Abstract No. 672 A quantitative venography technique using time-modulated contrast injections

Abstract

The intraprocedural evaluation of venous intervention is difficult due to limited number of techniques for measuring venous blood flow. Quantitative angiography methods have been described for quantifying blood flow in arteries using transient contrast boluses developed by cardiac pulsatility. The objective of this study was to determine the feasibility of performing quantitative venography by generating a pulsatile signal via modulated contrast injection. Preliminary in vivo evaluation of the quantitative venography techniques were performed in 2 50 kg female domestic swine. In animal 1, a flush catheter was positioned in the main portal vein. A 2D-DSA sequence was acquired during which contrast was manually injected (40 mL of contrast delivered in 10 pulses for 20 seconds). In animal 2, a flush catheter was positioned in the infra-renal inferior vena cava (IVC), and 2D-DSA sequences were acquired during which a modulated contrast injection (5-9 mL/s contrast pulses at 0.67Hz interleaved with 0-6 mL/s saline pulses at 0.67 Hz, for 10 seconds total) was performed using a custom-built power-injector. Blood velocity measurements were concurrently made in the IVC using an indwelling Doppler flow wire. A post-hoc analysis of all DSA sequences was performed using a shifted-least squares method for quantifying blood velocity. Triplicate calculations in the target regions were made on each DSA sequence. Calculated blood velocities using 2D-DSA (mean ± STD) in the IVC and portal vein were 12.4 ± 0.7 and 14.0 ± 2.0 cm/s respectively. Measured blood velocity in the IVC using the Doppler flow wire was 17.3 ± 6.5 cm/s. Hepatopetal blood velocity in the porcine portal vein has been previously reported to be 15.6 ± 9.0 cm/s. In the inferior vena cava, the calculated blood velocities were similar to measurements made using a Doppler flow wire. In the portal vein, calculated blood velocities were similar to values reported previously in porcine models. These results indicate the feasibility of quantitative venography, a novel method for intraprocedural characterization of changes in venous blood flow in response to venous intervention.