Visualization Of Vessels Research Articles

Aortic roadmapping during EVAR: a combined FEM-EM tracking feasibility study.

Currently, the intra-operative visualization of vessels during endovascular aneurysm repair (EVAR) relies on contrast-based imaging modalities. Moreover, traditional image fusion techniques lack a continuous and automatic update of the vessel configuration, which changes due to the insertion of stiff guidewires. The purpose of this work is to develop and evaluate a novel approach to improve image fusion, that takes into account the deformations, combining electromagnetic (EM) tracking technology and finite element modeling (FEM). To assess whether EM tracking can improve the prediction of the numerical simulations, a patient-specific model of abdominal aorta was segmented and manufactured. A database of simulations with different insertion angles was created. Then, an ad hoc sensorized tool with three embedded EM sensors was designed, enabling tracking of the sensors' positions during the insertion phase. Finally, the corresponding cone beam computed tomography (CBCT) images were acquired and processed to obtain the ground truth aortic deformations of the manufactured model. Among the simulations in the database, the one minimizing the in silico versus in vitro discrepancy in terms of sensors' positions gave the most accurate aortic displacement results. The proposed approach suggests that the EM tracking technology could be used not only to follow the tool, but also to minimize the error in the predicted aortic roadmap, thus paving the way for a safer EVAR navigation.

Ultrasound guided arterial access for combat medics: A blinded proof-of-concept study using echogenic needles.

Obtaining percutaneous vascular access in hemodynamically unstable patients with constricted vessels can be challenging. Training combat medics in this procedure is necessary for administration of fluid and blood products and introducing endovascular bleeding control tools in pre-hospital settings. Echogenic coated needles might provide better ultrasound visibility in invasive procedures and hereby lower complications. The primary aim was to evaluate the efficacy of a microteaching program for obtaining ultrasound-guided femoral artery access for ultrasound inexperienced combat medics. The secondary aim was to assess the additional value of innovative echogenic coated needles in ultrasound-guided vascular access. Combat medics participated in a four-step microteaching program. The program consisted of a theoretical and step-by-step practical part with three different models including live and dead tissue & a REBOA Access Task Trainer. During the final test, all participants had to obtain femoral artery access on a pressurized post-mortem human specimen model with both echogenic coated and conventional needles. Self-perceived and observed performance as well as procedure times were scored. All nine participants succeeded in blood vessel visualization and obtaining vascular access in the two models within 3 minutes and were significantly faster during the second attempt on the pressurized post-mortem human specimen model. Scoring comparison and usability preference by ultrasound inexperienced personnel showed a significant difference in favor of the echogenic coated needles. Microteaching may be an effective approach to train combat medics in obtaining ultrasound-guided percutaneous femoral artery access. The use of echogenic coatings on needles could be a valuable adjunct and provide advantage in obtaining vascular access. Future research should focus on realistic simulation of austere situations and further evaluation of the use of echogenic coated instruments for vascular access in these pre-hospital settings.

Synthetic Optical Coherence Tomography Angiographs for Detailed Retinal Vessel Segmentation Without Human Annotations.

Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality that can acquire high-resolution volumes of the retinal vasculature and aid the diagnosis of ocular, neurological and cardiac diseases. Segmenting the visible blood vessels is a common first step when extracting quantitative biomarkers from these images. Classical segmentation algorithms based on thresholding are strongly affected by image artifacts and limited signal-to-noise ratio. The use of modern, deep learning-based segmentation methods has been inhibited by a lack of large datasets with detailed annotations of the blood vessels. To address this issue, recent work has employed transfer learning, where a segmentation network is trained on synthetic OCTA images and is then applied to real data. However, the previously proposed simulations fail to faithfully model the retinal vasculature and do not provide effective domain adaptation. Because of this, current methods are unable to fully segment the retinal vasculature, in particular the smallest capillaries. In this work, we present a lightweight simulation of the retinal vascular network based on space colonization for faster and more realistic OCTA synthesis. We then introduce three contrast adaptation pipelines to decrease the domain gap between real and artificial images. We demonstrate the superior segmentation performance of our approach in extensive quantitative and qualitative experiments on three public datasets that compare our method to traditional computer vision algorithms and supervised training using human annotations. Finally, we make our entire pipeline publicly available, including the source code, pretrained models, and a large dataset of synthetic OCTA images.

