Coronary Artery Imaging Research Articles

Endothelial Function in Coronary Arteries from Pneumonia-Infected Pigs

This study investigated whether pneumonia is accompanied with endothelial dysfunction in coronary arteries. The lungs and hearts of normal and Mycoplasma hyopneumoniae-infected pigs (6-month-old females and castrated males) were obtained from a local abattoir, and left anterior descending coronary arteries were isolated from the hearts. Lymphocyte infiltration was observed in the lung tissue of pneumonia-infected pigs (PP). However, the histopathological images of coronary arteries in PP were not different from the images in normal pigs (NP). In organ chamber experiments, endothelium-dependent relaxation of coronary arteries by bradykinin (0.1 nM–0.1 μM) and A23187 (1 nM–1 μM) were identical between PP and NP; the relaxant responses were not different even in the presence of L-NAME (100 μM, nitric oxide synthase inhibitor) alone or in combination with indomethacin (10 μM, cyclooxygenase inhibitor). In addition, the relaxant responses to nitric oxide [sodium nitroprusside (1 nM–10 μM)], hydrogen peroxide (10 μM–1 mM), and 11, 12-epoxyeicosatrienoic acids (30 nM–3 μM), all of which function as endothelium-derived relaxing factors in pig coronary arteries, were also identical between PP and NP. These findings suggest that mycoplasma pneumonia in pigs is not a risk factor for endothelial dysfunction in coronary arteries.

Multiparameter Synchronous Measurement With IVUS Images for Intelligently Diagnosing Coronary Cardiac Disease

Intravascular ultrasound (IVUS) can provide high-resolution cross-sectional images of coronary arteries, showing detailed information of the vascular lumen, tube wall, and athermanous plaques, which is helpful for the discovery or identification of early coronary atherosclerotic plaques. Multiple parameters extractable from the IVUS image can help the cardiologist analyze the pathology and assist in disease diagnosis and postoperative treatment. Typically, cardiologists manually label the intima and adventitia in the IVUS image, and obtain a limited number of parameters through the IVUS instrument, which is time consuming and labor-intensive. To assist the cardiologist in automatically obtaining more clinically relevant value parameters, a fully automatic IVUS multiparameter extraction framework is proposed. Based on the intima and adventitia obtained by DeepLab V3+, we propose a targeted noise reduction preprocessing framework adapted to IVUS. The framework implements the basic parameter extraction of IVUS through two newly proposed algorithms. And through the standard medical formula, the basic parameters are converted into 10 standard medical indicators. Standardized medical indicators are obtained by clinically relevant basic parameters. In terms of accuracy, this article used a clinical database obtained from Qilu Hospital of Shandong University and compared the results of the framework with the gold standard of cardiologists. The relative error of continuous IVUS main parameters between frames did not exceed 10.10%. The relative error of independent IVUS did not exceed 10.03%. Based on the distribution consistency of the parameters and the gold standard, a Bland-Altman plot of the parameters is proposed. It was verified that this distribution is basically in line with the gold standard of cardiologists. The algorithm in this article obtained a total of 10 parameters, far exceeding the parameters obtained by cardiologists and traditional IVUS machines. Its accuracy and speed can also meet the requirements of cardiologists for clinical diagnosis.

Cardiac strangulation after epicardial pacing: the importance of non-specific symptoms and a low index of suspicion.

Cardiac strangulation is a rare and potentially deadly complication of epicardial pacemaker implantation. A young boy presenting with chest pain and tiredness almost 7 years after pacemaker implantation was found to have cardiac strangulation. Literature review revealed 22 cases reported to date with a worrying rise in the number of reports over the past 3 years. Strangulation is associated with implantation of leads at a young age and appears to be related to somatic growth. Serial assessment with chest X-ray and echocardiogram is recommended, at least until full adult growth is attained with further coronary artery imaging reserved for symptoms or suspicious echocardiographic findings. If cardiac strangulation is diagnosed prompt replacement of the offending system is needed.

