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Stevens BJ, Thompson JD. The efficacy of preliminary clinical evaluation for emergency department chest radiographs with trauma presentations in pre- and post-training situations. Radiography (Lond) 2022; 28:1122-1126. [PMID: 36103731 DOI: 10.1016/j.radi.2022.08.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/20/2022] [Accepted: 08/22/2022] [Indexed: 01/13/2023]
Abstract
INTRODUCTION The chest X-ray (CXR) is the most frequently performed radiographic examination. This study evaluates radiographers' ability to localise traumatic CXR pathology and provide a preliminary clinical evaluation (PCE) for these cases. METHODS This observer study was performed in a district general hospital in the United Kingdom (UK). A 58-case image bank was used with 20 positive cases. Participants were awarded a maximum of three points, based on abnormality recognition and descriptive accuracy. Localisation data were recorded with ROCView. Training was delivered via short online recorded tutorials covering an introduction of a systematic search strategy for CXR, how to recognise the common abnormalities covered in the tests, how to structure a PCE and multiple practice cases to review at participants' own pace. Pre- and post-training data was recorded. RESULTS Nine participants completed the study. Overall, pooled sensitivity remained consistent (78.9%-78.8%) following training, specificity and accuracy showed improvement of 79.0%-89.9% and 78.9%-86.0% respectively. An increase in the number of correct localisations and PCE scores were also evident. Participants performed better at correctly identifying a pneumothorax compared to skeletal abnormalities. CONCLUSION Improvements in performance were evident for most participants' abnormality localisations and PCE scores, following the training intervention. The study highlighted areas of CXR PCE that may require further training, such as detecting superimposed or subtle abnormalities. IMPLICATIONS FOR PRACTICE This study provides additional support for the development of PCE systems in additional areas of imaging practice.
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Affiliation(s)
| | - J D Thompson
- University of Salford, UK; University Hospitals of Morecambe Bay NHS Foundation Trust, UK
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2
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Thompson JD. Toward Consistent Design and Reporting of Observer Studies in Imaging. Radiology 2022; 303:531-532. [PMID: 35258379 DOI: 10.1148/radiol.220150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- John D Thompson
- From the Department of Radiography, University of Salford, Frederick Road Campus, Salford M6 6PU, UK
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Genske U, Jahnke P. Human Observer Net: A Platform Tool for Human Observer Studies of Image Data. Radiology 2022; 303:524-530. [PMID: 35258375 DOI: 10.1148/radiol.211832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Background Current software applications for human observer studies of images lack flexibility in study design, platform independence, multicenter use, and assessment methods and are not open source, limiting accessibility and expandability. Purpose To develop a user-friendly software platform that enables efficient human observer studies in medical imaging with flexibility of study design. Materials and Methods Software for human observer imaging studies was designed as an open-source web application to facilitate access, platform-independent usability, and multicenter studies. Different interfaces for study creation, participation, and management of results were implemented. The software was evaluated in human observer experiments between May 2019 and March 2021, in which duration of observer responses was tracked. Fourteen radiologists evaluated and graded software usability using the 100-point system usability scale. The application was tested in Chrome, Firefox, Safari, and Edge browsers. Results Software function was designed to allow visual grading analysis (VGA), multiple-alternative forced-choice (m-AFC), receiver operating characteristic (ROC), localization ROC, free-response ROC, and customized designs. The mean duration of reader responses per image or per image set was 6.2 seconds ± 4.8 (standard deviation), 5.8 seconds ± 4.7, 8.7 seconds ± 5.7, and 6.0 seconds ± 4.5 in four-AFC with 160 image quartets per reader, four-AFC with 640 image quartets per reader, localization ROC, and experimental studies, respectively. The mean system usability scale score was 83 ± 11 (out of 100). The documented code and a demonstration of the application are available online (https://github.com/genskeu/HON, https://hondemo.pythonanywhere.com/). Conclusion A user-friendly and efficient open-source application was developed for human reader experiments that enables study design versatility, as well as platform-independent and multicenter usability. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Thompson in this issue.
