Diagnostic accuracy of high-definition CT coronary angiography in high-risk patients.

AIM: To assess the diagnostic accuracy of computed tomography coronary angiography (CTCA) using a combination of high-definition CT (HD-CTCA) and high level of reader experience, with invasive coronary angiography (ICA) as the reference standard, in high-risk patients for the investigation of coronary artery disease (CAD). MATERIALS AND METHODS: Three hundred high-risk patients underwent HD-CTCA and ICA. Independent experts evaluated the images for the presence of significant CAD, defined primarily as the presence of moderate (≥ 50%) stenosis and secondarily as the presence of severe (≥ 70%) stenosis in at least one coronary segment, in a blinded fashion. HD-CTCA was compared to ICA as the reference standard. RESULTS: No patients were excluded. Two hundred and six patients (69%) had moderate and 178 (59%) had severe stenosis in at least one vessel at ICA. The sensitivity, specificity, positive predictive value, and negative predictive value were 97.1%, 97.9%, 99% and 93.9% for moderate stenosis, and 98.9%, 93.4%, 95.7% and 98.3%, for severe stenosis, on a per-patient basis. CONCLUSION: The combination of HD-CTCA and experienced readers applied to a high-risk population, results in high diagnostic accuracy comparable to ICA. Modern generation CT systems in experienced hands might be considered for an expanded role.

The safe practice of CT coronary angiography in adult patients in UK imaging departments.

Computed tomography coronary angiography is increasingly used in imaging departments in the investigation of patients with chest pain and suspected coronary artery disease. Due to the routine use of heart rate controlling medication and the potential for very high radiation doses during these scans, there is a need for guidance on best practice for departments performing this examination, so the patient can be assured of a good quality scan and outcome in a safe environment. This article is a summary of the document on 'Standards of practice of computed tomography coronary angiography (CTCA) in adult patients' published by the Royal College of Radiologists (RCR) in December 2014.

High-dose intravenous metoprolol usage for reducing heart rate at CT coronary angiography: efficacy and safety.

AIM: To evaluate the usage, safety, and efficacy of high-dose intravenous metoprolol for heart rate reduction in computer tomographic (CT) coronary angiography. MATERIALS AND METHODS: As this was retrospective analysis of anonymous data, medical ethics committee approval was waived by the regional health research authority. Patients, who had known iodinated contrast medium allergy, contraindications to ß-blockers, atrial fibrillation, and indications other than suspected coronary artery disease, were excluded from analysis. The ultimate study population of 662 were analysed with details of intravenous metoprolol doses, complications, heart rate before administration of intravenous metoprolol (resting heart rate, RHR), heart rate at acquisition of scan (acquisition heart rate, AHR), and usage of low radiation dose protocols. RESULTS: Of the ultimate study population of 662 patients, 183 had no intravenous metoprolol with mean acquisition heart rate (AHR) of 58 beats per minute (bpm), 257 had 1-15 mg intravenous metoprolol with mean AHR of 57 bpm, 114 had 16-29 mg intravenous metoprolol with mean AHR of 62 bpm and 108 had ≥30 mg intravenous metoprolol with mean AHR of 66 bpm. In the group receiving intravenous metoprolol, average usage was 19 mg (maximum 67 mg) with average reduction in HR of 15 bpm. There were no clinical incidents in relation to the use of high-dose intravenous metoprolol. CONCLUSION: Higher doses of intravenous metoprolol are beneficial in achieving target heart rates to facilitate usage of low radiation dose protocols. With appropriate exclusion criteria, higher doses of intravenous metoprolol, well in excess of 15 mg, can be safely administered when carefully titrated.

The role of multidetector computed tomography coronary angiography in imaging complications post-cardiac surgery.

There have been numerous advances in the field of cardiac imaging. The advent of multidetector computed tomography coronary angiography (MDCT-CA) and in particular electrocardiographic (ECG)-gated acquisition has revolutionized the investigation of the complete spectrum of complications of common cardiothoracic surgical procedures. Generic complications, such as mediastinitis, pericardial effusion, sternal osteomyelitis, and mediastinal fibrosis, are discussed with illustrative examples of multiplanar and volume-rendered three-dimensional reconstructions. Graft-related complications of both coronary artery bypass grafts and aortic root grafts are reviewed. The role of MDCT-CA in the investigation of prosthetic valve endocarditis and root abscesses is outlined. We present a complete illustration of the detailed images that are obtained when investigating a full range of graft-related complications from both aortic and coronary surgery using ECG-gated MDCT-CA. MDCT-CA has the potential to become established as the optimal technique with which to image a multitude of complications post-cardiac surgery.

Radiation-reduction strategies in cardiac computed tomographic angiography.