Abstract 14676: Landmark-based Functional Computed Tomography Reveals Diminished Left Atrial Appendage Contraction During Atrial Fibrillation

Introduction: The formation of thrombus in the left atrial appendage (LAA) and risk for systemic embolization may result in part from stasis and poor blood volume emptying during atrial fibrillation (AF). Functional 4-dimensional computed tomography (4DCT) is a promising technique to measure LAA ejection fraction and blood volume emptying. Hypothesis: We hypothesize that the LAA ejection fraction measured by 4DCT is decreased during AF compared to sinus rhythm. Methods: 256-slice 4DCT scans obtained in patients for coronary artery imaging or pre-procedurally for AF, VT or SVT ablation procedures were analyzed retrospectively. In each patient, LAA volumes were measured at multiple phases during one cardiac cycle using segmentation software (ITK-SNAP and Osirix MD). LAA ejection fraction was calculated as the difference between minimum and maximum volumes and was analyzed using Wilcoxon rank sum. Results: Out of 54 patients, 37 patients were in sinus rhythm and 17 patients were in AF. Between NSR vs. AF, mean age was 69.1±12.8 vs 73.2±11.5 years (p=0.13), 28% vs 36% female (p=0.54), LVEF was 58±11% vs 60±9% (p=0.95), and echo-derived left atrial volume index was 29.5±6.1 ml/m2 vs 41.7±12.8 ml/m2 (p=0.06). Patients who were in sinus rhythm during their CT scan had a higher LAA ejection fraction than those who were in AF (58±13% vs. 29±9%, p<0.0001). For patients who were in AF during their CT scan, there was no difference in LAA ejection fraction between patients with a history of paroxysmal AF compared to patients with a history of persistent AF (30±10% vs. 28±10%, p=0.75). Conclusions: Analysis of the LAA volumes using functional cardiac CT is a feasible method to quantify blood volume emptying from the LAA. Patients in AF were observed to have significantly decreased LAA ejection fraction and blood volume emptying compared to patients in sinus rhythm. Further studies are needed to determine whether this technique may improve personalized risk stratification for stroke.

The clinical implications of incidental coronary artery calcification in routine, non-triggered high-resolution thoracic computed tomography: a retrospective study

Abstract Background Coronary artery calcium (CAC) is a marker of atherosclerosis and an independent risk factor for cardiac-related mortality. The measurement of this score has traditionally been based on using ECG triggered computed tomography (CT). However, CAC, identified on non-contrast high resolution chest computed tomography (HRCT), should be considered diagnostic for coronary artery disease (CAD). We aimed to evaluate the incidental prevalence and burden of CAC on non-gated HRCT thorax used for patients undergoing lung cancer screening or follow-up for interstitial lung disease. We also assessed how often Radiologists reported CAC as an incidental finding on these scans. Methods Computerised Radiology Information Service (CRIS) was manually searched to determine all HRCT scans performed in our Trust from 01/05/2018 to 01/05/2019. The reports issued by Radiologists and images of selected studies were reviewed. Results 2185 HRCT scans were performed over this period. Patients were divided into three groups of age <50 (Group 1); 50-<60 (Group 2) and 60 (Group 3). 100 scans were randomly selected from each group using a random number generator to give a total of 300 patients. The mean ages of patients in Group 1, 2 and 3 were 48.3±2.3, 54.8±2.4 and 65±3.2 respectively. There was, approximately, the same number of males as females in each group. CAC was noted in 15% of scans in Group 1, 82% of scans in Group 2 and 94% scans in Group 3. CAC was only noted in 1/15 (6.7%) of scan reports in Group 1, 41/82 (50%) in Group 2 and 37/94 (39.4%) in Group 3. Among the 79 patients with radiologist-reported incidental CAC, statin and aspirin prescriptions increased by approximately 7 percentage points each. A diagnosis of CAD was eventually made in 9 (11.4%) patients through functional imaging or coronary angiogram. Two authors independently calculated the Agatston scores of HRCT scans whose reports did not comment on the degree of calcification. We excluded 15/112 (13.4%) scans as they were uninterpretable due to motion artefacts. Of the remaining 97 scans analysed 58/97 (59.8%) had severe CAC with an Agatston score of >400 with the remaining showing moderate calcification (101–400). Cohen κ agreement between the two authors rating was 0.90 (95% confidence interval [CI] 0.87–0.96). Group 2 and 3 had significantly more patients with severe CAC then group 1 (p<0.001). Left anterior descending artery was most commonly affected. Conclusion This study shows that CAC is under reported on non-gated HRCT scans which represents a missed opportunity to implement strategies for primary and secondary prevention. Given that respiratory disease is an independent risk factor for developing cardiac disease, it is incumbent upon the interpreting clinician to report all findings and ensure that critical findings are highlighted. The images of calcified coronary arteries may also potentially have a role in convincing people to make correct lifestyle choices. Funding Acknowledgement Type of funding source: None

