Prevalence of intra-osseous veins and venous lakes in the posterior skull base on 3T MRI

Background: Intra-osseous vessels are normal anatomic structures in the calvarium and skull base. On imaging, these structures—particularly venous lakes—can mimic pathologic abnormalities. This study sought to assess the prevalence of veins and lakes in the skull base on MRI. Materials and Methods: A retrospective review was completed of consecutive patients that underwent contrast-enhanced MRI imaging of the internal auditory canals. The clivus, jugular tubercles, and basio-occiput were assessed for the presence of both intra-osseous veins (serpentine and/or branching vessels) and venous lakes (well-circumscribed round or oval enhancing structures). Vessels in the adjacent synchondroses major foramina were excluded. Three board-certified neuroradiologists performed independent blinded reviews, with discrepancies agreed upon by consensus. Results: 96 patients were included in this cohort (58.3% female). Mean age was 58.4 years (range = 19–85). At least one intra-osseous vessel was identified in 71 (74.0%) patients. 67 (70.0%) had at least one skull base vein, and 14 (14.6%) had at least one venous lake. Both vessel subtypes were observed in 8.3% of patients. Vessels were more commonly observed in women, though this did not reach statistical threshold (p = 0.56). Age was not associated with the presence of vessels (0.59) or vessel location (p values ranged from 0.44–0.84). Conclusions: Intra-osseous skull base veins and venous lakes are relatively common findings on MRI. Both vascular structures should be considered normal anatomy, and care should be taken to not confuse these for pathologic entities.