Visualization Of Lumen Research Articles

Penetrating Crohn disease: does it occur in the absence of stricturing disease?

To establish the relationship between penetrating complications and bowel luminal narrowing/stricturing disease in pediatric Crohn disease (CD). This retrospective study was IRB-approved and HIPAA compliant with waiver of informed consent. CT and MRI examinations describing intra-abdominal penetrating complications in CD patients ≤18years old between January 1, 2009 and March 31, 2016 were reviewed to document: type of complication, affected bowel segment, minimum bowel luminal diameter, maximum upstream diameter, location of penetrating complication relative to luminal narrowing, length of narrowed bowel segment, and the presence of active bowel wall inflammation. Data were summarized using descriptive statistics including means, standard deviations, as well as counts and percentages. A total of 52 penetrating complications were identified in 45 patients. Mean patient age was 15.7±2.2years (range 11-18years) with 25/45 (56%) boys. Nearly all penetrating complications (51/52, 98%) were associated with a minimum bowel luminal diameter of ≤2mm, with no visible lumen in 26/52 (50%). Mean maximum upstream diameter was 2.8±0.8cm (range 1.2-5.2cm), and 17/52 (33%) penetrating complications were associated with >3cm upstream diameter. The mean ratio of maximum to minimum luminal diameter was 26.2±8.8 (range 3.6-52.0). Active intestinal inflammation was associated with 100% (52/52) of penetrating complications. Nearly every penetrating complication (51/52, 98%) involved the terminal or distal ileum. Penetrating complications in pediatric CD nearly always occur in the setting of considerable luminal narrowing or stricture and active intestinal inflammation.

MTE 19.01 Laser Therapy for Airway Obstruction

MTE 19.01 Laser Therapy for Airway Obstruction

Diagnostic accuracy of in-stent restenosis using model-based iterative reconstruction at coronary CT angiography: initial experience.

The purpose of our study was to compare the diagnostic performance of coronary CT angiography (CTA) subjected to model-based iterative reconstruction (IR) or hybrid IR to rule out coronary in-stent restenosis. We enrolled 16 patients who harboured 22 coronary stents. They underwent coronary CTA on a 320-slice CT scanner. The images were reconstructed with hybrid IR (AIDR 3D) and model-based IR (FIRST) algorithms. We calculated the stent lumen attenuation increase ratio and measured the visible stent lumen diameter. Two blinded observers visually graded the likelihood of in-stent restenosis (lesions ≥ 50%) on hybrid IR and FIRST images. The stent lumen attenuation increase ratio on FIRST- was lower than on AIDR 3D images (0.20 vs 0.32). The ratio of the visible- compared to the true stent lumen diameter was higher on FIRST- than AIDR 3D images (52.5 vs 47.5%). Invasive coronary angiography identified five stents (22.7%) with significant in-stent restenosis. The use of FIRST improved the sensitivity (60 vs 100%), positive (75.0 vs 83.3%) and negative predictive value (88.9 vs 100%) and the accuracy (86.4 vs 95.5%) for the detection of in-stent restenosis. Specificity was 94.1% for both reconstruction methods. The model-based IR algorithm may improve diagnostic performance for the detection of in-stent restenosis. Advances in knowledge: Compared to hybrid IR, the new model-based IR algorithm reduced blooming artefacts and improved the image quality. It can be expected to improve diagnostic performance for the detection of in-stent restenosis on coronary CTA images.

Imaging behind occluded areas with an iatrogenic perforated balloon: A safe, practical, and simple new method of visualizing the distal lumen in total occlusion.