Lipid-rich Plaques Detected by Near-infrared Spectroscopy Are More Frequently Exposed to High Shear Stress

High wall shear stress (WSS) and near-infrared spectroscopy (NIRS) detected lipid-rich plaque (LRP) are both known to be associated with plaque destabilization and future adverse cardiovascular events. However, knowledge of spatial co-localization of LRP and high WSS is lacking. This study investigated the co-localization of LRP based on NIRS and high WSS. Fifty-three patients presenting acute coronary syndrome underwent NIRS-intravascular-ultrasound (NIRS-IVUS) imaging of a non-culprit coronary artery. WSS was obtained using WSS profiling in 3D-reconstructions of the coronary arteries based on fusion of IVUS-segmented lumen and CT-derived 3D-centerline. Thirty-eight vessels were available for final analysis and divided into 0.5 mm/45° sectors. LRP sectors, as identified by NIRS, were more often colocalized with high WSS than sectors without LRP. Moreover, there was a dose-dependent relationship between lipid content and high WSS exposure. This study is a first step in understanding the evolution of LRPs to vulnerable plaques.Graphical

Research priorities in cardiovascular imaging

AimA modified Delphi approach was used to develop consensus opinion among British Society for Cardiac Imaging/British Society of Cardiac CT (BSCI/BSCCT) members in order to prioritise research questions in cardiovascular...

Coronary Computed Tomography Angiography and Coronary Artery Calcium Scoring in an Outpatient Setting: Barriers to implementation

Coronary Computed Tomography Angiography and Coronary Artery Calcium Scoring in an Outpatient Setting: Barriers to implementation

Coronary Artery Vasospasm: A Under-recognized Phenomenon in Orthotopic Heart Transplant

Introduction Cardiac allograft vasculopathy (CAV) is known as the primary cause of death in the first year after orthotopic heart transplant (OHT). Coronary artery spasm (CAS) in OHT is a rare and under-recognized phenomenon in patients undergoing surveillance. The mechanism of coronary vasospasm in OHT remain largely unknown. The presentation can vary from an incidental finding to severe episodes of symptomatic ventricular arrhythmias, high-degree atrioventricular block, syncope, cardiac arrest, or even myocardial infarction in cases of prolonged ischemia. Case Presentation 65 yo female with history of chronic kidney disease, diabetes mellitus type 2, hypertension, hyperlipidemia, and orthotopic heart transplantation with CMV mismatch in 2016 secondary to apical hypertrophic cardiomyopathy. Prior coronary angiography (CA) done at our institution had shown no evidence of vasculopathy. During one of her follow-up visits in the Clinic, she complained of increasing dyspnea on exertion, prompting urgent referral for CA, as per our surveillance protocols. Prior to the procedure, echocardiography was performed which revealed normal graft function and no valvular abnormalities. She underwent CA which showed a proximal significant diffuse luminal narrowing of the right coronary artery (RCA) (Image 1) and normal left coronary artery anatomy (Image 2). We proceed to repeat CA with intracoronary administration of nitroglycerin (ICN) and measurement of fractional flow reserve (FFR) of RCA (Image 3, 4). Angiography revealed near resolution of the RCA lesion, ultimately suggesting that transient vasospasm had been responsible for the previous angiographic appearance (Image 1). Summary CAS can present in patients with or without vasculopathy. It can produce luminal narrowing and can be difficult to distinguish angiographically from CAV. Misdiagnosis of this entity has led to the incorrect diagnosis of CAV and subsequent unnecessary stenting. ICN use can improve angiographic visualization, and prevent the adverse effects of coronary spasm. In conclusion, CAS is a rare and potential complication post OHT. It is a difficult entity to prognosticate due to scarcity of clinical evidence, as prevalence ranges from 4.9% to 12.1%. Some authors hypothesize that CAS in OHT carries a poor prognosis as it is often an early manifestation of CAV. However, this remains largely hypothetical and further studies are needed to better understand this disease.

