Relationship between Two Types of Coil Packing Densities Relative to Aneurysm Size.

BACKGROUND AND PURPOSECoil packing density (PD) can be calculated via a formula (PDF) or software (PDS). Two types of PD can be different from each other for same aneurysm. This study aimed to evaluate the interobserver agreement and relationships between the 2 types of PD relative to aneurysm size. METHODSConsecutive 420 saccular aneurysms were treated with coiling. PD (PDF, [coil volume]/[volume calculated by formula] and PDS, [coil volume]/[volume measured by software]) was calculated and prospectively recorded. Interobserver agreement was evaluated between PDF and PDS. Additionally, the relationships between PDF and PDS relative to aneurysm size were subsequently analyzed. RESULTSInterobserver agreement for PDF and PDS was excellent (Intraclass correlation coefficient, PDF; 0.967 and PDS; 0.998). The ratio of PDF and PDS was greater for smaller aneurysms and converged toward 1.0 as the maximum dimension (D-M) of aneurysm increased. Compared with PDS, PDF was overestimated by a mean of 28% for D-M < 5 mm, by 17% for 5 mm D-M < 10 mm, and by 9% for D-M 10 mm (P < 0.01). CONCLUSIONSInterobserver agreement for PDF and PDS was excellent. However, PDF was overestimated in smaller aneurysms and converged to PDS as aneurysm size increased.