Visualization of gadolinium transport across the blood-brain barrier along perivascular clearance pathways.

OBJECTIVE

We investigated the transport of gadolinium-based contrast agent (GBCA) across the blood-brain barrier (BBB) along the perivascular spaces as part of the glymphatic drainage in patients with iatrogenic BBB disruption following digital subtraction angiography (DSA).

MATERIALS AND

METHODS

A retrospective analysis was conducted on patients who underwent DSA for diagnosis and/or treatment of intracranial aneurysms and received a 3-T magnetic resonance imaging (MRI) within the following day. Exclusion criteria included states with a suggested impairment of BBB integrity, such as neurodegenerative diseases or suspected glymphatic impairment. BBB disruption was assessed using a pre- and post-contrast three-dimensional T1-weighted volume-isotropic turbo spin-echo sequence. Patterns of GBCA distributions were described. The localization of GBCA-extravasation was correlated with perivascular spaces visualized on the coregistered T2-weighted sequences. Fisher's exact test and logistic regression were used.

RESULTS

Out of 43 patients, 30 (69.8%) exhibited visible BBB disruption. BBB disruption was significantly more often observed after therapeutic DSA (p = 0.004). GBCA-enhancement patterns indicated a localized pial enhancement in 96.7% of affected patients, with additional parenchymal enhancement along the perivascular spaces in 56.7%. Enhancement was predominantly located in the downstream territories of probed vessels, suggesting a potential association with glymphatic transport. An illustrative case with serial MRI examinations is presented, demonstrating time-dependent GBCA-enhancement patterns.

CONCLUSION

The study provides in vivo evidence of GBCA transport patterns following iatrogenic BBB disruption, which may correspond to parts of the proposed glymphatic pathways. Our results indicate a sequential progression of contrast enhancement, initially manifesting at the brain surface and subsequently extending along perivascular spaces to the subarachnoid space.

RELEVANCE STATEMENT: Understanding BBB disruption and glymphatic transport with MRI imaging methods may improve neurovascular disease management.

KEY POINTS: BBB disruption post-DSA may facilitate GBCA transport via glymphatic pathways, offering novel and hypothesis-generating insights into brain clearance mechanisms. GBCA enhancement followed a chronological and spatial pattern, suggesting an organized cerebrospinal-interstitial exchange system relevant for brain clearance. Findings highlight potential implications for BBB integrity in neurovascular health with prospective implications for diagnostic imaging.