Systematic review and meta-analysis of endoscopic versus medical management of peptic ulcers with adherent clots.

Peptic ulcer disease is an important cause of upper gastrointestinal bleeding. Current guidelines recommend endoscopic treatment for ulcers with active bleeding or non-bleeding visible vessels, but the optimal management of ulcers with adherent clots is unclear. We performed a systematic review of the efficacy of endoscopic versus medical management of peptic ulcers with adherent clots. A systematic literature search was performed through September 2022 (MEDLINE, Embase, and CENTRAL). Randomized controlled trials (RCTs)comparing the effect of endoscopic versus medical management alone for peptic ulcers with adherent clots on the outcome of recurrent bleeding were incuded. A random-effects meta-analysis was performed to estimate the overall treatment effect. We included seven RCTs reporting on the endoscopic versus medical management of peptic ulcers with adherent clots. The pooled cohort comprised 268 patients with a mean age of 62.8years and a mean follow up of 20days. There was a significant reduction in the risk of recurrent bleeding with endoscopic hemostatic treatment for peptic ulcers with adherent clots, compared with medical management alone (risk ratio [RR]=0.40, 95% confidence interval [CI] 0.16-0.95, 268 participants). However, there was no difference in mortality (RR=0.90, 95% CI 0.23-3.59, 52 participants) or need for ulcer surgery (RR=0.48, 95% CI 0.10-2.28, 52 participants) between endoscopic and medical management groups. In summary, there was evidence for a reduction in recurrent bleeding from peptic ulcers with adherent clots treated with endoscopic hemostatic techniques compared with medical management alone but no difference in rates of mortality or need for surgery.

Oblique projections in the analysis of multislice computed tomography data in gunshot wounds

Background. The purpose is to determine the place and role of oblique projections in the analysis of multislice computed tomography (MSCT) data in gunshot wounds. Materials and me­thods. More than 3,300 MSCT studies performed in wounded and traumatized patients over a certain period in the Military Medical Clinical Center of the Northern Region of the Medical Forces Command were prospectively studied. All the wounded were male, the average age was 42.1 ± 2.4 years. MSCT of the head, thoracic and abdominal organs, pelvis, and limbs was performed. The frequency of using oblique projections and their informativeness were studied. Results. A prospective study demonstrated that coronal, axial, sagittal projections, and 3D modeling were used in 100 % of cases, and in 21.4 % — oblique projections to improve MSCT results. The distribution by localization of MSCT was as follows: head — 32.9 %, neck — 7.6 %, chest organs — 32.2 %, abdominal organs — 22.3 %, limbs — 5.0 %. MSCT in angiomode was performed in 3.5 % of injured and traumatized patients: head — 27.2 %, neck — 18.4 %, chest organs — 28.9 %, abdominal organs — 23.7 %, limbs — 1.8 %. Oblique projections in MSCT data analysis were used when studying the wound channel in 82.3 % of cases, to improve the visualization of vessels during MSCT in angiomode — in 12.6 % and to improve the visualization of bone fracture lines — in 5.1 %. Conclusions. In the structure of MSCT studies, the head, thoracic organs, abdominal organs, neck, and limbs prevail by localization (in descending order). Oblique projections are used is 1/5 of cases and allow to improve the visualization of the direction of the wound channel, vessels during angiography and lines of flat and long tubular bone fractures.

Recent advancements in image-enhanced endoscopy in the pancreatobiliary field.

Image-enhanced endoscopy (IEE) has advanced gastrointestinal disease diagnosis and treatment. Traditional white-light imaging has limitations in detecting all gastrointestinal diseases, prompting the development of IEE. In this review, we explore the utility of IEE, including texture and color enhancement imaging and red dichromatic imaging, in pancreatobiliary (PB) diseases. IEE includes methods such as chromoendoscopy, optical-digital, and digital methods. Chromoendoscopy, using dyes such as indigo carmine, aids in delineating lesions and structures, including pancreato-/cholangio-jejunal anastomoses. Optical-digital methods such as narrow-band imaging enhance mucosal details and vessel patterns, aiding in ampullary tumor evaluation and peroral cholangioscopy. Moreover, red dichromatic imaging with its specific color allocation, improves the visibility of thick blood vessels in deeper tissues and enhances bleeding points with different colors and see-through effects, proving beneficial in managing bleeding complications post-endoscopic sphincterotomy. Color enhancement imaging, a novel digital method, enhances tissue texture, brightness, and color, improving visualization of PB structures, such as PB orifices, anastomotic sites, ampullary tumors, and intraductal PB lesions. Advancements in IEE hold substantial potential in improving the accuracy of PB disease diagnosis and treatment. These innovative techniques offer advantages paving the way for enhanced clinical management of PB diseases. Further research is warranted to establish their standard clinical utility and explore new frontiers in PB disease management.

