Stent Lumen Research Articles

PERCUTANEOUS AXILLARY ACCESS IN THE ENDOVASCULAR ERA: A VIABLE ALTERNATIVE?

The common femoral artery is the most commonly used vascular access due to its low complication rate and high technical success rate. However, this approach may be less suitable in patients with certain factors such as obesity, the need to treat both lower limbs, and the inability to access the lesion via crossover. In this context, endovascular approaches using percutaneous puncture or upper arm access have emerged. Therefore, we evaluated the feasibility of percutaneous access to the axillary artery in routine endovascular procedures. This single-center observational study included consecutive patients requiring percutaneous access to the axillary artery for endovascular procedures from January 2020 to December 2023. Demographic and procedural characteristics were collected. The primary endpoint was efficacy (technical success rate) and safety (complications rate) at 30 days. Secondary endpoints were minor complications and risk factors of complications. 85 patients were included. Axillary approach was used to treat peripheral artery disease (PAD) in 77.6% (n=66), complex aortic aneurysm in 17.7% (n=15), and acute type B aortic dissection in 4.7% (n=4) of patients. This approach was used due to bilateral PAD treatment (n=20), obesity (n=18), prior EVAR (n=12), prior common femoral artery stenting (n=9), major iliac tortuosity (n=9), prior kissing stent (n=8), favorable angulation (n=5) and true lumen positioning in type B aortic dissection (n=4). The left axillary approach was used in 97.6% (n=83) of cases. The efficacy was 100%. At 30 days, safety was 85.6% with a major complication rate of 14.2% (n=12), including 10.6% (n=9) surgical conversion for hemostasis, 2.4% (n=2) covered stenting, and 1.2% (n=1) stroke. Body mass index was associated with a higher rate of complications (25.2 ± 6.17 vs. 29.0 ± 6.04, OR: 1.2 [1.05; 1.37] p=0.006). Axillary arteries are an effective alternative access route for patients with unsuitable iliofemoral arteries. Randomized clinical trials are needed to confirm our findings and to assess the best approach for the upper arm.

Monoenergetic reconstructions and iodine density maps for visualization of coronary artery stents using 8-cm dual-layer detector spectral computed tomography: an in vitro phantom study.

The effectiveness of coronary computed tomography (CT) angiography in assessing stent restenosis is hindered by heavy metal artifacts. This study aimed to evaluate the image quality of monoenergetic reconstructions and iodine density map for coronary stent imaging using an 8-cm dual-layer detector spectral CT. In this study, 8 stents with a diameter <3 mm (group A) and 10 with a diameter ≥3 mm (group B) were placed in plastic tubes filled with iodinated contrast media and scanned. The internal diameter of the prepared stents was then measured by intravascular ultrasound. The reconstructed images included iodine density maps, conventional images, and different energy levels. The visualization of the stent lumen and stent structure was subjectively assessed using a 4-point Likert scale. The objective evaluation was performed using the in-stent lumen signal-to-noise ratio (SNRis), non-stent lumen SNR (SNRns), internal diameter difference (IDD), and blooming artifact index (BAI). The Friedman test and analysis of variance were used for multiple comparisons. For lumen visualization, the optimal monoenergetic images received the highest score for both group A (2.56±0.51) and group B (3.1±0.55). Multiple comparisons showed that there were significant differences between the optimal monoenergetic images and iodine density maps. However, for stent structure, iodine density maps received the highest score for group A (3.0±0.52) and group B (3.8±0.41). For quantitative assessment, the optimal monoenergetic images had the highest SNRis and SNRns, while the iodine density maps had the lowest SNRis and SNRns. For IDD and BAI, the iodine density maps yielded the smallest value. The monoenergetic images on the second-generation dual-layer detector CT provide better visualization of the lumen and higher SNR. However, iodine density maps are superior for evaluating stent structure and IDD and BAI compared to monoenergetic and conventional reconstructions.