In the present study, we investigated the effectiveness and reliability of a new method that reveals whether guidewire advanced distal to the lesion is in the lumen in patients with acute (ATO) or chronic coronary total occlusion (CTO). Forty-one patients with symptomatic ATO and 22 patients with CTO who were admitted into our catheterization laboratory between January 2016 and March 2017 were included. In patients in whom antegrade filling could not be demonstrated after passing 0.014″ guidewire beyond the total lesion, a 1.25 × 15 mm balloon was punctured with a needle outside the operative field to visualize the total lesion. This perforated balloon was then used to deliver an opaque substance through this hole to visualize the distal part. The mean age of our 63 patients was 66 ± 12 years. They had diabetes (57%), hypertension (100%), and a history of PCI (85%). The mean procedural time was 27 ± 6.8 min, and the mean volume of contrast material used was 93.9 ± 24 mL. This technique was 100% successful in accurately demonstrating the distal lumen and preventing complications. This new method we developed is much simpler and more useful than other methods for visualization of the true lumen because we can re-orient the balloon at the time of opaque injection and use 190 cm guidewire without additional costs. Additionally, one balloon is sufficient for the operation.

A Rare and Fatal Case of Dobhoff Tube Placement-Associated Small Bowel Perforation Presenting With Acute Leukopenia

Enteral feeding with Dobhoff tubes is a common mode of nutrition in acute or chronically ill patients. Common adverse events associated with Dobhoff placement include epistaxis and sore throat. More serious complications such as esophageal perforation and pneumothorax have been reported. We report a case of small bowel perforation after Dobhoff placement with acute leukopenia as an initial laboratory manifestation. A 75-year-old female presented to the hospital with a 3-year history of worsening hoarseness and shortness of breath. Bedside laryngoscopy demonstrated a large laryngeal mass. Biopsy results were positive for squamous cell carcinoma. Bronchoscopy and esophagoscopy (to pre-pyloric region) were unremarkable. Due to severe protein malnutrition, a Dobhoff was placed for pre-operative optimization for laryngectomy. Post-placement KUB showed tube overlying the body of stomach. 12 hours post Dobhoff insertion, vital signs were notable for hypotension to 72/48 mmHg. Physical exam was notable for diminished bowel sounds. Laboratory results showed an acute leukopenia of 1100 mcL, and lactate of 3.6 mmol/L. KUB showed advancement of the Dobhoff tube, with visualization of bowel wall lumen suggesting pneumoperitoneum. The patient remained hypotensive despite fluid resuscitation and was transferred to the ICU for pressor support. A CT scan of the abdomen revealed intraperitoneal and retroperitoneal air, with the enteric tube noted to be extraluminal with suspected perforation of the second part of the duodenum. Surgery was consulted, however due to the patient progressing to multi-system organ failure, and high surgical mortality risk, the patient was made DNR/Comfort Care and expired 6 hours later. Dobhoff placement is a common procedure performed across the country. Although a relatively safe procedure, it can have complications such as bowel perforation. One of the initial presenting clues may be acute leukopenia. Acute leukopenia has also been reported in laparoscopic bowel perforations during urological surgery. The mechanism of acute leukopenia in bowel perforation could be due to peritonitis leading to sepsis. Sepsis has been shown to cause acute bone marrow suppression leading to leukopenia. Another explanation is the marginalization of leukocytes in conditions of decreased blood flow such as hypotension. Leukocytes are shifted outward by RBCs in laminar flow, and in slow flow the leukocytes will adhere to the endothelial surface in larger number.Figure: Enteric tip overlying the gastric pylorus. Arrow showing “Rigler's Sign”, suggesting air on both sides of bowel concerning for extraluminal air.Figure: Large arrow showing intraperitoneal air in the anterior extraluminal space. Small arrow shows enteric tube possibly in extraluminal space.

An artificial neural network architecture for non-parametric visual odometry in wireless capsule endoscopy

Wireless capsule endoscopy is a non-invasive screening procedure of the gastrointestinal (GI) tract performed with an ingestible capsule endoscope (CE) of the size of a large vitamin pill. Such endoscopes are equipped with a usually low-frame-rate color camera which enables the visualization of the GI lumen and the detection of pathologies. The localization of the commercially available CEs is performed in the 3D abdominal space using radio-frequency (RF) triangulation from external sensor arrays, in combination with transit time estimation. State-of-the-art approaches, such as magnetic localization, which have been experimentally proved more accurate than the RF approach, are still at an early stage. Recently, we have demonstrated that CE localization is feasible using solely visual cues and geometric models. However, such approaches depend on camera parameters, many of which are unknown. In this paper the authors propose a novel non-parametric visual odometry (VO) approach to CE localization based on a feed-forward neural network architecture. The effectiveness of this approach in comparison to state-of-the-art geometric VO approaches is validated using a robotic-assisted in vitro experimental setup.

