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Andersson, Torbjorn
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Publications (10 of 13) Show all publications
Krauss, W., Gunnarsson, M., Andersson, T. & Thunberg, P. (2015). Accuracy and reproducibility of a quantitative magnetic resonance imaging method for concurrent measurements of tissue relaxation times and proton density. Magnetic Resonance Imaging, 33(5), 584-591
Open this publication in new window or tab >>Accuracy and reproducibility of a quantitative magnetic resonance imaging method for concurrent measurements of tissue relaxation times and proton density
2015 (English)In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 33, no 5, p. 584-591Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the accuracy and reproducibility of a quantitative magnetic resonance (qMR) imaging method (QRAPMASTER) for simultaneous measurements of T1 and T2 relaxation times, and proton density (PD).

Materials and Methods: Measurements of T1, T2, and PD with qMR were performed using phantoms with different relaxation times and concentrations of heavy water. Healthy volunteers were examined with different head coils. Regional measurements were performed in normal-appearing white and gray matter from the healthy control subjects, and in multiple sclerosis (MS) patients.

Results: In phantom measurements, QRAPMASTER slightly underestimated T1, and T2 variations between repeated measurements were modest. PD was generally overestimated. The overall relative difference was 1.2 5.3% (T1), 6.6 1.9% (12), and 0.7 5.1% (PD). In healthy volunteers, there were no statistically significant differences of T1, T2 or PD using different head coils. Values of T1, T2, and PD obtained in healthy controls and MS patients were within reference ranges. However, significant differences were found in normal-appearing gray and white matter.

Conclusion: QRAPMASTER can be considered a sufficiently accurate and reproducible method for use in clinical practice. Neuropathology in normal-appearing brain tissue may be revealed using this MR method, with putative implications for quantification of tissue damage in neurological diseases. (C) 2015 Elsevier Inc. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Quantitative MRI, Synthetic MRI, T1 mapping, T2 mapping, PD mapping, Multiple sclerosis
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-44898 (URN)10.1016/j.mri.2015.02.013 (DOI)000354831500011 ()25708264 (PubMedID)
Available from: 2015-06-15 Created: 2015-06-15 Last updated: 2019-03-22Bibliographically approved
Andersson, T. (2012). The development of ultrasound in radiology in Sweden. In: Bo Eklöf, Kjell Lindström, Stig Persson (Ed.), Ultrasound in clinical diagnosis: from pioneering developments in Lund to global application in medicine (pp. 121-128). Oxford: Oxford University Press
Open this publication in new window or tab >>The development of ultrasound in radiology in Sweden
2012 (English)In: Ultrasound in clinical diagnosis: from pioneering developments in Lund to global application in medicine / [ed] Bo Eklöf, Kjell Lindström, Stig Persson, Oxford: Oxford University Press, 2012, p. 121-128Chapter in book (Other academic)
Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2012
National Category
Medical and Health Sciences Medical Laboratory and Measurements Technologies
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-21055 (URN)978-0-19-960207-0 (ISBN)
Available from: 2012-01-12 Created: 2012-01-12 Last updated: 2017-10-17Bibliographically approved
Lidén, M., Andersson, T., Broxvall, M., Thunberg, P. & Geijer, H. (2012). Urinary stone size estimation: a new segmentation algorithm-based CT method. European Radiology, 22(4), 731-737
Open this publication in new window or tab >>Urinary stone size estimation: a new segmentation algorithm-based CT method
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2012 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 22, no 4, p. 731-737Article in journal (Refereed) Published
Abstract [en]

The size estimation in CT images of an obstructing ureteral calculus is important for the clinical management of a patient presenting with renal colic. The objective of the present study was to develop a reader independent urinary calculus segmentation algorithm using well-known digital image processing steps and to validate the method against size estimations by several readers. Fifty clinical CT examinations demonstrating urinary calculi were included. Each calculus was measured independently by 11 readers. The mean value of their size estimations was used as validation data for each calculus. The segmentation algorithm consisted of interpolated zoom, binary thresholding and morphological operations. Ten examinations were used for algorithm optimisation and 40 for validation. Based on the optimisation results three segmentation method candidates were identified. Between the primary segmentation algorithm using cubic spline interpolation and the mean estimation by 11 readers, the bias was 0.0 mm, the standard deviation of the difference 0.26 mm and the Bland-Altman limits of agreement 0.0 +/- 0.5 mm. The validation showed good agreement between the suggested algorithm and the mean estimation by a large number of readers. The limit of agreement was narrower than the inter-reader limit of agreement previously reported for the same data. The size of kidney stones is usually estimated manually by the radiologist. An algorithm for computer-aided size estimation is introduced. The variability between readers can be reduced. A reduced variability can give better information for treatment decisions.

