Rationale and design of the Dynamic Coronary Roadmap for Contrast Reduction (DCR4Contrast) in PCI randomized controlled trial.

BACKGROUND: The clinical and anatomic complexity of patients undergoing percutaneous coronary interventions (PCI) has increased significantly over the past 2 decades. Contrast induced nephropathy (CIN) significantly impacts prognosis after PCI, therefore minimizing the risk of CIN is important in improving clinical outcomes. Dynamic Coronary Roadmap (DCR) is a PCI navigation support tool which may decrease CIN by projecting a motion-compensated virtual coronary roadmap overlay on fluoroscopy, potentially reducing iodinated contrast volume during PCI. STUDY DESIGN AND OBJECTIVES: The Dynamic Coronary Roadmap for Contrast Reduction trial (DCR4Contrast) is a multi-center, prospective, unblinded, stratified 1:1 randomized controlled trial investigating if DCR use reduces the total contrast volume administered during PCI compared to PCI performed without DCR guidance. DCR4Contrast aims to recruit 394 patients undergoing PCI. The primary end point is the total undiluted iodinated contrast volume administered during the PCI, performed with or without DCR. As of November 14, 2022, 346 subjects have been enrolled. CONCLUSIONS: The DCR4Contrast study will investigate the potential contrast-sparing effect of the DCR navigation support tool in patients undergoing PCI. By reducing iodinated contrast administration, DCR has the potential to contribute to reduced risk of CIN and thus increase PCI safety. CLINICAL TRIAL REGISTRATION URL: https://clinicaltrials.gov/ct2/show/NCT04085614.

Dynamic Coronary Roadmap versus standard angiography for percutaneous coronary intervention: the randomised, multicentre DCR4Contrast trial.

BACKGROUND: Decreasing the amount of iodinated contrast is an important safety aspect of percutaneous coronary interventions (PCI), particularly in patients with a high risk of contrast-induced acute kidney injury (CI-AKI). Dynamic Coronary Roadmap (DCR) is a PCI navigation support tool projecting a motion-compensated virtual coronary roadmap overlay on fluoroscopy, potentially limiting the need for contrast during PCI. AIMS: This study investigates the contrast-sparing potential of DCR in PCI, compared to standard angiographic guidance. METHODS: The Dynamic Coronary Roadmap for Contrast Reduction (DCR4Contrast) trial is a multicentre, international, prospective, unblinded, stratified 1:1 randomised controlled trial. Patients were randomised to either DCR-guided PCI or to conventional angiography-guided PCI. The primary endpoint was the total volume of iodinated contrast administered, and the secondary endpoint was the number of cineangiography runs during PCI. RESULTS: The study population included 356 randomised patients (179 in DCR and 177 in control groups, respectively). There were no differences in patient demographics, angiographic characteristics or estimated glomerular filtration rate (eGFR) between the two groups. The total contrast volume used during PCI was significantly lower with DCR guidance compared with conventional angiographic guidance (64.6±44.4 ml vs 90.8±55.4 ml, respectively; p<0.001). The total number of cineangiography runs was also significantly reduced in the DCR group (8.7±4.7 vs 11.7±7.6 in the control group; p<0.001). CONCLUSIONS: Compared to conventional angiography-guided PCI, DCR guidance was associated with a significant reduction in both contrast volume and the number of cineangiography runs during PCI. (ClinicalTrials.gov: NCT04085614).

Image quality improvements in C-Arm CT (CACT) for liver oncology applications: preliminary study in rabbits.

INTRODUCTION: C-Arm CT (CACT) is a new imaging modality in liver oncology therapy that allows for the acquisition of 3D images intra-procedurally. CACT has been used to enhance intra-arterial therapies for the liver by improving lesion detection, avoiding non-target embolization, and allowing for more selective delivery of agents. However, one of the limitations of this technology is image artifacts created by respiratory motion. PURPOSE: To determine in this preliminary study improvements in image acquisition, motion compensation, and high resolution 3D reconstruction that can improve CACT image quality (IQ). MATERIAL AND METHODS: Three adult male New Zealand white rabbits were used for this study. First, a control rabbit was used to select the best x-ray acquisition imaging protocol and then two rabbits were implanted with liver tumor to further develop 3D image reconstruction and motion compensation algorithms. RESULTS: The best IQ was obtained using the low 80 kVp protocol with motion compensated reconstruction with high resolution and fast acquisition speed (60 fps, 5 s/scan, and 312 images). CONCLUSION: IQ improved by: (1) decreasing acquisition time, (2) applying motion-compensated reconstruction, and (3) high resolution 3D reconstruction. The findings of this study can be applied to future animal studies and eventually could be translated into the clinical environment.

Experimental realization of a rotational ratchet in a granular gas.

We construct a ratchet of the Smoluchowski-Feynman type, consisting of four vanes that are allowed to rotate freely in a vibrofluidized granular gas. The necessary out-of-equilibrium environment is provided by the inelastically colliding grains, and the equally crucial symmetry breaking by applying a soft coating to one side of each vane. The onset of the ratchet effect occurs at a critical shaking strength via a smooth, continuous phase transition. For very strong shaking the vanes interact actively with the gas and a convection roll develops, sustaining the rotation of the vanes.