Simultaneous bright- and black-blood whole-heart MRI for noncontrast enhanced coronary lumen and thrombus visualization.

PurposeTo develop a 3D whole‐heart Bright‐blood and black‐blOOd phase SensiTive (BOOST) inversion recovery sequence for simultaneous noncontrast enhanced coronary lumen and thrombus/hemorrhage visualization.MethodsThe proposed sequence alternates the acquisition of two bright‐blood datasets preceded by different preparatory pulses to obtain variations in blood/myocardium contrast, which then are combined in a phase‐sensitive inversion recovery (PSIR)‐like reconstruction to obtain a third, coregistered, black‐blood dataset. The bright‐blood datasets are used for both visualization of the coronary lumen and motion estimation, whereas the complementary black‐blood dataset potentially allows for thrombus/hemorrhage visualization. Furthermore, integration with 2D image‐based navigation enables 100% scan efficiency and predictable scan times. The proposed sequence was compared to conventional coronary MR angiography (CMRA) and PSIR sequences in a standardized phantom and in healthy subjects. Feasibility for thrombus depiction was tested ex vivo.ResultsWith BOOST, the coronary lumen is visualized with significantly higher (P < 0.05) contrast‐to‐noise ratio and vessel sharpness when compared to conventional CMRA. Furthermore, BOOST showed effective blood signal suppression as well as feasibility for thrombus visualization ex vivo.ConclusionA new PSIR sequence for noncontrast enhanced simultaneous coronary lumen and thrombus/hemorrhage detection was developed. The sequence provided improved coronary lumen depiction and showed potential for thrombus visualization. Magn Reson Med 79:1460–1472, 2018. © 2017 International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

In vivo MR-angiography for the assessment of aortic aneurysms in an experimental mouse model on a clinical MRI scanner: Comparison with high-frequency ultrasound and histology.

BackgroundMR-angiography currently represents one of the clinical reference-standards for the assessment of aortic-dimensions. For experimental research in mice, dedicated preclinical high-field MRI scanners are used in most studies. This type of MRI scanner is not available in most institutions. The aim of this study was to evaluate the potential of MR-angiography performed on a clinical MR scanner for the assessment of aortic aneurysms in an experimental mouse model, compared to a preclinical high-resolution ultrasound imaging system and histopathology.MethodsAll in vivo MR imaging was performed with a clinical 3T MRI system (Philips Achieva) equipped with a clinical gradient system in combination with a single-loop surface-coil (47 mm). All MR sequences were based on clinically used sequences. For ultrasound, a dedicated preclinical high-resolution system (30 MHz linear transducer, Vevo770, VisualSonics) was used. All imaging was performed with an ApoE knockout mouse-model for aortic aneurysms. Histopathology was performed as reference-standard at all stages of aneurysm development.ResultsMR-angiography on a clinical 3T system enabled the clear visualization of the aortic lumen and aneurysmal dilation at different stages of aneurysm development. A close correlation (R2 = 0.98; p < 0.001) with histological area measurements was found. Additionally, a good agreement between MR and ultrasound area measurements in systole (R2 = 0.91; p < 0.001) and diastole (R2 = 0.94; p < 0.001) were measured. Regarding interobserver reproducibility, MRI measurements yielded a smaller 95% confidence interval and a closer interreader correlation compared to ultrasound measurements (-0.37–0.46; R2 = 0.97 vs. -0.78–0.88; R2 = 0.87).ConclusionThis study demonstrates that MR-angiography, performed on a clinical 3T MR scanner, enables the reliable detection and quantification of the aortic dilatation at different stages of aneurysm development in an experimental mouse model.

