A Proposed Grading Scale Based on Radiographic Imaging for Wall Apposition to Estimate Neurological Complications after Flow Diverter Treatment.

Background And Purpose: The evaluation of wall apposition following flow diverter (FD) treatment remains poorly defined. This study aims to establish a radiographic grading scale for wall apposition after FD deployment and to investigate its association with FD-related neurological complications.

Materials And Methods: This retrospective study included patients treated with the Pipeline Embolization Device (PED). A wall apposition grading scale (Grades I-IV) was developed based on radiographic imaging, incorporating anatomical location and the degree of malapposition: Grade I, perfect wall apposition; Grade II, mild malapposition; Grade III, moderate malapposition; and Grade IV, severe malapposition. Cases were categorized into two groups: complete wall apposition (Grade I) and malapposition (Grades II-IV). The association between malapposition and neurological complications was further analyzed.

Results: A total of 197 PED cases were included. Incomplete wall apposition was observed in 29 cases (14.7%), while 168 cases (85.3%) demonstrated complete wall apposition (Grade I). In the malapposition group, 13 cases (6.6%) were classified as Grade II, 11 cases (5.6%) as Grade III, and 5 cases (2.5%) as Grade IV. FD-related perioperative and follow-up neurological complications occurred in 10.3% and 13.8% of the malapposition group, respectively, compared to 1.8% and 1.2% in the complete wall apposition group (P<0.05). Multivariate logistic regression analysis identified malapposition as an independent risk factor for FD-related neurological complications (P<0.05). The Cochran-Armitage test revealed a significant trend of increasing neurological complications with worsening malapposition from Grade II to IV (P<0.05).

Conclusions: The proposed grading scale is a feasible and practical tool for assessing wall apposition following FD treatment. Neurological complications are significantly more likely in cases with moderate to severe malapposition (Grades III and IV).

Abbreviations: FD = flow diverter; PED = Pipeline Embolization Device; 2D DSA = two-dimensional digital subtraction angiography; OCT = optical coherence tomography; TIA = transient ischemic attack; IQR = interquartile range.