uu.seUppsala University Publications
Change search
Refine search result
1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Andersson, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Johansson, Birgitta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Experimental and Clinical Oncology.
    Wassberg, Cecilia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Johansson, Silvia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Experimental and Clinical Oncology.
    Sundin, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Ahlström, Häkan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Assessment of Whether Patients' Knowledge, Satisfaction, and Experience Regarding Their 18F-Fluoride PET/CT Examination Affects Image Quality2016In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 44, no 1, p. 21-25Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate patients’ previous knowledge, satisfaction and experience regarding a (18F)-fluoride positron emission tomography / computed tomography examination ((18F)-fluoride PET/CT) and to explore whether experienced discomfort during the examination or pain was associated with reduced image quality. A further aim was to explore whether patients’ health-related quality of life (HRQoL) was associated with their satisfaction and experiences of the examination.

    Methods: Fifty consecutive patients with a histopathological diagnosis of prostate cancer who were scheduled for (18F)-fluoride PET/CT were asked to participate in the study, which was performed between November 2011 and April 2013. A questionnaire was used to collect information regarding the patients’ previous knowledge and experience of the examination. Image quality assessment was performed according to an arbitrary scale. The EORTC-QLQ-C30 and QLQ-PR25 were used to assess HRQoL.

    Results: Forty-six patients (96%) completed the questionnaires. Twenty-six per cent of participants did not know at all what a (18F)-fluoride PET/CT examination was. The majority (52-70%) were to a very high degree satisfied with the care provided by the nursing staff but less satisfied with the information given prior to the examination. The image quality was similar in patients who were exhausted or claustrophobic during the examination and those who were not. No correlations between HRQoL and the participants’ experience of (18F)-fluoride PET/CT were found.

    Conclusion: The majority of participants were satisfied with the care provided by the nursing staff, but there is still room for improvement especially regarding the information prior to the examination. Long examination time may be strenuous, for the patient but there was no difference in image quality between patients who felt discomfort during the examination or pain and those who did not.

  • 2.
    Andersson, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Trampal Pulido, Carlos
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Ahlström, Håkan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Johansson, Birgitta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Randomized Controlled Trial Examining Effects of Web-Based Information on Patient Satisfaction and Image Quality in 18F-FDG PET/CT Examinations2019In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, no 1, p. 36-46Article in journal (Refereed)
    Abstract [en]

    Our aim was to compare the effect that having access, versus not having access, to web-based patient information on 18F-FDG PET/CT has on image quality and on patient satisfaction with their care during and knowledge about the examination, as well as to explore whether patients utilized and were satisfied with the web-based information.

    Methods: We recruited 148 patients between October 2015 and December 2016 and randomly assigned them to a standard-care group or an intervention group. Both groups received standard information about the 18F-FDG PET/CT examination, but the intervention group also received access to web-based information. A questionnaire was used to evaluate patient satisfaction with, knowledge about, and discomfort during the examination, and a masked assessment of image quality was conducted.

    Results: Overall satisfaction was high in both groups. The lowest satisfaction was with information about how the patients would receive the results of the examination. More patients in the intervention group than in the standard-care group knew how the 18F-FDG PET/CT examination would be conducted. Descriptive data suggest that image quality was slightly better in the intervention group than in the standard-care group, but none of the outcomes significantly differed between the groups. However, several obstacles were encountered during recruitment that led to insufficient power to detect differences. Also, only 54 of 75 patients (72%) in the intervention group utilized the web-based information. However, those who did utilize the information were satisfied with it and found it helpful.

    Conclusion: The effects of web-based information need to be investigated in a larger sample of patients. Having access to improved information before undergoing 18F-FDG PET/CT may help patients prepare for and undergo the examination. It may also improve image quality. However, this possibility needs to be investigated using image quality as the primary outcome. The results may be used to improve patient information and care and thereby optimize the 18F-FDG PET/CT procedure.

  • 3. Engbrant, Fredrik
    et al.
    Monazzam, Azita
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Svensson, Per-Edvin
    Olsson, Johan
    Bengtsson, Ewert
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Razifar, Pasha
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Signal Extraction and Separation in In Vivo Animal PET Studies with Masked Volumewise Principal-Component Analysis2010In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 38, no 2, p. 53-60Article in journal (Refereed)
    Abstract [en]

    The standardized uptake value is commonly used as a tool tosupplement visual interpretation and to quantify the imagesacquired from static in vivo animal PET. The preferred approachfor analyzing PET data is either to sum the images and calculatethe standardized uptake value or to use kinetic modeling. Theaim of this study was to investigate the performance of maskedvolumewise principal-component analysis (MVW-PCA) used in dynamicin vivo animal PET studies to extract and separate signals withdifferent kinetic behaviors. Methods: PET data were acquiredwith a small-animal PET scanner and a fluorine tracer in a studyof rats and mice. After acquisition, the data were reconstructedby use of 4 time protocols with different frame lengths. Datawere analyzed by use of MVW-PCA with applied noise prenormalizationand a new masking technique developed in this study. Results:The resulting principal-component images showed a clear separationof the activity in the spine into the first MVW-PCA componentand the activity in the kidneys into the second MVW-PCA component.In addition, the different time protocols were shown to havelittle or no impact on the results obtained with MVW-PCA. Conclusion:MVW-PCA can efficiently separate different kinetic behaviorsinto different principal-component images. Moreover, MVW-PCAis a stable technique in the sense that the time protocol chosenhas only a small impact on the resulting principal-componentimages.

  • 4. Hatherly, Robert
    et al.
    Brolin, Fredrik
    Oldner, Åsa
    Sundin, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Radiology. Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
    Lundblad, Henrik
    Maguire, Gerald Q
    Jonsson, Cathrine
    Jacobsson, Hans
    Noz, Marilyn E
    Technical requirements for Na¹⁸F PET bone imaging of patients being treated using a Taylor spatial frame2014In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 42, no 1, p. 33-36Article in journal (Refereed)
    Abstract [en]

    Diagnosis of new bone growth in patients with compound tibia fractures or deformities treated using a Taylor spatial frame is difficult with conventional radiography because the frame obstructs the images and creates artifacts. The use of Na18F PET studies may help to eliminate this difficulty.

    Methods:

    Patients were positioned on the pallet of a clinical PET/CT scanner and made as comfortable as possible with their legs immobilized. One bed position covering the site of the fracture, including the Taylor spatial frame, was chosen for the study. A topogram was performed, as well as diagnostic and attenuation correction CT. The patients were given 2 MBq of Na18F per kilogram of body weight. A 45-min list-mode acquisition was performed starting at the time of injection, followed by a 5-min static acquisition 60 min after injection. The patients were examined 6 wk after the Taylor spatial frame had been applied and again at 3 mo to assess new bone growth.

    Results:

    A list-mode reconstruction sequence of 1 × 1,800 and 1 × 2,700 s, as well as the 5-min static scan, allowed visualization of regional bone turnover.

    Conclusion:

    With Na18F PET/CT, it was possible to confirm regional bone turnover as a means of visualizing bone remodeling without the interference of artifacts from the Taylor spatial frame. Furthermore, dynamic list-mode acquisition allowed different sequences to be performed, enabling, for example, visualization of tracer transport from blood to the fracture site.

  • 5. Häggström, Ida
    et al.
    Axelsson, Jan
    Schmidtlein, Charles Ross
    Karlsson, Mikael
    Garpebring, Anders
    Johansson, Lennart
    Sörensen, Jens
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Section of Nuclear Medicine and PET.
    Larsson, Anne
    A Monte Carlo study of the dependence of early frame sampling on uncertainty and bias in pharmacokinetic parameters from dynamic PET2015In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 43, no 1, p. 53-60Article in journal (Refereed)
    Abstract [en]

    Compartmental modeling of dynamic PET data enables quantification of tracer kinetics in vivo, through the calculated model parameters. In this study, we aimed to investigate the effect of early frame sampling and reconstruction method on pharmacokinetic parameters obtained from a 2-tissue model, in terms of bias and uncertainty (SD).

    Methods:

    The GATE Monte Carlo software was used to simulate 2 × 15 dynamic 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) brain PET studies, typical in terms of noise level and kinetic parameters. The data were reconstructed by both 3-dimensional (3D) filtered backprojection with reprojection (3DRP) and 3D ordered-subset expectation maximization (OSEM) into 6 dynamic image sets with different early frame durations of 1, 2, 4, 6, 10, and 15 s. Bias and SD were evaluated for fitted parameter estimates, calculated from regions of interest.

    Results:

    The 2-tissue-model parameter estimates K1, k2, and fraction of arterial blood in tissue depended on early frame sampling, and a sampling of 6–15 s generally minimized bias and SD. The shortest sampling of 1 s yielded a 25% and 42% larger bias than the other schemes, for 3DRP and OSEM, respectively, and a parameter uncertainty that was 10%–70% higher. The schemes from 4 to 15 s were generally not significantly different in regards to bias and SD. Typically, the reconstruction method 3DRP yielded less frame-sampling dependence and less uncertain results, compared with OSEM, but was on average more biased.

    Conclusion:

    Of the 6 sampling schemes investigated in this study, an early frame duration of 6–15 s generally kept both bias and uncertainty to a minimum, for both 3DRP and OSEM reconstructions. Very-short frames of 1 s should be avoided because they typically resulted in the largest parameter bias and uncertainty. Furthermore, 3DRP may be preferred over OSEM for short frames with poor statistics.