Natural History of Low-stage Urethral Strictures

To determine the natural history and rate of progression of incidental wide-caliber, anterior urethral strictures (USs) in men using a validated stricture staging system. Men with incidental findings of anterior US on cystoscopy performed for urologic conditions other than US were retrospectively reviewed from 2001 through 2016. Diagnosis of US on cystoscopy was made according to a validated staging system: stage 0 = no stricture; stage 1 = wide-caliber stricture; stage 2 = requires gentle dilation with a flexible cystoscope; stage 3 = impassable stricture with a visible lumen; and stage 4 = no visible lumen. Using this staging system, this study assessed the change over time of US in patients found to have a stage 1 stricture. The primary outcome was the US grade at time of follow-up. Secondary outcomes include the need for further intervention. Thirty-two patients with 42 separate strictures were evaluated. Median length of follow-up between first cystoscopy and ultimate cystoscopy was 23 months, with a median of 4 cystoscopies per patient. Of the 42 strictures, 15 regressed to a stage 0 (36%), 22 remained as stage 1 (52%), and 5 (12%) progressed to stage 2. None of the patients required additional intervention. The majority of low-stage USs does not progress. This supports the notion that strictures are a graded phenomenon, and not all require surgical intervention.

Predictors of Stable Aortic Dimensions in Medically Managed Acute Aortic Syndromes

We aimed to identify predictors of stable aortic dimensions in medically managed type B aortic dissections (TBAD). Medically managed TBAD patients from the International Registry of Acute Aortic Dissection with available aortic measurements at up to 24months were included. Growth rate was calculated by dividing the largest descending diameter at the latest end point not influenced by intervention minus initial descending diameter, by the recorded time interval. Patients were split into 2 groups: without aortic growth (<0.0mm/year, group I) and with aortic growth (>0.0mm/year, group II). 219 patients had available data for our inclusion criteria and comprised group I (n=89, 40.6%) and group II (n=130, 59.4%). Mean expansion rate of the total cohort was 0.19±0.81cm, mean expansion rate in group I was -0.47±0.54cm, and in group II, it was +0.63±0.64cm. Patients in group I were more frequently of Asian descent (15.9% vs. 3.1%, P=0.001), showed more often intramural hematoma on imaging (57.3% vs. 30.0%, P<0.001) and demonstrated complete false lumen thrombosis more frequently (25.0% vs. 9.9%, P=0.009). Group II patients were more Caucasian (77.3% vs. 92.2%, P=0.002), presented more with posterior chest pain (57.8% vs. 74.7%, P=0.025), back pain (68.2% vs. 80.2%, P=0.046), a visible double lumen (50.6% vs. 63.8%, P=0.050), dissection originating from the left subclavian artery (51.2% vs. 68.5%, P=0.011), and a completely patent false lumen (37.5% vs. 62.4%, P=0.002). Mortality rates between groups were similar (2.2% vs. 1.5%, P=0.708). Complete false lumen thrombosis was an independent predictor of no growth (hazard ratio [HR]: 3.640, P=0.011), while a larger sinotubular junction (STJ) (HR: 0.304, P=0.004) and female gender (HR: 0.325, P=0.030) were negative predictors of no growth. Complete false lumen thrombosis was a predictor of no growth, while a large STJ and female gender were predictors of aortic growth. This study might help predict which medically treated TBAD patients might show a stable clinical course during follow-up.

Spontaneous coronary artery dissection

A new Study Group for this unusual and serious condition was announced at ESC Congress in Rome by the Acute Cardiovascular Care Association (ACCA) of the ESC. Spontaneous Coronary Artery...