Optimal Dual Antiplatelet Therapy Duration For Carotid Artery Stenting On the Basis of Angioscopic Findings

Background Dual antiplatelet therapy plays a crucial role in preventing thrombosis in the perioperative period of carotid artery stenting (CAS); however, it has been associated with a risk of hemorrhagic complications. A standard regimen for the duration and combination of antiplatelet therapy is yet to be established. Angioscopy enables direct visualization of neointimal coverage and might help determine the optimal duration of dual antiplatelet therapy through the assessment of post‐CAS neointimal coverage. Methods This prospective study enrolled 20 patients who were scheduled to undergo CAS at the Osaka Police Hospital. A 2‐month post‐CAS period was chosen for angioscopic neointima evaluation on the basis of previous evidence of reliable neointimal coverage 2 months following coronary artety stenting. Furthermore, antiplatelet therapy was initiated 1 week before CAS and continued until angioscopic examination. Angioscopic evaluation categorized the degree of neointimal coverage and was supplemented with carotid ultrasonography and biplane angiography. Results Coincidentally, a dual‐layer stent was used in all cases. The stent lumen was observed in 19 of the 20 cases. One case was difficult to evaluate owing to poor visibility. Angioscopy showed complete neointimal coverage in 18 of 19 cases and partial coverage in 1 case. Ultrasonography could detect neointima in 9 of 20 cases, and angiography showed a radiolucent gap suggestive of neointima in all cases in which neointima was confirmed via angioscopy. No post‐CAS or procedural complications occurred. Conclusion Angioscopy performed 2 months following CAS revealed large neointimal coverage, suggesting that a 2‐month duration of dual antiplatelet therapy is generally sufficient. However, as a limitation, this study was performed using the same dual‐layer stent; thus, additional studies with other stents are required.

Enhancing image quality in computed tomography angiography follow-ups after endovascular aneurysm repair: a comparative study of reconstruction techniques

BackgroundThe image quality of computed tomography angiography (CTA) images following endovascular aneurysm repair (EVAR) is not satisfactory, since artifacts resulting from metallic implants obstruct the clear depiction of stent and isolation lumens, and also adjacent soft tissues. However, current techniques to reduce these artifacts still need further advancements due to higher radiation doses, longer processing times and so on. Thus, the aim of this study is to assess the impact of utilizing Single-Energy Metal Artifact Reduction (SEMAR) alongside a novel deep learning image reconstruction technique, known as the Advanced Intelligent Clear-IQ Engine (AiCE), on image quality of CTA follow-ups conducted after EVAR.MaterialsThis retrospective study included 47 patients (mean age ± standard deviation: 68.6 ± 7.8 years; 37 males) who underwent CTA examinations following EVAR. Images were reconstructed using four different methods: hybrid iterative reconstruction (HIR), AiCE, the combination of HIR and SEMAR (HIR + SEMAR), and the combination of AiCE and SEMAR (AiCE + SEMAR). Two radiologists, blinded to the reconstruction techniques, independently evaluated the images. Quantitative assessments included measurements of image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), the longest length of artifacts (AL), and artifact index (AI). These parameters were subsequently compared across different reconstruction methods.ResultsThe subjective results indicated that AiCE + SEMAR performed the best in terms of image quality. The mean image noise intensity was significantly lower in the AiCE + SEMAR group (25.35 ± 6.51 HU) than in the HIR (47.77 ± 8.76 HU), AiCE (42.93 ± 10.61 HU), and HIR + SEMAR (30.34 ± 4.87 HU) groups (p < 0.001). Additionally, AiCE + SEMAR exhibited the highest SNRs and CNRs, as well as the lowest AIs and ALs. Importantly, endoleaks and thrombi were most clearly visualized using AiCE + SEMAR.ConclusionsIn comparison to other reconstruction methods, the combination of AiCE + SEMAR demonstrates superior image quality, thereby enhancing the detection capabilities and diagnostic confidence of potential complications such as early minor endleaks and thrombi following EVAR. This improvement in image quality could lead to more accurate diagnoses and better patient outcomes.

High-resolution vessel wall imaging for quantitatively and qualitatively evaluating in-stent stenosis of intracranial aneurysms.

