AIM: To study and compare the diagnostic accuracy of region of interest (ROI) density measurement and pixel mapping [computed tomography (CT) density of individual pixels] for the diagnosis of renal angiomyolipoma (AML) using CT.MATERIALS AND METHODS: A study group of histologically proven AMLs was compared with a control group of histologically proven renal cell cancers, normal renal parenchyma, and simple renal cysts. The mean tissue density (ROI circle) and a pixel density map were recorded. The diagnostic accuracy of various thresholds of ROI and pixel mapping values were compared using receiver operating characteristic curves.RESULTS: Twenty-two AMLs, 16 renal cell carcinomas (RCCs), 30 simple cysts, and 30 sites of renal parenchyma were evaluated. The mean (+/- 1 SD) density of the AMLs was significantly Lower [-15.2(20.8) units] than the three control groups [+36.0(8.1) units, +5.4(3.4) units and +22.2(46.5) units for RCC, renal cyst and parenchyma respectively; p < 0.001 (analysisof variance)]. The sensitivities and specificities of the ROI diagnostic thresholds of <= 0units, <= -10 units and <= -20 units were 77 and 97%, 73 and 100% and 50 and 100%, respectively. Using pixel mapping [diagnostic thresholds of either a line of 4 pixels <=-10 units or a square of 4 pixels <=-10 units] the sensitivity improves to 86% with a specificity of 97%.CONCLUSION: Although a ROI threshold value of <=-10 units has a very high specificity (100% in the present study) the sensitivity is modest at only 73%. Pixel mapping is more sensitive for recognizing small clusters of fat. In practice, both methods can be recommended for the analysis of suspected AMLs. ROI density measurement is convenient when anatysing large areas of suspected fat and <=-10 units should be used as the diagnostic threshold. When faced with small lucent areas or indeterminate values after ROI analysis, pixel mapping is recommended using a tine of 4 pixels <=-10 units or a square of 4 pixels <=-10 units as the discriminating thresholds. (c) 2006 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Picture quizPicture quizD LL Cochlin, K C Potter, H Evans, U Patel, D Svasti-Salee, C J Wilkins, P S Sidhu, E Simpson, C Allen, G Rottenberg, J Eaton and J RichenbergD LL Cochlin1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, K C Potter1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, H Evans1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, U Patel1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, D Svasti-Salee1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, C J Wilkins1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, P S Sidhu1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, E Simpson1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, C Allen1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, G Rottenberg1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author, J Eaton1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this author and J Richenberg1Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, 2Department of Radiology, St George's Hospital, London SW17 0QT, 3Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, 4Department of Radiology, University College London Hospitals, London, 5Department of Radiology, Guy's Hospital, St Thomas' Street, London SE1 9RT, 6Departments of Urology and 7Imaging, The Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UKSearch for more papers by this authorPublished Online:28 Jan 2014https://doi.org/10.1259/imaging/12170461SectionsPDF/EPUBFull Text ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail About Previous article Next article FiguresReferencesRelatedDetails Volume 17, Issue 2October 2005Pages: 91-viii © The British Institute of Radiology History Published onlineJanuary 28,2014 Metrics 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