Coronary Artery Stent Evaluation with Model-based Iterative Reconstruction at Coronary CT Angiography

This study aims to compare the image quality of coronary artery stent scans on computed tomography images reconstructed with forward projected model-based iterative reconstruction solution (FIRST) and adaptive iterative dose reduction 3D (AIDR 3D). Coronary computed tomography angiography scans of 23 patients with 32 coronary stents were used. The images were reconstructed with AIDR 3D and FIRST. We generated computed tomography attenuation profiles across the stents and measured the width of the edge rise distance and the edge rise slope (ERS). We also calculated the stent lumen attenuation increase ratio (SAIR) and measured visible stent lumen diameters. Two radiologists visually evaluated the image quality of the stents using a 4-point scale (1 = poor, 4 = excellent). There was no significant difference in the edge rise distance between the two reconstruction methods (P = 0.36). The ERS on FIRST images was greater than the ERS on AIDR 3D images (325.2 HU/mm vs 224.4 HU/mm; P <0.01). The rate of the visible stent lumen diameter compared to the true diameter on FIRST images was higher than that on AIDR 3D images (51.4% vs 47.3%, P <0.01). The SAIR on FIRST images was lower than the SAIR on AIDR 3D images (0.19 vs 0.30, P <0.01). The mean image quality scores for AIDR 3D and FIRST images were 3.18 and 3.63, respectively; the difference was also significant (P <0.01). The image quality of coronary artery stent scans is better on FIRST than on AIDR 3D images.

Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging?

BackgroundComplications might occur after great vessel stent implantation in children. Therefore follow-up using imaging is warranted.PurposeTo determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children.Material and methodsFive different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1), placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RF-spoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D sequence. Two blinded observers assessed stent lumen visibility (measured diameter/true diameter *100%) in the center and at the outlets of the stent. Reproducibility of diameter measurements was evaluated using the intraclass correlation coefficient for reliability and 95% limits of agreement for agreement analysis.ResultsMedian stent lumen visibility was 88 (IQR 86–90)% with CT for all stents at both the center and outlets. With MRI, the T2-weighted turbo spin echo sequence was preferred which resulted in 82 (78–84%) stent lumen visibility. Interobserver reliability and agreement was good for both CT (ICC 0.997, mean difference -0.51 [-1.07–0.05] mm) and MRI measurements (ICC 0.951, mean difference -0.05 [-2.52 –-2.41] mm).ConclusionGood in-stent lumen visibility was achievable in this in-vitro study with both CT and MRI in different great vessel stents. Overall reliability was good with clinical acceptable limits of agreement for both CT and MRI. However, common conditions such as in-stent stenosis and associated aneurysms were not tested in this in-vitro study, limiting the value of the in-vitro study.

Monoenergetic reconstructions for imaging of coronary artery stents using spectral detector CT: In-vitro experience and comparison to conventional images

PurposeAccurate assessment of coronary stents using non-invasive CT imaging remains challenging despite new stent materials and improvements in CT technology. Virtual monoenergetic (monoE) images reconstructed from dual energy CT acquisitions potentially decrease artifacts caused by coronary stents. A novel spectral detector technology provides monoE and conventional images simultaneously for all conducted scans. The purpose of our study was to systematically investigate the influence of different monoE reconstructions on the visualization of coronary stent lumen in comparison to conventional images. Method and materialsTen different coronary stents (diameter 3.0 mm) embedded in plastic tubes filled with contrast agent (500 HU) were scanned with a 128-row spectral detector CT (IQon, Philips, 120 kV, 125 mAs). Images were reconstructed (0.67 mm slice thickness, 0.35 mm increment) with a stent-specific conventional reconstruction kernel and 6 different monoE settings (60, 70, 80, 90, 100, 150 keV). Image quality for each stent and reconstruction was quantified using established parameters: image noise (standard deviation (SD) within a standardized ROI), in-stent attenuation difference (mean attenuation difference between stented and non-stented lumen) and visible lumen diameter (mean visible diameter of the stented tube). ResultsImage noise was significantly lower in all monoE data dets compared to conventional images (conventional: 13.41, 60 keV: 11.62, 70 keV: 11.67, 80 keV: 11.69, 90 keV: 11.71, 100 keV: 11.75, 150 keV: 11.80 HU SD; p < 0.01). The in-stent attenuation difference was significantly smaller in monoE data with higher keV levels than in conventional images (conventional: 148.18, 60 keV: 154.13 p = 0.036, 70 keV: 143.43 p = 0.109, 80 keV: 137.25 p = 0.052, 90 keV: 133.02 p = 0.043, 100 keV: 130.12 p = 0.039, 150 keV: 123.99 HU p = 0.035). The visible lumen diameter was significantly greater in monoE data with higher keV levels than in conventional images (conventional: 0.65, 60 keV: 0.68 p = 0.542, 70 keV: 0.71 p = 0.053, 80 keV: 0.74 p < 0.01, 90 keV: 0.77 p < 0.01, 100 keV: 0.82 p < 0.01, 150 keV: 0.87 mm p < 0.01). ConclusionIn comparison to conventional CT images, well-established parameters for objective assessment of CT image quality for coronary stents are significantly improved by utilization of monoE reconstructions with adequate keV levels derived from data acquired on a novel spectral detector CT platform.