It is critical to accurately and noninvasively evaluate the stented parent artery of intracranial aneurysms (IAs) with endovascular treatment. To investigate high-resolution vessel wall imaging (HR-VWI) for quantitative and qualitative evaluation of in-stent stenosis (ISS) in IAs treated with stent placement (SP). Fifty-five patients (58 aneurysms) underwent HR-VWI, contrast-enhanced (CE)-HR-VWI, CE-MR angiography (MRA), time-of-flight (TOF)-MRA, and digital subtraction angiography (DSA) six months after SP, and the reliability of quantitative stent lumen measurements was evaluated by intraclass correlation coefficient (ICC) analysis. Agreement and correlation of quantitative evaluation were estimated by comparing the four MR imaging modalities with DSA. The diagnostic performance for >0%, ≥25%, and ≥50% of ISS degrees and overall diagnostic accuracy for the ISS degrees of the four MR imaging modalities were calculated to qualitative evaluation. The reliability of CE-HR-VWI and HR-VWI for ISS quantitative measurements was excellent (ICC 0.955-0.989). The agreement and correlation of CE-HR-VWI, HR-VWI versus DSA for ISS quantitative measurements were better than those of CE-MRA and TOF-MRA (p < 0.05). The diagnostic performance for distinguishing the degree of ISS >0%, ≥25%, and ≥50% by CE-HR-VWI and HR-VWI was superior to CE-MRA and TOF-MRA, and their overall diagnostic accuracy was 96.55 and 94.83%, respectively. HR-VWI and CE-HR-VWI were not statistically significant in the quantitative and qualitative evaluation of ISS performance (p > 0.05). HR-VWI and CE-HR-VWI have similar performance and value in the quantitative and qualitative evaluation of ISS, and HR-VWI without contrast media could be used as an ideal long-term follow-up approach after SP treatment for IAs.

관상동맥 CT 조영 검사 시, 초 고해상도 딥러닝 알고리즘이 적용된 스텐트 영상의 진단적 가치

Recently, with the advancement of artificial intelligence image reconstruction technology, we are attempting to evaluate the accuracy of coronary artery stent lumen by developing ultra-high-resolution deep learning image reconstruction technology based on the most accurate 0.25mm multi-detector available. This study was divided into patient studies and phantom studies. Images were reconstructed in the same patient using four different methods: filter correction reverse projection, repetitive reconstruction, deep learning reconstruction, and artificial intelligence ultra-high resolution reconstruction. To objectively evaluate image quality, four parameters, image noise, CT density, signal-to-noise ratio, and contrast-to-noise ratio, were analyzed for each dataset. The phantom study installed a latex Nelaton sterilized catheter to express the coronary artery in the dummy chest phantom. Subsequently, a coronary stent (2.5mm and 3.5mm in diameter) was inserted into each catheter. Images were obtained using various reconstruction techniques (FBP, IR, DLR, and UHR-DLR) for each CT manufacturer. Stent clarity was evaluated using edge rise distance (ERD) and edge rise slope (ERS). We showed that the average Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) of coronary arteries reconstructed with Ultra-High Resolution Deep Learning Reconstruction (UHR-DLR) improved by 29.2% and 36.4% compared to those reconstructed with DLR, respectively. Image noise was reduced by about 21.4% in UHR-DLR. The ERS average value of the coronary stent phantom measured by the CT manufacturers was highest in the UHR-DLR of Aquilion ONE Prism (Canon), and the ERD value is statistically significant for each CT manufacturer. Compared to FBP, HIR, and DLR, UHR-DLR not only improved image clarity and reduced image noise and blooming artifacts but also clearly showed the stent support structure and stent lumen.

The Influence of Coronavirus Infection on the Results of Percutaneous Coronary Intervention in Patients with Coronary Artery Disease

