THE EFFECTS OF CONE-BEAM COMPUTED TOMOGRAPHY IMAGING GUIDANCE ON PATIENT RADIATION EXPOSURES IN TRANS-ARTERIAL CHEMOEMBOLISATION FOR HEPATOCELLULAR CARCINOMA.

This study investigated the effects of cone-beam computed tomography (CBCT) guidance in trans-arterial chemoembolisation (TACE) procedures on the number of digital subtraction angiography (DSA) runs acquired and total patient radiation exposure in patients with hepatocellular carcinoma (HCC). A retrospective, analytical cross-sectional, single institution, study was conducted. Dose data were compared across the control (DSA guidance alone) and study (DSA and CBCT guidance) groups. A total of 122 procedures were included within the study. There was a significant reduction in the number of DSA runs (3 vs 5, p < 0.001) and DSA air kerma-area product (PKA) (3077.3 vs 4276.6 µGym2, p = 0.042) for the study group when compared to the control group. Total procedural PKA and total procedural reference air kerma (Ka,r) were shown to be 50 and 73% higher, respectively, for the study group when compared to the control group. CBCT imaging guidance does reduce the number of DSA runs and DSA PKA required to complete the TACE procedure for patients diagnosed with HCC; however, a substantial increase in total procedural PKA is to be expected and it is thus important that this increased dose is carefully considered and justified.

Evaluation of a prospective adverse event reporting system in interventional radiology.

AIM: To assess the performance of a prospective adverse event (AE) reporting system. MATERIALS AND METHODS: Four hundred and seventy-one consecutive arterial procedures were performed in 465 patients (median age, 65 years; interquartile range, 54-77; 276 men) over 2 years by four interventional radiologists at a single centre where clinical follow-up was not performed routinely by interventional radiology (IR). AEs were reported prospectively using a radiology information system or in interventional radiologists' electronic records and combined in a departmental listing of adverse events (DLAE). A retrospective medical record review was performed to identify a reference standard list of AEs for this observational cohort study. AEs were graded according to the Society of Interventional Radiology AE classification system. Descriptive statistics were calculated for the performance of the DLAE. A model comparing the rate of reporting of AEs with and without integration of clinical follow-up was tested for significance. RESULTS: Thirty-eight of the 471 (8%) IR procedures had an AE according to the reference standard. The DLAE identified 20/38 (53%) of AEs (K=0.67 [good agreement], 95% confidence interval [CI] agreement=0.53-0.81; p=0.0001; sensitivity 52.6% [95% CI, 36-69%], specificity 100% [95% CI, 99-100%], positive predictive value [PPV] 100%, negative predictive value [NPV] 96 [95% CI, 94.5-97%], accuracy 96% [95% CI, 94-97%]). The performance of the AE reporting system will improve with integration of clinical follow-up (p=0.0015). CONCLUSION: A prospective AE reporting system without clinical integration will not detect all procedure complications.

Reducing complexity and unidentifiability when modelling human atrial cells.

Mathematical models of a cellular action potential (AP) in cardiac modelling have become increasingly complex, particularly in gating kinetics, which control the opening and closing of individual ion channel currents. As cardiac models advance towards use in personalized medicine to inform clinical decision-making, it is critical to understand the uncertainty hidden in parameter estimates from their calibration to experimental data. This study applies approximate Bayesian computation to re-calibrate the gating kinetics of four ion channels in two existing human atrial cell models to their original datasets, providing a measure of uncertainty and indication of potential issues with selecting a single unique value given the available experimental data. Two approaches are investigated to reduce the uncertainty present: re-calibrating the models to a more complete dataset and using a less complex formulation with fewer parameters to constrain. The re-calibrated models are inserted back into the full cell model to study the overall effect on the AP. The use of more complete datasets does not eliminate uncertainty present in parameter estimates. The less complex model, particularly for the fast sodium current, gave a better fit to experimental data alongside lower parameter uncertainty and improved computational speed. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Creation and application of virtual patient cohorts of heart models.