Coronary artery aneurysms detected by computed tomography coronary angiography.

Coronary artery aneurysms (CAAs) are incidentally revealed by coronary angiography and consist in a localized dilation of a coronary artery. Although invasive coronary angiography (ICA) is the gold standard imaging technique, it can lead to the underestimation of CAAs diameter in presence of parietal thrombi. Computed tomography coronary angiography (CTCA) is a very sensitive tool in CAAs detection and provides a clear visualization of coronary lumen highlighting intraluminal thrombi. We retrospectively reviewed 390 CTCA performed at our institution, 9 patients (6 men, 3 women) resulted affected by CAAs and represented the aneurysmal group (A group). Matched controls were identified among the non-aneurysmal patients with healthy coronaries to CTCA (NAH group). Clinical variables and imaging findings were compared and correlated. CAAs prevalence in our population was 2.31%. 15 CAAs were detected, mainly on the right coronary artery (RCA) (9 aneurysms) followed by the left anterior descending coronary artery (LAD) (three aneurysms) and the left circumflex coronary artery (CX) (three aneurysms). In six patients (66.7%) CTCA displayed an aneurysmal thrombosis and in 5 patients (55.5%) CAAs were associated to coronary artery stenoses. A statistically significant difference was found between the diameters of coronary vessels measured in healthy segments in A and NAH group. CTCA has led to a non-invasive estimation of CAAs prevalence and characterization of aneurysmal features and coronary anatomy. Overcoming ICA limitations, CTCA has provided a fine analysis of the aneurysms, also in presence of intraluminal thrombi.

Diagnostic and Interventional Optical Angioscopy in Ex Vivo Carotid Arteries.

Angioscopy - or endovascular endoscopy - is a catheter-based technique employing a flexible fiberoptic angioscope to directly visualize arterial lumen. Poor resolution and excessive stiffness of pre-existent angioscopes limited their use clinically. Recent advances resulted in novel fused optical fiber bundle angioscopes with improved flexibility and imaging resolution. Use of these devices in endovascular neurosurgery is still largely unexplored. To evaluate image quality and feasibility of optical angioscopes for diagnostic and interventional neuro-angioscopy in carotid arteries of human cadavers. A 5-F optical angioscope was used in human cadaveric carotid arteries to inspect integrity of arterial walls, identify atherosclerotic plaques and associated lesions prone to thrombogenicity, place intravascular occlusion coils, and deploy endovascular stents with real-time visualization. Angioscopy provided key information about endoluminal anatomy such as presence and characteristics of atherosclerotic plaques and thrombogenic lesions not detected by conventional diagnostic methods. Direct real-time visualization of vascular lumen during endovascular interventions provided information on spatial distribution of coils, coil loop herniation, and apposition of stent cells against carotid artery wall complementary to angiography. Fused optical fiber bundle angioscopes provide good-quality endoluminal images in human carotid arteries. Their use can feasibly assist in navigation of extracranial carotid arteries to inspect integrity of the arterial wall and identify atherosclerotic plaques and associated lesions vulnerable to thrombogenicity, allow placement of intravascular occlusion coils, and assess apposition of stents to vessel wall. Further in Vivo validation needs to be conducted along with additional research to improve image quality, flexibility, and size of angioscopes.

Influence of cardiac motion on stent lumen visualization in third generation dual-source CT employing a pulsatile heart model.