Objective — to determine the impact of coronavirus infection incidence on the post-procedural condition of patients after percutaneous coronary intervention (PCI). Materials and methods. This single-centre study was conducted at the «Ukrainian Children’s Cardiac Center, Clinic for Adults» from June 1, 2020, to December 31, 2021. A total of 158 patients participated, of whom 78 had a history of COVID-19 infection and 80 did not, all with stable obstructive coronary artery disease (CAD). All patients underwent PCI, and their long-term outcomes were evaluated within a 6-month period. The study endpoints included repeated myocardial revascularization (defined as narrowing of the stented lumen by more than 70 % in diameter or acute stent thrombosis) and an assessment of CAD progres­sion (formation or progression of atherosclerotic plaques compared to baseline coronary angio­graphy). Results and discussion. The frequency of repeated coronary angio in the first 6 months after PCI due to tension angina or acute coronary syndrome was equal to 10 (12.8 %) patients in the COVID-19 +-group and 3 (3.8 %) cases in the COVID-19 — –group (p &lt; 0.05). According to the study data, patients with coronavirus infection tended to reach endpoints more quickly during the 6-month follow-up, in contrast to patients who did not have the incidence of COVID-19 during the same period. The frequency of repeated PCI within 6 months after the primary PCI in the group of patients with previous PCI was higher — 8 cases out of 78 patients compared to patients in the second group who did not suffer from COVID-19 in the first 6 months after the initial PCI (2 cases out of 80, c2 = 4 .0, p = 0.045). Conclusions. Patients with a mild and moderate course of coronavirus infection and existing stable coronary heart disease with atherosclerotic lesions of the coronary arteries were more likely to undergo repeat PCI within 6 months of the initial PCI. The most common causes of repeat PCI in patients with previous COVID-19 were thrombosis and restenosis of the stent, as well as progression of stenosis at a site other than the location of the previous PCI.

Can Three-Dimensional T1-weighted MR Imaging Visualize the Vascular Lumen after Carotid Artery Stenting?

We aimed to evaluate the quality of various 3D T1-weighted images (T1WIs) of the stent lumen using a carotid stent phantom and determine the suitable T1WI sequence for visualization of the stent lumen after carotid artery stenting. The carotid stent phantom consisted of polypropylene tubes that mimicked common carotid arteries with and without stenting. On 1.5T and 3.0T MRI scanners, transverse T1WIs of the carotid stent phantom were obtained using 3D turbo spin-echo (TSE), 3D fast field-echo (3D-FFE), and 3D turbo field echo volumetric interpolated breath-hold examination (VIBE) under clinical conditions. The signal intensity ratio (SIR) was determined using the mean signal intensity of the stent lumen (SIstent) divided by the lumen without a stent in each T1WI. The SNR of the stent lumen (SNRstent) was calculated from SIstent divided by the standard deviation of the uniform region near the stent lumen. The 3D-FFE and VIBE had higher SNRstent than other T1WIs and clearly visualized the stent lumen. The 3D-TSE had the lowest SIR and SNRstent, preventing stent lumen visualization. T1WIs obtained using 3D-FFE and VIBE allows stent lumen visualization.

Nanogold-coated stent facilitated non-invasive photothermal ablation of stent thrombosis and restoration of blood flow.

In-stent restenosis (ISR) and stent thrombosis (ST) are the most serious complications of coronary angioplasty and stenting. Although the evolution of drug-eluting stents (DES) has significantly restricted the incidence of ISR, they are associated with an enhanced risk of ST. In the present study, we explore the photothermal ablation of a thrombus using a nano-enhanced thermogenic stent (NETS) as a modality for revascularization following ST. The photothermal activity of NETS, fabricated by coating bare metal stents with gold nanorods generating a thin plasmonic film of gold, was found to be effective in rarefying clots formed within the stent lumen in various in vitro assays including those under conditions mimicking blood flow. NETS implanted in the rat common carotid artery generated heat following exposure to a NIR-laser that led to effective restoration of blood flow within the occluded vessel in a model of ferric chloride-induced thrombosis. Our results present a proof-of-concept for a novel photothermal ablation approach by employing coated stents in the non-invasive management of ST.

Anterior Segment Optical Coherence Tomography for Cases of High Intraocular Pressure Following XEN Implant for Glaucoma.

