Abstract
Purpose To assess quantitative stenosis grading by color-coded fluoroscopy using an in vitro pulsatile flow phantom. Methods Three different stenotic tubes (80%, 60%, and 40% diameter restriction) and a nonstenotic reference tube were compared regarding their different flow behavior by using contrast-enhanced fluoroscopy with a flat-detector system for visualisation purposes. Time-density curves (TDC), area under the curve (AUC), time-to-peak (TTP), and different ROI sizes were analyzed in three independent measurements using two different postprocessing software solutions. In addition, exemplary TDCs of a patient with a high-grade stenosis before and after stent angioplasty were acquired. Results Color-coded fluoroscopy enabled depiction of differences in AUC and TDC between high-grade (80%), middle (60%), low-grade (40%), and nonstenotic tubes. The best correlation between high-, middle-, and low-grade stenosis was appreciated in ROIs behind the stenosis. This effect was enhanced by using longer integration times (5s, 7s) and a maximum frame rate of image acquisition for analysis (correlation coefficient rho=0.9284 at 5s). TTP showed no significant differences between high- and low-grade stenosis. Conclusions Various clinical studies in the literature already demonstrated reproducible and reliable stenosis grading by analyzing TDCs acquired with color-coded fluoroscopy. In contrast to TTP, AUC values derived in ROIs behind the stenosis proved to be reliable parameters for stenosis grading. However, our results also demonstrate that several factors are able to significantly impact the evaluation of AUC values. More precisely, accuracy of acquired AUC values can be improved by choosing longer integration times, a large ROI size adapted to the vessel diameter, and a higher frame rate of image acquisition.
Highlights
The incidence and prevalence of peripheral artery disease (PAD) are steadily rising in developed countries [1,2,3]
Results of the analysis of variance (ANOVA) analysis for all different integration times, stenosis grades, and measurement regions of interest (ROI) using ImageJ and iFlow are listed in Tables 1 and 2, respectively
A significant difference between the 40% and 80% stenosis model was seen for integration times of 3 s, 5 s, and 7 s (p=0.0484, p=0.0202, and p=0.0484, respectively)
Summary
The incidence and prevalence of peripheral artery disease (PAD) are steadily rising in developed countries [1,2,3]. Highgrade stenosis in patients with PAD can reduce or stop the blood supply to the lower extremities, thereby causing claudication and limb ischemia. For endovascular treatment of PAD, current guidelines recommend different treatment approaches depending on the stage and location of PAD, including plain balloon angioplasty, drug-coated balloons, Nitinol-stents, drug-eluting stents, and covered stents [1, 2]. In clinical practice high-grade stenosis can be detected and quantified using different imaging modalities, including color-coded duplex sonography (CCDS), contrast-enhanced CT angiography (CTA), contrast-enhanced magnetic resonance angiography (MRA), and digital subtraction angiography (DSA) [3]. The current gold standard for the diagnosis and grading of PAD is invasive DSA which is associated Waste water. Contrast agent pump Hose 5cm 5cm 10cm Water supply
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