Xanthone Derivatives and Their Potential Usage in the Treatment of Telangiectasia and Rosacea

Xanthone derivatives, a class of natural compounds abundantly found in plants such as mangosteen (Garcinia mangostana) and certain herbs, have garnered substantial interest due to their diverse pharmacological properties, including antioxidant, anti-inflammatory, and anti-cancer activities. Recent investigations have unveiled their potential as modulators of enzymatic activity, prompting exploration into their effects on hyaluronidase-mediated hyaluronic acid (HA) degradation, and their effects in topical treatment of telangiectasia and rosacea. Telangiectasia and rosacea are common dermatological conditions characterized by chronic skin inflammation, vascular abnormalities, and visible blood vessels, resulting in significant cosmetic concerns and impaired quality of life for affected individuals. This review aims to provide a comprehensive overview of the current understanding regarding the interplay between the mechanisms of action by which xanthone derivatives exert their therapeutic effects, including the inhibition of pro-inflammatory cytokines, modulation of oxidative stress pathways, and regulation of vascular endothelial growth factors. Furthermore, we will discuss the implications of harnessing xanthone derivatives as therapeutic agents for mitigating vascular dysfunction and its associated pathologies, thereby offering insights into future research directions and therapeutic strategies in the field of vascular biology.

Analysis on efficacy of magnetic resonance lymphangiography using INV-001 in healthy beagle dogs

We aimed to conduct a proof-of-concept study of INV-001 in visualizing lymphatic vessels and nodes without venous contamination and to determine the optimal dose condition of INV-001 for magnetic resonance lymphangiography (MRL) in healthy beagles. MRL was performed using a 3.0-Tesla (T) whole body clinical magnetic resonance imaging (MRI) scanner. A dose-finding study of INV-001 for MRL in beagles (N = 6) was carried out according to an adaptive optimal dose finding design. For the reproducibility study (N = 6), MRL was conducted at selected INV-001 doses (0.056 and 0.112 mg Fe/kg) with a 15 mM concentration. Additionally, an excretion study (N = 3) of INV-001 was conducted by analyzing T1, T2, and T2* maps of the liver and kidney 48 h post-administration. INV-001 administration at doses of 0.056 and 0.112 mg Fe/kg (concentration: 15 mM) consistently demonstrated the visualization of contrast-enhanced lymphatic vessels and nodes without venous contamination in the beagles. The contrast enhancement effect was highest at 30 min after INV-001 administration, then gradually decreasing. No toxicity-related issues were identified during the study. After 48 h, the T1, T2, and T2* values in the liver and both kidneys were found to be comparable to the pre-administration values, indicating thorough INV-001 excretion. The optimal dosing conditions of INV-001 for MRL for contrast-enhanced visualization of lymphatic vessels and nodes exclusively with no venous contamination in beagles was determined to be 0.056 mg Fe/kg with a 15 mM concentration.

CAVE: Cerebral artery–vein segmentation in digital subtraction angiography

Cerebral X-ray digital subtraction angiography (DSA) is a widely used imaging technique in patients with neurovascular disease, allowing for vessel and flow visualization with high spatio-temporal resolution. Automatic artery–vein segmentation in DSA plays a fundamental role in vascular analysis with quantitative biomarker extraction, facilitating a wide range of clinical applications. The widely adopted U-Net applied on static DSA frames often struggles with disentangling vessels from subtraction artifacts. Further, it falls short in effectively separating arteries and veins as it disregards the temporal perspectives inherent in DSA. To address these limitations, we propose to simultaneously leverage spatial vasculature and temporal cerebral flow characteristics to segment arteries and veins in DSA. The proposed network, coined CAVE, encodes a 2D+time DSA series using spatial modules, aggregates all the features using temporal modules, and decodes it into 2D segmentation maps. On a large multi-center clinical dataset, CAVE achieves a vessel segmentation Dice of 0.84 (±0.04) and an artery–vein segmentation Dice of 0.79 (±0.06). CAVE surpasses traditional Frangi-based k-means clustering (P < 0.001) and U-Net (P < 0.001) by a significant margin, demonstrating the advantages of harvesting spatio-temporal features. This study represents the first investigation into automatic artery–vein segmentation in DSA using deep learning. The code is publicly available at https://github.com/RuishengSu/CAVE_DSA.

