Introduction: Treatment of giant intracranial aneurysms are often associated with larger complications rates, related to hemodynamic changes of intracranial flow distal to the intracranial aneurysms. In this paper we evaluated the baseline contrast transit times on angiography for patients with proximal anterior circulation aneurysms.
Methods: Digital subtraction angiographic (DSA) films for patients with intracranial aneurysms were reviewed. Only proximal, unruptured anterior circulations aneurysms were included. DSA images were analyzed over M1 segment, using custom made software for the time-density. Analysis included TT 10%-100% (time needed for the contrast to change from 10%-100% image intensity) , TT 100 10% (time needed for the contrast to change from 100%-10% image intensity), and TT 25-25% (time needed for the contrast to change from 25%-25% image intensity. This was compared to the contralateral M1 transit times.
Results: A total of 50 patients were included in this study. Aneurysm size ranged from 2-40 mm, mean 12 mm. Analysis over the M1 segment showed a significant increase in the TT25%-25% (7.6 to 8.46 seconds, P=0.006) compared to the contralateral side. There was significant correlation (Spearman’s correlation) between the TT10%-100%, the TT25%-25% and the aneurysm size (rho = 0.291, 0.362 and P=0.041, 0.01 respectively) (Figure 1), indicating a slower contrast time in larger aneurysms. Similarly, there was significant correlation between the absolute difference between the ipsilateral and contralateral TTs and aneurysm size (TT10%-100% : P=0.005, rho=0.393 ; TT25%-25% : P<0.001 , rho=0.52) (Figure2).
Conclusions: Our analysis shows that statistically significant difference in the intracranial contrast TT as a function of proximal aneurysm size. The mechanism for this might be related to the Windkessel effect where the aneurysm as a blood reservoir in systole and partially release the contrast in diastole. Changes to this baseline phenomenon might contribute to complications post flow diverters implementation.
Patient Care: This research will provide a basic understanding on the understanding of hemodynamic changes seen with larger aneurysms.
Learning Objectives: 1-Understand the basics of transit time analysis by angiography.
2-Understand the relationship between transit time by DSA and aneurysm size.
3-Provide hemodynamic understanding of the effect of aneurysm size on outcome of treatment.