Title: E-059 Calculation of mean arterial blood flow rate from digital subtraction angiography: effect of injection conditions
Abstract: <h3>Introduction</h3> Several methods of extracting arterial blood flow rates from angiography have been attempted over the past decades.<sup>1</sup> However, such methods are not used clinically, primarily because catheter-based contrast injections in arteries can result in substantial pressure and flow disturbances during the injection.<sup>2</sup> We hypothesize that injections which cause minimal hemodynamic disturbance in the vessel of interest would result in greater accuracy of angiographically calculated mean flow rates. We conducted an <i>in vitro</i> study under various injection conditions to evaluate this hypothesis. <h3>Methods</h3> Angiography at 15 FPS was acquired in a Circle of Willis silicone replica assembled on a pulsatile flow simulator (figure 1, Vascular Simulations, Stony Brook, NY). Injection conditions included (total n=72): catheter-tip position (right carotid, ascending aorta), catheter type (6F end-hole, 6F side-holes), baseline internal carotid flow (4.3, 5.3, 8.3 cc/s), injection rate (carotid: 2, 6 cc/s; aorta: 10, 20 cc/s). Contrast concentration-time curves were recorded at proximal and distal locations on the right internal carotid artery (figure 1) and the bolus transit-time between these two locations was calculated using three different methods (Mean Transit Time, Time to Peak, Cross Correlation). Then, arterial mean flow rate (ml/s)=arterial segment volume(ml)/transit-time(s). Actual flow in the vessel was measured with a flow meter. <h3>Results</h3> Statistically significant linear correlations were observed between measured and angiographically calculated flow rates under nearly all injection conditions. Cross correlation was substantially superior to the other two methods (p<0.0001). The error between measured and calculated flows was significantly (p=0.001) lower with the side-hole catheter (11%±11%) as compared to the end-hole catheter (22%±15%). Similarly, the aortic injections showed lower error (13%±11%) than the carotid injections (20%±17%), but without statistical significance (p=0.64). <h3>Conclusions</h3> Calculation of mean arterial flow rates by angiography is feasible. The accuracy is higher when the injection causes the least hemodynamic disturbance (side-hole catheter, aortic injection). Improvements to the technique need to be made in order to achieve reliable accuracy in patients, especially under standard (˜4 FPS) frame rate acquisitions. <h3>References</h3> Lieber BB, <i>et al. Crit Rev Biomed Eng.</i> 2005;33(1):1–1022. Kovarovic B, <i>et al. Cardiovasc Eng Technol.</i> 2018. doi:10.1007/s13239-018-0344-3 <h3>Disclosures</h3> <b>M. Gross:</b> None. <b>B. Kovarovic:</b> None. <b>H. Woo:</b> 4; C; Vascular Simulations. 6; C; Cerenovus, JnJ. <b>D. Fiorella:</b> 2; C; Penumbra, Microvention, Medtronic. 4; C; Vascular Simulations. 6; C; Cerenovus JnJ. <b>C. Sadasivan:</b> 4; C; Vascular Simulations.
Publication Year: 2018
Publication Date: 2018-07-01
Language: en
Type: article
Indexed In: ['crossref']
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