Cardiovascular computed tomography in cardiovascular disease:An overview of its applications from diagnosis to prediction

Cardiovascular computed tomography angiography(CTA)is a widely used imaging modality in the diagnosis of cardiovascular disease.Advancements in CT imaging technology have further advanced its applications from high diagnostic value to minimising radiation exposure to patients.In addition to the standard application of assessing vascular lumen changes,CTA-derived applications including 3D printed personalised models,3D visualisations such as virtual endoscopy,virtual reality,augmented reality and mixed reality,as well as CT-derived hemodynamic flow analysis and fractional flow reserve(FFRCT)greatly enhance the diagnostic performance of CTA in cardiovascular disease.The widespread application of artificial intelligence in medicine also significantly contributes to the clinical value of CTA in cardiovascular disease.Clinical value of CTA has extended from the initial diagnosis to identification of vulnerable lesions,and prediction of disease extent,hence improving patient care and management.In this review article,as an active researcher in cardiovascular imaging for more than 20 years,I will provide an overview of cardiovascular CTA in cardiovascular disease.It is expected that this review will provide readers with an update of CTA applications,from the initial lumen assessment to recent developments utilising latest novel imaging and visualisation technologies.It will serve as a useful resource for researchers and clinicians to judiciously use the cardiovascular CT in clinical practice.

Multislice computed tomography angiography in the diagnosis of coronary artery disease

Multislice CT angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease. Rapid improvements in multislice CT scanners over the last decade have allowed this technique to become a potentially effective alternative to invasive coronary angiography in patients with suspected coronary artery disease. High diagnostic value has been achieved with multislice CT angiography with use of 64- and more slice CT scanners. In addition, multislice CT angiography shows accurate detection and analysis of coronary calcium, characterization of coronary plaques, as well as prediction of the disease progression and major cardiac events. Thus, patients can benefit from multislice CT angiography that provides a rapid and accurate diagnosis while avoiding unnecessary invasive coronary angiography procedures. The aim of this article is present an overview of the clinical applications of multislice CT angiography in coronary artery disease with a focus on the diagnostic accuracy of coronary artery disease; prognostic value of coronary artery disease with regard to the prediction of major cardiac events; detection and quantification of coronary calcium and characterization of coronary plaques. Limitations of multislice CT angiography in coronary artery disease are also briefly discussed, and future directions are highlighted.

Abdominal aortic aneurysm： Treatment options, image visualizations and follow-up procedures

Abdominal aortic aneurysm is a common vascular disease that affects elderly population.Open surgical repair is regarded as the gold standard technique for treatment of abdominal aortic aneurysm,however,endovaseular aneurysm repair has rapidly expanded since its first introduction in 1990s.As a less invasive technique,endovascular aneurysm repair has been confirmed to be an effective alternative to open surgical repair,especially in patients with co-morbid conditions.Computed tomography （CT） angiography is currently the preferred imaging modality for both preoperative planning and post-operative follow-up.2D CT images are complemented by a number of 3D reconstructions which enhance the diagnostic applications of CT angiography in both planning and follow-up of endovascular repair.CT has the disadvantage of high cummulative radiation dose,of particular concern in younger patients,since patients require regular imaging follow-ups after endovascular repair,thus,exposing patients to repeated radiation exposure for life.There is a trend to change from CT to ultrasound surveillance of endovascular aneurysm repair.Medical image visualizations demonstrate excellent morphological assessment of aneurysm and stent-grafts,but fail to provide hemodynamic changes caused by the complex stent-graft device that is implanted into the aorta.This article reviews the treatment options of abdominal aortic aneurysm,various image visualization tools,and follow-up procedures with use of different modalities including both imaging and computational fluid dynamics methods.Future directions to improve treatment outcomes in the follow-up of endovascular aneurysm repair are outlined.

Bonding strength of Invar/Cu clad strips fabricated by twin-roll casting process

Based on traditional twin-roll casting process,Invar/Cu clad strips were successfully fabricated by using solid Invar alloy strip and molten Cu under conditions of high temperature,high pressure and plastic deformation.A series of tests including tensile test,bending test,T-type peeling test and scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)measurements were carried out to analyze the mechanical properties of Invar/Cu clad strips and the micro-morphology of tensile fracture surfaces and bonding interfaces.The results indicate that no delamination phenomenon occurs during the compatible deformation of Invar/Cu in bending test and only one stress platform exists in the tensile stress-strain curve when the bonding strength is large.On the contrary,different mechanical properties of Invar and Cu lead to delamination phenomenon during the uniaxial tensile test,which determines that two stress platforms occur on the stress-strain curve of Invar/Cu clad strips when two elements experience necking.The average peeling strength can be increased from13.85to42.31N/mm after heat treatment at800℃for1h,and the observation of the Cu side at peeling interface shows that more Fe is adhered on the Cu side after the heat treatment.All above illustrate that heat treatment can improve the strength of the bonding interface of Invar/Cu clad strips.

Use of coronary CT angiography in the diagnosis of patients with suspected coronary artery disease： findings and clinical indications

Objective To investigate the clinical applications of coronary CT angiography in patients with suspected coronary artery disease and identify factors that affect CT findings. Methods Medical records of patients suspected of coronary artery disease over a period of 12 months from a tertiary teaching hospital were retrospectively reviewed. Patient age, sex （male/female）, duration of symptoms and abnormal rates of coronary CT angiography scans were analysed to investigate the relationship among these parameters. The patients by age were characterized into five groups： under 36 years, 36-45 years, 46-55 years, 56455 years and more than 66 years, respectively; while the duration of symptoms was also classified into five groups： less than one week, one week to one month, one to three months, three to six months and more than six months. Results Of the 880 patient records reviewed, 800 met the above study criteria. Five hundred and forty nine patients demonstrated abnormal CT findings （68.6%）. There was no significant difference in the percentage of abnormal CT findings based on patient sex and the duration of symptoms （P = 0.14）. The abnormal rates of coronary CT angiography, however, increased significantly with increasing age （P 〈 0.001）; with patients over 65 years of age 2.5 times more likely to have an abnormal CT scan relative to a patient under 45 years. A significant difference was found between abnormal coronary CT angiography and the duration of symptoms （P = 0.012）. Conclusions Our results indicate coronary CT angiography findings are significantly related to the patient age group and duration of symptoms. Clinical referral for coronary CT angiography of patients with suspected coronary artery disease needs to be justified with regard to the judicious use of this imaging modality.

Diagnostic value of18F-FDG PET in the assessment of myocardial viability in coronary artery disease：A comparative study with99mTc SPECT and echocar-diography

ObjectiveTo investigate the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography （18F-FDG PET） in the as-sessment of myocardial viability in patients with known coronary artery disease （CAD） when compared to99mTc single photon emission computed tomography （SPECT） and echocardiography, with invasive coronary angiography as the gold standard.MethodsThirty patients with diagnosed CAD met the selection criteria, with 10 of them （9 men, mean age 59.5 ± 10.5 years） undergoing all of these imaging proce-dures consisting of SPECT and PET, echocardiography and invasive angiography. Diagnostic sensitivity of these less invasive modalities for detection of myocardial viability was compared to invasive coronary angiography. Inter- and intra-observer agreement was assessed for di-agnostic performance of SPECT and PET.ResultsOf all patients with proven CAD, 50% had triple vessel disease. Diagnostic sensitivity of SPECT, PET and echocardiography was 90%, 100% and 80% at patient-based assessment, respectively. Excellent agreement was achieved between inter-observer and intra-observer agreement of the diagnostic value of SPECT and PET in myocardial viability （k= 0.9）. Conclusion18F-FDG PET has high diagnostic value in the assessment of myocardial viability in patients with known CAD when com-pared to SPECT and echocardiography. Further studies based on a large cohort with incorporation of18F-FDG PET into patient management are warranted.

Inter-hospital transfers and door-to-balloon times for STEMI: a single centre cohort study

Background Key performance indices such as door-to-balloon times have long been recognized as quality metrics in reducing time to care for patients with acute coronary syndromes(ACS). In the situation where patients do not present to a facility capable of 24/7 percutaneous coronary interventions(PCI) delays in time to therapy can exceed the recommendation of 90 min or less. This study aimed to evaluate the impact of transfers on performance indices for patients diagnosed with ST-segment elevation myocardial infarction(STEMI). Methods Over a seven month collection period, all patients presenting with symptoms suggestive of ACS and admitted for PCI were studied. Patients were divided into dichotomous groups of direct presentations or transfers from a secondary non-PCI capable hospital with key times recorded, including symptom-onset, first hospital and PCI-capable hospital arrival and balloon inflation times to evaluate time of treatment for STEMI patients. Results Of the 87 patients diagnosed with STEMI, transferred patients experienced statistically significant delays in symptom-onset to the PCI-capable hospital(PCI-H) arrival(215 vs. 95 min, P < 0.001), symptom-onset to balloon inflation(225 vs. 160 min, P = 0.009) and first hospital arrival to balloon inflation times(106 vs. 56 min, P < 0.001). Only 28%(n = 9) of transferred patients underwent balloon inflation within 90 min from first hospital arrival, while 60%(n = 19) did within 120 min, although all received balloon inflation within 90 min from arrival at the PCI-H. After controlling for confounding factors of socio-economic status, presentation date/time and diagnostic category, transferred patients experienced an average 162% longer delays from symptom-onset to PCI-H door arrival, and 98% longer delays in symptom-onset to balloon inflation;compared to patients who present directly to the PCI-H. No statistically significant differences were noted between transferred and direct patients when measured from PCI-H door-to-balloon times. Conclusions This study shows that transferred patients experience a greater overall system delay, compared to patients who present directly for PCI, significantly increasing their time to treatment and therefore infarct times. Despite the majority of transfers experiencing pre-hospital activation, their treatment hospital arrival to balloon times are no less than direct presenters after controlling for confounding factors, further compounding the overall delay to therapy.

Clinical outcomes of COVID-19 in elderly male patients

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-Co V-2)has spread throughout the world involving more than 200 countries with more than 3 million confirmed cases and over 200,000 deaths worldwide.[1]COVID-19 patients primarily present with respiratory symptoms showing abnormal lung changes on chest X-ray or computed tomography(CT)with typical imaging appearances of ground glass opacities and consolidation.

Molecular imaging of plaques in coronary arteries with PET and SPECT

Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lu-men stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increas-ingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography （PET） and single photon emission computed tomography （SPECT） has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging tech-niques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coro-nary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed.