| 1. |
- Allwood, Carl Martin, et al.
(författare)
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Contagious contacts: How police trainees influence each other’s memories for a criminal event
- 2004
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Ingår i: Paper presented at the 14th European Conference on Psychology and Law of the EAP & L Crakow, Polen, July 7–10, 2004.
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Konferensbidrag (refereegranskat)abstract
- This study investigated the effect of confirmatory and disconfirmatory feedback on the accuracy (realism) in witnesses’ confidence judgements of their event memory. After watching a short video of a kidnapping the participants answered 44 two-alternative questions on the videotape. Two weeks later the participants were handed their old question-answering sheet with the original questions and their own answers. In addition feedback was provided in writing for each answer. The participants were asked to give confidence ratings with respect to the correctness of each answer. In the Control condition the participants received no feedback. Overall, the witnesses’ confidence ratings showed overconfidence in all conditions. Furthermore, confirmatory feedback caused higher overconfidence, compared both with disconfirmatory feedback and no feedback. The results show that the realism in the eyewitnesses’ confidence judgements of their event memory is indeed sensitive to co-witness feedback, especially to confirming feedback.
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| 2. |
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| 3. |
- Allwood, Carl Martin, 1952, et al.
(författare)
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Eyewitnesses under influence: How feedback affect the realism in confidence
- 2006
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Ingår i: Psychology, Crime & Law. - : Informa UK Limited. ; 12:1, s. 25-38
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of two types of feedback (confirmatory and disconfirmatory) on the accuracy in witness’ confidence judgements of their event memory. Overall the witnesses evidenced overconfidence both when they received feedback and in the control condition (no feedback). The results showed that confirmatory feedback caused higher overconfidence, compared both with when receiving disconfirmatory and no feedback. The results suggest that the impact of feedback on the accuracy of confidence judgments show the same pattern of results for event memory as for line-up identification tasks. Finally, when witnesses rated the total number of questions that they had answered correctly they gave fairly correct estimates compared with their actual number of correct answers.
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| 4. |
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| 5. |
- Bäckström, Beata, et al.
(författare)
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Adolescent and Family-Focused Cognitive-Behavioral Therapy for Pediatric Bipolar Disorders : An Open Trial and Individual Trajectories Study in Routine Psychiatric Care
- 2024
-
Ingår i: Child Psychiatry and Human Development. - : Springer Science and Business Media LLC. - 0009-398X .- 1573-3327.
-
Tidskriftsartikel (refereegranskat)abstract
- Psychosocial treatments improve outcome in Pediatric bipolar disorder (PBD), but few are developed specifically for adolescents and none has been evaluated in Europe. This study evaluates family-focused cognitive-behavioral therapy for adolescents (ages 13-18) with PBD in routine psychiatric care in Sweden, adapted for teenagers in a European setting from the Child and Family-Focused Cognitive Behavioral Therapy for PBD (ages 8-12) developed in the US. In a repeated-measure open trial, psychosocial functioning, depression, skills and knowledge about PBD, and family climate were assessed at pre-treatment, post-treatment, and after 6 months. Assessments were made by adolescents (n = 45), parents (n = 61) and clinicians. Both group statistics and individual trajectories are reported. Psychosocial function, as rated by parents and clinicians, improved at post-treatment, and parents reported less mania and improved family climate at post-treatment. Both parents and adolescents reported improved skills and knowledge. Most results after treatment showed medium effect sizes. Significant improvements were seen in most individual trajectories, however no change and even deterioration was observed in some. The present trial shows that AFF-CBT is well accepted and associated with improved psychosocial function in adolescents and improved skills and knowledge about PBD in adolescents and their parents. Regarding mood symptoms and family climate the results showed more individual variability, indicating that adjustments in delivery of the treatment according to the unique patient could be of importance. AFF-CBT seems to be a valuable addition to pharmacological treatments in PBD.
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| 6. |
- Knutsson, Björn, et al.
