Now showing 1 - 10 of 18
  • 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
    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
    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.
      160Scopus© Citations 16
  • Publication
    Exploring the translational challenge for medical applications of ionising radiation and corresponding radiation protection research
    (Springer Science and Business Media LLC, 2022-03-18) ; ; ;
    Background: Medical applications of ionising radiation and associated radiation protection research often encounter long delays and inconsistent implementation when translated into clinical practice. A coordinated effort is needed to analyse the research needs for innovation transfer in radiation-based high-quality healthcare across Europe which can inform the development of an innovation transfer framework tailored for equitable implementation of radiation research at scale. Methods: Between March and September 2021 a Delphi methodology was employed to gain consensus on key translational challenges from a range of professional stakeholders. A total of three Delphi rounds were conducted using a series of electronic surveys comprised of open-ended and closed-type questions. The surveys were disseminated via the EURAMED Rocc-n-Roll consortium network and prominent medical societies in the field. Approximately 350 professionals were invited to participate. Participants’ level of agreement with each generated statement was captured using a 6-point Likert scale. Consensus was defined as median ≥ 4 with ≥ 60% of responses in the upper tertile of the scale. Additionally, the stability of responses across rounds was assessed. Results: In the first Delphi round a multidisciplinary panel of 20 generated 127 unique statements. The second and third Delphi rounds recruited a broader sample of 130 individuals to rate the extent to which they agreed with each statement as a key translational challenge. A total of 60 consensus statements resulted from the iterative Delphi process of which 55 demonstrated good stability. Ten statements were identified as high priority challenges with ≥ 80% of statement ratings either ‘Agree’ or ‘Strongly Agree’. Conclusion: A lack of interoperability between systems, insufficient resources, unsatisfactory education and training, and the need for greater public awareness surrounding the benefits, risks, and applications of ionising radiation were identified as principal translational challenges. These findings will help to inform a tailored innovation transfer framework for medical radiation research.
      42Scopus© Citations 1
  • 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.
      388Scopus© Citations 63
  • 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).
      196Scopus© Citations 1
  • Publication
    Paediatric CT optimisation utilising Catphan® 600 and age-specific anthropomorphic phantoms
    The purpose of the study is to perform phantom-based optimisation of paediatric computed tomography (CT) protocols and quantify the impact upon radiation dose and image noise levels. The study involved three Portuguese paediatric centres. Currently employed scanning protocols for head and chest examinations and combinations of exposure parameters were applied to a Catphan®600 phantom to review the CT dose impact. Contrast–noise ratio (CNR) was quantified using Radia Diagnostic® tool. Imaging parameters, returning similar CNRs (<1) and dose savings were applied to three paediatric anthropomorphic phantoms. OsiriX software based on standard deviation pixel values facilitated image noise analysis. Currently employed protocols and age categorisation varied between centres. Manipulation of exposure parameters facilitated mean dose reductions of 33 and 28 % for paediatric head and chest CT examinations, respectively. The majority of the optimised CT examinations resulted in image noise similar to currently employed protocols. Dose reductions of up to 33 % were achieved with image quality maintained.
      362Scopus© Citations 5
  • 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.
      140Scopus© Citations 23
  • Publication
    Variability of Breast Density Classification Between US and UK Radiologists
    Purpose: To assess whether subjective breast density categorization remains the most useful way to categorize mammographic breast density and whether variations exist across geographic regions with differing national legislation. Methods: Breast radiologists from two countries (UK, USA) were voluntarily recruited to review sets of anonymized mammographic images (n = 180) and additional repeated images (n = 70), totaling 250 images, to subjectively rate breast density according to the Breast Imaging Reporting and Data system (BI-RADS) categorization. Images were reviewed using standardized viewing conditions and Ziltron software. Inter-rater reliability was analyzed using the Kappa test. Results: The US radiologists (n = 25) judged fewer images as being “mostly fatty” than UK radiologists (n = 24), leading a greater number of images classified in the higher BI-RADS categories, particularly in BI-RADS 3. Overall agreement for all data sets was k = 0.654 indicating substantial agreement between the two cohorts. When the data were split into BI-RADS categories, the level of agreement varied from fair to substantial. Conclusion: Variations in how radiologists from the USA and UK classify breast density was established, especially when the data were divided into breast density categories. This variation supports the need for a reliable breast density assessment method to enhance the individualized supplemental screening pathways for dense breasts. The use of two-scale categorization method demonstrated improved agreement.
      264Scopus© Citations 9
  • Publication
    The establishment of computed tomography diagnostic reference levels in Portugal
    The aims of this study were to investigate the frequency of Portuguese computed tomography (CT) examinations, identify protocol application and establish diagnostic reference levels (DRLs). CT departments (n=211) were surveyed nationally (June 2011–January 2012) and CT protocol information and dose data were collected, as were retrospective age-categorised paediatric CT data from three national paediatric centres. The proposed national CT DRLs (CTDIvol) for adults were 75, 18, 14, 18, 17, 36, 22, 27 and 16 mGy for head, neck, chest, abdomen, pelvis, cervical, dorsal, lumbar and joints, respectively. The levels for paediatric head and chest examinations were as follows: 48 and 2 mGy (newborns), 50 and 6 mGy (5 y olds), 70 and 6 mGy (10 y olds) and 72 and 7 mGy (15 y olds). A limited number of current paediatric protocols aligned to recommended international age categorisations. Portuguese DRLs were generally higher than European recommendations, suggesting potential for optimisation. The need for greater standardisation of age-categorised paediatric protocols was identified.
      634Scopus© Citations 45