Place, publisher, year, edition, pages
New York, USA: Springer, 2012
Keywords
X-ray computed tomography, ureteral calculi, kidney stone, computer-assisted image processing, computer-assisted image interpretation
National Category
Medical and Health Sciences Radiology, Nuclear Medicine and Medical Imaging
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-22493 (URN)10.1007/s00330-011-2309-x (DOI)000301496900002 ()22160167 (PubMedID)2-s2.0-84861461077 (Scopus ID)
Note

Funding Agency:

Knowledge Foundation, Stockholm, Sweden 

Available from: 2012-04-10 Created: 2012-04-10 Last updated: 2019-03-26Bibliographically approved
Lidén, M., Andersson, T. & Geijer, H. (2011). Alternative user interface devices for improved navigation of CT datasets. Journal of digital imaging, 24(1), 126-134
Open this publication in new window or tab >>Alternative user interface devices for improved navigation of CT datasets
2011 (English)In: Journal of digital imaging, ISSN 0897-1889, E-ISSN 1618-727X, Vol. 24, no 1, p. 126-134Article in journal (Refereed) Published
Abstract [en]

The workflow in radiology departments has changed dramatically with the transition to digital PACS, especially with the shift from tile mode to stack mode display of volumetric images. With the increasing number of images in routinely captured datasets, the standard user interface devices (UIDs) become inadequate. One basic approach to improve the navigation of the stack mode datasets is to take advantage of alternative UIDs developed for other domains, such as the computer game industry. We evaluated three UIDs both in clinical practice and in a task-based experiment. After using the devices in the daily image interpretation work, the readers reported that both of the tested alternative UIDs were better in terms of ergonomics compared to the standard mouse and that both alternatives were more efficient when reviewing large CT datasets. In the task-based experiment, one of the tested devices was faster than the standard mouse, while the other alternative was not significantly faster. One of the tested alternative devices showed a larger number of traversed images during the task. The results indicate that alternative user interface devices can improve the navigation of stack mode datasets and that radiologists should consider the potential benefits of alternatives to the standard mouse.

Place, publisher, year, edition, pages
Springer, 2011
Keywords
navigation, user interface, PACS, computed tomography
National Category
Medical and Health Sciences Radiology, Nuclear Medicine and Medical Imaging
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-12074 (URN)10.1007/s10278-009-9252-2 (DOI)000286469600014 ()19949832 (PubMedID)2-s2.0-79751523933 (Scopus ID)
Available from: 2010-10-05 Created: 2010-10-05 Last updated: 2019-03-26Bibliographically approved
Hultgren Hörnquist, E., Nilsson, K., Andersson, T., Tidefelt, U. & Lidskog, M. (2011). Building a PBL-based integrated curriculum for a new medical school in Sweden. In: : . Paper presented at Celebrating the Past and Embracing the Future: Evolution and Innovation in Problem-based Larning, Conference, Grange-Over-Sands, UK, March 30-31, 2011.
Open this publication in new window or tab >>Building a PBL-based integrated curriculum for a new medical school in Sweden
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2011 (English)Conference paper, Oral presentation only (Other academic)
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-24440 (URN)
Conference
Celebrating the Past and Embracing the Future: Evolution and Innovation in Problem-based Larning, Conference, Grange-Over-Sands, UK, March 30-31, 2011
Available from: 2012-08-15 Created: 2012-08-15 Last updated: 2018-02-05Bibliographically approved
Lidén, M., Andersson, T. & Geijer, H. (2011). Making renal stones change size: impact of CT image post processing and reader variability. European Radiology, 21(10), 2218-2225
Open this publication in new window or tab >>Making renal stones change size: impact of CT image post processing and reader variability
2011 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 21, no 10, p. 2218-2225Article in journal (Refereed) Published
Abstract [en]