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Affiliation(s)
- Ulrich Genske
- From the Department of Radiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany (U.G., P.J.); Data Analytics and Computational Statistics, Hasso Plattner Institute, Digital Engineering Faculty, University of Potsdam, Potsdam, Germany (U.G.); and Berlin Institute of Health, Berlin, Germany (P.J.)
| | - Paul Jahnke
- From the Department of Radiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany (U.G., P.J.); Data Analytics and Computational Statistics, Hasso Plattner Institute, Digital Engineering Faculty, University of Potsdam, Potsdam, Germany (U.G.); and Berlin Institute of Health, Berlin, Germany (P.J.)
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Stevens BJ, Thompson JD. The value of preliminary clinical evaluation for decision making in injuries of the hand and wrist. Int Emerg Nurs 2020; 48:100775. [DOI: 10.1016/j.ienj.2019.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 05/09/2019] [Accepted: 05/23/2019] [Indexed: 11/29/2022]
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Stevens BJ, Thompson JD. The impact of focused training on abnormality detection and provision of accurate preliminary clinical evaluation in newly qualified radiographers. Radiography (Lond) 2018; 24:47-51. [DOI: 10.1016/j.radi.2017.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/02/2017] [Accepted: 08/19/2017] [Indexed: 10/18/2022]
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Thompson JD, Wareing A, Szczepura KR, Vinjamuri S, Hogg P. A JAFROC study of nodule detection performance in CT images of a thorax acquired during PET/CT. Radiography (Lond) 2017; 23:191-196. [PMID: 28687285 DOI: 10.1016/j.radi.2017.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/01/2017] [Accepted: 03/03/2017] [Indexed: 11/27/2022]
Abstract
PURPOSE Two types of CT images (modalities) are acquired in PET/CT: for attenuation correction (AC) and diagnosis. The purpose of the study was to compare nodule detection and localization performance between these two modalities. METHODS CT images, using both modalities, of an anthropomorphic chest phantom containing zero or more simulated spherical nodules of 5, 8, 10 and 12 mm diameters and contrasts -800, -630 and 100 HU were acquired. An observer performance study using nine observers interpreting 45 normal (zero nodules) images and 47 abnormal images (1-3 nodules; average 1.26) was conducted using the free-response receiver operating characteristic (FROC) paradigm. Data were analysed using an R software package implemented jackknife alternative FROC (JAFROC) analysis. Both empirical areas under the equally weighted AFROC curve (wAFROC) and under the highest rating inferred ROC (HR-ROC) curve were used as figures of merit (FOM). To control the probability of Type I error test alpha was set at 0.05. RESULTS Nodule detection as measured by either FOM was significantly better on the diagnostic quality images (2nd modality), irrespective of the method of analysis, [reader averaged inter-modality wAFROC FOM difference = -0.07 (-0.11,-0.04); reader averaged inter-modality HR-ROC FOM difference = -0.05 (-0.09, -0.01)]. CONCLUSION Nodule detection was statistically worse on images acquired for AC; suggesting that images acquired for AC should not be used to evaluate pulmonary pathology.
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Affiliation(s)
- J D Thompson
- Directorate of Radiography, University of Salford, Greater Manchester, M6 6PU, UK; Radiology, Furness General Hospital, University Hospitals of Morecambe Bay NHS Foundation Trust, Dalton Lane, Barrow-in-Furness, Cumbria, LA14 4LF, UK.
| | - A Wareing
- School of Health Sciences, Faculty of Health and Social Care, Robert Gordon University, Garthdee Road, Aberdeen, AB10 7QG, UK
| | - K R Szczepura
- Radiology, Furness General Hospital, University Hospitals of Morecambe Bay NHS Foundation Trust, Dalton Lane, Barrow-in-Furness, Cumbria, LA14 4LF, UK
| | - S Vinjamuri
- Department of Nuclear Medicine, Royal Liverpool and Broadgreen University Hospitals NHS Trust, Prescot Street, Liverpool, L7 8XP, UK
| | - P Hogg
- Radiology, Furness General Hospital, University Hospitals of Morecambe Bay NHS Foundation Trust, Dalton Lane, Barrow-in-Furness, Cumbria, LA14 4LF, UK; Karolinska Institute, Stockholm, SE-171 77, Sweden
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Abdullah AK, Kelly J, Thompson JD, Mercer CE, Aspin R, Hogg P. The impact of simulated motion blur on lesion detection performance in full-field digital mammography. Br J Radiol 2017; 90:20160871. [PMID: 28508724 DOI: 10.1259/bjr.20160871] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Motion blur is a known phenomenon in full-field digital mammography, but the impact on lesion detection is unknown. This is the first study to investigate detection performance with varying magnitudes of simulated motion blur. METHODS 7 observers (15 ± 5 years' reporting experience) evaluated 248 cases (62 containing malignant masses, 62 containing malignant microcalcifications and 124 normal cases) for 3 conditions: no blurring (0 mm) and 2 magnitudes of simulated blurring (0.7 and 1.5 mm). Abnormal cases were biopsy proven. Mathematical simulation was used to provide a pixel shift in order to simulate motion blur. A free-response observer study was conducted to compare lesion detection performance for the three conditions. The equally weighted jackknife alternative free-response receiver operating characteristic was used as the figure of merit. Test alpha was set at 0.05 to control probability of Type I error. RESULTS The equally weighted jackknife alternative free-response receiver operating characteristic analysis found a statistically significant difference in lesion detection performance for both masses [F(2,22) = 6.01, p = 0.0084] and microcalcifications [F(2,49) = 23.14, p < 0.0001]. The figures of merit reduced as the magnitude of simulated blurring increased. Statistical differences were found between some of the pairs investigated for the detection of masses (0.0 vs 0.7 and 0.0 vs 1.5 mm) and all pairs for microcalcifications (0.0 vs 0.7, 0.0 vs 1.5 and 0.7 vs 1.5 mm). No difference was detected between 0.7 and 1.5 mm for masses. CONCLUSION The mathematical simulation of motion blur caused a statistically significant reduction in lesion detection performance. These false-negative decisions could have implications for clinical practice. Advances in knowledge: This research demonstrates for the first time that motion blur has a negative and statistically significant impact on lesion detection performance in digital mammography.
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Affiliation(s)
- Ahmed K Abdullah
- 1 University of Diyala, Baqubah, Diyala, Iraq.,2 Directorate of Radiography, University of Salford, Greater Manchester, UK
| | - Judith Kelly
- 4 Chester Breast Imaging Unit, Countess of Chester Hospital NHS Foundation Trust, Chester, UK
| | - John D Thompson
- 2 Directorate of Radiography, University of Salford, Greater Manchester, UK
| | - Claire E Mercer
- 2 Directorate of Radiography, University of Salford, Greater Manchester, UK
| | - Rob Aspin
- 3 School of Computing, Science and Engineering, University of Salford, Greater Manchester, UK
| | - Peter Hogg
- 2 Directorate of Radiography, University of Salford, Greater Manchester, UK.,5 Karolinska Institute, Stockholm, Sweden
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A method to determine the impact of reduced visual function on nodule detection performance. Radiography (Lond) 2017; 23:19-24. [DOI: 10.1016/j.radi.2016.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 11/20/2022]
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Thompson JD, Thomas NB, Manning DJ, Hogg P. The impact of greyscale inversion for nodule detection in an anthropomorphic chest phantom: a free-response observer study. Br J Radiol 2016; 89:20160249. [PMID: 27266374 PMCID: PMC5124894 DOI: 10.1259/bjr.20160249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Objective: The aim of this work was to assess the impact of greyscale inversion on nodule detection on posteroanterior chest X-ray images. Previous work has attempted this, with no consensus opinion formed. We assessed the value of “fast-flicking” between standard and inverted display modes for nodule detection. Methods: Six consultant radiologists (with 5–32 years' reporting experience) completed an observer task under the free-response paradigm. An anthropomorphic chest phantom was loaded with 50 different configurations of simulated nodules (1–4 nodules per case) measuring 5, 8, 10 and 12 mm in spherical diameter; each configuration represented a single case. In addition, 25 cases contained no nodules. Images were displayed in three modes: (i) standard, (ii) inverted and (iii) fast-flicking between standard and inverted display modes. Each observer completed the study in a different order of display (i, ii, iii) using a calibrated 5-megapixel monitor. Nodules were localized with mouse clicks and ratings assigned using a 1–10 discrete slider-bar confidence scale. Rjafroc (Pittsburgh, PA) was used for data analysis; differences in nodule detection performance were considered significant at 0.05. Results: The observer-averaged weighted jackknife alternative free-response receiver-operating characteristic figures of merit were 0.715 (standard), 0.684 (inverted) and 0.717 (fast-flicking). Random-reader fixed-case analysis revealed no statistically significant difference between any treatment pair [F(2,8) = 1.22; p = 0.345]. Conclusion: No statistically significant difference in nodule detection was found for the three display conditions. Advances in knowledge: We have investigated the impact of fast-flicking between standard and inverted display modes for the detection of nodules. We found no benefit.
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Affiliation(s)
- John D Thompson
- Directorate of Radiology, University of Salford, Manchester, UK.,Radiology, University Hospitals of Morecambe Bay NHS Foundation Trust, Barrow-in-Furness, UK
| | - Nigel B Thomas
- Directorate of Radiology, University of Salford, Manchester, UK
| | - David J Manning
- Directorate of Radiology, University of Salford, Manchester, UK.,Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Peter Hogg
- Directorate of Radiology, University of Salford, Manchester, UK.,Karolinska Institute, Stockholm, Sweden
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Svalkvist A, Svensson S, Håkansson M, Båth M, Månsson LG. VIEWDEX: A STATUS REPORT. RADIATION PROTECTION DOSIMETRY 2016; 169:38-45. [PMID: 26822421 DOI: 10.1093/rpd/ncv543] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
ViewDEX (Viewer for Digital Evaluation of X-ray images) is an image viewer and task manager suitable for research and optimisation tasks in medical imaging. The software has undergone continuous development during more than a decade and has during this time period been used in numerous studies. ViewDEX is DICOM compatible, and the features of the interface (tasks, image handling and functionality) are general and flexible. The set-up of a study is determined by altering properties in a text-editable file, enabling easy and flexible configuration. ViewDEX is developed in Java and can run from any disc area connected to a computer. It is free to use for non-commercial purposes and can be downloaded from http://www.vgregion.se/sas/viewdex The purposes of the present article are to give a short overview of the development of ViewDEX and to describe recent updates of the software. In addition, a description on how to configure a viewing session in ViewDEX is provided.
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Affiliation(s)
- Angelica Svalkvist
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Sune Svensson
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden
| | - Markus Håkansson
- Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden Department of Diagnostic Radiology, Södra Älvsborgs sjukhus, SE-501 82 Borås, Sweden
| | - Magnus Båth
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Lars Gunnar Månsson
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden
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Thompson JD, Chakraborty DP, Szczepura K, Tootell AK, Vamvakas I, Manning DJ, Hogg P. Effect of reconstruction methods and x-ray tube current-time product on nodule detection in an anthropomorphic thorax phantom: A crossed-modality JAFROC observer study. Med Phys 2016; 43:1265-74. [PMID: 26936711 PMCID: PMC4752545 DOI: 10.1118/1.4941017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose: To evaluate nodule detection in an anthropomorphic chest phantom in computed tomography (CT) images reconstructed with adaptive iterative dose reduction 3D (AIDR3D) and filtered back projection (FBP) over a range of tube current–time product (mAs). Methods: Two phantoms were used in this study: (i) an anthropomorphic chest phantom was loaded with spherical simulated nodules of 5, 8, 10, and 12 mm in diameter and +100, −630, and −800 Hounsfield units electron density; this would generate CT images for the observer study; (ii) a whole-body dosimetry verification phantom was used to ultimately estimate effective dose and risk according to the model of the BEIR VII committee. Both phantoms were scanned over a mAs range (10, 20, 30, and 40), while all other acquisition parameters remained constant. Images were reconstructed with both AIDR3D and FBP. For the observer study, 34 normal cases (no nodules) and 34 abnormal cases (containing 1–3 nodules, mean 1.35 ± 0.54) were chosen. Eleven observers evaluated images from all mAs and reconstruction methods under the free-response paradigm. A crossed-modality jackknife alternative free-response operating characteristic (JAFROC) analysis method was developed for data analysis, averaging data over the two factors influencing nodule detection in this study: mAs and image reconstruction (AIDR3D or FBP). A Bonferroni correction was applied and the threshold for declaring significance was set at 0.025 to maintain the overall probability of Type I error at α = 0.05. Contrast-to-noise (CNR) was also measured for all nodules and evaluated by a linear least squares analysis. Results: For random-reader fixed-case crossed-modality JAFROC analysis, there was no significant difference in nodule detection between AIDR3D and FBP when data were averaged over mAs [F(1, 10) = 0.08, p = 0.789]. However, when data were averaged over reconstruction methods, a significant difference was seen between multiple pairs of mAs settings [F(3, 30) = 15.96, p < 0.001]. Measurements of effective dose and effective risk showed the expected linear dependence on mAs. Nodule CNR was statistically higher for simulated nodules on images reconstructed with AIDR3D (p < 0.001). Conclusions: No significant difference in nodule detection performance was demonstrated between images reconstructed with FBP and AIDR3D. mAs was found to influence nodule detection, though further work is required for dose optimization.
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Affiliation(s)
- J D Thompson
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom and Department of Radiology, Furness General Hospital, University Hospitals of Morecambe Bay NHS Foundation Trust, Dalton Lane, Barrow-in-Furness LA14 4LF, United Kingdom
| | - D P Chakraborty
- Department of Radiology, University of Pittsburgh, FARP Building, Room 212, 3362 Fifth Avenue, Pittsburgh, Pennsylvania 15213
| | - K Szczepura
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom
| | - A K Tootell
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom
| | - I Vamvakas
- Department of Radiology, Christie Hospitals NHS Foundation Trust, 550 Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - D J Manning
- Faculty of Health and Medicine, Lancaster Medical School, Furness College, Lancaster University, Lancaster LA1 4YG, United Kingdom
| | - P Hogg
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom and Department of Radiography, Karolinksa Institute, Solnavägen 1, Solna 171 77, Sweden
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Buissink C, Thompson J, Voet M, Sanderud A, Kamping L, Savary L, Mughal M, Rocha C, Hart G, Parreiral R, Martin G, Hogg P. The influence of experience and training in a group of novice observers: A jackknife alternative free-response receiver operating characteristic analysis. Radiography (Lond) 2014. [DOI: 10.1016/j.radi.2014.06.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Analysing data from observer studies in medical imaging research: An introductory guide to free-response techniques. Radiography (Lond) 2014. [DOI: 10.1016/j.radi.2014.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Mraity H, England A, Akhtar I, Aslam A, De Lange R, Momoniat H, Nicoulaz S, Ribeiro A, Mazhir S, Hogg P. Development and validation of a psychometric scale for assessing PA chest image quality: A pilot study. Radiography (Lond) 2014. [DOI: 10.1016/j.radi.2014.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Thompson JD, Hogg P, Manning DJ, Szczepura K, Chakraborty DP. A free-response evaluation determining value in the computed tomography attenuation correction image for revealing pulmonary incidental findings: a phantom study. Acad Radiol 2014; 21:538-45. [PMID: 24594424 DOI: 10.1016/j.acra.2014.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/08/2014] [Accepted: 01/08/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE AND OBJECTIVES The purpose of this study was to compare lesion-detection performance when interpreting computed tomography (CT) images that are acquired for attenuation correction when performing single photon emission computed tomography/computed tomography (SPECT/CT) myocardial perfusion studies. In the United Kingdom, there is a requirement that these images be interpreted; thus, it is necessary to understand observer performance on these images. MATERIALS AND METHODS An anthropomorphic chest phantom with inserted spherical lesions of different sizes and contrasts was scanned on five different SPECT/CT systems using site-specific CT protocols for SPECT/CT myocardial perfusion imaging. Twenty-one observers (0-4 years of CT experience) searched 26 image slices (17 abnormal, containing 1-3 lesions, and 9 normal, containing no lesions) for each CT acquisition. The observers marked and rated perceived lesions under the free-response paradigm. Four analyses were conducted