Visualization of proximal coronary arteries on high-pitch electrocardiogram-triggered computed tomography in pediatric congenital heart disease: effects of heart rate and body surface area.

As CT technology has advanced, techniques for pediatric cardiac CT in congenital heart disease have evolved from retrospective electrocardiography (ECG)-gating with relatively high radiation doses to lower-dose prospective ECG-gating and even single-beat gated scans. Despite these advances, coronary artery imaging in children remains challenging because of their small vessel size and high heart rates, often necessitating retrospective gating. Evaluate coronary artery visualization in pediatric patients (<20years) who underwent low-dose high-pitch ECG-triggered scans and stratify the probability of coronary artery visualization based upon heart rate and body surface area (BSA). Two hundred eleven high-pitch ECG-triggered studies from April 2014 to November 2017 were reviewed by two pediatric cardiac imagers in this retrospective study. Patient age, gender, BSA, average heart rate, heart rate variability and use of general anesthesia were recorded as well as dose-length product (DLP) and volumetric CT dose index (CTDIvol). We assessed the coronary artery score using a 5-point scale, with score of ≥3 considered of diagnostic quality. We performed multivariate statistical analysis including logistic regression to analyze effects of heart rate and BSA. Patient age range was 1day to 19years (median age 3years). Heart rate range was 49-188 beats per minute (bpm; median 122bpm) and BSA range was 0.15-2.07m2 (median 0.53m2). The origin and proximal coronary arteries were confidently seen (score ≥3) in 61% of studies in this cohort. Coronary artery visualization scores further increased with increased BSA (P<0.002) and with decreased heart rate (P<0.001). At heart rates <100bpm or in patients with BSA>0.58, adequate coronary artery visualization was present 72% of the time. While in many patients the coronary artery origins are visualized using high-pitch ECG-triggered technique, the importance of coronary artery visualization needs to be weighed with the radiation dose penalty in individual patients to achieve optimal imaging.

A coronary artery segmentation method based on region growing with variable sector search area

BACKGROUND: Coronary artery image segmentation is an important auxiliary method for coronary artery disease diagnosis.OBJECTIVE: The classical region growing algorithms, which only consider the intensity of pixels, are noise-sensitive and require manual interaction. To this end, recent methods simultaneously consider the intensity of pixels and multi-scale analysis with the region growing. Nevertheless, these methods are not fully optimized and they suffer from the drawbacks of over- or under-segmentation in many cases.METHODS: In this paper, we propose a region growing based coronary artery segmentation method. Different from the existing methods, the variable sector search area is considered in the region growing technique. A growing rule is proposed to segment the vessel, which combines the Hessian vector and the region growing with the variable sector search area. To further improve the quality of segmentation, we propose an optimization of removing some small disconnected regions.RESULTS: Our proposed method can search more branches while segmenting the vessel, even the small ones. It keeps an acceptable performance when dealing with stenosis and large curvature of blood vessels.CONCLUSIONS: Quantitative evaluations are conducted on coronary angiography and the results show that the proposed method achieves a higher DSC ratio and a more reliable sensitivity ratio.

