Now showing 1 - 10 of 22
  • Publication
    Association Between 18-FDG Positron Emission Tomography and MRI Biomarkers of Plaque Vulnerability in Patients With Symptomatic Carotid Stenosis
    Purpose: Pathologic studies suggest that unstable plaque morphology and inflammation are associated with cerebrovascular events. 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) is a validated technique for non-invasive imaging of inflammation-related plaque metabolism, and MRI can identify morphologic features of plaque instability. The aim of this study was to investigate the association of selected imaging characteristics of plaque vulnerability measured with MRI and PET in patients with symptomatic carotid stenosis. Methods: Patients from the BIOVASC study were selected based on the following inclusion criteria: (1) age ≥ 50 years; (2) recent (<30 days) ischaemic stroke (modified Rankin scale ≤3) or motor/speech/vision TIA; (3) ipsilateral internal carotid artery stenosis (≥5 0% lumen-narrowing); (4) carotid PET/CTA and MRI completed. Semi-automated plaque analysis of MRI images was performed to quantify morphologic features of plaque instability. PET images were co-registered with CTA and inflammation-related metabolism expressed as maximum standardised uptake value (SUVmax). Results: Twenty-five patients met inclusion criteria (72% men, mean age 65 years). MRI-measured plaque volume was greater in men (1,708–1,286 mm3, p = 0.03), patients who qualified with stroke (1,856–1,440 mm3, p = 0.05), and non-statin users (1,325–1,797 mm3, p = 0.03). SUVmax was associated with MRI-measured plaque lipid-rich necrotic core (LRNC) in the corresponding axial slice (rs = 0.64, p < 0.001) and was inversely associated with whole-plaque fibrous cap thickness (rs = −0.4, p = 0.02) and calcium volume (rs = −0.4, p = 0.03). Conclusion: This study demonstrated novel correlations of non-invasive imaging biomarkers of inflammation-related plaque metabolism with morphological MRI markers of plaque instability. If replicated, our findings may support the application of combined MRI and PET to detect vulnerable plaque in future clinical practise and randomised trials.
      161Scopus© Citations 4
  • Publication
    Radiation Protection No. 185 European Guidelines on Diagnostic Reference Levels for Paediatric Imaging
    The establishment and use of diagnostic reference levels (DRLs) have been recommended by the International Commission on Radiological Protection (ICRP) and required in the European Council Directive 2013/59/Euratom Basic Safety Standards (BSS). DRLs are a useful tool in the quest to optimise patient doses in diagnostic radiology and interventional radiology (IR). Particular attention should be paid to establishing and using DRLs in paediatric radiology because children have a higher risk (for some organs and body areas) compared to adults from the detrimental effects of radiation. A comprehensive European and worldwide review of DRLs for paediatric examinations (Section 5 and Annex C) has indicated that only a few countries have set DRLs for paediatric examinations and there is a complete lack of national DRLs for many examinations, in particular for all paediatric interventional procedures. Furthermore, the existing DRLs are often adopted from the old European Commission (EC) recommendations or from other countries, and only a few countries have based their DRLs on their own national patient dose surveys. In many countries, the initial DRLs have never been updated. Due to the huge variation of patient sizes among the paediatric population, several age, size or weight groups are needed to establish the DRLs, and there has been little consistency in grouping of the patients. Extensive patient dose surveys are needed to establish DRLs but there has been no detailed guidance on how to carry out and report such surveys in order to ensure consistent methods and comparability of the DRLs, in particular for reliable evaluation of DRLs for use at a European level.