This study showed that the XEN patency should be verified by OCT imaging in cases of encapsulated blebs. Although fibrosis plays the principal role, humor aqueous flow reduction could affect the "spacer" effect that inhibits the fibroblast attachments. To evaluate the application of the anterior segment optical coherence tomography (AS-OCT) imaging in studying the relationship between a low flow rate through the XEN63 and the development of a cystic bleb. Retrospective case series of 3 eyes presenting a cystic bleb after an XEN63 implantation for uncontrolled intraocular pressure (IOP). Demographic and clinical data were obtained from medical records. The imaging findings, complications, and managements following the surgery were evaluated. Three patients, with an average age of 67.3 years, initially showed a patent stent lumen and a functional bleb after surgery. The IOP of all eyes increased on average at 28.3 days from the surgery, with a mean value of 39.66mmHg. The slit lamp examination showed a cystic bleb. The AS-OCT imaging confirmed the previous finding and revealed either a partial or total occlusion of the stent internal ostium. A Nd:YAG laser, in proximity to the ostium, was performed to resolve the obstruction. Although the AS-OCT imaging showed the device patency and the IOP immediately decreased, the latter became elevated again. Consequently, in all the cases, a further needling procedure was needed to achieve an adequate IOP reduction. Six months after the two-step procedure, the IOP averaged 13.33mmHg, the XEN63 lumens appeared cleared, and the blebs showed a functional morphology. No adverse events were observed. The development of a cystic bleb may result from an altered balance between the flow rate through the XEN63 and the fibrosis development in the postoperative healing process. A proper follow-up based on slit lamp biomicroscopy, IOP measurement, and AS-OCT imaging is advisable to estimate and manage a cystic bleb following XEN63 implantation.

Coronary stent imaging in photon counting computed tomography: improved imaging of in-stent stenoses in a phantom with optimized reconstruction kernels.

Coronary CT angiography (CCTA) is becoming increasingly important in the workup of coronary artery disease. Imaging of stents and in-stent stenoses remains a challenge. This work investigates the assessability of in-stent stenoses in photon counting CT (PCCT) using ultra-high-resolution (UHR) imaging and optimized reconstruction kernels. In an established phantom, 6 stents with inserted hypodense stenoses were scanned in both standard resolution (SRM) and UHR in a clinical PCCT scanner (NAEOTOM Alpha, Siemens Healthineers, Germany). Reconstructions were made both with the clinically established and optimized kernels. The visible stent lumen and the extent of stenosis were quantitatively measured and compared with the angiographic reference standard. Also, region-of-interest (ROI)-based measurements and a qualitative assessment of image quality were performed. The visible stent lumen and the extent of stenosis were measured more precisely in UHR compared to SRM (0.11 ± 0.19 vs 0.41 ± 0.22 mm, P < .001). The optimized kernel further improved the accuracy of the measurements and image quality in UHR (0.35 ± 0.23 vs 0.47 ± 0.19 mm, P < .001). Compared to angiography, stenoses were overestimated in PCCT, on average with an absolute difference of 18.20% ± 4.11%. Photon counting CCTA allows improved imaging of in-stent stenoses in a phantom using UHR imaging and optimized kernels. These results support the use of UHR and optimized kernels in clinical practice and further studies. UHR imaging and optimized reconstruction kernels should be used in CCTA in the presence of cardiac stents.

Antimicrobial and Antiproliferative Coatings for Stents in Veterinary Medicine-State of the Art and Perspectives.

Microbial colonization in veterinary stents poses a significant and concerning issue in veterinary medicine. Over time, these pathogens, particularly bacteria, can colonize the stent surfaces, leading to various complications. Two weeks following the stent insertion procedure, the colonization becomes observable, with the aggressiveness of bacterial growth directly correlating with the duration of stent placement. Such microbial colonization can result in infections and inflammations, compromising the stent's efficacy and, subsequently, the animal patient's overall well-being. Managing and mitigating the impact of these pathogens on veterinary stents is a crucial challenge that veterinarians and researchers are actively addressing to ensure the successful treatment and recovery of their animal patients. In addition, irritation of the tissue in the form of an inserted stent can lead to overgrowth of granulation tissue, leading to the closure of the stent lumen, as is most often the case in the trachea. Such serious complications after stent placement require improvements in the procedures used to date. In this review, antibacterial or antibiofilm strategies for several stents used in veterinary medicine have been discussed based on the current literature and the perspectives have been drawn. Various coating strategies such as coating with hydrogel, antibiotic, or other antimicrobial agents have been reviewed.

Coronary computed tomography angiographic detection of in-stent restenosis via deep learning reconstruction: a feasibility study.

