Automated detection of enteric tubes misplaced in the respiratory tract on chest radiographs using deep learning with two centre validation.

AIM: To develop and test a model based on a convolutional neural network that can identify enteric tube position accurately on chest radiography. MATERIALS AND METHODS: The chest radiographs of adult patients were classified by radiologists based on enteric tube position as either critically misplaced (within the respiratory tract) or not critically misplaced (misplaced within the oesophagus or safely positioned below the diaphragm). A deep-learning model based on the 121-layer DenseNet architecture was developed using a training and validation set of 4,693 chest radiographs. The model was evaluated on an external test data set from a separate institution that consisted of 1,514 consecutive radiographs with a real-world incidence of critically misplaced enteric tubes. RESULTS: The receiver operator characteristic area under the curve was 0.90 and 0.92 for the internal validation and external test data sets, respectively. For the external data set with a prevalence of 4.4% of critically misplaced enteric tubes, the model achieved high accuracy (92%), sensitivity (80%), and specificity (92%) for identifying a critically misplaced enteric tube. The negative predictive value (99%) was higher than the positive predictive value (32%). CONCLUSION: The present study describes the development and external testing of a model that accurately identifies an enteric tube misplaced within the respiratory tract. This model could help reduce the risk of the catastrophic consequences of feeding through a misplaced enteric tube.

Putting machine learning into motion: applications in cardiovascular imaging.

Heart and circulatory diseases cause a quarter of all deaths in the UK and cardiac imaging offers an effective tool for early diagnosis and risk-stratification to improve premature death and disability. This domain of radiology is unique in that assessing flow and motion is essential for understanding and quantifying normal physiology and disease processes. Conventional image interpretation relies on manual analysis but this often fails to capture important prognostic features in the complex disturbances of cardiovascular physiology. Machine learning (ML) in cardiovascular imaging promises to be a transformative tool and addresses an unmet need for patient-specific management, accurate prediction of future events, and the discovery of tractable molecular mechanisms of disease. This review discusses the potential of ML across every aspect of image analysis including efficient acquisition, segmentation and motion tracking, disease classification, prediction tasks and modelling of genotype-phenotype interactions; however, significant challenges remain in access to high-quality data at scale, robust validation, and clinical interpretability.

The impact of behavioural skills training on the knowledge, skills and well-being of front line staff in the intellectual disability sector: a clustered randomised control trial.

BACKGROUND: Staff with varying backgrounds and educational qualifications can be effectively trained to implement procedures in line with evidence-based practice. Behavioural skills training (BST) is a competency-based training model used to effectively educate a broad selection of professionals, including front line staff, in a range of work-related skills. However, BST has yet to be evaluated in a large group-based experiment. METHODS: This study involved a parallel cluster randomised control trial. Six service sites, with a total of 54 participants, were randomised to the intervention condition using the 'coin toss' method. The intervention condition used BST to coach intellectual disability staff in reinforcement, systematic prompting, functional communication training and task analysis. Six service sites, with a total of 50 participants, were also randomised to a control condition in which generalised training in behavioural interventions was restricted. Recruited service sites were randomly assigned to the intervention condition (N = 6, n = 54) or the control condition (N = 6, n = 50) at one point in time, immediately after recruitment and before baseline testing took place. Allocations were stratified by service type (residential or day) and geographical region. One member of the research team allocated service sites using the 'coin toss' method, and another member, blind to the allocations, decided which experimental arm would receive the intervention and which would be designated as control. It was not possible to mask the intervention from participants, but they were recruited prior to randomisation. RESULTS: Participants in the intervention condition demonstrated statistically significant improvements in their knowledge scores over the study period. Participants in the control condition showed no change or a statistically significant decrease in their knowledge scores. No statistically significant changes to well-being were observed for either group. There was clear evidence of knowledge maintenance, as well as skill acquisition and subsequent generalisation to the workplace environment, among participants in the intervention condition. Participants also evaluated the BST intervention positively. CONCLUSIONS: Results support BST as a method for disseminating evidence-based practice to front line staff working with adults with intellectual and developmental disabilities.

Identifying the optimal regional predictor of right ventricular global function: a high-resolution three-dimensional cardiac magnetic resonance study.

Right ventricular (RV) function has prognostic value in acute, chronic and peri-operative disease, although the complex RV contractile pattern makes rapid assessment difficult. Several two-dimensional (2D) regional measures estimate RV function, however the optimal measure is not known. High-resolution three-dimensional (3D) cardiac magnetic resonance cine imaging was acquired in 300 healthy volunteers and a computational model of RV motion created. Points where regional function was significantly associated with global function were identified and a 2D, optimised single-point marker (SPM-O) of global function developed. This marker was prospectively compared with tricuspid annular plane systolic excursion (TAPSE), septum-freewall displacement (SFD) and their fractional change (TAPSE-F, SFD-F) in a test cohort of 300 patients in the prediction of RV ejection fraction. RV ejection fraction was significantly associated with systolic function in a contiguous 7.3 cm2 patch of the basal RV freewall combining transverse (38%), longitudinal (35%) and circumferential (27%) contraction and coinciding with the four-chamber view. In the test cohort, all single-point surrogates correlated with RV ejection fraction (p < 0.010), but correlation (R) was higher for SPM-O (R = 0.44, p < 0.001) than TAPSE (R = 0.24, p < 0.001) and SFD (R = 0.22, p < 0.001), and non-significantly higher than TAPSE-F (R = 0.40, p < 0.001) and SFD-F (R = 0.43, p < 0.001). SPM-O explained more of the observed variance in RV ejection fraction (19%) and predicted it more accurately than any other 2D marker (median error 2.8 ml vs 3.6 ml, p < 0.001). We conclude that systolic motion of the basal RV freewall predicts global function more accurately than other 2D estimators. However, no markers summarise 3D contractile patterns, limiting their predictive accuracy.

Computational study of aortic hemodynamics for patients with an abnormal aortic valve: The importance of secondary flow at the ascending aorta inlet.

Blood flow in the aorta is helical, but most computational studies ignore the presence of secondary flow components at the ascending aorta (AAo) inlet. The aim of this study is to ascertain the importance of inlet boundary conditions (BCs) in computational analysis of flow patterns in the thoracic aorta based on patient-specific images, with a particular focus on patients with an abnormal aortic valve. Two cases were studied: one presenting a severe aortic valve stenosis and the other with a mechanical valve. For both aorta models, three inlet BCs were compared; these included the flat profile and 1D through-plane velocity and 3D phase-contrast magnetic resonance imaging derived velocity profiles, with the latter being used for benchmarking. Our results showed that peak and mean velocities at the proximal end of the ascending aorta were underestimated by up to 41% when the secondary flow components were neglected. The results for helical flow descriptors highlighted the strong influence of secondary velocities on the helical flow structure in the AAo. Differences in all wall shear stress (WSS)-derived indices were much more pronounced in the AAo and aortic arch (AA) than in the descending aorta (DAo). Overall, this study demonstrates that using 3D velocity profiles as inlet BC is essential for patient-specific analysis of hemodynamics and WSS in the AAo and AA in the presence of an abnormal aortic valve. However, predicted flow in the DAo is less sensitive to the secondary velocities imposed at the inlet; hence, the 1D through-plane profile could be a sufficient inlet BC for studies focusing on distal regions of the thoracic aorta.

Attributes of excellent surgical trainers: An analysis of outstanding trainers.

