Accuracy and safety of CO 2 digital subtraction angiography during endovascular treatment of symptomatic peripheral artery occlusive disease. A prospective study on Egyptian patients

Safety and Effectiveness of Carbon Dioxide Contrast Medium in Infra-Inguinal Endovascular Interventions for Patients With Chronic Threatening Lower Limb Ischemia and Renal Impairment: A Multicentric Trial

PURPOSE

To assess the safety and effectiveness of using carbon dioxide (CO2) contrast in both supra- and infra-genicular endovascular interventions in patients with renal impairment.

MATERIAL AND METHODS

This is a multicentric prospective observational study conducted over a period of 3 years from 2017 to 2020; the study included 114 patients presented with chronic threatening limb ischemia (CTLI) and renal impairment (lowest serum creatinine levels ≥1.3 mg/dL) for whom endovascular procedures were done using CO2 as a contrast medium. Endovascular angiography was guided by CO2 either exclusively (zero contrast) or with the aid of small amount of supplementary iodinated contrast media (ICM) injections. The qualitative assessment of the angiographic images in both supra- and infra-genicular fields were reported and scaled.

RESULTS

The qualitative diagnostic images were excellent in 86.5% in the supra-genicular and 66.5% in infra-genicular images. There were no significant changes in mean serum creatinine levels from baseline to first and fifth days post procedural (mean 1.8 mg/dL vs mean 1.9 mg/dL and mean 1.7 mg/dL).

CONCLUSION

CO2 is a non-nephrotoxic alternative to traditional ICM that could be safely used and well tolerated during endovascular interventions for peripheral arterial disease in patients with renal impairment. Primary safety and efficacy endpoints were achieved in 100% of cases. The use of automated injector system provides adequate delivery, optimizes the dose, and avoids air contamination. For infra-genicular segment opacification, we recommend super-selective injections and some changes in angiographic techniques from contrast preparation to image post-processing.

CLINICAL IMPACT

Co2 is a non-nephrotoxic alternative to traditional ICM that could be safely used and well tolerated during peripheral endovascular interventions in patients with renal impairment. The use of automated injector system would provide adequate delivery, optimizes the dose and avoids air contamination. For infra-genicular segment opacification, its recommended to use selective injection as close to the target artery as possible and some changes in angiographic techniques from contrast preparation to image post-processing.

Parameter optimisation for image acquisition and stacking in carbon dioxide digital subtraction angiography

The aim of this study was to optimise the vessel angle as well as the stack number from the profiles of carbon dioxide digital subtraction angiography (CO2-DSA) images of a water phantom containing an artificial vessel tilted at different angles which imitate arteries in the body. The artificial vessel was tilted at 0°, 15°, and 30° relative to the horizontal axis with its centre as the pivot point, and CO2-DSA images were acquired at each vessel tilt angle. The maximum opacity method was used to stack up to four images of the next frame one by one. The signal-to-noise ratio (SNR) was determined from the profile curves. The Wilcoxon rank sum test was used to evaluate whether the profile curve and SNR differed depending on the vessel tilt angle or stack number, and a p-value of less than 0.05 was considered statistically significant. Images acquired at 0° had a significantly lower SNR than images acquired at 15° (p = 0.10). When the vessel angle was 30°, the profile curves were significantly improved (p < 0.05) when two or more images were stacked over the original image. Images with a good SNR were acquired at the vessel tilt angle of 15°, and the shape of the profile curve was improved when two or more images were stacked on the original image. This study demonstrates that the quality of images acquired using CO2-DSA can be significantly improved through parameter optimisation for image acquisition and post-processing.

Digital Variance Angiography as a Paradigm Shift in Carbon Dioxide Angiography

OBJECTIVES

Our aim was to investigate the feasibility of digital variance angiography (DVA) in lower extremity CO2 angiography and to compare the quantitative and qualitative performance of the new image processing technique with that of the current reference standard digital subtraction angiography (DSA).

MATERIALS AND METHODS

This prospective study enrolled 24 patients (mean age ± SD, 65.5 ± 9.2 years; 14 males, 65.1 ± 7.5 years; 10 females, 66.1 ± 11.6 years) undergoing lower-limb CO2 angiography between December 2017 and April 2018 at 2 clinical centers: The Heart and Vascular Center (HVC) of Semmelweis University, Budapest (7 patients), and the Bács-Kiskun County Hospital (BKCH) in Kecskemét (17 patients). The interventional protocol was similar at both sites, but the image acquisition instruments and protocols were different, which allowed us to investigate DVA in different settings. For comparison, the signal-to-noise ratio (SNR) of DSA and DVA images were calculated. The visual quality of DSA and DVA images were compared by independent clinical specialists using an online questionnaire. Interrater agreement was characterized by percent agreement and Fleiss kappa. The specialists also evaluated in a random and blinded manner the individual DSA and DVA images on a 5-grade scale ranging from poor (1) to outstanding (5) image quality, and the mean ± standard error of mean (SEM) was calculated.

RESULTS

A total of 4912 regions of interest were carefully selected in 110 image pairs to determine the SNRs. The ratio of SNRDVA/SNRDSA was calculated. At HVC, it ranged between 2.58 and 4.16 in the anatomical regions (abdominal, iliac, femoral, popliteal, crural, talar), and the overall median value was 3.53, whereas at BKCH the range was 2.71 to 4.92 and the overall median value was 4.52. During the visual evaluation, 120 DSA and DVA image pairs were compared. At HVC in 78%, although at BKCH in 90% of comparisons, it was judged that DVA provided higher quality images. The interrater agreement was 88% (P < 0.001) and 90% (P < 0.01), respectively. DVA images received consistently higher individual rating than DSA images, regardless of the research site and anatomical region. At HVC, the overall DSA and DVA scores (mean ± SEM) were 2.75 ± 0.12 and 3.23 ± 0.16, respectively (P < 0.05), whereas at BKCH these values were 2.49 ± 0.10 and 3.03 ± 0.09, respectively (P < 0.001).

CONCLUSIONS

These data show that lower-limb CO2 angiography DVA, regardless of the image acquisition instruments and protocols, produces higher SNR and significantly better image quality than DSA; therefore this new image processing technique might help the widespread use of CO2 as a safer contrast agent in clinical practice.