Intravascular ultrasound imaging of isolated and non aorto-ostial coronary Takayasu arteritis: a case report

BackgroundIsolated coronary Takayasu arteritis is a rare form of ischemic heart disease that typically appears as an aorto-ostial lesion. Although several vascular imaging modalities including ultrasonography, computed tomographic angiography, magnetic resonance angiography or catheter angiography, play crucial roles for diagnosing Takayasu arteritis, the intravascular ultrasound imaging of Takayasu arteritis is not well studied.Case presentationA 55-year-old woman who was diagnosed with heterozygous familial hypercholesterolemia underwent coronary angiography due to effort angina, which showed ostial left anterior descending coronary artery (LAD) stenosis. Although directional coronary atherectomy followed by drug-coated balloon was successfully performed, 6 months later restenosis occurred at the ostial LAD, and the ostial left circumflex coronary artery (LCx) progressed significantly. The intravascular ultrasound imaging in these lesions was noteworthy, in which the media was partly unrecognizable and an echo intensity similar to fibrotic intimal thickening traversed from the intima to the adventitia, thereby causing the whole image of the coronary artery to become unclear. Directional coronary atherectomy followed by drug-coated balloon procedures for both LAD and LCx lesions were performed again. Systemic examination of computed tomographic angiography found no other stenotic lesions except for those in the coronary arteries. Five months later, the LAD and LCx lesions progressed diffusely, therefore the coronary artery bypass graft was done. The histopathological findings of specimens of the coronary artery that were obtained during the bypass graft showed excessive fibrous thickening of the intima and adventitia, with granulomatous inflammation in the media, which led to the diagnosis of isolated coronary Takayasu arteritis. Systemic corticosteroid therapy was then started.ConclusionsWe described an extremely rare case of isolated and non aorto-ostial Takayasu arteritis. The characteristic intravascular ultrasound images of diseased coronary arteries may help in the diagnosis of coronary Takayasu arteritis.

Healthy Strut Coverage After Coronary Stent Implantation: An Ex Vivo Human Autopsy Study.

Struts have been considered as covered when tissue overlying the struts is >0 μm by optical coherence tomography (OCT). However, there is no confirmatory study to validate this definition by histology which is the gold standard. The aim of the present study was to assess the appropriate cutoff value of neointimal thickness of stent strut coverage by OCT with histology confirmation. We performed ex vivo OCT imaging of human coronary arteries with stents at autopsy. A total of 46 stents in 39 vessels from 25 patients were examined in this study, and a total of 165 cross-sectional images were co-registered with histology to determine the optimal cutoff value for strut coverage by OCT which was defined as luminal endothelial cells with 2 abluminal layers of smooth muscles cells and matrix. Considering the resolution of OCT is 10 to 20 μm, the cutoff values were assessed at ≥20, ≥40, and ≥60 μm. A total of 2235 struts were reviewed by histology, 1216 were considered as well-matched struts which were analyzed in this study. By histology, 160 struts were identified as uncovered, while 1056 struts were covered. The OCT assessment without consideration of neointimal thickness yielded a poor specificity of 37.5% and sensitivity 100%. Of 3 cutoff values, the cutoff value of ≥40 μm yielded the best sensitivity (99.3%), specificity (91.0%), positive predictive value (98.6%), and negative predictive value (95.6%) as compared with ≥20 and ≥60 μm. Neointimal thickness ≥40 μm by OCT yielded the most accurate cutoff value to identify stent strut coverage validated by histology.

Detection of cholesterol crystals by optical coherence tomography.

The aim of this study was to determine the ability of optical frequency domain imaging (OFDI)/optical coherence tomography (OCT) imaging systems to visualise the presence of cholesterol crystals (CCR) in human atherosclerotic coronary arteries. We performed ex vivo imaging of human coronary arteries by OFDI/OCT. A total of 559 cross-sectional images from 45 autopsy cases were co-registered with histology; 117 histologic sections showed presence of necrotic core with cholesterol clefts (CC). We modified a previously used OFDI/OCT definition for identification of CCRs which we now define as a linear and discrete high-intensity signal (bright area) within the plaque with sharp borders between it and adjacent low-/intermediate-intensity tissue. Additionally, the high-intensity signal is not a spot but a well-defined area distinguishing it from macrophages which lack sharp borders. OFDI/OCT imaging identified the presence of CCR in 30 of the 117 histologic sections. The sensitivity and specificity of OFDI/OCT for detection of CCR was 25.6% and 100.0%, respectively. By multivariate analysis, significant predictors to visualise CCR by OCT/OFDI were 1) an overlying fibrous plaque, and 2) the presence of stacked CC, defined as CC arranged one on top of another with >3 layers of CC. The prevalence of complicated plaques (i.e., plaque haemorrhage and late necrotic core) was significantly higher in detectable CCR by OFDI/OCT as compared to undetectable CCR. The presence of stacked CCs is required to detect CCR by OFDI/OCT. Detection of CCR by OCT/OFDI may help us to identify the late stages of atherosclerotic coronary plaque progression and improve risk stratification.