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  • Publication
    An evaluation of in-plane shields during thoracic CT
    (Oxford University Press, 2013-08) ; ;
    The object of this study was to compare organ dose and image quality effects of using bismuth and barium vinyl in-plane shields with standard and low tube current thoracic CT protocols. A RANDO phantom was scanned using a 64-slice CT scanner and three different thoracic protocols. Thermoluminescent dosemeters were positioned in six locations to record surface and absorbed breast and lung doses. Image quality was assessed quantitatively using region of interest measurements.Scanning was repeated using bismuth and barium vinyl in-plane shields to cover the breasts and the results were compared with standard and reduced dose protocols. Dose reductions were most evident in the breast, skin and anterior lung when shielding was used, with mean reductions of 34, 33 and 10 % for bismuth and 23, 18 and 11 % for barium, respectively. Bismuth was associated with significant increases in both noise and CT attenuation values for all the three protocols, especial-ly anteriorly and centrally. Barium shielding had a reduced impact on image quality. Reducing the overall tube current reduced doses in all the locations by 20-27% with similar increases in noise as shielding, without impacting on attenuation values. Reducing the overall tube current best optimises dose with minimal image quality impact. In-plane shields increase noise and attenuation values, while reducing anterior organ doses primarily. Shielding remains a useful optimisation tool in CT and barium is an effective alternative to bismuth especially when image quality is of concern.
      411Scopus© Citations 15
  • Publication
    Early experiences of radiographers in Ireland during the COVID-19 crisis
    BACKGROUND:Imaging is crucial for assessing the severity and progression of COVID-19. Radiographers are amongst the first-line health professionals that may be exposed to infected persons. This work describes the early experience of radiographers in Ireland to the impact of COVID-19 using two electronic surveys distributed 6 weeks apart. Results were analysed using descriptive statistics and thematic analysis. RESULTS:A total of 370 responded to the first survey and 276 the second, with all six Irish health regions represented. Three quarters of radiographers (77%) reported having adequate personal protective equipment (PPE) available to them. However, almost half of the radiographers were inadvertently exposed to COVID-19-positive patients without appropriate PPE, largely attributed to poor communication and testing. Anxiety levels while initially high, reduced substantially 6 weeks into the crisis period. However, obvious distress was noted amongst some respondents. Forty percent of radiographers reported burnout symptoms due to the COVID-19 crisis and 30% reported considering changing jobs or retiring since the COVID-19 outbreak. CONCLUSION:Clear communication regarding changing protocols and importantly patients' infectious status are essential to safeguard healthcare workers and to minimise unnecessary anxiety and distress. Attention is required to staff mental health including the identification of burnout symptoms to prevent long-term negative consequences of the pandemic on radiography services.
      315Scopus© Citations 40
  • Publication
    High-resolution MRI (HR-MRI) of atherosclerotic plaque in symptomatic carotid stenosis – relationship with risk factors, treatment, and CT angiographic features
    Purpose: Traditional imaging techniques rely on arterial lumen stenosis as an indirect measure of mural plaque. HR-MRI allows direct imaging of mural plaque burden and composition. However, few data exist on the relationship of these parameters to clinical factors in patients with symptomatic carotid stenosis. We investigated the relationship between MR plaque features, clinical characteristics, and plaque morphology on CT angiography. Methods: A sub-group of patients included in the prospective BIOVASC plaque imaging study were included. Inclusion criteria were: (1) Speech/motor TIA or non-severe stroke (Rankin≤3) <72hours (2) Ipsilateral carotid stenosis ≥50% (3) Age≥50 (4) Carotid HR-MRI and CTA performed. Exclusions were pregnancy, malignancy, dementia, renal impairment, cervical irradiation/endarterectomy/stent. Semi-automated analysis of HR-MRI axial plaque images was done using PlaqueView and manual analysis of co-registered CTA performed. Results: 27 patients met inclusion criteria (78% men, mean age 66 years, 36% stroke/64%TIA, 39% current smoking). By HR-MRI, maximum plaque wall area was greater in patients with index stroke compared with TIA (p=0.007). Plaque maximum wall thickness was greater in diabetes (p=0.016) and statin-untreated patients (p=0.003). Volume of lipid-rich necrotic core was less (p=0.018) and fibrous cap thickness (p=0.05) greater in aspirin-treated patients. When HR-MRI was compared with CTA, high correlations were observed for lumen area (rho=0.976, p<0.001), maximum wall thickness (rho=0.878, p<0.001), and maximum wall area (Pearson r=0.981, p<0.001). Conclusion: If replicated, our findings may inform the application of plaque HR-MRI and CTA as surrogate markers in future clinical practice and randomised trials for stroke prevention.
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  • Publication
    Best single slice location to measure visceral adipose tissue on paediatric CT scans and the relations between anthropometric measurements, gender and VAT volume in children
    (British Institute of Radiology, 2015-09-21) ; ;
    Objective: Visceral adipose tissue (VAT) is a significant risk factor for obesity-related metabolic diseases. This study investigates (1) the best single CT slice location for predicting total abdominal VAT volume in paediatrics and (2) the relationship between waist circumference (WC), sagittal diameter (SD), gender and VAT volume. Methods: A random sample of 130 paediatric abdomen CT scans, stratified according to age and gender, was collected. Three readers measured VAT area at each intervertebral level between T12 and S1 using ImageJ analysis (National Institute of Health, Bethesda, MD) software by thresholding −190 to −30 HU and manually segmenting VAT. Single-slice VAT measurements were correlated with total VAT volume to identify the most representative slice. WC and SD were measured at L3–L4 and L4–L5 slices, respectively. Regression analysis was used to evaluate WC, SD and gender as VAT volume predictors. Results: Interviewer and intraviewer reliability were excellent (intraclass correlation coefficient = 0.99). Although VAT measured at multiple slices correlated strongly with abdominal VAT, only one slice in females at L2–L3 and two slices in males at L1–L2 and L5–S1 were strongly correlated across all age groups. Linear regression analysis showed that WC was strongly correlated with VAT volume (beta = 0.970, p < 0.001). Conclusion: Single-slice VAT measurements are highly reproducible. Measurements performed at L2–L3 in females and L1–L2 or L5–S1 in males were most representative of VAT. WC is indicative of VAT. Advances in knowledge: VAT should be measured at L2–L3 in female children and at either L1–L2 or L5–S1 in males. WC is a strong indicator of VAT in children.
      415Scopus© Citations 17
  • Publication
    Effect of Directed Training on Reader Performance for CT Colonography: Multicenter study
    Purpose: To define the interpretative performance of radiologists experienced in computed tomographic (CT) colonography and to compare it with that of novice observers who had undergone directed training, with colonoscopy as the reference standard. Materials and Methods: Physicians at each participating center received ethical committee approval and followed the committees' requests regarding informed consent. Nine experienced radiologists, nine trained radiologists, and 10 trained technologists from nine centers read 40 CT colonographic studies selected from a data set of 51 studies and modeled to simulate a population with positive fecal occult blood test results: Studies were obtained in eight patients with cancer, 12 patients with large polyp, four patients with medium polyp, and 27 patients without colonic lesions. Findings were verified with colonoscopy. An experienced radiologist used 50 endoscopically validated studies to train novice observers before they were allowed to participate. Observers used one software platform to read studies over 2 days. Responses were collated and compared with the known diagnostic category for each subject. The number of correctly classified subjects was determined for each observer, and differences between groups were examined with bootstrap analysis. Results: Overall, 28 observers read 1084 studies and detected 121 cancers, 134 large polyps, and 33 medium polyps; 448 healthy subjects were categorized correctly. Experienced radiologists detected 116 lesions; trained radiologists and technologists detected 85 and 87 lesions, respectively. Overall accuracy of experienced observers (74.2%) was significantly better than that of trained radiologists (66.6%) and technologists (63.2%). There was no significant difference (P = .33) between overall accuracy of trained radiologists and that of technologists; however, some trainees reached the mean performance achieved by experienced observers. Conclusion: Experienced observers interpreted CT colonographic images significantly better than did novices trained with 50 studies. On average, no difference between trained radiologists and trained technologists was found; however, individual performance was variable and some trainees outperformed some experienced observers.