Role of Personalized Medicine in Myocardial Infarction With Nonobstructive Coronary Artery Disease (MINOCA): An Updated Review

Cardiovascular diseases, notably myocardial infarction (MI), contribute significantly to global mortality. While traditional MIs are often associated with notable coronary artery blockages, a subgroup experiences MI without such blockages, termed myocardial infarction with nonobstructive coronary arteries (MINOCA). Current diagnostic methods, like invasive coronary angiograms, are inadequate in diagnosing MINOCA due to the absence of visible vessel blockages. Personalized medicine endeavors to introduce novel diagnostic tools for early identification and tailored management of MINOCA. Unlike percutaneous coronary intervention, which lacks efficacy in MINOCA, personalized medical management aligned with the specific underlying pathophysiological cause is essential. Treatments may include statins, agents modulating the renin-angiotensin system, and antiplatelet therapies if linked to plaque disruption. At the same time, calcium channel blockers may be pivotal if coronary artery spasm is the primary cause. Research is ongoing to refine tailored therapies and discover new biomarkers, highlighting the crucial need for individualized approaches in managing MINOCA.

Immediate lymphatic reconstruction: Lessons learned over eight years

Immediate lymphatic reconstruction (ILR) is recognized as a surgical approach used to reduce the risk of developing secondary lymphedema, and evidence demonstrating the efficacy of ILR is favorable. Our Lymphatic Center has become a centralized location offering ILR for the risk-reduction in breast cancer-related lymphedema (BCRL) in New England. Over the course of our experience, we made several modifications and adapted our approach to enhance the operative success of this procedure. These include advancements in our use of indocyanine green (ICG) imaging to identify baseline lymphatic anatomical variation, utilization of fluorescein isothiocyanate for lymphatic vessel visualization, application of the lymphosome concept to guide arm injection sites, verification of anastomotic patency (using ICG), localization of reconstruction to guide radiation therapy, incorporation of intraoperative tools to facilitate better anatomic visualization of the axilla, and addition of a lower extremity vein graft to mitigate venous-related complications. Collecting information from each surgery in a standardized manner, including intraoperative lymphatic channel measurements, and deploying clips for possible future radiation exposure, enables future studies on ILR patient outcomes. In this contribution, we aimed to share our institutional modifications with the surgical community to facilitate further adoption, conversation, and advancement of ILR for the risk-reduction in BCRL.

Predictive value of the hemispheric magnetic resonance angiography score on the development of indirect pial synangiosis after combined revascularization surgery for adult moyamoya disease.

It is difficult to precisely predict indirect bypass development in the context of combined bypass procedures in moyamoya disease (MMD). We aimed to investigate the predictive value of magnetic resonance angiography (MRA) signal intensity in the peripheral portion of the major cerebral arteries for indirect bypass development in adult patients with MMD. We studied 93 hemispheres from 62 adult patients who underwent combined direct and indirect revascularization between 2005 and 2019 and genetic analysis for RNF213 p.R4810K. The signal intensity of the peripheral portion of the major intracranial arteries during preoperative MRA was graded as a hemispheric MRA score (0-3 in the middle cerebral artery and 0-2 in the anterior cerebral and posterior cerebral arteries, with a high score representing low visibility) according to each vessel's visibility. Postoperative bypass development was qualitatively evaluated using MRA, and we evaluated the correlation between preoperative factors, including the hemispheric MRA score and bypass development, using univariate and multivariate analyses. A good indirect bypass was observed in 70% of the hemispheres. Hemispheric MRA scores were significantly higher in hemispheres with good indirect bypass development than in those with poor indirect bypass development (median: 3 vs. 1; p < 0.0001). Multiple logistic regression analysis revealed hemispheric MRA score as an independent predictor of good indirect bypass development (odds ratio, 2.1; 95% confidence interval, 1.3-3.6; p < 0.01). The low hemispheric MRA score (< 2) and wild-type RNF213 predicted poor indirect bypass development with a specificity of 0.92. Hemispheric MRA score was a predictive factor for indirect bypass development in adult patients who underwent a combined bypass procedure for MMD. Predicting poor indirect bypass development may lead to future tailored bypass surgeries for MMD.