Swine Disease Models for Optimal Vascular Engineering.

Swine disease models are essential for mimicry of human metabolic and vascular pathophysiology, thereby enabling high-fidelity translation to human medicine. The worldwide epidemic of obesity, metabolic disease, and diabetes has prompted the focus on these diseases in this review. We highlight the remarkable similarity between Ossabaw miniature swine and humans with metabolic syndrome and atherosclerosis. Although the evidence is strongest for swine models of coronary artery disease, findings are generally applicable to any vascular bed. We discuss the major strengths and weaknesses of swine models. The development of vascular imaging is an example of optimal vascular engineering in swine. Although challenges regarding infrastructure and training of engineers in the use of swine models exist, opportunities are ripe for gene editing, studies of molecular mechanisms, and use of swine in coronary artery imaging and testing of devices that can move quickly to human clinical studies.

Image quality and attenuation values of multidetector CT coronary angiography using high iodine-concentration contrast material: A comparison of the use of iopromide 300 and iopromide 370

Abstract Background Iodine concentration is one of the main determinants of arterial enhancement in CTA, and current low-osmolar and iso-osmolar nonionic CM for intravascular administration still come in a handful of molecules, but a relatively wide range of different iodine concentrations. This gives the opportunity to optimize CTA protocols as a function of several factors such as patient characteristics, CT technology, and CM features in an attempt to maximize the diagnostic yield of CTA examinations while considering patient safety and avoiding unnecessary extra costs. Objective To compare image quality and attenuation values of multidetector CT coronary angiography (MDCT) between iopromide 300 and iopromide 370 and to evaluate whether the higher iodine contrast material has better image quality or not. Material and Methods Patients were prospectively enrolled and were randomized into two groups (group A, 30 patients received iopromide 300, iodine flux 1.2g I/s; group B, 30 patients received iomeprol 370, iodine flux 1.48g I/s). CT attenuation values were measured in the proximal end coronary arteries,ascending aorta and main pulmonary artery. The image quality of 15 coronary artery segments was graded by cardiologist in consensus with the use of a four-point scale (1 excellent enhancement to 4 poor enhancement). Non-parametric statistical approaches were used to compare the two groups. Results No statistically significant differences were found between the mean attenuation values (302 HU for iopromide 300 and 326 HU for iopromide 370, P = 0.175) in the coronary arteries in the two groups. The mean attenuation value of the proximal ascending aorta (AA)and main pulmonary artery (MPA) was found to be 345+/-63 HU and 241+/- 89 in group A respectively, whereas the mean attenuation value in proximal ascending aorta and main pulmonary artery in group B was found to be 348+/-74 and 238+/- 50 respectively. No significant difference was found between iopromide 300 and iopromide 370 in terms of contrast enhancement at the level of great arteries, P value AA = 0.826 and P value for MPA = 0.884. 92.9% of coronary arterial segments got score (range 1–2) in group A whereas 93.6 of coronary arterial segments got score (range 1-2) in group with no statistically significant difference P value = 0.755. Conclusion With the current CT technology iopromide 300 is not inferior to iopromide 370 in terms of coronary artery attenuation values and image quality. Iopromide 300 provides similar enhancement of coronary arteries and excellent image quality as compared with iopromide 370 using identical amount of total iodine with fewer cost and less estimated adverse effects owing to low iodine concentration of iopromide 300.