Patient-specific cardiac models are now being used to guide therapies. The increased use of patient-specific cardiac simulations in clinical care will give rise to the development of virtual cohorts of cardiac models. These cohorts will allow cardiac simulations to capture and quantify inter-patient variability. However, the development of virtual cohorts of cardiac models will require the transformation of cardiac modelling from small numbers of bespoke models to robust and rapid workflows that can create large numbers of models. In this review, we describe the state of the art in virtual cohorts of cardiac models, the process of creating virtual cohorts of cardiac models, and how to generate the individual cohort member models, followed by a discussion of the potential and future applications of virtual cohorts of cardiac models. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Radiological findings in ischaemic cholangiopathy.

Ischaemic cholangiopathy occurs as a consequence of deficient arterial blood flow to the bile duct wall. Bile duct ischaemia can lead to full-thickness necrosis, bile leakage, biloma formation, and sepsis. It is an important cause of graft failure post-orthotopic liver transplantation. In the native liver, the causes of biliary ischaemia are diverse and include vasculitis or a complication of endovascular procedures. The present review describes the pathology and radiological findings of ischaemic cholangiopathy and outlines the role of interventional radiology in its management.

The Role of Interventional Radiology in the Management of Obstetric and Gynaecological Haemorrhage

Aim We will review our experience of emergent arterial embolization used to treat haemodynamically unstable patients with obstetric and gynaecological haemorrhage. Methods This is a retrospective study of patients with haemodynamically unstable obstetric and gynaecological haemorrhage treated with emergent arterial embolization from 2010 to 2015. Results 22 patients (average age 41 (SD +/-9) years) had emergent arterial embolization. 63% had post-partum haemorrhage (PPH). 82% of cases were performed with conscious sedation and local anaesthesia. Embolization was technically successful in all cases. Embolization was clinically successful in 95% (21/22). In one case of PPH the patient represented six days later with recurrent bleeding and was treated with surgical suturing of the cervix. There were no complications or deaths. Conclusion Arterial embolization is a highly successful treatment of obstetric and gynaecological haemorrhage in unstable patients.

An adaptable parallel algorithm for the direct numerical simulation of incompressible turbulent flows using a Fourier spectral/hp element method and MPI virtual topologies.

A hybrid parallelisation technique for distributed memory systems is investigated for a coupled Fourier-spectral/hp element discretisation of domains characterised by geometric homogeneity in one or more directions. The performance of the approach is mathematically modelled in terms of operation count and communication costs for identifying the most efficient parameter choices. The model is calibrated to target a specific hardware platform after which it is shown to accurately predict the performance in the hybrid regime. The method is applied to modelling turbulent flow using the incompressible Navier-Stokes equations in an axisymmetric pipe and square channel. The hybrid method extends the practical limitations of the discretisation, allowing greater parallelism and reduced wall times. Performance is shown to continue to scale when both parallelisation strategies are used.

Is diffusion-weighted MRI sufficient for follow-up of neuroendocrine tumour liver metastases?

AIM: To assess if diffusion-weighted imaging (DWI) alone could be used for follow-up of neuroendocrine hepatic metastases. MATERIAL AND METHODS: This was a retrospective study, approved by the institutional review board. Twenty-two patients with neuroendocrine liver metastases who had undergone more than one liver magnetic resonance imaging (MRI) examination, (including DWI and using hepatocyte-specific contrast medium) were evaluated. Up to five metastases were measured at baseline and at each subsequent examination. The reference standard measurement was performed on the hepatocyte phase by one reader. Three independent readers separately measured the same lesions on DWI sequences alone, blinded to other sequences, and recorded the presence of any new lesions. RESULTS: The longest diameters of 317 liver metastases (91 on 22 baseline examinations and a further 226 measurements on follow-up) were measured on the reference standard by one reader and on three b-values by three other readers. The mean difference between DWI measurements and the reference standard measurement was between 0.01-0.08 cm over the nine reader/b-value combinations. Based on the width of the Bland and Altman interval containing approximately 95% of the differences between the reader observation and the mean of reference standard and DWI measurement, the narrowest interval over the nine reader/b-value combinations was -0.6 to +0.7 cm and the widest was -0.9 to 1 cm. In the evaluation of overall response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria, the weighted kappa statistic was between 0.49 and 0.86, indicating moderate-to-good agreement between the reference standard and DWI. CONCLUSION: The visualisation and measurement of hepatic metastases using DWI alone are within acceptable limits for clinical use, allowing the use of this rapid technique to restage hepatic disease in patients with neuroendocrine metastases.

Techniques for automated local activation time annotation and conduction velocity estimation in cardiac mapping.

Measurements of cardiac conduction velocity provide valuable functional and structural insight into the initiation and perpetuation of cardiac arrhythmias, in both a clinical and laboratory context. The interpretation of activation wavefronts and their propagation can identify mechanistic properties of a broad range of electrophysiological pathologies. However, the sparsity, distribution and uncertainty of recorded data make accurate conduction velocity calculation difficult. A wide range of mathematical approaches have been proposed for addressing this challenge, often targeted towards specific data modalities, species or recording environments. Many of these algorithms require identification of activation times from electrogram recordings which themselves may have complex morphology or low signal-to-noise ratio. This paper surveys algorithms designed for identifying local activation times and computing conduction direction and speed. Their suitability for use in different recording contexts and applications is assessed.

Pancreatic metastasectomy: experience of the Irish National Surgical Centre for Pancreatic Cancer.

BACKGROUND: Metastatic tumours of the pancreas are rare and the optimal management of these tumours remains unclear, given the paucity of data existing in the literature. We report our experience of pancreatic metastasectomy. METHODS: Data were reviewed on all patients who underwent pancreatic resection for pathologically confirmed metastatic lesions over a consecutive 7-year period. RESULTS: Seven patients (two men and five women) underwent a pancreatectomy for a metastatic pancreatic tumour. The primary tumours were renal cell carcinoma (n = 3), colorectal carcinoma (n = 2) and leiomyosarcoma (n = 2). There was no operative mortality. Postoperative morbidities occurred in two patients. The median follow-up was 49 months (range 17-76). Overall 1- and 2-year survivals were 100 and 86 %, respectively, with a 2-year disease-free survival of 72 %. CONCLUSIONS: Our series further supports that pancreatic metastasectomy can be performed safely and achieves acceptable survival outcomes.

From h to p efficiently: optimal implementation strategies for explicit time-dependent problems using the spectral/hp element method.

We investigate the relative performance of a second-order Adams-Bashforth scheme and second-order and fourth-order Runge-Kutta schemes when time stepping a 2D linear advection problem discretised using a spectral/hp element technique for a range of different mesh sizes and polynomial orders. Numerical experiments explore the effects of short (two wavelengths) and long (32 wavelengths) time integration for sets of uniform and non-uniform meshes. The choice of time-integration scheme and discretisation together fixes a CFL limit that imposes a restriction on the maximum time step, which can be taken to ensure numerical stability. The number of steps, together with the order of the scheme, affects not only the runtime but also the accuracy of the solution. Through numerical experiments, we systematically highlight the relative effects of spatial resolution and choice of time integration on performance and provide general guidelines on how best to achieve the minimal execution time in order to obtain a prescribed solution accuracy. The significant role played by higher polynomial orders in reducing CPU time while preserving accuracy becomes more evident, especially for uniform meshes, compared with what has been typically considered when studying this type of problem.© 2014. The Authors. International Journal for Numerical Methods in Fluids published by John Wiley & Sons, Ltd.

Evaluate, assess, treat: development and evaluation of the EAT framework to increase effective communication regarding sensitive oral-systemic health issues.

Oral healthcare providers are likely to encounter a number of sensitive oral/systemic health issues whilst interacting with patients. The purpose of the current study was to develop and evaluate a framework aimed at oral healthcare providers to engage in active secondary prevention of eating disorders (i.e. early detection of oral manifestations of disordered eating behaviours, patient approach and communication, patient-specific oral treatment, and referral to care) for patients presenting with signs of disordered eating behaviours. The EAT Framework was developed based on the Brief Motivational Interviewing (B-MI) conceptual framework and comprises three continuous steps: Evaluating, Assessing, and Treating. Using a group-randomized control design, 11 dental hygiene (DH) and seven dental (D) classes from eight institutions were randomized to either the intervention or control conditions. Both groups completed pre- and post-intervention assessments. Hierarchical linear models were conducted to measure the effects of the intervention whilst controlling for baseline levels. Statistically significant improvements from pre- to post-intervention were observed in the Intervention group compared with the Control group on knowledge of eating disorders and oral findings, skills-based knowledge, and self-efficacy (all P < 0.01). Effect sizes ranged from 0.57 to 0.95. No statistically significant differences in outcomes were observed by type of student. Although the EAT Framework was developed as part of a larger study on secondary prevention of eating disorders, the procedures and skills presented can be applied to other sensitive oral/systemic health issues. Because the EAT Framework was developed by translating B-MI principles and procedures, the framework can be easily adopted as a non-confrontational method for patient communication.

Computational study of subcritical response in flow past a circular cylinder.

Flow past a circular cylinder is investigated in the subcritical regime, below the onset of Bénard-von Kármán vortex shedding at Reynolds number Re(c)≃47 . The transient response of infinitesimal perturbations is computed. The domain requirements for obtaining converged results is discussed at length. It is shown that energy amplification occurs as low as Re=2.2 . Throughout much of the subcritical regime the maximum energy amplification increases approximately exponentially in the square of Re reaching 6800 at Re(c). The spatiotemporal structure of the optimal transient dynamics is shown to be transitory Bénard-von Kármán vortex streets. At Re≃42 the long-time structure switches from exponentially increasing downstream to exponentially decaying downstream. Three-dimensional computations show that two-dimensional structures dominate the energy growth except at short times.

Abdominal aortic invasion by leiomyosarcoma.

We describe a case of retroperitoneal leiomyosarcoma with extra- and intravascular involvement. The patient presented with abdominal aortic rupture secondary to tumor invasion and extensive tumor thrombus in the inferior vena cava. The presence of a rupture of the abdominal aorta is an important radiologic diagnosis to make because early endovascular or surgical repair can prevent a catastrophic free rupture. Inferior vena cava involvement by leiomyosarcoma may be locally resected in some cases but has a poor long-term survival rate.

CT guided radiofrequency ablation of intra-articular osteoid osteoma of the hip.

BACKGROUND: Osteoid osteoma is a painful benign bone tumour. Previously the standard therapy was surgical excision. Image guided radiofrequency ablation can be clinically applied to ablate the tumour in a minimally invasive manner. AIMS: We present a case of an 18-year-old boy who presented with features of chronic left hip arthropathy secondary to intra-articular osteoid osteoma, subsequently successfully treated by percutaneous CT guided radiofrequency ablation. RESULTS: The CT guided radiofrequency ablation was technically successful as a day case procedure without complication. The patient returned to normal function within one week. No recurrence occurred in the three-year follow-up period. CONCLUSION: Radiofrequency ablation is a safe, minimally invasive and effective technique for treatment of osteoid osteoma.

A comparison of fast MRI of hips with and without parallel imaging using SENSE.

This study was undertaken to qualitatively and quantitatively compare fast MRI of hips with and without parallel imaging using SENSE (sensitivity encoding). 27 patients underwent MRI of the hips with coronal T1 turbo spin echo (TSE) (repetition time (TR) 500 ms, effective echo time (TEeff) 15 ms, Turbo Factor 4), coronal IR-TSE (TR 2000 ms, TEeff 30 ms, inversion time (TI) 160 ms, Turbo Factor 20) and axial T2 TSE (TR 3000 ms, TEeff 80 ms, Turbo Factor 20) weighted images acquired with and without SENSE with a reduction factor of 2. Conventional imaging was performed in 8 min and 36 s. Images acquired with SENSE were acquired in 5 min and 31 s without a discernible reduction in image quality or a significant quantitative reduction in image signal to noise ratio, contrast to noise ratio or edge enhancement.