beware volume averaging)
- 1. Chen SS, Shao KN, Chiang JH, Chang CY, Lao CB, Lirng JF, Teng MM. Fat in the cerebral falx. (2000) Zhonghua yi xue za zhi = Chinese medical journal; Free China ed. 63 (11): 804-8. Pubmed