  • 6.
    Owenius, Rikard
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Zanette, Michelle
    GE Healthcare, Life Sci, Imaging R&D, Marlborough, MA USA..
    Cella, Patrick
    GE Healthcare, Life Sci, Imaging R&D, Marlborough, MA USA..
    Variability in Heart-to-Mediastinum Ratio from Planar 123I-MIBG Images of a Thorax Phantom for 6 Common γ-Camera Models2017In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 45, no 4, p. 297-303Article in journal (Refereed)
    Abstract [en]

    A heart-to-mediastinum (H/M) ratio of 1.6 or greater on planar I-123-iobenguane (I-123-MIBG) images identifies heart failure patients at low risk of experiencing an adverse cardiac event. This phase-4 study used standardized phantoms to assess the intercamera, intracamera, and interhead variability in H/M ratio determinations from planar cardiac I-123-MIBG imaging using commercially available, dual-head.-cameras. Methods: A fillable thorax phantom was developed to simulate the typical uptake of I-123-MIBG. The phantom had a nominal H/M ratio of 1.6 on the reference camera. Commercial cameras used in the study were dual-head and capable of 90 degrees configuration for cardiac imaging. The target sample size was 8 units (examples) per camera model. Two imaging technologists independently analyzed planar images of simulated I-123-MIBG uptake from the thorax phantom. H/M was the ratio of the average counts per pixel of the heart and mediastinum regions of interest. The primary endpoint, intercamera variability in H/M ratio from head 1, was determined for each camera model via comparison with the H/M ratio on the reference camera. Only cameras with at least 8 units tested (n >= 8) were included in the primary analysis. Intracamera and interhead variability in the H/M ratio were also evaluated. Results: Nine camera models were studied. The mean H/M ratio ranged from 1.342 to 1.677. The primary analysis (6 camera models) using a mixed-model, repeated-measures analysis showed no significant difference in H/M ratio between any camera model and the reference camera. Intracamera variability (head 1) in the H/M ratio among camera models with 8 units or more was high, with SDs ranging from 0.0455 to 0.1193. Interhead variability was low (SDs of the interhead difference, 0.017-0.074). Conclusion: Commonly used.-cameras produced H/M ratios from simulated I-123-MIBG phantom images that were not significantly different from those on the reference camera. This finding indicates that the results of previous clinical trials of I-123-MIBG, involving many different clinical sites and camera models, are valid. The assessment of the performance of a given camera unit using an I-123 planar phantom before H/M results from I-123-MIBG imaging are used for classifying risk in heart failure patients is encouraged.

  • 7.
    Razifar, Pasha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Engler, Henry
    Ringheim, Anna
    Estrada, Sergio
    Wall, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Section of Nuclear Medicine and PET.
    Långström, Bengt
    An automated method for delineating a reference region using masked volumewise principal-component analysis in 11C-PIB PET2009In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 37, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    Kinetic modeling using a reference region is a common method for the analysis of dynamic PET studies. Available methods for outlining regions of interest representing reference regions are usually time-consuming and difficult and tend to be subjective; therefore, MRI is used to help physicians and experts to define regions of interest with higher precision. The current work introduces a fast and automated method to delineate the reference region of images obtained from an N-methyl-(11)C-2-(4'-methylaminophenyl)-6-hydroxy-benzothiazole ((11)C-PIB) PET study on Alzheimer disease patients and healthy controls using a newly introduced masked volumewise principal-component analysis.

    METHODS: The analysis was performed on PET studies from 22 Alzheimer disease patients (baseline, follow-up, and test/retest studies) and 4 healthy controls, that is, a total of 26 individual scans. The second principal-component images, which illustrate the kinetic behavior of the tracer in gray matter of the cerebellar cortex, were used as input data for automatic delineation of the reference region. To study the variation associated with the manual and proposed automatic methods, we defined the reference region repeatedly.

    RESULTS: As expected, the automatic method showed no variation whereas the manual method varied significantly on repetition. Furthermore, the automatic method was significantly faster, more robust, and less biased.

    CONCLUSION: The automatic method is helpful in the delineation of the reference region of (11)C-PIB PET studies of the human brain and is much faster and more precise than manual delineation.

  • 8. Svensson, Per-Edvin
    et al.
    Olsson, Johan
    Engbrant, Fredrik
    Bengtsson, Ewert
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Razifar, Pasha
    Characterization and reduction of noise in dynamic PET data using masked volumewise principal component analysis2011In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 39, no 1, p. 27-34Article in journal (Refereed)
    Abstract [en]

    Masked volumewise principal component (PC) analysis (PCA) is used in PET to distinguish structures that display different kinetic behaviors after administration of a tracer. When masked volumewise PCA was introduced, one article proposed noise prenormalization because of temporal and spatial variations of the noise between slices. However, the noise prenormalization proposed in that article was applicable only to datasets reconstructed using filtered backprojection (FBP). The study presented in this article aimed at developing a new noise prenormalization that is applicable to datasets regardless of whether they were reconstructed with FBP or an iterative reconstruction algorithm, such as ordered-subset expectation maximization (OSEM).

    Methods: A phantom study was performed to investigate differences in the expectation values and SDs of datasets reconstructed with FBP and OSEM. A novel method, higher-order PC noise prenormalization, was suggested and evaluated against other prenormalization methods on clinical datasets.

    Results: Masked volumewise PCA of data reconstructed with FBP was much more dependent on an appropriate prenormalization than was analysis of data reconstructed with OSEM. Higher-order PC noise prenormalization showed an overall good performance with both FBP and OSEM reconstructions, whereas the other prenormalization methods performed well with only 1 of the 2 methods.

    Conclusion: Higher-order PC noise prenormalization has potential for improving the results from masked volumewise PCA on dynamic PET datasets independent of the type of reconstruction algorithm.

1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf