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Krauss, Wolfgang
Publications (8 of 8) Show all publications
Krauss, W., Gunnarsson, M., Nilsson, M. & Thunberg, P. (2018). Conventional and synthetic MRI in multiple sclerosis: a comparative study. European Radiology, 28(4), 1692-1700
Open this publication in new window or tab >>Conventional and synthetic MRI in multiple sclerosis: a comparative study
2018 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 28, no 4, p. 1692-1700Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: To compare the assessment of patients with multiple sclerosis (MS) using synthetic and conventional MRI.

MATERIALS AND METHODS: Synthetic and conventional axial images were prospectively acquired for 52 patients with diagnosed MS. Quantitative MRI (qMRI) was used for measuring proton density and relaxation times (T1, T2) and then, based on these parameters, synthetic T1W, T2W and FLAIR images were calculated. Image stacks were reviewed blindly, independently and in random order by two radiologists. The number and location for all lesions were documented and categorised. A combined report of lesion load and presence of contrast-enhancing lesions was compiled for each patient. Agreement was evaluated using kappa statistic.

RESULTS: There was no significant difference in lesion detection using synthetic and conventional MRI in any anatomical region or for any of the three image types. Inter- and intra-observer agreements were mainly higher (p < 0.05) using conventional images but there was no significant difference in any specific region or for any image type. There was no significant difference in the outcome of the combined reports.

CONCLUSION: Synthetic MR images show potential to be used in the assessment of MS dissemination in space (DIS) despite a slightly lower inter- and intra-observer agreement compared to conventional MRI.

KEY POINTS:

• Synthetic MR images may potentially be useful in the assessment of MS.

• Examination times may be shortened.

• Inter- and intra-observer agreement is generally higher using conventional MRI.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Multiple sclerosis; Magnetic resonance imaging; Inter- and intra-observer agreement; Synthetic MRI; Quantitative MRI
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:oru:diva-63025 (URN)10.1007/s00330-017-5100-9 (DOI)000426645600039 ()29134354 (PubMedID)2-s2.0-85033566123 (Scopus ID)
Note

Funding Agency:

Research Committee of Region Örebro County, Sweden

Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2018-08-16Bibliographically approved
Alshamari, M., Geijer, M., Norrman, E., Lidén, M., Krauss, W., Jendeberg, J., . . . Geijer, H. (2017). Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine. Acta Radiologica, 58(6), 702-709
Open this publication in new window or tab >>Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine
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2017 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 58, no 6, p. 702-709Article in journal (Refereed) Published
Abstract [en]

Background: Iterative reconstruction (IR) is a recent reconstruction algorithm for computed tomography (CT) that can be used instead of the standard algorithm, filtered back projection (FBP), to reduce radiation dose and/or improve image quality.

Purpose: To evaluate and compare the image quality of low-dose CT of the lumbar spine reconstructed with IR to conventional FBP, without further reduction of radiation dose.

Material and Methods: Low-dose CT on 55 patients was performed on a Siemens scanner using 120 kV tube voltage, 30 reference mAs, and automatic dose modulation. From raw CT data, lumbar spine CT images were reconstructed with a medium filter (B41f) using FBP and four levels of IR (levels 2-5). Five reviewers scored all images on seven image quality criteria according to the European guidelines on quality criteria for CT, using a five-grade scale. A side-by-side comparison was also performed.

Results: There was significant improvement in image quality for IR (levels 2-4) compared to FBP. According to visual grading regression, odds ratios of all criteria with 95% confidence intervals for IR2, IR3, IR4, and IR5 were: 1.59 (1.39-1.83), 1.74 (1.51-1.99), 1.68 (1.46-1.93), and 1.08 (0.94-1.23), respectively. In the side-by-side comparison of all reconstructions, images with IR (levels 2-4) received the highest scores. The mean overall CTDIvol was 1.70 mGy (SD 0.46; range, 1.01-3.83 mGy). Image noise decreased in a linear fashion with increased strength of IR.

Conclusion: Iterative reconstruction at levels 2, 3, and 4 improves image quality of low-dose CT of the lumbar spine compared to FPB.

Place, publisher, year, edition, pages
London: Sage Publications, 2017
Keywords
X-ray computed tomography (CT), image manipulation/reconstruction, lumbar vertebrae, radiation dosage, spine
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:oru:diva-57646 (URN)10.1177/0284185116669870 (DOI)000399995700011 ()28157395 (PubMedID)2-s2.0-85019010032 (Scopus ID)
Available from: 2017-05-12 Created: 2017-05-12 Last updated: 2019-03-26Bibliographically approved
Alshamari, M., Geijer, M., Norrman, E., Lidén, M., Krauss, W., Wilamowski, F. & Geijer, H. (2016). Low dose CT of the lumbar spine compared with radiography: a study on image quality with implications for clinical practice. Acta Radiologica, 57(5), 602-611
Open this publication in new window or tab >>Low dose CT of the lumbar spine compared with radiography: a study on image quality with implications for clinical practice
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2016 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 57, no 5, p. 602-611Article in journal (Refereed) Published
Abstract [en]

Background: Lumbar spine radiography is often performed instead of CT for radiation dose concerns.