Excellent surgical trainers play a key role in teaching, mentoring and inspiring the next generation of trainee surgeons. Although there are differences in approach, personality and technique among trainers, common themes exist for those that truly shine as examples of good training. The good surgical trainer has long been the "unsung hero" of patient safety, inspiring and imparting wisdom and skill in trainee surgeons, and instilling a sense of confidence and compassion. In order to recognise exceptional trainers, the Association of Surgeons in Training (ASiT) introduced the Silver Scalpel Award in 2000. The award acknowledges talented trainers who go the "extra mile" for their trainees, and the selection process includes both written nominations and structured interviews with the nominees. We wished to identify what makes the best trainers excellent, to see if these attributes could be used to develop recommendations on how to train and how to support trainers. Here we present an outline of key attributes of an excellent surgical trainer, based on qualitative synthesis of the interview sheets from Silver Scalpel interviews. These results clearly highlight that good trainers are first and foremost good doctors, and that good training goes hand-in-hand with excellent patient care. This symbiotic relationship between training and patient outcomes should be acknowledged, and trainers should be supported by their employers to empower them to carry out their dual roles of training and patient care to the best of their ability. Trainers are key role models to inspire the next generation of surgeons and exceptional trainers should be celebrated.

On the choice of outlet boundary conditions for patient-specific analysis of aortic flow using computational fluid dynamics.

Boundary conditions (BCs) are an essential part in computational fluid dynamics (CFD) simulations of blood flow in large arteries. Although several studies have investigated the influence of BCs on predicted flow patterns and hemodynamic wall parameters in various arterial models, there is a lack of comprehensive assessment of outlet BCs for patient-specific analysis of aortic flow. In this study, five different sets of outlet BCs were tested and compared using a subject-specific model of a normal aorta. Phase-contrast magnetic resonance imaging (PC-MRI) was performed on the same subject and velocity profiles extracted from the in vivo measurements were used as the inlet boundary condition. Computational results obtained with different outlet BCs were assessed in terms of their agreement with the PC-MRI velocity data and key hemodynamic parameters, such as pressure and flow waveforms and wall shear stress related indices. Our results showed that the best overall performance was achieved by using a well-tuned three-element Windkessel model at all model outlets, which not only gave a good agreement with in vivo flow data, but also produced physiological pressure waveforms and values. On the other hand, opening outlet BCs with zero pressure at multiple outlets failed to reproduce any physiologically relevant flow and pressure features.

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.

Acute myocardial infarction: susceptibility-weighted cardiac MRI for the detection of reperfusion haemorrhage at 1.5 T.

AIM: To assess whether susceptibility-weighted imaging (SWI) provides better image contrast for the detection of haemorrhagic ischaemia-reperfusion injury in the heart. MATERIALS AND METHODS: Thirty patients (all men; mean age 53 years) underwent cardiac magnetic resonance imaging (MRI) within 7 days of primary percutaneous intervention for acute ST elevation myocardial infarction (STEMI). Multiple gradient-echo T2* sequences with magnitude and phase reconstructions were acquired. A high-pass filtered phase map was used to create a mask for the SWI reconstructions. The difference in image contrast was assessed in those patients with microvascular obstruction. A mixed effects regression model was used to test the effect of echo time and reconstruction method on phase and contrast-to-noise ratio (CNR). Medians and interquartile ranges (IQR) are reported. RESULTS: T2* in haemorrhagic infarcts was shorter than in non-haemorrhagic infarcts (33.5 ms [24.9-43] versus 49.9 ms [44.6-67.6]; p=0.0007). The effect of echo time on phase was significant (p<0.0001), as was the effect of haemorrhage on phase (p=0.0016). SWI reconstruction had a significant effect on the CNR at all echo times (echoes 1-5, p<0.0001; echo 6, p=0.01; echo 7, p=0.02). The median echo number at which haemorrhage was first visible was less for SWI compared to source images (echo 2 versus echo 5, p=0.0002). CONCLUSION: Cardiac SWI improves the contrast between myocardial haemorrhage and the surrounding tissue following STEMI and has potential as a new tool for identifying patients with ischaemia-reperfusion injury.

Self-assembled quantum dots in a nanowire system for quantum photonics.

Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-in-nanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells.

A numerical study of aortic flow stability and comparison with in vivo flow measurements.

The development of an engineering transitional turbulence model and its subsequent evaluation and validation for some diseased cardiovascular flows have been suggestive of its likely utility in normal aortas. The existence of experimental data from human aortas, acquired in the early 1970s with catheter-mounted hot film velocimeters, provided the opportunity to compare the performance of the model on such flows. A generic human aorta, derived from magnetic resonance anatomical and velocity images of a young volunteer, was used as the basis for varying both Reynolds number (Re) and Womersley parameter (α) to match four experimental data points from human ascending aortas, comprising two with disturbed flow and two with apparently undisturbed flow. Trials were made with three different levels of inflow turbulence intensity (Tu) to find if a single level could represent the four different cases with 4000 < Re < 10,000 and 17 < α < 26. A necessary boundary condition includes the inflow "turbulence" level, and convincing results were obtained for all four cases with inflow Tu = 1.0%, providing additional confidence in the application of the transitional model in flows in larger arteries. The Reynolds-averaged Navier-Stokes (RANS)-based shear stress transport (SST) transitional model is capable of capturing the correct flow state in the human aorta when low inflow turbulence intensity (1.0%) is specified.

Stereo-selective inhibition of transient receptor potential TRPC5 cation channels by neuroactive steroids.

BACKGROUND AND PURPOSE: Transient receptor potential canonical 5 (TRPC5) channels are widely expressed, including in the CNS, where they potentiate fear responses. They also contribute to other non-selective cation channels that are stimulated by G-protein-coupled receptor agonists and lipid and redox factors. Steroids are known to modulate fear and anxiety states, and we therefore investigated whether TRPC5 exhibited sensitivity to steroids. EXPERIMENTAL APPROACH: Human TRPC5 channels were conditionally expressed in HEK293 cells and studied using intracellular Ca2+ measurement, whole-cell voltage-clamp and excised patch techniques. For comparison, control experiments were performed with cells lacking TRPC5 channels or expressing another TRP channel, TRPM2. Native TRPC channel activity was recorded from vascular smooth muscle cells. KEY RESULTS: Extracellular application of pregnenolone sulphate, pregnanolone sulphate, pregnanolone, progesterone or dihydrotestosterone inhibited TRPC5 activity within 1-2min. Dehydroepiandrosterone sulphate or 17ß-oestradiol had weak inhibitory effects. Pregnenolone, and allopregnanolone, a progesterone metabolite and stereo-isomer of pregnanolone, all had no effects. Progesterone was the most potent of the steroids, especially against TRPC5 channel activity evoked by sphingosine-1-phosphate. In outside-out patch recordings, bath-applied progesterone and dihydrotestosterone had strong and reversible effects, suggesting relatively direct mechanisms of action. Progesterone inhibited native TRPC5-containing channel activity, evoked by oxidized phospholipid. CONCLUSIONS AND IMPLICATIONS: Our data suggest that TRPC5 channels are susceptible to relatively direct and rapid stereo-selective steroid modulation, leading to channel inhibition. The study adds to growing appreciation of TRP channels as non-genomic steroid sensors.

Cellular mechanisms by which proinsulin C-peptide prevents insulin-induced neointima formation in human saphenous vein.

AIMS/HYPOTHESIS: Endothelial cells (ECs) and smooth muscle cells (SMCs) play key roles in the development of intimal hyperplasia in saphenous vein (SV) bypass grafts. In diabetic patients, insulin administration controls hyperglycaemia but cardiovascular complications remain. Insulin is synthesised as a pro-peptide, from which C-peptide is cleaved and released into the circulation with insulin; exogenous insulin lacks C-peptide. Here we investigate modulation of human SV neointima formation and SV-EC and SV-SMC function by insulin and C-peptide. METHODS: Effects of insulin and C-peptide on neointima formation (organ cultures), EC and SMC proliferation (cell counting), EC migration (scratch wound), SMC migration (Boyden chamber) and signalling (immunoblotting) were examined. A real-time RT-PCR array identified insulin-responsive genes, and results were confirmed by real-time RT-PCR. Targeted gene silencing (siRNA) was used to assess functional relevance. RESULTS: Insulin (100 nmol/l) augmented SV neointimal thickening (70% increase, 14 days), SMC proliferation (55% increase, 7 days) and migration (150% increase, 6 h); effects were abrogated by 10 nmol/l C-peptide. C-peptide did not affect insulin-induced Akt or extracellular signal-regulated kinase signalling (15 min), but array data and gene silencing implicated sterol regulatory element binding transcription factor 1 (SREBF1). Insulin (1-100 nmol/l) did not modify EC proliferation or migration, whereas 10 nmol/l C-peptide stimulated EC proliferation by 40% (5 days). CONCLUSIONS/INTERPRETATION: Our data support a causative role for insulin in human SV neointima formation with a novel counter-regulatory effect of proinsulin C-peptide. Thus, C-peptide can limit the detrimental effects of insulin on SMC function. Co-supplementing insulin therapy with C-peptide could improve therapy in insulin-treated patients.

Environmental disturbance confounds prenatal glucocorticoid programming experiments in Wistar rats.

Low birth weight in humans is predictive of hypertension in adult life, and while the mechanisms underlying this link remain unknown, fetal overexposure to glucocorticoids has been implicated. We have previously shown that prenatal dexamethasone (DEX) exposure in the rat lowers birth weight and programmes adult hypertension. This current study aimed to unravel the molecular nature of this hypertension. However, unknowingly, post hoc investigations revealed that our animals had been subjected to environmental noise stresses from an adjacent construction site, which were sufficient to confound our prenatal DEX-programming experiments. This perinatal stress successfully established low birth weight, hypercorticosteronaemia, insulin resistance, hypertension and hypothalamic-pituitary-adrenal axis dysfunction in vehicle (VEH)-treated offspring, such that the typical distinctions between both treatment groups were ameliorated. The lack of an additional effect on DEX-treated offspring is suggestive of a maximal effect of perinatal stress and glucocorticoids, serving to prevent against the potentially detrimental effects of sustained glucocorticoid hyper-exposure. Finally, this paper serves to inform researchers of the potential detrimental effects of neighbouring construction sites to their experiments.

Implementation of a process-orientated multidisciplinary approach (POMA), a system of cost-effective healthcare delivery within a cardiac surgical unit.

BACKGROUND: The process-orientated multidisciplinary approach (POMA) is a means of delivering consultant-led healthcare from the first outpatient clinic visit through to discharge, bringing together clinical and operational management that can result in effective resource utilisation and improved patient care. METHODS: Prospectively collected data from patients undergoing primary isolated coronary artery bypass graft (CABG) were collected before and after the application of POMA (246 and 260 patients, respectively). The impact of POMA was analysed on the number of cancellations (NOC), postoperative clinical incidents (POCI), postoperative length of stay (PLOS) and cost in the practice of one consultant surgeon. Data were obtained from our clinical database (PATS-Dendrite), which is used risk stratify patients and prospectively to collect clinical/operative data and outcomes. RESULTS: Patients were matched for all variables except for the European Cardiac Surgical Risk Score (EuroSCORE) which was 1.93 for pre-POMA patients and 2.73 for post-POMA patients (p<0.05). Cancellations significantly decreased from 4.5% (n = 11, pre-POMA) to 0.4% (n = 1, post-POMA) (p<0.05). POCI significantly decreased from 44.3% (n = 109, pre-POMA) to 36.2% (n = 94, post-POMA) (p<0.05). PLOS significantly decreased from 6.3 (pre-POMA) to 6.1 days (post-POMA) (p = 0.002). Regression analysis showed that implementation of POMA was the only significant factor in the reduction of POCI and PLOS (p<0.05). POMA resulted in an overall saving of 285,868 pound (400,215 euro; US $508,845) calculated using the 2005 National Health Service (NHS) tariffs. CONCLUSIONS: The implementation of POMA was the only significant known (or measured) factor that improved the operational efficiency and clinical outcome of a single surgeon's practice. The authors believe the principles deserve to be studied further to see if the results can be replicated.

White matter brain lesions in midlife familial hypercholesterolemic patients at 3-Tesla magnetic resonance imaging.

BACKGROUND: Patients with hypercholesterolemia of 60 years and older have an increased risk for white matter brain lesions and dementia. PURPOSE: To investigate whether patients with familial hypercholesterolemia (FH) develop white matter lesions at 3-Tesla (T) MRI as early as in midlife. MATERIAL AND METHODS: Non-diabetic, nonsmoking, and non-hypertensive heterozygous FH patients on treatment with maximally tolerated dose of a statin for more than 5 years (n = 14) and matched controls (n = 22) aged 25 to 60 years of age were studied. Imaging was performed at 3T with a fluid-attenuated T2-weighted MR pulse sequence and a T1-weighted spin-echo pulse sequence following 10 ml of i.v. gadopentetate dimeglumine. Images were evaluated by two independent readers. Fasting blood samples were taken. Student's t test was employed at P<0.05. RESULTS: Three volunteers and one FH patient had white matter lesions (P<0.53). No other evidence of past ischemic stroke was observed. Mean total serum cholesterol and low-density lipoprotein (LDL) cholesterol were significantly higher in the FH group (6.0+/-1.1 vs. 5.1+/-0.9 mmol/l, P<0.02 and 4.1+/-0.9 vs. 3.1+/-0.8 mmol/l, P<0.004, respectively). CONCLUSION: Heterozygous FH patients on statin treatment in the age range of 25 to 60 years are not at increased risk of white matter lesions at 3T MRI.

Quantitative assessment of iron-oxide-enhanced magnetic resonance imaging of the liver: Vessel isointensity is a potential characteristic of liver hemangiomas on late T1-weighted images.

PURPOSE: To test whether a new quantitative measure, the tumor-to-vessel ratio, obtained from late post-iron-oxide-enhanced T1-weighted images allows for differentiating hemangiomas from liver metastases or all malignant liver lesions. MATERIAL AND METHODS: Twenty-six patients (mean 57, range 33-79 years) were prospectively studied at 1.5T magnetic resonance imaging (MRI) with a T1-weighted 2D fast low-angle shot (FLASH) sequence (repetition time/echo time/flip angle; 200 ms/4.8 ms/90 degrees ) and a T2-weighted turbo spin-echo sequence (4072 ms/99 ms/180 degrees ). Imaging was carried out before and at intervals up to 18 min after IV injection of Ferucarbotran (Resovist, Schering, Germany). In 19 patients, one representative malignant lesion was analysed. Eleven hemangiomas were evaluated in 7 patients. Two readers performed a consensus reading with a signal intensity measurement in a lesion, normal liver and hepatic veins, from which ratios were computed. RESULTS: On T1-weighted iron-oxide-enhanced MRI of 30 lesions, tumor-to-vessel signal intensity ratios were distinct in hemangiomas (median 1.04, range 0.99-1.10) as opposed to either metastases (0.64, 0.33-0.77; P < 0.05) or all malignant lesions taken together (0.64, 0.33-0.98; P < 0.05), while the tumor-to-liver ratio was not. CONCLUSION: The tumor-to-vessel ratio may help to differentiate between hemangiomas and metastases. A ratio greater than 0.98 allowed differentiating hemangiomas from metastases with a wide safety margin.

An audit of follow-up chest radiography after coronary artery bypass graft.