Ionizing radiation has long been known to increase the risk of cancer. X-rays and γ-rays are officially classified as a carcinogen by the World Health Organization's International Agency for Research on Cancer.(1) Of the 5 billion imaging investigations performed worldwide two-thirds employ ionizing radiation.(2) Diagnostic x-rays are the largest man-made source of radiation exposure to the general population, and computed tomography (CT) represents the largest proportion of these.(3) Diagnostic CT has seen a dramatic increase in applications in the last two decades, not least in the higher dose applications. Whilst the increased use of CT has undoubtedly been of patient benefit, it inevitably will be associated with an increase in malignancy due to medical exposure. In fact a recent study from the USA has estimated that the CT examinations performed in 2007 could result in 29,000 future cancers based on current risk estimations.(4) Whilst the numbers in the UK will be less (only 4 million examinations are performed compared to 70 million), it is clear that it is the responsibility of all radiologists to carefully examine their CT techniques and protocols with the aim to reduce the dose of examinations without compromising their accuracy. Cardiac computed tomographic angiography (CTA) initially was a very high dose application. However, both clinicians and CT system manufacturers have done a large amount of work to reduce dose. Dramatic changes have been achieved and the aim of this review is to highlight these. However, such developments are not exclusively applicable to cardiac CTA and many can be utilized in CT in general.

Imaging of illicit drug use.

Illicit drug abuse is a continuing menace of epidemic proportions associated with serious medical and social problems. Drug abuse can have a wide variety of presentations some of which can be life-threatening. The clinical diagnosis can be challenging as the history is usually limited or absent. Radiologists need to be familiar with varied imaging presentations and the related complications of illicit drug abuse to ensure correct diagnosis and appropriate timely treatment. This review will illustrate the imaging spectrum of illicit drug abuse involving several organ systems and also discuss the pathophysiological consequences of drug abuse.

Prognostic and accuracy data of multidetector CT coronary angiography in an established clinical service.

AIM: To assess the accuracy of clinical coronary computed tomography angiography (CTA) data compared to invasive coronary angiography, and to determine the prognostic value of a negative coronary CTA examination in symptomatic, intermediate-risk patients. METHODS: Thirty-seven months of coronary CTA data were audited. Seventy-eight patients were identified who had undergone coronary CTA followed by invasive coronary angiography (ICA) to determine the accuracy of CTA versus ICA. One hundred and seventy-eight patients were identified who had a "negative" coronary CTA to enable evaluation of the prognostic value of a negative CTA examination. RESULTS: Of the 78 patients in the accuracy analysis group there were 43 true-negative, two false-negative, 26 true-positive, and seven false-positive results producing a sensitivity of 92.9%, specificity of 86%, negative predictive value of 95.6%, and positive predictive value of 78.8%. The 178 patients who had a negative coronary CTA examination were followed up for a mean of 366 days and were all alive (0% mortality) with no episodes of myocardial infarction or unstable angina; two patients underwent elective revascularization procedures (1.1%). CONCLUSION: According to medium-term analysis, the accuracy of the clinical coronary CTA programme is in line with published trial data, producing excellent sensitivity and negative predictive values. The finding of a negative coronary CTA in symptomatic, intermediate-risk patients appears to confer a good prognosis, at mean follow-up of 1 year, with no deaths or episodes of myocardial infarction or unstable angina. This suggests that the prognostic value of a negative coronary CTA may be similar to that conferred by negative myocardial perfusion scintigraphy or stress echocardiography.

Efficacy and complications of Angioseal in antegrade puncture.

AIM: Although arterial closure devices are in use for over a decade, there have been no specific study to assess the use of the same in antegrade puncture. MATERIAL AND METHOD: Consecutive patients undergoing antegrade puncture for peripheral vascular disease in a single centre performed by a single operator were included in this study. The notes and the angiograms were reviewed retrospectively for possible complications and the severity of disease. RESULT: Over a 25-month period, 21 patients with antegrade puncture had Angioseal deployed for haemostasis. Post-procedure complications recorded from the case notes showed one episode of haematoma formation and one case of worsening ischaemia. The severity of the disease at the puncture site did not influence the outcome. CONCLUSION: Use of Angioseal is safe and effective in antegrade punctures for peripheral vascular disease. The result is independent of the severity of disease at the puncture site.

The effect of radiographic contrast media on leukocyte motility.

