Introduction Liquid embolic agents (LEAs) such as cryanoacrylates or ethylene vinyl alcohol (EVOH) may be advantageous for middle meningeal artery embolization (MMAE) treatment of chronic subdural hematomas (cSDH) because they are radiopaque during fluoroscopy, can penetrate the microvasculature of the subdural membranes, allow for permanent embolization, and may be overall more effective radiographically for hematoma resolution compared to particulate agents. The segmentation of LEA surface area has not yet been described in the literature and is of interest in both refining MMAE technique and understanding cSDH pathophysiology.

Methods Under IRB approval, we retrospectively and anonymously collected CT scans from 74 patients (with 95 cSDH) who underwent first-line MMAE with an EVOH liquid embolic. Non-contrast head CTs acquired pre-embolization, and at 1-month (n=81), 3-month (n=69), and 6-month (n=52) follow-up, as well as immediate post-embolization flat-detector CTs were analyzed. Patients who received any neurosurgical intervention were excluded. 3D-Slicer (slicer.org) was used to segment and calculate hematoma volumes in the non-contrast CTs and the flat-detector CTs were segmented (Figure A) to calculate the surface area of the LEA. We hypothesized that greater LEA surface area would be correlated with greater improvements in cSDH volumetric resolution over follow-up imaging.

Results There was significant reduction in cSDH volumes over the follow-up period with respect to the preoperative volume (p<0.001). cSDH volumes did not differ significantly between 3-months and 6-months (p=0.9). The liquid embolic surface area was significantly correlated with the rate of cSDH resorption at 3-months (R²=0.08, p=0.025, n=63) and at 6-months (Figure B). 33% of patients had complete hematoma resolution within 6 months, and this group showed a trend toward greater LEA surface area (1596±870mm²) compared to the patients with residual hematomas (1298±695mm^{^2}) without statistical significance (p=0.15).

Conclusion Results indicate a plateau effect on cSDH resorption between the 3- and 6-month time frame after MMAE. LEA surface area (as opposed to volume) is a quantitative measure of distal penetration of the embolic cast. The positive correlation of LEA surface area with rate of hematoma resolution suggests greater LEA penetration can improve radiographic outcomes in cSDH patients. Surface area correlations to cSDH resolution were weak, which may be because the LEA segmentation from the flat-detector CTs was sub-optimal with all cases showing a disconnected, patchy appearance (Figure A). LEA segmentation needs to be improved. To our knowledge, this study uniquely provides a quantitative radiological perspective on the effect of LEA penetration on cSDH resolution.

• Download figure
• Open in new tab
• Download powerpoint

Abstract E-263 Figure 1

(A) example of a MMAE liquid embolic cat segmented using a global threshold in 3-D slicer. This example has a surface area of 2683 mm2. (B) liquid embolic agent (LEA) surface area correlated with rate of hematoma resolution at 6-month follow-up

Disclosures K. John: None. S. Syed: None. T. Kaestner: 5; C; Siemens Medical Solutions. R. Dashti: None. D. Fiorella: 1; C; Siemens Medical Solutions, Medtronic Neurovascular. 2; C; Medtronic Neurovascular. 3; C; Medtronic Neurovascular. C. Sadasivan: 1; C; Medtronic Neurovascular. 6; C; Siemens Medical Solutions.