Evaluation of in-stent restenosis (ISR), especially for small stents, remains challenging during computed tomography (CT) angiography. We used deep learning reconstruction to quantify stent strut thickness and lumen vessel diameter at the stent and compared it with values obtained using conventional reconstruction strategies. We examined 166 stents in 85 consecutive patients who underwent CT and invasive coronary angiography (ICA) within 3months of each other from 2019-2021 after percutaneous coronary intervention with coronary stent placement. The presence of ISR was defined as percent diameter stenosis ≥ 50% on ICA. We compared a super-resolution deep learning reconstruction, Precise IQ Engine (PIQE), and a model-based iterative reconstruction, Forward projected model-based Iterative Reconstruction SoluTion (FIRST). All images were reconstructed using PIQE and FIRST and assessed by two blinded cardiovascular radiographers. PIQE had a larger full width at half maximum of the lumen and smaller strut than FIRST. The image quality score in PIQE was higher than that in FIRST (4.2 ± 1.1 versus 2.7 ± 1.2, p < 0.05). In addition, the specificity and accuracy of ISR detection were better in PIQE than in FIRST (p < 0.05 for both), with particularly pronounced differences for stent diameters < 3.0mm. PIQE provides superior image quality and diagnostic accuracy for ISR, even with stents measuring < 3.0mm in diameter. With improvements in the diagnostic accuracy of in-stent stenosis, CT angiography could become a gatekeeper for ICA in post-stenting cases, obviating ICA in many patients after recent stenting with infrequent ISR and allowing non-invasive ISR detection in the late phase. • Despite CT technology advancements, evaluating in-stent stenosis severity, especially in small-diameter stents, remains challenging. • Compared with conventional methods, the Precise IQ Engine uses deep learning to improve spatial resolution. • Improved diagnostic accuracy of CT angiography helps avoid invasive coronary angiography after coronary artery stenting.

Coronary stent imaging in photon counting computed Tomography: Optimization of reconstruction kernels in a phantom

PurposeImaging stents and in-stent stenosis remains a challenge in coronary computed tomography angiography (CCTA). In comparison to conventional Computed Tomography, Photon Counting CT (PCCT) provides decisive clinical advantages, among other things by providing low dose ultra-high resolution imaging of coronary arteries. This work investigates the image quality in CCTA using clinically established kernels and those optimized for the imaging of cardiac stents in PCCT, both for in-vitro stent imaging in 400 μm standard resolution mode (SRM) and 200 μm Ultra High Resolution Mode (UHR). MethodsBased on experimental scans, vascular reconstruction kernels (Bv56, Bv64, Bv72) were optimized. In an established phantom, 10 different coronary stents with 3 mm diameter were scanned in the first clinically available PCCT. Scans were reconstructed with clinically established and optimized kernels. Four readers measured visible stent lumen, performed ROI-based density measurements and rated image quality. ResultsRegarding the visible stent lumen, UHR is significantly superior to SRM (p < 0.001). In all levels, the optimized kernels are superior to the clinically established kernels (p < 0.001). One optimized kernel showed a significant reduction of noise compared to the clinically established kernels. Overall image quality is improved with optimized kernels. ConclusionsIn a phantom study PCCT UHR with optimized kernels for stent imaging significantly improves the ability to assess the in-stent lumen of small cardiac stents. We recommend using UHR with an optimized sharp vascular reconstruction kernel (Bv72uo) for imaging of cardiac stent.

Intimal tear closure by false lumen stent graft placement for postdissection thoracoabdominal aortic aneurysm

We report a false lumen (FL) stent graft technique to close the intimal tears at the visceral segment for a postdissection thoracoabdominal aneurysm after initial thoracic endovascular aortic repair. Following endovascular abdominal aortic repair, a stent graft was deployed in the FL, overlapping the main bodies from both previous repairs just after a bare metal stent was implanted in the FL proximal to the target lesion to prevent overdilation. A reentry tear at the iliac level was intentionally preserved to protect spinal cord perfusion and develop a collateral network and will be closed in the future staged procedure.

Improving image quality and resolution of coronary arteries in coronary computed tomography angiography by using high-definition scans and deep learning image reconstruction.