      524Scopus© Citations 65
  • Publication
    Education and training in radiation protection in Europe: an analysis from the EURAMED rocc-n-roll project
    Background: A Strengths, weaknesses, opportunities and threats analysis was performed to understand the status quo of education and training in radiation protection (RP) and to develop a coordinated European approach to RP training needs based on stakeholder consensus and existing activities in the field. Fourteen team members represented six European professional societies, one European voluntary organisation, two international healthcare organisations and five professions, namely: Medical Physicists; Nuclear Medicine Physicians; Radiologists; Radiation Oncologists and Radiographers. Four subgroups analysed the “Strengths”, “Weaknesses”, “Opportunities” and “Threats” related to E&T in RP developed under previous European Union (EU) programmes and on the Guidelines on Radiation Protection Education and Training of Medical Professionals in the EU. Results: Consensus agreement identified four themes for strengths and opportunities, namely: (1) existing structures and training recommendations; (2) RP training needs assessment and education & training (E&T) model(s) development; (3) E&T dissemination, harmonisation, and accreditation; (4) financial supports. Weaknesses and Threats analysis identified two themes: (1) awareness and prioritisation at a national/global level and (2) awareness and prioritisation by healthcare professional groups and researchers. Conclusions: A lack of effective implementation of RP principles in daily practice was identified. EuRnR strategic planning needs to consider processes at European, national and local levels. Success is dependent upon efficient governance structures and expert leadership. Financial support is required to allow the stakeholder professional agencies to have sufficient resources to achieve a pan European radiation protection training network which is sustainable and accredited across multiple national domains.
      142Scopus© Citations 1
  • Publication
    Cohort profile: BIOVASC-late, a prospective multicentred study of imaging and blood biomarkers of carotid plaque inflammation and risk of late vascular recurrence after non-severe stroke in Ireland
    Purpose Inflammation is important in stroke. Anti-inflammatory therapy reduces vascular events in coronary patients. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) identifies plaque inflammation-related metabolism. However, long-term prospective cohort studies investigating the association between carotid plaque inflammation, identified on 18F-FDG PET and the risk of recurrent vascular events, have not yet been undertaken in patients with stroke. Participants The Biomarkers Imaging Vulnerable Atherosclerosis in Symptomatic Carotid disease (BIOVASC) study and Dublin Carotid Atherosclerosis Study (DUCASS) are two prospective multicentred observational cohort studies, employing near-identical methodologies, which recruited 285 patients between 2008 and 2016 with non-severe stroke/transient ischaemic attack and ipsilateral carotid stenosis (50%–99%). Patients underwent coregistered carotid 18F-FDG PET/CT angiography and phlebotomy for measurement of inflammatory cytokines. Plaque 18F-FDG-uptake is expressed as maximum standardised uptake value (SUVmax) and tissue-to-background ratio. The BIOVASC-Late study is a follow-up study (median 7 years) of patients recruited to the DUCASS/BIOVASC cohorts. Findings to date We have reported that 18F-FDG-uptake in atherosclerotic plaques of patients with symptomatic carotid stenosis predicts early recurrent stroke, independent of luminal narrowing. The incorporation of 18F-FDG plaque uptake into a clinical prediction model also improves discrimination of early recurrent stroke, when compared with risk stratification by luminal stenosis alone. However, the relationship between 18F-FDG-uptake and late vascular events has not been investigated to date.
      193Scopus© Citations 3
  • Publication
    Development of a synthetic phantom for the selection of optimal scanning parameters in CAD-CT colonography
    The aim of this paper is to present the development of a synthetic phantom that can be used for the selection of optimal scanning parameters in computed tomography (CT) colonography. In this paper we attempt to evaluate the influence of the main scanning parameters including slice thickness, reconstruction interval, field of view, table speed and radiation dose on the overall performance of a computer aided detection (CAD)–CTC system. From these parameters the radiation dose received a special attention, as the major problem associated with CTC is the patient exposure to significant levels of ionising radiation. To examine the influence of the scanning parameters we performed 51 CT scans where the spread of scanning parameters was divided into seven different protocols. A large number of experimental tests were performed and the results analysed. The results show that automatic polyp detection is feasible even in cases when the CAD–CTC system was applied to low dose CT data acquired with the following protocol: 13 mAs/rotation with collimation of 1.5 mm × 16 mm, slice thickness of 3.0 mm, reconstruction interval of 1.5 mm, table speed of 30 mm per rotation. The CT phantom data acquired using this protocol was analysed by an automated CAD–CTC system and the experimental results indicate that our system identified all clinically significant polyps (i.e. larger than 5 mm).
      269Scopus© Citations 1