Super High Contrast USPIO-Enhanced Cerebrovascular Angiography Using Ultrashort Time-to-Echo MRI.

Ferumoxytol (Ferahame, AMAG Pharmaceuticals, Waltham, MA) is increasingly used off-label as an MR contrast agent due to its relaxivity and safety profiles. However, its potent T2∗ relaxivity limits achievable T1-weighted positive contrast and leads to artifacts in standard MRI protocols. Optimization of protocols for ferumoxytol deployment is necessary to realize its potential. We present first-in-human clinical results of the Quantitative Ultrashort Time-to-Echo Contrast Enhanced (QUTE-CE) MRA technique using the superparamagnetic iron oxide nanoparticle agent ferumoxytol for vascular imaging of the head/brain in 15 subjects at 3.0T. The QUTE-CE MRA method was implemented on a 3T scanner using a stack-of-spirals 3D Ultrashort Time-to-Echo sequence. Time-of-flight MRA and standard TE T1-weighted (T1w) images were also collected. For comparison, gadolinium-enhanced blood pool phase images were obtained retrospectively from clinical practice. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and intraluminal signal heterogeneity (ISH) were assessed and compared across approaches with Welch's two-sided t-test. Fifteen volunteers (54 ± 17 years old, 9 women) participated. QUTE-CE MRA provided high-contrast snapshots of the arterial and venous networks with lower intraluminal heterogeneity. QUTE-CE demonstrated significantly higher SNR (1707 ± 226), blood-tissue CNR (1447 ± 189), and lower ISH (0.091 ± 0.031) compared to ferumoxytol T1-weighted (551 ± 171; 319 ± 144; 0.186 ± 0.066, respectively) and time-of-flight (343 ± 104; 269 ± 82; 0.190 ± 0.016, respectively), with p < 0.001 in each comparison. The high CNR increased the depth of vessel visualization. Vessel lumina were captured with lower heterogeneity. Quantitative Ultrashort Time-to-Echo Contrast-Enhanced MR angiography provides approximately 5-fold superior contrast with fewer artifacts compared to other contrast-enhanced vascular imaging techniques using ferumoxytol or gadolinium, and to noncontrast time-of-flight MR angiography, for clinical vascular imaging. This trial is registered with NCT03266848.

Extensive Macular Atrophy with Pseudodrusen-like appearance: Progression Kinetics and Late-Stage Findings

To describe the clinical outcome and late-stage findings of extensive macular atrophy with pseudodrusen-like appearance (EMAP). Retrospective cohort study. Seventy-eight patients (156 eyes) affected by EMAP. We collected data on best-corrected visual acuity, kinetic perimetry, OCT, short-wavelength autofluorescence, and near-infrared autofluorescence findings. Genetic testing for the TIMP3 and C1QTNF5 genes was performed via Sanger sequencing for 58 patients, with no pathogenic variants identified. The primary outcomes were best-corrected visual acuity at the last examination, visual field at the last examination, and incidence rates and time-to-event curves for blindness with the United States Social Security Administration and World Health Organization (WHO) criteria, foveal involvement, and atrophy enlargement beyond the 30° and 55° field of view. Imaging findings at the last examination were secondary outcomes. At the most recent visit, mean age was 70.9 ± 5.2 years. Using United States criteria, 58.1% of the patients were blind, and 25.8% were blind according to WHO criteria. All eyes showed large central scotomas, which were associated with visual field constriction in 22.2% of eyes. We detected focal openings or large dehiscences of Bruch's membrane (BM) in 25.4% of eyes. Near-infrared autofluorescence showed increased visibility of the choroidal vessels beyond the atrophy in 87.2% of eyes. The incidence rates for blindness were 3.95 per 100 patient-years with United States criteria and 1.54 per 100 patient-years according to WHO criteria. The incidence rates were 22.8 per 100 eye-years for foveal involvement, 12.0 per 100 eye-years for atrophy enlargement beyond 30°, and 6.6 per 100 eye-years for atrophy enlargement beyond 55°. The estimates were not influenced by the age at onset. We identified characteristic imaging findings, including BM ruptures, in elder patients with EMAP and calculated incidence rates for different functional and anatomic outcomes. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A Review on the Design of Carbon-Based Nanomaterials as MRI Contrast Agents.