RATIONALE AND OBJECTIVES: Studies describing the effects of radiographic contrast media (RCM) in leukocyte chemotaxis have been contradictory. No studies have been performed after in-vivo exposure. The authors assess the effect of RCM on leukocytes following in-vivo exposure. METHODS: Seventeen patients were studied after intraarterial bolus injection of 75 mL of iohexol (300 mg/mL) or iotrolan (300 mg/mL), 30 minutes and 24 hours postinjection; chemotaxis was assessed using an ex-vivo whole-blood under-agarose method. RESULTS: With iohexol, there was a profound reduction in chemotaxis compared with the preinjection state (P = .001) at 30 minutes. No effect, however, was seen at 24 hours. With iotrolan, no significant reduction in chemotaxis was seen at 30 minutes or at 24 hours. CONCLUSIONS: Radiographic contrast media have differing effects on leukocyte chemotaxis. This may be of significance in the selection of appropriate RCM in certain patients.

The effect of bed rest and intra-articular steroids on the acute phase response in rheumatoid arthritis.

The impact of therapeutic interventions on the disease process in patients with rheumatoid arthritis (RA) is complex. The effect on the acute phase response was studied in 25 in-patients on imposed bed rest, who were randomised to treatment with (n = 12) or without (n = 13) intra-articular steroids. C-reactive protein (CRP), ESR and IgA alpha-1 antitrypsin complex levels were measured on admission and on days 3 and 5. Levels at onset were not different between groups. At day 3 and day 5, a significant (p < 0.001) fall in CRP was seen only in the intra-articular steroid group. Other cytokine and disease parameter measures did not alter during the study period (although IL-6 and CRP correlated at onset in all 25 patients). The mean duration of the hospital stay was longer for the patients treated with bed rest only. Thus, bed rest when combined with intra-articular steroids produced a rapid systemic effect, while bed-rest alone did not have an effect on the acute phase response over this short time scale.

Aortic valve imaging with computed tomography: a review.

The finding of aortic valve calcification is of clinical relevance. Thickening and calcification of the aortic valve ('aortic sclerosis') may progress over time to calcific aortic stenosis, and calcification of the aortic valve has prognostic importance even in the absence of valve obstruction. Aortic valve calcification may also have effects on the conduction system. There is progressive awareness of the need for an imaging technique that can accurately and reproducibly quantify calcification of native and prosthetic aortic valves. Through adaptation of techniques from electron beam computed tomography (CT) coronary calcium scoring, CT has been proposed as the appropriate imaging modality. Although originally described as a method of comparing the calcification of different aortic valve bioprostheses, the major role suggested for CT aortic valve calcium quantification is now in the field of preventive medicine. This has stemmed from the recognition that traditional vascular risk factors also have a role in the etiology of calcific aortic stenosis. Subsequently, the realization that pharmacological modification of lipid profiles may result in slowing of progression or even regression of aortic valve calcification has led to a need to quantify aortic valve calcification for follow up purposes. Echocardiography has been used to estimate aortic valve calcification in studies of the natural history of aortic stenosis, but it does not accurately quantify calcium. CT appears able to fulfil this requirement, though the technique is still relatively novel. This review examines the need for aortic valve calcium quantification and the evolution of imaging to the current status. Future directions and the promise of new helical CT technologies with respect to cardiac imaging are explored.

Effects of radiographic contrast media on leukocyte phagocytosis.

RATIONALE AND OBJECTIVES: Differences in leukocyte phagocytosis following exposure to different classes of radiographic contrast media (RCM) may help in the development of less toxic alternatives and be useful as a guide to contrast selection in certain patient groups. The effect of RCM on leukocyte phagocytosis of Escherichia coli was examined. METHODS: Cell population phagocytosis and individual cell phagocytic activity were assessed in a control group and in samples exposed both to the ionic RCM diatrizoate and ioxaglate and to the nonionic RCM iohexol and iotrolan by using a flow cytometer. RESULTS: The percentage of granulocytes undergoing phagocytosis was 88.4% in the control population. Following exposure to RCM, this value fell to 79.2% with iohexol, 77.6% with iotrolan, 70.5% with diatrizoate, and 68.7% with ioxaglate. The number of bacteria phagocytosed by active leukocytes was not affected by RCM. CONCLUSION: RCM adversely affect the percentage of granulocytes involved in phagocytosis but not the number of pathogenic bacteria that are phagocytosed by individual granulocytes.

The effects of radiographic contrast media on leucocyte orientation.

The effects of radiographic contrast media (RCM) on leucocyte orientation in vitro were studied using a Zigmond chamber. Leucocyte orientation was assessed following exposure of the leucocytes to iotrolan, iohexol, ioxaglate and diatrizoate. The RCM used were diluted to a concentration similar to that obtained in vivo during routine angiography. At this concentration there was a significant reduction in leucocyte orientation for all RCM investigated but the effect was more pronounced in the monomeric than the dimeric RCM. The results may have significance when deciding which radiographic contrast medium to use in selected patients, particularly those who are immunosuppressed or septicaemic.