To detect an in-stent restenosis, an invasive coronary angiography is commonly performed. Owing to the risk associated with this procedure, a non-invasive method to detect or exclude an in-stent restenosis is desirable. The purpose of this study was to evaluate the influence of cardiac motion on stent lumen visibility in a third-generation dual-source CT scanner (SOMATOM Force; Siemens Healthcare, Forchheim, Germany), employing a pulsatile heart model (CoroSim®; Mecora, Aachen, Germany). 13 coronary stents with a diameter of 3.0 mm were implanted in plastic tubes filled with a contrast medium and then fixed onto the pulsatile phantom heart model. The scans were performed while the heart model mimicked the heartbeat. Coronary stents were scanned in an orientation parallel to the scanner z-axis. The evaluation of the stents was performed by employing a medium sharp convolution kernel optimized for vascular imaging. The mean visible stent lumen was reduced from 65.6 ± 5.7% for the stents at rest to 60.8 ± 4.4% for the stents in motion (p-value: <0.001). While the difference in lumen visibility between stents in motion and at rest was significant, the use of this third-generation dual-source CT scanner enabled a high stent lumen visibility under the influence of cardiac motion. Whether this translates into a clinical setting has to be evaluated in further patient studies. Advances in knowledge: The employed modern CT scanner enables a high stent lumen visibility even under the influence of cardiac motion, which is important to detect or exclude an in-stent restenosis.

Spontaneous coronary artery dissection.

A new Study Group for this unusual and serious condition was announced at ESC Congress in Rome by the Acute Cardiovascular Care Association (ACCA) of the ESC. Spontaneous Coronary Artery Dissection (SCAD) is an increasingly recognized cause of non-atherosclerotic acute coronary syndromes afflicting predominantly younger women. It is characterized by a separation of the layers of the coronary arterial wall by an accumulation of blood to form a false lumen. A build-up of pressure within the false lumen leads to external compression of the true coronary lumen restricting coronary blood flow and leading to myocardial ischaemia or infarction. SCAD should be distinguished from atherosclerotic dissections arising from plaque rupture events or erosions and from traumatic dissections or iatrogenic dissections arising during coronary procedures. Historically SCAD was primarily considered to be a condition of pregnancy or associated with known connective tissue disorders. However, it is now clear these cases make up a small proportion of the prevalent population and most events occur unheralded in patients with minimal cardiovascular risk factors.1–3 In this conventionally low-risk group, diagnosis is frequently missed or significantly delayed. Furthermore, characteristic angiographic and intracoronary imaging appearances are not widely recognized, partly because of a common misconception that a visible dual lumen or linear dissection ‘flap’ will usually be present.2,4 Accurate diagnosis of SCAD is important because of key differences in management compared to atherosclerotic coronary disease. Success rates following revascularisation are lower in SCAD and if conservative management is possible (e.g. in haemodynamically stable patients with TIMI 3 flow in the infarct related artery), the dissection usually heals over a few weeks/months.5 Stenting may be essential to restore coronary blood flow but is complicated by the risk of proximal and distal migration of the mural haematoma such that long lengths of stenting may be required to restore coronary integrity and flow. Bypass surgery can be used as a bail out where percutaneous coronary intervention has failed or for high-risk left main stem or proximal dissections but longevity of grafts in the context of SCAD is reduced by healing of the native coronary and subsequent competitive flow leading to high-graft occlusion rates. Management of SCAD-survivors is challenging with considerable uncertainty about the optimal approach. For example, antiplatelet therapy, whilst required in patients following coronary stenting, can precipitate menorrhagia and the indication in conservatively managed patients for a condition whose primary pathophysiological event is an intramural bleed, is less clear, especially after the acute phase. Likewise, the use of statins has been questioned for a condition whose primary pathophysiology appears distinct from atherosclerosis and unrelated to cholesterol. Furthermore, SCAD patients face particular questions unusual in an atherosclerotic population, such as about safe contraception and the risk of pregnancy. Of particular concern is recurrent SCAD which is well recognized and may affect as many as one in four patients over 5 years.4,6 To date research in Europe has been limited to a number of national registries, small clinical studies, and case series. Globally the largest reported series contain just a few hundred cases. As a result, SCAD represents a substantial area of unmet clinical need. There is therefore an urgent necessity to coordinate research internationally to enable larger numbers of patients to be studied. This will advance our knowledge of the epidemiology, pathophysiology, and clinical management of SCAD. With this aim, an inaugural meeting was held to welcome the SCAD Study Group within the Acute Cardiovascular Care Association of the ESC at the recent ESC Congress in Rome. Support from the European Fibromuscular Dysplasia (FMD) Group (a condition which occurs in a significant proportion of SCAD patients1–3) was especially welcome. The aims of the Study Group are: •To establish a collaborative partnership to advance research into SCAD •To maintain a European registry of SCAD patients to advance understanding of epidemiology and variations in patient management and outcomes •To coordinate and support clinical and pre-clinical research into SCAD •To formulate and disseminate a European consensus on the diagnosis and management of SCAD •To improve accurate diagnosis by raising awareness of SCAD •To support patients with this condition The Study Group welcomes any interested clinicians to make contact and hope by working together we can make an important contribution to better understanding SCAD and improving our care and support for SCAD-survivors.