Onset of convection in strongly shaken granular matter.

Strongly vertically shaken granular matter can display a density inversion: A high-density cluster of beads is elevated by a dilute gaslike layer of fast beads underneath ("granular Leidenfrost effect"). For even stronger shaking the granular Leidenfrost state becomes unstable and granular convection rolls emerge. This transition resembles the classical onset of convection in fluid heated from below at some critical Rayleigh number. The same transition is seen in molecular dynamics (MD) simulations of the shaken granular material. The critical shaking strength for the onset of granular convection can be calculated from a linear stability analysis of a hydrodynamiclike model of the granular flow. Experiment, MD simulations, and theory quantitatively agree.

Exploring the limits of granular hydrodynamics: a horizontal array of inelastic particles.

The limits of granular hydrodynamics are explored in the context of the one-dimensional granular system introduced by Du, Li, and Kadanoff [Phys. Rev. Lett. 74, 1268 (1995)]. The density profile of the characteristic steady state, in which a single particle commutes between the driving wall and a dense cluster, is well captured by a hydrodynamic description provided that the finite size of the particles is incorporated. The temperature, however, is not well described: since all energy exchange is located at the border of the cluster, it is precisely for this quantity that the continuum approach breaks down.

Use of short roll C-arm computed tomography and fully automated 3D analysis tools to guide transcatheter aortic valve replacement.

Determination of the coplanar view is a critical component of transcatheter aortic valve replacement (TAVR). The safety and accuracy of a novel reduced angular range C-arm computed tomography (CACT) approach coupled with a fully automated 3D analysis tool package to predict the coplanar view in TAVR was evaluated. Fifty-seven patients with severe symptomatic aortic stenosis deemed prohibitive-risk for surgery and who underwent TAVR were enrolled. Patients were randomized 2:1 to CACT vs. angiography (control) in estimating the coplanar view. These approaches to determine the coplanar view were compared quantitatively. Radiation doses needed to determine the coplanar view were recorded for both the CACT and control patients. Use of CACT offered good agreement with the actual angiographic view utilized during TAVR in 34 out of 41 cases in which a CACT scan was performed (83 %). For these 34 cases, the mean angular magnitude difference, taking into account both oblique and cranial/caudal angulation, was 1.3° ± 0.4°, while the maximum difference was 7.3°. There were no significant differences in the mean total radiation dose delivered to patients between the CACT and control groups as measured by either dose area product (207.8 ± 15.2 Gy cm(2) vs. 186.1 ± 25.3 Gy cm(2), P = 0.47) or air kerma (1287.6 ± 117.7 mGy vs. 1098.9 ± 143.8 mGy, P = 0.32). Use of reduced-angular range CACT coupled with fully automated 3D analysis tools is a safe, practical, and feasible method by which to determine the optimal angiographic deployment view for guiding TAVR procedures.

Effect of air on granular size separation in a vibrated granular bed.

Using high-speed video and magnetic resonance imaging (MRI) we study the motion of a large sphere in a vertically vibrated bed of smaller grains. As previously reported we find a nonmonotonic density dependence of the rise and sink time of the large sphere. We show that air drag causes relative motion between the intruder and the bed during the shaking cycle and is ultimately responsible for the observed density dependence of the risetime. We investigate in detail how the motion of the intruder sphere is influenced by size of the background particles, initial vertical position in the bed, ambient pressure, and convection. We explain our results in the framework of a simple model and find quantitative agreement in key aspects with numerical simulations to the model equations.

Limited angle C-arm tomography and segmentation for guidance of atrial fibrillation ablation procedures.

Angiographic projections of the left atrium (LA) and the pulmonary veins (PV) acquired with a rotational C-arm system are used for 3D image reconstruction and subsequent automatic segmentation of the LA and PV to be used as roadmap in fluoroscopy guided LA ablation procedures. Acquisition of projections at high oblique angulations may be problematic due to increased collision danger of the detector with the right shoulder of the patient. We investigate the accuracy of image reconstruction and model based roadmap segmentation using limited angle C-arm tomography. The reduction of the angular range from 200 degrees to 150 degrees leads only to a moderate increase of the segmentation error from 1.5 mm to 2.0 mm if matched conditions are used in the segmentation, i.e., the model based segmentation is trained on images reconstructed with the same angular range as the test images. The minor decrease in accuracy may be outweighed by clinical workflow improvement, gained when large C-arm angulations can be avoided.

Granular Leidenfrost effect: experiment and theory of floating particle clusters.

Granular material is vertically vibrated in a 2D container: above a critical shaking strength, and for a sufficient number of beads, a crystalline cluster is elevated and supported by a dilute gaseous layer of fast beads underneath. We call this phenomenon the granular Leidenfrost effect. The experimental observations are explained by a hydrodynamic model featuring three dimensionless control parameters: the energy input S, the number of particle layers F, and the inelasticity of the particle collisions epsilon. The (S,F) phase diagram, in which the Leidenfrost state lies between the purely solid and gas phases, shows accurate agreement between experiment and theory.