Coronary computed tomography angiography (CTA) has been increasingly used to identify the degree of coronary artery stenosis and plaque lesions in vessels. This study evaluated the feasibility of using high-definition (HD) scanning with high-level deep learning image reconstruction (DLIR-H) to improve the image quality and spatial resolution when imaging calcified plaques and stents in coronary CTA as compared to the standard definition (SD) reconstruction mode with adaptive statistical iterative reconstruction-V (ASIR-V). A total of 34 patients (age 63.3±10.9 years; 55.88% female) with calcified plaques and/or stents who underwent coronary CTA in HD-mode were included in this study. Images were reconstructed with SD-ASIR-V, HD-ASIR-V, and HD-DLIR-H. Subjective image quality with image noise and clarity of vessels, calcifications, and stented lumens was evaluated by 2 radiologists using a 5-point scale. The kappa (κ) test was used to analyze the interobserver agreement. Objective image quality with image noise, signal-to-noise-ratio (SNR), and contrast-to-noise-ratio (CNR) was measured and compared. Image spatial resolution and beam-hardening artifacts (BHAs) were also evaluated using the calcification diameter and CT numbers in 3 points along the stented lumen (inside, at the proximal and distal ends just outside stent). There were 45 calcified plaques and 4 coronary stents. HD-DLIR-H images had the highest overall image quality score (4.50±0.63) with the lowest image noise (22.59±3.59 HU) and the highest SNR (18.30±4.88) and CNR (26.56±6.33), followed by SD-ASIR-V50% image quality score (4.06±2.49), image noise (35.02±8.09 HU), SNR (12.77±1.59), CNR(15.67±1.92) and HD-ASIR-V50% image quality score (3.90±0.64), image noise (57.7±12.03 HU), SNR (8.16±1.86), CNR (10.01±2.39). HD-DLIR-H images also had the smallest calcification diameter measurement (2.36±1.58 mm), followed by HD-ASIR-V50% (3.46±2.07 mm) and SD-ASIR-V50% (4.06±2.49 mm). HD-DLIR-H images had the closest CT value measurements for the 3 points along the stented lumen, indicating much less BHA. Interobserver agreement on the image quality assessment was good to excellent (HD-DLIR-H: κ value =0.783; HD-ASIR-V50%: κ value =0.789; SD-ASIR-V50%: κ value =0.671). Coronary CTA with HD scan mode and DLIR-H significantly improves the spatial resolution for displaying calcifications and in-stent lumens while simultaneously reducing image noise.

Detection of microbial biofilms inside the lumen of ureteral stents: two case reports

BackgroundWe report large biofilm structures that covered almost the entirety of the lumen and surface of double-J stents in two postrenal transplant patients, with no development of urinary tract infection. Biofilm bacteria of one patient were integrated by coccus in a net structure, whereas overlapping cells of bacilli were present in the other patient. To the best of our knowledge, this is the first time that high-quality images of the architecture of noncrystalline biofilms have been found inside double-J stents from long-term stenting in renal transplant recipients.Case presentationTwo renal transplant recipients, a 34-year-old male and a 39-year-old female of Mexican-Mestizo origin, who underwent a first renal transplant and lost it due to allograft failure, had a second transplant. Two months after the surgical procedure, double-J stents were removed and analyzed using scanning electron microscopy (SEM). None of the patients had an antecedent of UTI, and none developed UTI after urinary device removal. There were no reports of injuries, encrustation, or discomfort caused by these devices.ConclusionThe bacterial biofilm inside the J stent from long-term stenting in renal transplant recipients was mainly concentrated on unique bacteria. Biofilm structures from the outside and inside of stents do not have crystalline phases. Internal biofilms may represent a high number of bacteria in the double-J stent, in the absence of crystals.

A Simplified Computational Workflow for Evaluation of Aortic Hemodynamics After Frozen Elephant Trunk Intervention in Type A Aortic Dissection

This study aimed to predict the hemodynamic performance of frozen elephant trunk (FET) intervention in surgically repaired type A aortic dissection (TAAD) patients through computational simulations of post-operative scenarios. Patient-specific geometries of a single patient were reconstructed from pre- and post-FET intervention computed tomography angiography (CTA) images. The pre-FET geometry was used to create post-FET geometry through anatomical modifications and a simplified finite element simulation to inflate the stented true lumen (TL) segment. Computational fluid dynamics (CFD) simulations were then performed on the virtually created post-FET geometry, and the results were compared with those obtained with the actual post-FET geometry. Various intervention scenarios with different stent-graft (SG) lengths and TL volume expansion were also simulated and compared to study their impacts on hemodynamic performance. A good overall agreement was achieved between the virtual and real post-FET models, with the maximum difference in true and false lumen (FL) pressures along the dissected aorta being 4.2%. Simulation results for the actual intervention revealed high wall shear stress (WSS) and pressure around a distal tear that was found to have expanded on post-FET scan. Extending the SG length dramatically reduced the maximum WSS and pressure around the distal tear. This pilot study demonstrates the feasibility of using the simplified simulation workflow for personalized assessment of aortic hemodynamics following FET intervention in repaired TAAD. Further studies in a large patient cohort are warranted.

Successful retrieval of migrated and embedded fully covered self-expanding metal stent using "snare and lithotripter" technique.

A 52-year-old woman with benign perihilar left intrahepatic duct stricture underwent repeated stricture dilation and multiple plastic stent placements. Subsequently, an 8 mm × 12 cm multi-hole fully covered self-expanding metal stent (MH-FCSEMS) was inserted. Six months later, she had abnormal liver biochemistry. Endoscopic retrograde cholangiography (ERC) revealed supra-papillary stent migration and tissue ingrowth at the proximal end ([Fig. 1]). Cholangioscopy (SpyGlass System; Boston Scientific Corp., Marlborough, Massachusetts, USA) showed that the stent lumen was obliterated by stone cast ([Fig. 2]). Stent removal with forceps and snare failed. The patient was referred to our center for a second opinion.

Stent imaging on a clinical dual-source photon-counting detector CT system-impact of luminal attenuation and sharp kernels on lumen visibility.

To assess the impact of scan modes and reconstruction kernels using a novel dual-source photon-counting detector CT (PCD-CT) on lumen visibility and sharpness of different stent sizes. A phantom containing six balloon-expandable stents (2.5 to 9 mm diameter) in silicone tubing was scanned on a PCD-CT with standard (0.6 mm and 0.4 mm thicknesses) and ultra-high-resolution (0.2 mm thickness) modes. With the use of increasing contrast medium concentrations, densities of 0, 200, 400, and 600 HU were achieved. Standard-resolution scans were reconstructed using increasing sharpness kernels, using both polyenergetic quantitative soft tissue "conventional" ((Qr40c(0.6 mm), Qr40c(0.4 mm), Qr72c(0.2 mm)) and vascular (Bv) virtual monoenergetic reconstructions (Bv44m(0.4 mm), Bv60m(0.4 mm)) at 70 keV. In-stent lumen visibility, sharpness (max. ΔHU of the stent measured in profile plots), and in-stent noise (standard deviation of HU) were measured. In-stent lumen visibility was highest for Qr72c(0.2 mm) (86.5 ± 2.8% to 88.3 ± 2.6%) and in Bv60m(0.4 mm) reconstructions (77.3 ± 2.9 to 82.7 ± 2.5%). Lumen visibility was lowest in the smallest stent (2.5 mm) ranging from 54.1% in Qr40c(0.6 mm) to 74.1% in Qr72c(0.2 mm) and highest in the largest stent (9 mm) ranging from 93.8% in Qr40c(0.6 mm) to 99.1% in the Qr72c(0.2 mm) series. Lumen visibility decreased by 2.1% for every 200-HU increase in lumen attenuation. Max. ΔHU between stents and stent lumen was highest in Qr72c(0.2 mm) (ΔHU 892 ± 504 to 1526 ± 517) and Bv60m(0.4 mm) series (ΔHU 480 ± 357 to 1030 ± 344). Improvement of lumen visibility and sharpness in UHR and Bv60m(0.4 mm) series was strongest in smaller stent sizes. UHR acquisition mode and sharp reconstruction kernels on a novel PCD-CT system significantly improve in-stent lumen visibility and sharpness-especially for smaller stent sizes. • In-stent lumen visibility and sharpness of stents significantly improve using sharp reconstruction kernels (Bv60) and ultra-high-resolution mode in photon-counting detector computed tomography. • The observed improvement of stent-lumen visibility was highest in smaller stent sizes.