Clinical Feasibility of Performing Quantitative Angiography to Determine Objective Treatment Endpoints During Vascular Interventions

Quantitative digital subtraction angiography (qDSA) is a recently developed technique which permits the quantification of blood velocity from intra-procedural angiographic images. This technique has been validated in phantom and porcine models of hepatic embolization, peripheral artery disease, and chronic venous obstruction {1-4}. The purpose of this study was to evaluate the clinical feasibility of using the qDSA algorithm by retrospectively applying it to fluoroscopic images acquired during a variety of clinical vascular interventions.

Materials and Methods:

Fluoroscopic images from four clinical cases were retrospectively analyzed using the qDSA algorithm in order to calculate blood velocities in vessels of interest. These included images from a venoplasty and follow-up venography for a chronic venous obstruction, stent placement in a transplant renal artery stenosis, a pre-embolization renal angiogram, and a pre-embolization super-selective hepatic angiogram. Motion-compensation and de-noising techniques were employed to improve image quality and quantification accuracy.

Results:

In a case of chronic venous obstruction, right iliac venous blood velocity increased from pre-intervention (24 cm/s) to post-recanalization (30 cm/s) to post-venoplasty (45 cm/s), and decreased at a four-week follow up diagnostic venogram (32 cm/s). In a case of transplant renal artery stenosis, blood velocity in the proximal artery near the stenosis increased from pre-intervention (33 cm/s) to post-stenting (61 cm/s). In a pre-embolization renal angiogram, the blood velocity was 46 cm/s. In a pre-embolization super-selective hepatic angiogram, blood velocity was 19 cm/s.

Conclusion:

Intra-procedural blood velocity quantification was successful in a variety of arterial and venous cases including a super-selective angiogram with reduced image signal. Calculated blood velocities were within the expected physiologic ranges. Lower radiation dose fluoroscopic images provided sufficient image quality to perform blood velocity quantification and may be improved by motion-compensation and de-noising. Determination of objective treatment endpoints using qDSA may improve the safety and efficacy of flow-altering vascular interventions.