Objectives The objectives of this study were to quantify the impact of image post-processing parameters on the apparent renal stone size, and to quantify the intra- and inter-reader variability in renal stone size estimation. Methods Fifty CT datasets including a renal or ureteral stone were included retrospectively during a prospective inclusion period. Each of the CT datasets was post-processed in different ways regarding slice thickness, slice increment and window setting. In the first part of the study a single reader repeated size estimations for the renal stones using different post-processing parameters. In the intra-reader variability experiment one reader reported size estimations for the same images with a one-week interval. The inter-reader variability data were obtained from 11 readers reporting size estimations for the same renal stones. Results The apparent stone size differed according to image post-processing parameters with the largest mean differences seen with regard to the window settings experiment (1.5 mm, p < 0.001) and slice thickness (0.8 mm, p < 0.001). Changes in parameters introduced a bias and a pseudo-random variability. The inter-reader variability was considerably larger than the intra-reader variability. Conclusion Our results indicate a need for the standardisation of making measurements on CT images.

National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-18641 (URN)10.1007/s00330-011-2171-x (DOI)000294471100027 ()
Available from: 2011-09-30 Created: 2011-09-29 Last updated: 2019-03-26Bibliographically approved
Almroth, H., Andersson, T., Fengsrud, E., Friberg, L., Linde, P., Rosenqvist, M. & Englund, A. (2011). The safety of flecainide treatment of atrial fibrillation: long-term incidence of sudden cardiac death and proarrhythmic events. Journal of Internal Medicine, 270(3), 281-290
Open this publication in new window or tab >>The safety of flecainide treatment of atrial fibrillation: long-term incidence of sudden cardiac death and proarrhythmic events
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2011 (English)In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 270, no 3, p. 281-290Article in journal (Refereed) Published
Abstract [en]

Objective:To assess the safety of long-term treatment with flecainide in patients with atrial fibrillation (AF), particularly with regard to sudden cardiac death (SCD) andproarrhythmic events.

Design: Retrospective,observational cohort study.Setting.Single-centre study at Örebro University Hospital, Sweden.

Setting: Single-centre study at Orebro University Hospital, Sweden.

Subjects: A total of 112 patients with paroxysmal (51%) or persistent (49%) AF (mean age 60 ± 11 years) were included after identifying all patients with AF who initiated oral flecainide treatment (mean dose 203 ± 43 mg per day) between 1998 and 2006. Standard exclusion⁄inclusion criteria for flecainide were used,andflecainidetreatmentwasusually combined withanatrioventricular-blocking agent (89%).

Main outcome measure: Death was classified as sudden or nonsudden according to standard definitions. Proarrhythmia was defined as cardiac syncope or lifethreatening arrhythmia.

Results: Eight deaths were reported during a mean follow- up of 3.4 ± .4 years. Compared to the general population, the standardized mortality ratios were 1.57 (95% confidence interval (CI) 0.68–3.09) for allcause mortality and 4.16 (95% CI 1.53–9.06) for death from cardiovascular disease. Three deaths were classified as SCDs. Proarrhythmic events occurred in six patients (two each with wide QRS tachycardia, 1 : 1 conducted atrial flutter and syncope during exercise).

Conclusion: We found an increased incidence of SCD or proarrhythmic events in this real-world study of flecainide used for the treatment of AF. The findings suggest that further investigation into the safety of flecainide for the treatment of patients with AF is warranted.

Place, publisher, year, edition, pages
John Wiley & Sons, 2011
Keywords
atrial fibrillation, flecainide, proarrhythmia, safety, sudden cardiac death
National Category
General Practice
Identifiers
urn:nbn:se:oru:diva-22942 (URN)10.1111/j.1365-2796.2011.02395.x (DOI)000293793600011 ()21635583 (PubMedID)2-s2.0-80051576394 (Scopus ID)
Note

Funding Agencies:

