To compare the image quality produced by kinetic imaging in x-ray angiography and the current reference standard digital subtraction angiography (DSA). Materials and Methods: This prospective observational crossover study enrolled 42 patients undergoing lower limb x-ray angiography between February and June 2017 (mean age, 68.7 years; age range, 49-89 years; 32 men [mean age, 67.1 years; age range, 49-89 years] and 10 women [mean age, 75 years; age range, 57-85 years]). Signal-to-noise ratios (SNRs) of DSA and kinetic image pairs were compared. Visual quality comparisons were also performed by specialists who used an online questionnaire. Interrater agreement was characterized by percent agreement and Fleiss k. Results: A total of 1902 regions of interest were carefully selected in 110 image pairs to calculate and compare the SNRs. Median SNR in raw kinetic images was 3.3-fold and 2.3-fold higher than raw and postprocessed DSA images, respectively. A total of 232 pairs of raw and postprocessed kinetic images were compared. It was indicated that postprocessing improved the quality of kinetic images in 63.9% (2668 of 4176) of the comparisons. Interrater agreement was 75% and Fleiss k was 0.12 (P , .001). Also, 238 pairs of kinetic and DSA images were compared. Kinetic imaging was judged to have provided higher quality images than DSA in 69.0% (2462 of 3570) of the comparisons. The interrater agreement was 81% and Fleiss k was 0.17 (P , .001). Conclusion: Kinetic imaging helps to view the same structures as digital subtraction angiography but offers better image quality. The improved signal-to-noise ratio suggests that this approach could reduce radiation exposure and improve the ability to view smaller vessels.

Purpose In retrospective clinical studies digital variance angiography (DVA) provided higher contrast-to-noise ratio and better image quality than digital subtraction angiography (DSA). Our aim was to verify the clinical usefulness and benefits of DVA in carbon dioxide (CO 2)-assisted lower limb interventions. Materials and Methods A workstation running the DVA software was integrated into a Siemens Artis Zee with Pure angiography system, and this new image processing technology was used in four patients (3 male, 1 female, age: 76.2 ± 4.2 years) with peripheral artery disease (PAD, Rutherford 2-3) and impaired renal function (average eGFR 25.5 ± 11.2 ml/min/1.73 m 2). The DSA and DVA images of 46 CO 2-assisted runs were visually evaluated by five experts in single-image evaluation using a 5-grade Likert scale and in paired comparisons. Results DVA images received significantly higher score (3.84 ± 0.10) than DSA images (3.31 ± 0.10, p \ 0.001). Raters preferred DVA images in terms of diagnostic value and usefulness for therapeutic decisions in 85.2% and 83.9% of all comparisons, respectively. These benefits were achieved at lower frame rates (1-3 FPS) than usually recommended for CO 2 angiography (4-6 FPS). No adverse events were recorded during or after the procedures. Conclusions Our initial experience shows that DVA might facilitate the correct diagnostic and therapeutic decisions, and potentially help to reduce radiation exposure in lower limb CO 2 angiography. Although the dose management capabilities of DVA have to be validated in further clinical studies, this technology might be a useful new tool in the operating room and contributes to the safety and efficacy of CO 2-enhanced endovascular interventions. Level of Evidence Level IV. Keywords Digital variance angiography (DVA) Á Carbon dioxide (CO 2) angiography Á Image quality Á Impaired renal function Á Contrast-induced nephropathy (CIN) Á Lower limb interventions Á Dose management Á Iodine-free angiography Electronic supplementary material The online version of this article (

Objectives: Our aim was to investigate the feasibility of digital variance angiography (DVA) in lower extremity CO 2 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 CO 2 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 signalto-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 SNR DVA /SNR DSA 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 CO 2 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 CO 2 as a safer contrast agent in clinical practice.

Purpose The presence of metal implants may reduce angiographic image quality due to automated beam adjustments. Digital variance angiography (DVA) is reported to be superior to digital subtraction angiography (DSA) with increased contrast-to-noise ratio (CNR) and better image quality. The aim of the study was to evaluate whether DVA could counterbalance the image quality impairment of lower-limb angiographies with metal implants. Materials and Methods From November 2019 to January 2020, 85 raw lower-limb iodine contrast angiograms of 12 patients with metal implants were processed retrospectively with DVA analyses. For objective comparison, CNR of DSA and DVA images was calculated and the ratio CNRDVA/CNRDSA was determined. Visual image quality was evaluated in a paired comparison and by a five-grade Likert scale by three experienced radiologists. Results The CNR was calculated and compared in 1252 regions of interest in 37 image pairs containing metal implants. The median ratio of CNRDVA/CNRDSA was 1.84 with an interquartile range of 1.35–2.32. Paired comparison resulted in 84.5% in favour of DVA with an interrater agreement of 83.2% (Fleiss κ 0.454, p < 0.001). The overall image quality scores for DSA and DVA were 3.64 ± 0.08 and 4.43 ± 0.06, respectively (p < 0.001, Wilcoxon signed-rank test) with consistently higher individual ratings for DVA. Conclusion Our small-sample pilot study shows that DVA provides significantly improved image quality in lower-limb angiography with metal implants, compared to DSA imaging. The improved CNR suggest that this approach could reduce radiation exposure for lower-limb angiography with metal implants. Level of Evidence Level 4, case studies

Our aim was to investigate whether the previously observed higher contrast-to-noise ratio (CNR) and better image quality of Digital Variance Angiography (DVA) - compared to Digital Subtraction Angiography (DSA) - can be used to reduce radiation exposure in lower limb X-ray angiography. This prospective study enrolled 30 peripheral artery disease patients (mean ± SD age 70 ± 8 years) undergoing diagnostic angiography. In all patients, both normal (1.2 µGy/frame; 100%) and low-dose (0.36 µGy/frame; 30%) protocols were used for the acquisition of images in three anatomical regions (abdominal, femoral, crural). The CNR of DSA and DVA images were calculated, and the visual quality was evaluated by seven specialists using a 5-grade Likert scale. For investigating non-inferiority, the difference of low-dose DVA and normal dose DSA scores (DVA30-DSA100) was analyzed. DVA produced two- to three-fold CNR and significantly higher visual score than DSA. DVA30 proved to be superior to DSA100 in the crural region (difference 0.25 ± 0.07, p < 0.001), and there was no significant difference in the femoral (− 0.08 ± 0.06, p = 0.435) and abdominal (− 0.10 ± 0.09, p = 0.350) regions. Our data show that DVA allows about 70% reduction of DSA-related radiation exposure in lower limb X-ray angiography, providing a potential new radiation protection tool for the patients and the medical staff.