4:10 PM Abstract No. 221 - Quantitative endpoints for embolization utilizing real-time pressure measurements: anti-reflux infusion system versus end-hole catheter

Abstract

Purpose Embolization procedures are currently performed using end-hole catheters; contrast agent flow dynamics provide a qualitative indicator of the degree of embolization. This research investigates the feasibility of monitoring real-time pressures as a quantitative endpoint for embolization. Results from an anti-reflux infusion system are compared to those of an end-hole catheter. Materials and Methods A benchtop model of the hepatic anatomy was constructed from 3D CT imaging. This model included left and right hepatic arteries and 16 distal target vessels (1mm ID). To simulate hepatic flow, the model was perfused with distilled water at a constant pressure of 120 mmHg and an initial flow rate of 400 mL/min. Real-time pressures were acquired at 100 Hz from multiple arterial locations: Proper Hepatic (PH), Right Hepatic (RH), Left Hepatic (LH), and three distal RH and LH branches. Embolization was modeled and controlled by occluding distal vessels with pinch valves. Degree of Embolization (DE) was used to quantify the amount of flow occluded by the pinch valves; at baseline DE was 0% and at full stasis DE was 100%. Recovery of Pressure (RP) was defined to be the normalized pressure difference from baseline (or DE=0) to the pressure at a specific DE. Least squares regression and paired t-tests were used to quantify dependence of RP on PE. Results After deployment of the anti-reflux catheter, average tip pressure decreased by 38.4 +/- 8.2 mmHg, which was significantly more than the pressure drop of an end-hole catheter (0.5 +/- 0.4 mmHg, p=.00004). For the anti-reflux catheter, RP correlated with DE, such that at complete embolization RP was 100%. Least squares regression quantified this relationship for locations in the PH (R2=0.9956), LH (R2=0.9996) and RH (R2=0.9998). End-hole catheter data was also fit for the PH (R2=0.9307) and the RH (R2=0.9572), but RP did not equal 100% when DE was 100%. Conclusion Standard end-hole catheters cannot accurately quantify degree of embolization. However, after deployment of an anti-reflux catheter, recovery of pressure gradients from baseline can be used to accurately quantify degree of embolization.