Computed tomography coronary angiography – past, present and future

Computed tomography coronary angiography (CTCA) is a robust and reliable non-invasive alternative imaging modality to invasive coronary angiography, which is the reference standard in evaluating the degree of coronary artery stenosis. CTCA has high negative predictive value and can confidently exclude significant coronary artery disease (CAD) in low to intermediate risk patients. Over the years, substantial effort has been made to reduce the radiation dose and increase the cost efficiency of CTCA. In this review, we present the evolution of computed tomography scanners in the context of coronary artery imaging as well as its clinical applications and limitations. We also highlight the future directions of CTCA as a one-stop non-invasive imaging modality for anatomic and functional assessment of CAD.

Effect of side branch flow upon physiological indices in coronary artery disease

Recent efforts have demonstrated the ability of computational models to predict fractional flow reserve from coronary artery imaging without the need for invasive instrumentation. However, these models include only larger coronary arteries as smaller side branches cannot be resolved and are therefore neglected. The goal of this study was to evaluate the impact of neglecting the flow to these side branches when computing angiography-derived fractional flow reserve (vFFR) and indices of volumetric coronary artery blood flow. To compensate for the flow to side branches, a leakage function based upon vessel taper (Murray’s Law) was added to a previously developed computational model of coronary blood flow. The augmented model with a leakage function (1Dleaky) and the original model (1D) were then applied to predict FFR as well as inlet and outlet flow in 146 arteries from 80 patients who underwent invasive coronary angiography and FFR measurement. The results show that the leakage function did not significantly change the vFFR but did significantly impact the estimated volumetric flow rate and predicted coronary flow reserve. As both procedures achieved similar predictive accuracy of vFFR despite large differences in coronary blood flow, these results suggest careful consideration of the application of this index for quantitatively assessing flow.

Dispersion correction for optical coherence tomography by the stepped detection algorithm in the fractional Fourier domain

Dispersion in optical coherence tomography (OCT) leads to a series of wavelength-dependent phase distortions, which cause degradation of axial resolution. Due to the lack of prior information or the complexity of an exhaustive search calculation, all-depth dispersion suppression can hardly be realized in practical cases, especially for high-speed processing and irregular-structure samples. This paper explores the understanding of the depth-dependent dispersion in the fractional Fourier domain (FRFD) and addresses a new method for dispersion correction based on the FRFD stepped detection algorithm that is able to adaptively compensate the dispersion at all depths of the sample. For the detection of each dispersion component, a coarse search followed by a localized fine search is presented in our algorithm to reduce the calculation complexity with high accuracy guaranteed. A signal separation method utilizing FRFD filtering is also designed to avoid the interference between the dispersion from different depths of the sample, which allows all-depth dispersion correction. The proposed algorithm is verified to be effective through the stratified media of ZnSe. The application of the proposed algorithm in OCT imaging of onion and human coronary artery also demonstrates the feasibility of our algorithm for dispersion correction in bio-tissues.

Intraoperative echocardiographic coronary artery imaging in congenital and acquired heart disease.

Transoesophageal and epicardial echocardiography are indispensible intraoperative imaging modalities to guide paediatric heart disease surgeries and influence surgical decision-making. A less well-described role of intraoperative imaging is its utility in evaluating coronary artery patency and flow. Focused two-dimensional, colour, and spectral Doppler imaging of the coronary arteries should be performed during surgeries involving coronary manipulation or re-implantation, or in cases where there is unexpected ventricular dysfunction or electrographic signs concerning for ischaemia. Intraoperative imaging allows for any anatomical issues to be detected and addressed promptly in the operating room. Imaging of the coronary arteries should identify unobstructed coronary ostia and proximal course without kinking, angulation, narrowing, or significant calibre change to suggest stenosis or extrinsic compression from neighbouring structures. The aim of this review is to highlight the usefulness of transoesophageal and epicardial echocardiography in evaluating coronary artery patency and flow, provide a how-to guide for optimal imaging, and to introduce a practical guideline to achieve best clinical practice.