The administration of magnetic resonance imaging (MRI) contrast agents (CAs) has been conducted since 1988 by clinicians to enhance the clarity and interpretability of MR images. CAs based on gadolinium chelates are the clinical standard used worldwide for the diagnosis of various pathologies, such as the detection of brain lesions, the visualization of blood vessels, and the assessment of soft tissue disorders. However, due to ongoing concerns associated with the safety of gadolinium-based contrast agents, considerable efforts have been directed towards developing contrast agents with better relaxivities, reduced toxicity, and eventually combined therapeutic modalities. In this context, grafting (or encapsulating) paramagnetic metals or chelates onto (within) carbon-based nanoparticles is a straightforward approach enabling the production of contrast agents with high relaxivities while providing extensive tuneability regarding the functionalization of the nanoparticles. Here, we provide an overview of the parameters defining the efficacy of lanthanide-based contrast agents and the subsequent developments in the field of nanoparticular-based contrast agents incorporating paramagnetic species.

Design Optimization of A Triple-Layer Flat-Panel Detector for Three-Material Decomposition.

Spectral radiography and fluoroscopy with multi-layer flat-panel detectors (FPD) is being actively investigated in a range of clinical applications. For applications involving contrast administration, maximal contrast resolution is achieved when overlaying background anatomy is completely removed. This calls for three-material decomposition (soft tissue, bone, and contrast) enabled by measurements in three energy channels. We have previously demonstrated the feasibility of such decomposition using a triple-layer detector. While algorithmic solutions can be adopted to mitigate noise in the material basis images, in this work, we seek to fundamentally improve the conditioning of the problem through optimized system design. Design parameters include source voltage, the thickness of the top two CsI scintillators, and the thickness of two copper interstitial filters. The design objective is to minimize noise in the basis image containing contrast, chosen as gadolinium in this work to improve separation from bone. The optimized design was compared with other designs with unoptimized scintillator thickness and/or without interstitial filtration. Results show that CsI thickness optimization and interstitial filtration can significantly reduce noise in the gadolinium image by 35.7% and 42.7% respectively within a lung ROI, which in turn boosts detectability of small vessels. Gadolinium and bone signals are separated in all cases. Visualization of coronary vessels is enabled by the combining optimized system design and regularization. Results from this work demonstrate that three-material decomposition can be significantly improved with system design optimization. Optimized designs obtained from this work can inform imaging techniques selection and triple-layer detector fabrication for spectral radiography.

Development of a novel endoscopic hemostasis-assisted navigation AI system in the standardization of post-ESD coagulation

Abstract Background and study aims While gastric endoscopic submucosal dissection (ESD) has become a treatment with fewer complications, delayed bleeding remains a challenge. Post-ESD coagulation (PEC) is performed to prevent delayed bleeding. Therefore, we developed an artificial intelligence (AI) to detect vessels that require PEC in real time. Materials and methods Training data were extracted from 153 gastric ESD videos with sufficient images taken with a second-look endoscopy (SLE) and annotated as follows: (1) vessels that showed bleeding during SLE without PEC; (2) vessels that did not bleed during SLE with PEC; and (3) vessels that did not bleed even without PEC. The training model was created using Google Cloud Vertex AI and a program was created to display the vessels requiring PEC in real time using a bounding box. The evaluation of this AI was verified with 12 unlearned test videos, including four cases that required additional coagulation during SLE. Results The results of the test video validation indicated that 109 vessels on the ulcer required cauterization. Of these, 80 vessels (73.4%) were correctly determined as not requiring additional treatment. However, 25 vessels (22.9%), which did not require PEC, were overestimated. In the four videos that required additional coagulation in SLE, AI was able to detect all bleeding vessels. Conclusions The effectiveness and safety of this endoscopic treatment-assisted AI system that identifies visible vessels requiring PEC should be confirmed in future studies.

Evaluation of four computed tomography reconstruction algorithms using a coronary artery phantom.