AIM: To investigate the clinical value and audit chest radiography, which is currently undertaken as part of routine practice, in the follow-up of coronary artery bypass graft (CABG) patients. MATERIAL AND METHODS: Six hundred and sixty-six first time CABG patients were identified from the Patient Analysis and Tracking System database representing the work of a single surgeon between February 2001 and September 2005. The data regarding the clinical and radiological findings on follow-up were collected from the follow-up clinic letters and case notes. Any need for re-admission/intervention was also noted. RESULTS: Of the 666 patients, 11 died and a further 10 either refused or failed to arrive for follow-up. Chest radiography was undertaken in 645 patients. Only 13 patients (2%) were found to have an abnormality on chest radiography. In all cases this was a pleural effusion that was confirmed on clinical examination in seven patients (53.9%) patients. Only one patient needed re-admission and intervention. In this case the effusion had been noted on clinical examination. Seven patients were discharged and the remaining five were followed up with repeat chest radiography before discharge. Seventy-four patients had a respiratory complication postoperatively, but only three had any evidence of an effusion on follow-up. CONCLUSION: The diagnostic yield of a routine chest radiography in a CABG follow-up clinic is low (2%) and the need for intervention is rare and is determined by clinical examination. The practice of routine radiography in this group of patients has now stopped and follow-up audit will be conducted in 12 months.

Establishing a clinical cardiac MRI service.

After several years of research development cardiovascular MRI has evolved into a widely accepted clinical tool. It offers important diagnostic and prognostic information for a variety of clinical indications, which include ischaemic heart disease, cardiomyopathies, valvular dysfunction and congenital heart disorders. It is a safe non-invasive technique that employs a variety of imaging sequences optimized for temporal or spatial resolution, tissue-specific contrast, flow quantification or angiography. Cardiac MRI offers specific advantages over conventional imaging techniques for a significant number of patients. The demand for cardiac MRI studies from cardiothoracic surgeons, cardiologists and other referrers is likely to continue to rise with pressure for more widespread local service provision. Setting up a cardiac MRI service requires careful consideration regarding funding issues and how it will be integrated with existing service provision. The purchase of cardiac phased array coils, monitoring equipment and software upgrades must also be considered, as well as the training needs of those involved. The choice of appropriate imaging protocols will be guided by operator experience, clinical indication and equipment capability, and is likely to evolve as the service develops. Post-processing and offline analysis form a significant part of the time taken to report studies and an efficient method of providing quantitative reports is an important requirement. Collaboration between radiologists and cardiologists is needed to develop a successful service and multi-disciplinary meetings are key component of this. This review will explore these issues from our perspective of a new clinical cardiac MRI service operating over its first year in a teaching hospital imaging department.

Technical report: Magnetic resonance direct thrombus imaging at 3 T field strength in patients with lower limb deep vein thrombosis: a feasibility study.

AIM: To investigate the feasibility of imaging lower limb deep vein thrombosis using magnetic resonance imaging (MRI) at 3.0 T magnetic field strength with an optimized a T1 magnetization prepared rapid gradient echo technique (MP-RAGE) in patients with normal volunteers as controls. MATERIALS AND METHODS: Patients with deep vein thrombosis (n = 4), thrombophlebitis (n = 2) and healthy volunteers (n = 9) were studied. MRI of the distal thigh and upper calf was performed at 3.0 T with MP-RAGE using two pre-pulses to suppress blood and fat (flip angle 15 degrees, echo time 5 ms, and repetition time 10 ms). A qualitative analysis was performed for detection of thrombi and image quality. Contrast-to-noise ratios were determined in thrombosed and patent veins. RESULTS: Thrombi were clearly visible as high-signal intensity structures with good suppression of the anatomical background. A blinded reader accurately diagnosed 15 out of 16 cases. The contrast-to-noise ratio measurements showed a positive contrast of thrombus over background muscle 16.9 (SD 4.3, 95% CI: 12.5-21.3) and a negative contrast of the lumen to muscle in patent veins of normal volunteers -7.8 (SD 4.3, 95% CI: -11.1 to -4.5), with p = 0.0015. CONCLUSION: Thrombi generate high signal intensity at 3.0 T allowing for their direct visualization if flowing blood, stationary blood and fat are sufficiently suppressed. This preliminary data supports the development of these techniques for other vascular applications.