Pulmonary venous evaluation using electrocardiogram-gated 64-detector row cardiac CT.

OBJECTIVES: Radiofrequency ablation of the pulmonary veins is an accepted treatment for atrial fibrillation. An accurate knowledge of pulmonary venous anatomy and dimensions is desirable prior to such a procedure. The objective of this study was to use 64-detector row cardiac CT to investigate the changes in pulmonary venous dimensions during the cardiac cycle. METHODS: Data from 44 consecutive patients with no significant cardiovascular pathology who underwent electrocardiogram (ECG)-gated 64-detector row coronary angiography were retrospectively analysed. Average diameter and cross-sectional area were measured at 5 mm intervals from each pulmonary vein ostium, in ventricular end-diastole and ventricular end-systole, using curved multiplanar reformats. RESULTS: 4 (9.1%) patients had pulmonary vein anomalies and were excluded. In the remaining 40 patients, pulmonary vein diameter and area at the ostium were significantly larger in end-systole in all four veins, with the largest differences in the superior pulmonary veins. Dimensional changes for diameter (millimetres) and area (square millimetres) were as follows: left superior pulmonary vein, 2.5 (p<0.001), 65.48 (p<0.001); right superior pulmonary vein, 1.63 (p<0.001), 56.27 (p<0.001); left inferior pulmonary vein, 1.1 (p<0.001), 30.41 (p<0.001); and right inferior pulmonary vein, 0.68 (p=0.005), 30.14 (p=0.005). Less marked changes were seen at measurement sites further from the atrium. Interobserver correlation was high (all but one measurement >0.9). CONCLUSION: Pulmonary vein dimensions change significantly between end-systole and end-diastole, and the ostia of the superior pulmonary veins are potentially the most vulnerable to dimensional inaccuracies. ECG-gated cardiac CT may provide a more precise method of pulmonary venous dimensional measurement than non-gated techniques. Knowledge of change in pulmonary vein diameter offers interesting potential research into the effect of pulmonary vein function.

Prognostic value of coronary multidetector CT angiography in patients with an intermediate probability of significant coronary heart disease.

The aim of this study was to determine the prognostic value of coronary multidetector CT angiography (MDCTA) in patients with an intermediate pre-test probability of significant coronary artery disease (CAD). Patients who underwent 64-slice coronary MDCTA and met the selection criteria were identified and assessed for intermediate pre-test probability. Coronary MDCTA scans were preceded by calcium scoring, whereas all MDCTA scans were interrogated for the presence of plaque composition and the distribution and degree of stenosis. Significant stenosis was classified as being >50% of the luminal diameter. All patients were followed up for the occurrence of (i) cardiac death, (ii) non-fatal myocardial infarction, (iii) unstable angina requiring hospital admission and (iv) revascularisation. 138 patients were included (follow-up of 19.9 months); of these, 8 had a cardiac event (all revascularisations) and all had a positive coronary MDCTA. Patients with normal coronary arteries or non-significant stenosis suffered no cardiac events during follow-up. There were significant differences between the two groups regarding the presence of significant stenosis (p<0.001), the presence of plaque (p = 0.011) and a calcium score >10 (p = 0.003); 36.4% of patients with significant stenosis underwent revascularisation. In conclusion, this is the first UK study to investigate survival data in a population of intermediate-risk patients with no prior history of CAD who were investigated with coronary MDCTA. Coronary MDCTA can confidently rule out significant CAD in the intermediate-risk population and guide risk factor modification in patients with demonstrated coronary atheroma.

Imaging the pericardium: appearances on ECG-gated 64-detector row cardiac computed tomography.

Multidetector row computed tomography (MDCT) with its high spatial and temporal resolution has now become an established and complementary method for cardiac imaging. It can now be used reliably to exclude significant coronary artery disease and delineate complex coronary artery anomalies, and has become a valuable problem-solving tool. Our experience with MDCT imaging suggests that it is clinically useful for imaging the pericardium. It is important to be aware of the normal anatomy of the pericardium and not mistake normal variations for pathology. The pericardial recesses are visible in up to 44% of non-electrocardiogram (ECG)-gated MDCT images. Abnormalities of the pericardium can now be identified with increasing certainty on 64-detector row CT; they may be the key to diagnosis and therefore must not be overlooked. This educational review of the pericardium will cover different imaging techniques, with a significant emphasis on MDCT. We have a large research and clinical experience of ECG-gated cardiac CT and will demonstrate examples of pericardial recesses, their variations and a wide variety of pericardial abnormalities and systemic conditions affecting the pericardium. We give a brief relevant background of the conditions and reinforce the key imaging features. We aim to provide a pictorial demonstration of the wide variety of abnormalities of the pericardium and the pitfalls in the diagnosis of pericardial disease.