Despite advancements in coronary computed tomography angiography (CTA), challenges in positive predictive value and specificity remain due to limited spatial resolution. The purpose of this experimental study was to investigate the effect of 2nd generation deep learning-based reconstruction (DLR) on the quantitative and qualitative image quality in coronary CTA. A vessel model with stepwise non-calcified plaque was scanned using 320-detector CT. Image reconstruction was performed using four techniques: hybrid iterative reconstruction (HIR), model-based iterative reconstruction (MBIR), DLR, and 2nd generation DLR. The luminal peak CT number, contrast-to-noise ratio (CNR), and edge rise slope (ERS) were quantitatively evaluated via profile curve analysis. Two observers qualitatively graded the graininess, lumen sharpness, and overall lumen visibility on the basis of the degree of confidence for the stenosis severity using a five-point scale. The image noise with HIR, MBIR, DLR, and 2nd generation DLR was 23.0, 21.0, 16.9, and 9.5 HU, respectively. The corresponding CNR (25% stenosis) was 15.5, 15.9, 22.1, and 38.3, respectively. The corresponding ERS (25% stenosis) was 203.2, 198.6, 228.9, and 262.4 HU/mm, respectively. Among the four reconstruction methods, the 2nd generation DLR achieved the significantly highest CNR and ERS values. The score of 2nd generation DLR in all evaluation points (graininess, sharpness, and overall lumen visibility) was higher than those of the other methods (overall vessel visibility score, 2.6±0.5, 3.8±0.6, 3.7±0.5, and 4.6±0.5 with HIR, MBIR, DLR, and 2nd generation DLR, respectively). 2nd generation DLR provided better CNR and ERS in coronary CTA than HIR, MBIR, and previous-generation DLR, leading to the highest subjective image quality in the assessment of vessel stenosis.

조영 증강 CT 검사 시 금식 여부에 따른 조영제 과민반응 사례 비교

Contrast agent is a medication that aids in diagnosis by enhancing the visibility of tissues or blood vessels during a CT scan. However, to prevent hypersensitivity reactions, patients were inconvenienced by having to fast for more than a few hours before the contrast-enhanced CT examination. Recently, the importance of fasting is gradually diminishing as indicated by numerous studies. Our hospital has also revised the fasting guidelines accordingly. As a result, tests other than the abdomen test are now being conducted without requiring fasting. The number of cases of hypersensitivity reactions and nausea before and after the revision was not significant, and retesting did not occur either. Currently, many hospitals in Korea are implementing various fasting guidelines before contrast-enhanced CT scans. It is urgently necessary to revise these guidelines in accordance with the recently announced trend.

Reduced Retinal Blood Vessel Densities Measured by Optical Coherence Tomography Angiography in Keratoconus Patients Are Negatively Correlated with Keratoconus Severity.

Keratoconus (KC) is the most common corneal ectasia. Optical coherence tomography angiography (OCT-A) is a relatively new non-invasive imaging technique that allows the visualization and quantification of retinal and choriocapillary blood vessels. The aim of this study is to assess retinal and choriocapillary vessel density (VD) differences between KC patients and healthy controls and to investigate correlations between VD and KC severity. Fifty-two eyes were included in this exploratory study: twenty-six eyes from 26 KC patients and twenty-six eyes from 26 age- and gender-matched healthy controls. All patients underwent Scheimpflug corneal topography with Pentacam, axis lengths measurement and optical coherence tomography angiography (OCT-A). The thinnest spot in corneal pachymetry, maximum K (Kmax) and KC severity indices from the Belin/Ambrósio enhanced ectasia display (BAD) were also assessed. There was a distinct reduction particularly in the retinal VD of the superficial capillary plexus (SCP). Correlation analyses showed strong and moderate negative correlations between the VD in the macular SCP and BAD KC scores and between the SCP VD and Kmax. There was no difference in retinal thickness between the KC and healthy controls. With this study, further evidence for altered VD measurements by OCT-A in KC patients is given. For the first time, we demonstrated negative correlations between BAD KC scores and retinal blood vessel alterations. A major limitation of the study is the relatively small sample size. Since an artefactual reduction of the quantitative OCT-A measurements due to irregular corneal topography in KC must be assumed, it remains to be investigated whether there are also actual changes in the retinal microcirculation in KC.