Boehringer-Ingelheim  

Sanofi-Aventis  

Astra Zeneca  

Bristol-Myers Squibb 

Available from: 2012-05-23 Created: 2012-05-23 Last updated: 2018-09-11Bibliographically approved
Andersson, T. (2008). Den digitala röntgenavdelningen. In: Peter Aspelin, Holger Pettersson (Ed.), Radiologi (pp. 125-134). Lund: Studentlitteratur
Open this publication in new window or tab >>Den digitala röntgenavdelningen
2008 (Swedish)In: Radiologi / [ed] Peter Aspelin, Holger Pettersson, Lund: Studentlitteratur , 2008, p. 125-134Chapter in book (Other academic)
Place, publisher, year, edition, pages
Lund: Studentlitteratur, 2008
National Category
Medical and Health Sciences Radiology, Nuclear Medicine and Medical Imaging Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-3505 (URN)978-91-44-03887-2 (ISBN)
Available from: 2008-12-08 Created: 2008-12-08 Last updated: 2017-10-18Bibliographically approved
Jansson, M., Geijer, H. & Andersson, T. (2007). Bowel preparation for excretory urography is not necessary: a randomized trial. British Journal of Radiology, 80(956), 617-624
Open this publication in new window or tab >>Bowel preparation for excretory urography is not necessary: a randomized trial
2007 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 80, no 956, p. 617-624Article in journal (Refereed) Published
Abstract [en]

Despite the fact that computed tomography is becoming more commonly used to investigate the genitourinary tract, intravenous urography still plays an important role in uroradiology. The aim of this study was to compare bowel purgation and two other preparation methods - dietary restrictions and no preparations at all - in an attempt to find the optimal procedure for uniform practice. 210 consecutive patients were randomised to three preparation groups with 70 in each group. Group 1 received standard bowel purgation, Group 2 was instructed to fast, while Group 3 had no preparation at all. Irrespective of preparation, all patients underwent the same examination procedure. The examining radiographer and evaluating radiologists were unaware of the type of preparation given. Image quality was assessed according to European Commission criteria for excretory urography. The effectiveness of bowel purgation and the amount of residual gas were scored separately. There was no statistically significant difference in the proportions with fulfilled criteria between preparation Groups 1 and 2 and Groups 1 and 3. A criterion was regarded as fulfilled only when all three observers agreed. Assessment of the amount of residual faeces proved the effectiveness of our standard bowel purgation. The results of our study show equality of the evaluated preparation methods and cannot justify further use of bowel purgation before excretory urography.

Keywords
Adult, Aged, Aged; 80 and over, Cathartics/*therapeutic use, Contrast Media, Diet, Female, Humans, Iohexol/diagnostic use, Male, Middle Aged, Urography/*methods
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-4677 (URN)10.1259/bjr/78311002 (DOI)17681986 (PubMedID)
Available from: 2008-11-04 Created: 2008-11-04 Last updated: 2017-12-14Bibliographically approved
Jansson, M., Geijer, H., Persliden, J. & Andersson, T. (2006). Reducing dose in urography while maintaining image quality - a comparison of storage phosphor plates and a flat-panel detector. European Radiology, 16(1), 221-226
Open this publication in new window or tab >>Reducing dose in urography while maintaining image quality - a comparison of storage phosphor plates and a flat-panel detector
2006 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 16, no 1, p. 221-226Article in journal (Refereed) Published
Abstract [en]

The introduction of new flat-panel detector technology often forces us to accept too high dose levels as proposed by the manufacturers. We need a tool to compare the image quality of a new system with the accepted standard. The aim of this study was to obtain a comparable image quality for two systems-storage phosphor plates and a flat-panel system using intravenous urography (IVU) as a clinical model. The image quality figure was calculated using a contrast-detail phantom (CDRAD) for the two evaluated systems. This allowed us to set a dose for the flat-panel system that gave equivalent image quality to the storage phosphor plates. This reduced detector dose was used in an evaluation of clinical images to find out if the dose reduction from the phantom study indeed resulted in images of equal clinical image quality. The image quality was assessed using image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems.

Place, publisher, year, edition, pages
Berlin / Heidelberg: Springer, 2006
National Category
Medical and Health Sciences Radiology, Nuclear Medicine and Medical Imaging
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-11168 (URN)10.1007/s00330-005-2772-3 (DOI)15856242 (PubMedID)
Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2017-12-12Bibliographically approved
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