In vitro stent assessment by MRI: visibility of lumen and artifacts for 27 modern stents.

The purpose of this study was to measure artifacts and visibility of lumen for modern and most commonly used stents in vascular interventions according to a standardized test method of the American Society for Testing and Materials (ASTM). Twenty-four peripheral self-expanding nitinol stents and three stainless steel stents with diameters between 5 and 8 mm and lengths between 30 and 250 mm from seven different manufacturers were compared on a 1.5T and a 3T magnetic resonance (MR) scanner. The visualization of lumen and artifacts was measured according to ASTM F2119 for a turbo spin echo (TSE) [repetition time(TR)/echo time (TE) 500/26 ms] and a gradient echo (GRE) (TR/TE 100/15 ms) sequence. The stents were placed parallel and perpendicular to the radio frequency field (B1). There were large differences in visibility of the lumen for the stent models. The visualization of the lumen varies between 0% and 93% (perpendicular to B1), and 0% and 78% (parallel to B1), respectively. The maximum signal loss beyond the actual diameter was 6 mm (TSE) and 10 mm (GRE) for stents made of stainless steel, and lower than 1 mm (TSE) and 4 mm (GRE) for nitinol stents. Reliable stent lumen visualization is possible for Misago, Supera, Tigris, and Viabahn stents, if their axis is perpendicular to B1, and independent of the orientation with respect to B1 for short Tigris stents at 1.5T.

In Vitro Comparison of Second- and Third-generation Dual-source CT for Coronary Stent Visualization at Different Tube Potentials

The study aimed to evaluate in vitro stent lumen visibility of coronary stents in a second- and third-generation dual-source computed tomography (CT) system at 100 and 120 kVp tube potential. Twenty-six coronary stents ranging from 2.25 to 4.0 mm in diameter were implanted in a coronary vessel phantom. Scans were performed at 100 and 120 kVp tube potential. Evaluation was performed using a medium-sharp kernel in both systems (B46f in the second-generation and Bv49 in the third-generation model) and a sharp (Bv59) convolution kernel optimized for vascular imaging in the third-generation CT. The median visible stent lumen diameter in the second-generation system was higher at 120 kVp with a median of 62.0% compared to 56.3% at 100 kVp (P < 0.001). The median visible diameter in the third-generation system was significantly higher applying the Bv49 kernel with 66.7% at 120 kVp and 61.1% at 100 kVp (both P < 0.001). When applying the Bv59 kernel, visible stent lumen further increased to 69.3% at 120 kVp and 66.7% at 100 kVp. Additionally, stent lumen was assessed using full width at half maximum, resulting in a comparable increase in luminal diameter at corresponding tube potential. Third-generation dual-source CT provides superior stent lumen visibility at equivalent tube potential and at reduced tube potential of 100 kVp when compared to 120 kVp in a second-generation system, at least when manually assessed.