using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis: (1) 20-pixel acceptance radius (AR) with all 21 readers, abbreviated to 20/ALL analysis, (2) 40-pixel AR with 21 readers (40/ALL), (3) 20-pixel AR with 14 readers experienced in CT (20/EXP), and (4) 20-pixel AR with 7 readers with no CT experience (20/NOT). The significance level of the test was set so as to conservatively control the overall probability of a type I error to <0.05. RESULTS The mean JAFROC figure of merit (FOM) for the five CT acquisitions for the 20/ALL study were 0.602, 0.639, 0.372, 0.475, and 0.719 with a significant difference in lesion-detection performance evident between all individual treatment pairs (P < .0001) with the exception of the 1-2 pairing, which was not significant (these differed only in milliamp seconds). System 5, which had the highest performance, had the smallest slice thickness and the largest matrix size. For the other analyses, the system orderings remained unchanged, and the significance of FOM difference findings remained identical to those for 20/ALL, with one exception: for 20/EXP analysis the 1-2 difference became significant with the higher milliamp seconds superior. Improved detection performance was associated with a smaller slice thickness, increased matrix size, and, to a lesser extent, increased tube charge. CONCLUSIONS Protocol variations for CT-based attenuation correction (AC) in SPECT/CT imaging have a measurable impact on lesion-detection performance. The results imply that z-axis resolution and matrix size had the greatest impact on lesion detection, with a weaker but detectable dependence on the product of milliamp and seconds.
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Affiliation(s)
- John D Thompson
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK; University Hospitals of Morecambe Bay NHS Foundation Trust, Nuclear Medicine, Furness General Hospital, Dalton Lane, Barrow-in-Furness, Cumbria, LA14 4LF, UK.
| | - Peter Hogg
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK
| | - David J Manning
- Lancaster Medical School, Faculty of Health & Medicine, Furness College, Lancaster University, Lancaster LA1 4YG, UK
| | - Katy Szczepura
- University of Salford, Directorate of Radiography, 6th Floor Allerton Building, Frederick Road Campus, Greater Manchester, M6 6PU, UK
| | - Dev P Chakraborty
- Medical Image Interpretation Assessment Laboratory, University of Pittsburgh, Presby South Tower, Room 4771, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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Accurate localization of incidental findings on the computed tomography attenuation correction image: the influence of tube current variation. Nucl Med Commun 2012. [PMID: 23196677 DOI: 10.1097/mnm.0b013e32835c0984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This observer performance study assessed lesion detection in the computed tomography attenuation correction image, as would be produced for myocardial perfusion imaging over a tube current (mA) range. A static anthropomorphic chest phantom containing simulated pulmonary lesions was scanned using the four available mA values (1, 1.5, 2 and 2.5) on a GE Infinia Hawkeye 4. All other computed tomography acquisition parameters remained constant throughout. Twenty-seven cases showing zero to four lesions were produced for a free-response receiver-operating characteristic method. Image observations were completed using our novel web-based ROCView software under controlled conditions. The Jackknife alternative free-response receiver-operating characteristic (JAFROC) figure of merit was used for significance testing, wherein a difference in lesion detection performance was considered significant at P values less than 0.05. Twenty readers with varying computed tomography experience (0-24 years) evaluated 108 images using an ordinal scale to score confidence. The JAFROC analysis showed that there was no statistically significant difference in performance between mA values (P=0.439) for this sample of observers. In conclusion, no significant difference in lesion detection performance was seen between the mA values. This suggests that there is no value in using anything other than the lowest mA value for the investigation of incidental extracardiac findings.
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