Purpose: To compare image quality and diagnostic information from low dose lumbar spine CT at an effective dose of about 1 mSv with lumbar spine radiography.

Material and Methods: Fifty-one patients were examined by both methods. Five reviewers scored all examinations on eight image quality criteria using a five-graded scale and also assessed three common pathologic changes.

Results: Low dose CT scored better than radiography on the following: sharp reproduction of disc profile and vertebral end-plates (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.3-2.5), intervertebral foramina and pedicles (OR, 4.3; 95% CI, 3.1-5.9), intervertebral joints (OR, 139; 95% CI, 59-326), spinous and transverse processes (OR, 7.0; 95% CI, 4.3-11.2), sacro-iliac joints (OR, 4.2; 95% CI, 3.2-5.7), reproduction of the adjacent soft tissues (OR, 2.9; 95% CI, 2.1-4.0), and absence of any obscuring superimposed gastrointestinal gas and contents (OR, 188; 95% CI, 66-539). Radiography scored better on sharp reproduction of cortical and trabecular bone (OR, 0.3; 95% CI, 0.2-0.4). The reviewers visualized disk degeneration, spondylosis/diffuse idiopathic skeletal hyperostosis (DISH) and intervertebral joint osteoarthritis more clearly and were more certain with low dose CT. Mean time to review low dose CT was 204 s (95% CI, 194-214 s.), radiography 152 s (95% CI, 146-158 s.). The effective dose for low dose CT was 1.0-1.1 mSv, for radiography 0.7 mSv.

Conclusion: Low dose lumbar spine CT at about 1 mSv has superior image quality to lumbar spine radiography with more anatomical and diagnostic information.

Place, publisher, year, edition, pages
London, United Kingdom: Sage Publications, 2016
Keywords
Radiation dose, radiography, tomography, X-ray computed, axial skeleton
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-47090 (URN)10.1177/0284185115595667 (DOI)000374327600014 ()26221055 (PubMedID)
Available from: 2015-12-16 Created: 2015-12-16 Last updated: 2019-03-26Bibliographically approved
de Flon, P., Gunnarsson, M., Laurell, K., Söderström, L., Birgander, R., Lindqvist, T., . . . Svenningsson, A. (2016). Reduced inflammation in relapsing-remitting multiple sclerosis after therapy switch to rituximab. Neurology, 87(2), 141-147
Open this publication in new window or tab >>Reduced inflammation in relapsing-remitting multiple sclerosis after therapy switch to rituximab
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2016 (English)In: Neurology, ISSN 0028-3878, E-ISSN 1526-632X, Vol. 87, no 2, p. 141-147Article in journal (Refereed) Published
Abstract [en]

Objective: To describe the effects of switching treatment from ongoing first-line injectable therapies to rituximab on inflammatory activity measured by MRI and levels of CSF neurofilament light chain (CSF-NFL) in a cohort of patients with clinically stable relapsing-remitting multiple sclerosis (RRMS).

Method: Seventy-five patients with clinically stable RRMS treated with the first-line injectables interferon-β (IFN-β) and glatiramer acetate (GA) at 3 Swedish centers were switched to rituximab in this open-label phase II multicenter study. After a run-in period of 3 months, 2 IV doses of 1,000 mg rituximab were given 2 weeks apart followed by repeated clinical assessment, MRI, and CSF-NFL for 24 months.

Results: The mean cumulated number of gadolinium-enhancing lesions per patient at months 3 and 6 after treatment shift to rituximab was reduced compared to the run-in period (0.028 vs 0.36, p = 0.029). During the first year after treatment shift, the mean number of new or enlarged T2 lesions per patient was reduced (0.01 vs 0.28, p = 0.004) and mean CSF-NFL levels were reduced by 21% (p = 0.01).

Conclusions: For patients with RRMS, a treatment switch from IFN or GA to rituximab is associated with reduced inflammatory activity measured by MRI and CSF-NFL.

Classification of evidence: This study provides Class IV evidence that rituximab has an equal or superior effect in reducing inflammatory activity in RRMS measured by MRI and CSF-NFL compared to first-line injectables during the first year after treatment shift.

Place, publisher, year, edition, pages
Philadelphia, USA: Lippincott Williams & Wilkins, 2016
National Category
Neurology
Research subject
Neurology
Identifiers
urn:nbn:se:oru:diva-50951 (URN)10.1212/WNL.0000000000002832 (DOI)000381470700032 ()27316241 (PubMedID)2-s2.0-84979021541 (Scopus ID)
Note

Funding Agencies:

County Council of Västerbotten

County Council of Jämtland

County Council of Örebro

Unit of Research, Education and Development, Region Jämtland Härjedalen, "Syskonen Perssons Donationsfond"

Department of Clinical Neuroscience at Umeå University

Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2018-04-27Bibliographically approved
Andersson, K. M., Norrman, E., Geijer, H., Krauss, W., Cao, Y., Jendeberg, J., . . . Thunberg, P. (2016). Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography. British Journal of Radiology, 89(1063), Article ID 20150993.
Open this publication in new window or tab >>Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography
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2016 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 89, no 1063, article id 20150993Article in journal (Refereed) Published
Abstract [en]

Objectives: To evaluate metal artefact reduction (MAR) techniques from four computed tomography (CT) vendors in hip prosthesis imaging.

Methods: Bilateral hip prosthesis phantom images, obtained by using MAR algorithms for single energy CT data or dual energy CT (DECT) data and by monoenergetic reconstructions of DECT data, were visually graded by five radiologists using ten image quality criteria. Comparisons between the MAR images and a reference image were performed for each scanner separately. Ordinal probit regression analysis was used.

Results: The MAR algorithms in general improved the image quality based on the majority of the criteria (up to between 8/10 and 10/10) with a statistically improvement in overall image quality (P<0.001). However, degradation of image quality, such as new artefacts, was seen in some cases. A few monoenergetic reconstruction series improved the image quality (P<0.004) for one of the DECT scanners, but it was only improved for some of the criteria (up to 5/10). Monoenergetic reconstructions resulted in worse image quality for the majority of the criteria (up to 7/10) for the other DECT scanner.

Conclusions: The MAR algorithms improved the image quality of the hip prosthesis CT images. However, since additional artefacts and degradation of image quality were seen in some cases, all algorithms should be carefully evaluated for every clinical situation. Monoenergetic reconstructions were in general concluded to be insufficient for reducing metal artifacts. Advances in knowledge: Qualitative evaluation of the usefulness of several MAR techniques from different vendors in CT imaging of hip prosthesis.

Place, publisher, year, edition, pages
London, United Kingdom: British Institute of Radiology, 2016
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-50103 (URN)10.1259/bjr.20150993 (DOI)000378096400009 ()27123700 (PubMedID)
Available from: 2016-05-03 Created: 2016-05-03 Last updated: 2019-04-12Bibliographically approved
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
Ilicki, J., Krauss, W. & Andersson, S.-O. (2012). Partial Segmental Thrombosis of the Corpus Cavernosum: A Case Report and a Review of the Literature. Urology, 79(3), 708-712
Open this publication in new window or tab >>Partial Segmental Thrombosis of the Corpus Cavernosum: A Case Report and a Review of the Literature
2012 (English)In: Urology, ISSN 0090-4295, E-ISSN 1527-9995, Vol. 79, no 3, p. 708-712Article, review/survey (Refereed) Published
Abstract [en]

Partial segmental thrombosis of the corpus cavernosum (PSTCC) is a rare urological condition characterized by a painful, firm mass in the proximal part of the corpus cavernosum. The underlying pathophysiology of this condition is not fully understood. We present a case diagnosed by magnetic resonance imaging with complete clinical recovery after conservative treatment and novel associated findings, such as excessive alcohol intake. We also review the previous cases of PSTCC and propose a two hit model explaining PSTCC's etiology. UROLOGY 79: 708-712, 2012.

Place, publisher, year, edition, pages
Elsevier, 2012
National Category
Urology and Nephrology
Identifiers
urn:nbn:se:oru:diva-58684 (URN)10.1016/j.urology.2011.11.032 (DOI)000301154400061 ()22386425 (PubMedID)2-s2.0-84857824198 (Scopus ID)
Available from: 2017-07-12 Created: 2017-07-12 Last updated: 2018-05-15Bibliographically approved
Alshamari, M., Geijer, M., Norrman, E., Lidén, M., Krauss, W., Jendeberg, J., . . . Geijer, H.Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine.
Open this publication in new window or tab >>Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Surgery
Research subject
Surgery
Identifiers
urn:nbn:se:oru:diva-49423 (URN)
Available from: 2016-03-17 Created: 2016-03-17 Last updated: 2019-03-26Bibliographically approved
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