(författare)
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The association between tobacco smoking and surgical intervention for lumbar spinal stenosis : cohort study of 331,941 workers
- 2018
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Ingår i: The spine journal. - : Elsevier. - 1529-9430 .- 1878-1632. ; 18:8, s. 1313-1317
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND CONTEXT: Tobacco smoking is an injurious habit associated with a number of chronic disorders. Its influence on disc metabolism and degeneration including lumbar spinal stenosis (LSS) has been investigated in the literature.PURPOSE: We aimed to investigate whether tobacco smoking is an independent risk factor for undergoing surgical intervention for LSS.STUDY DESIGN/SETTING: This is a prospective cohort study.PATIENT SAMPLE: The patient sample of 331,941 workers was derived from a Swedish nationwide occupational surveillance program for construction workers.OUTCOME MEASURE: The outcome measure included the incidence of undergoing surgical intervention for LSS in tobacco smokers versus no smokers.MATERIALS AND METHODS: At inclusion, age, sex, body mass index (BMI), workers' job title, and self-reported smoking habits were registered. The workers were divided into four categories: never smoked, former smoker, moderate current (1-14 cigarettes/day), and heavy current (≥15 cigarettes/day). Patients who underwent a surgically treated LSS were defined using the relevant International Classification of Diseases (ICD) disease code derived from the Swedish National Patient Register.RESULTS: A total of 331,941 participants were included in the analysis. Forty-four percent of the participants were non-smokers, 16% were former smokers, 26% were moderate smokers, and 14% were heavy smokers. The vast majority of construction workers were males (95%). During the average follow-up of 30.7 years, 1,623 participants were surgically treated for LSS. The incidence rate ratio (IRRs) of LSS varied across smoking categories, with the highest values found in heavy smokers. Compared with non-smokers, all smoking categories show an increased incidence of surgically treated LSS. The findings were consistent even when the comparison was performed for participants with BMIs between 18.5 and 25 and for participants aged between 40 and 74 years.CONCLUSIONS: Tobacco smoking is associated with an increased incidence of surgically treated LSS. The effect seems to be dose related, whereby heavy smokers have a higher risk than moderate or former smokers.
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| 7. |
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| 8. |
- Knutsson, Jens, et al.
(författare)
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Adolescent and Family-Focused Cognitive-Behavioural Therapy for Paediatric Bipolar Disorders: A Case Series
- 2017
-
Ingår i: Clinical Psychology & Psychotherapy. - : Wiley. - 1099-0879 .- 1063-3995. ; 24:3, s. 589-617
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Tidskriftsartikel (refereegranskat)abstract
- Although pharmacological treatments can help alleviate mood symptoms in youth with paediatric bipolar disorder (PBD), residual symptoms still commonly persist. In many cases, these symptoms seriously affect the social and psychological development of children and adolescents suffering from PBD. Complementary interventions, such as psychosocial and psychoeducational treatments, can help children and their families manage mood regulation and other challenges throughout childhood and adolescence. However, most research on such interventions has focused on children, single-family psychoeducation, and individual cognitive behavioural therapy. The present study, conducted in Sweden, used a case-series design to explore whether child- and family-focused cognitive behavioural therapy (CFF-CBT) for PBD, adapted from children (8-12 years) to adolescents (13-18 years) and applied in a multi-family format, could help reduce symptoms, improve psychosocial functioning, increase parents' knowledge of and skills for coping with the disorder, and improve family expressed emotion for adolescents with PBD. Furthermore, we aimed to assess whether the effects of such CFF-CBT are maintained at a one-year follow-up. Seven adolescents and 11 parents in two multi-family groups received twelve sessions of CFF-CBT. Self-rating questionnaires and clinical observations were used to evaluate clinically significant changes for individual cases. The results suggest that CFF-CBT is feasible to deliver in an outpatient psychiatric setting and may be effective for developing parents' skills and knowledge for coping with PBD, increasing adolescents' psychosocial functioning, and improving family climate. The results are in line with previous findings on CFF-CBT for children with PBD, suggesting that CFF-CBT is a valuable adjunctive treatment for adolescents with PBD. Key Practitioner Message: Preliminary evidence indicates that CFF-CBT (RAINBOW) is both acceptable and an important complement to pharmacological treatment for adolescents suffering from paediatric bipolar disorder (PBD). Adolescent PBD populations show a high degree of comorbidity and individual clinical presentations that influence treatment results. Families show a large variation in ability to participate and benefit from RAINBOW treatment. Assessing and addressing pre-treatment environmental stressors and family climate during treatment is important for optimizing treatment effect. Symptoms of PBD fluctuate and new episodes can occur spontaneously. It is therefore important to follow PBD symptoms over time to draw more precise conclusions on treatment effects. When assessing treatment effects on psychiatric symptoms, social functioning, and family climate, it is important to use multiple rating sources, as ratings can vary considerably between adolescents, parents, and clinicians.
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| 9. |
- Knutsson, Jens
(författare)
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Child and Adult Witness Event Memory Reporting and Metamemory Capabilities : Social Aspects and Legal Professionals’ Opinions
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation focuses on aspects of the social context of child and adult eyewitness memory reports, along with their relation to report accuracy and metamemory performance. More specifically, it investigates the effects on memory reports and metamemory judgments of i) receiving feedback from co-witnesses, ii) being probed for further eventmemory reports, and iii) retelling eventmemory contents. It also investigates the attitudes of legal professionals toward child and adult witnesses, regarding factors – including social influences – that may affect memory and eventmemory reporting. The results support the conclusion that both adults’ and children’s memory reports given under free recall, can, in many cases, be quite reliable; but also that eyewitnesses – especially children – are highly vulnerable to social influences. In the first study, eyewitnesses showed overconfidence in answering questions about a film clip. Confirmatory co-witness feedback on the answers caused higher overconfidence compared to both receiving disconfirmatory feedback and receiving no feedback. These results on eventmemory reporting mirror results from research on co-witness feedback in line-up identification contexts (i.e., recognition memory). The second study shows that probing i) increases the amount of information recalled both for children and adults, ii) decreases the proportion of correct statements for children but not adults, iii) decreases confidence both for children and adults, and iv) increases overconfidence for children but not adults. Meanwhile, repetition of event-memory reports results in i) richer recall (i.e., more information reported) both for children and adults and ii) children – but not adults – show higher overconfidence compared with one recall. Finally, combining two recalls with probing disrupts metacognitive performance for children but not adults. These effects are then interpreted within the model of report monitoring (Koriat & Goldsmith, 1994, 1996). The third and final study shows that legal professionals believe children to have poorer event-memory and metamemory capacities than adults when making direct comparisons of child and adult witnesses. The pattern does not hold when making indirect comparisons such that either a child or an adult witness is considered. Meanwhile, consensus in beliefs among legal professionals about eyewitness memory and metamemory capacities is low.
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| 10. |
- Knutsson, Jens, et al.
(författare)
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Child and adult witnesses: the effect of repetition and invitation-probes on free recall and metamemory realism
- 2011
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Ingår i: Metacognition and Learning. - : Springer Science and Business Media LLC. - 1556-1631 .- 1556-1623. ; 6:3, s. 213-228
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Tidskriftsartikel (refereegranskat)abstract
- Witnesses' event recall and the realism in their evaluation of the correctness of their recall are of great importance in forensic processes. These issues were investigated in the present study by use of calibration methodology. More specifically, we analyzed the effects of two recalls of the same event (repetition) and of probes (non-informative follow-up questions at recall) on 9-11 year-old children's and adults' open free recall and the degree of realism in the participants' confidence judgments of the correctness of the recall after they had seen a short video clip. The findings were that repetition resulted in more units recalled both for children and for adults, and in that the children showed higher overconfidence compared with one recall, but not the adults. Moreover, when only the statements in the repetition conditions that were recalled twice were included in the analysis, higher confidence was found for the children (independent of an increase in the proportion correct statements of all statements) but not for the adults. Probing increased the number of units recalled for both children and adults, decreased the children's proportion correct statements but not the adults', decreased both children's and adults' confidence and increased the children's overconfidence, but not the adults'. Finally, the combination of two recalls and probing disrupted the children's but not the adults' metacognitive performance.
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| 11. |
- Knutsson, Jens, et al.
(författare)
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Imagery Rescripting and Exposure in Social Anxiety : A Randomized Trial Comparing Treatment Techniques
- 2020
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Ingår i: Journal of Contemporary Psychotherapy. - : Springer Science and Business Media LLC. - 0022-0116 .- 1573-3564. ; 50:3, s. 233-240
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Tidskriftsartikel (refereegranskat)abstract
- This randomized trial compared the effects of imagery rescripting against in vivo exposure administered separately during a single session with 27 socially anxious individuals. Previous research shows that imagery rescripting is a promising treatment technique for various disorders including social anxiety, although imagery rescripting and exposure for social anxiety have not yet been compared. Social anxiety self-report measures (LSAS-SR and BFNE-II); the distress, vividness, and frequency of fear images (i.e., Imagery condition); and the levels of anxiety, avoidance, and the strength of convictions of a feared social situation (i.e., exposure condition) were rated at baseline, before treatment, and after a 2- and 4-week follow up period. Both treatment groups improved significantly on all measures pre- to post treatment and the effects largely remained at the 4-week follow-up. No significant differences between the treatment groups were found on the anxiety measures. The results suggest that either a single session of imagery rescripting or of exposure are effective in reducing social anxiety, and that both treatment techniques, even when administered in a single session, reduces social anxiety.
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| 12. |
- Knutsson, Jens, et al.
(författare)
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Imagery rescripting of early memories in health anxiety disorder : A feasibility and non-randomized pilot study
- 2019
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Ingår i: Journal of Behavior Therapy and Experimental Psychiatry. - : Elsevier BV. - 1873-7943 .- 0005-7916. ; 65
-
Tidskriftsartikel (refereegranskat)abstract
- Background and objectives:Health anxiety is a common problem and is associated with frequent primary carevisits, increased health care costs, and poor prognosis and low recovery rates. Previous research shows thatimagery rescripting (IR) is a promising treatment technique for various disorders. To date, IR has not beenexamined as a viable treatment for health anxiety. The purpose of the present feasibility and pilot study was totest one session of IR of early anxiety-laden health-related memories in a small sample of patients suffering fromHA.Methods:A within-groups design was used with a sample of 18 patients suffering from HA, whofirst underwenta control condition (reading about CBT), and then one week later a session of IR. After another week, the effectswere measured on self-reported health anxiety and early anxiety provoking health-related mental images(memories).Results:After the IR intervention, significant reductions of health anxiety and health worry, as well as image andmemory distress, vividness and frequency were observed.Limitations:Among the most important limitations are the absence of an active control group, the small size ofthe sample, the absence of a longer follow-up, and the use of only self-report measures.Conclusions:The results suggest that IR is a feasible technique in the treatment of health anxiety, and that morecontrolled research along these lines may be worthwhile.
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| 13. |
- Knutsson, Jens, et al.
(författare)
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Opinions of legal professionals: Comparing child and adult witnesses' memory report capabilities
- 2014
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Ingår i: The European Journal of Psychology Applied To Legal Context. - : Colegio Oficial de Psicologos de Madrid. - 1989-4007 .- 1889-1861. ; 6:2, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- The opinions of legal professionals about child and adult witnesses might influence the likelihood that a case is allowed to proceed through the different stages of the legal process. With the aim of knowing the opinions of legal practitioners about child and adult witnesses, 84 legal professionals (Swedish police, prosecutors, and attorneys) were surveyed about their beliefs about child and adult eyewitness memory (and metamemory) abilities. The respondents answered 27 questions relating to nine forensically relevant belief areas in which they compared the memory ability of children (ages 7 to 11 years) and adults. The results showed no differences in assessment among members of different professions and a general trend suggesting that, across the professions, children were believed to be poorer witnesses than adults regarding their memory abilities. Moreover, the professionals' within-group consensus was very low. These results are discussed in the context of eyewitness research findings and with respect to the implications for both legal and research practice. (C) 2014 Colegio Oficial de Psicologos de Madrid. Production by Elsevier Espana, S.L. All rights reserved.
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| 14. |
- Knutsson, Jens, et al.
(författare)
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Swedish Legal Professionals' Opinions on Child and Adult Witness Memory-reporting Capabilities: Using the Method of Indirect Comparisons
- 2015
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Ingår i: Applied Cognitive Psychology. - : Wiley. - 0888-4080. ; 29:3, s. 392-406
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Tidskriftsartikel (refereegranskat)abstract
- Legal professionals' opinions about the memory abilities of child and adult witnesses are important in the legal process. We surveyed 266 legal professionals (Swedish police, prosecutors, and attorneys) and 33 lay judges about their beliefs about child and adult eyewitnesses' recall and metacognitive abilities. Prior research has usually asked for direct comparisons of children and adults but this may be rare in forensic practice. The respondents completed a story questionnaire (about a 9- or 45-year-old person witnessing an event), allowing indirect, or researcher-made, comparisons. In contrast to previous research (direct comparisons), our participants mostly rated children and adults to be on an equal level, but within-group consensus was low. Also, fairly few differences emerged between the groups' beliefs. Finally, the participants' opinions in our study were less in line with results from eyewitness research, compared with previous research using direct comparisons. Implications for legal and research practice are discussed. Copyright (c) 2015 John Wiley & Sons, Ltd.
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| 15. |
- Mbiydzenyuy, Gideon, et al.
(författare)
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Opportunities for Machine Learning in District Heating
- 2021
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Ingår i: Applied Sciences. - Basel : MDPI. - 2076-3417. ; 11:13
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Tidskriftsartikel (refereegranskat)abstract
- The district heating (DH) industry is facing an important transformation towards more efficient networks that utilise significantly lower water temperatures to distribute the heat. This change requires taking advantage of new technologies, and Machine Learning (ML) is a popular direction. In the last decade, we have witnessed an extreme growth in the number of published research papers that focus on applying ML techniques to the DH domain. However, based on our experience in the field, and an extensive review of the state-of-the-art, we perceive a mismatch between the most popular research directions, such as forecasting, and the challenges faced by the DH industry. In this work, we present our findings, explain and demonstrate the key gaps between the two communities and suggest a road-map ahead towards increasing the impact of ML research in the DH industry. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
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| 16. |
- Sjölund, Jens, 1987-
(författare)
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Algorithms for magnetic resonance imaging in radiotherapy
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radiotherapy plays an increasingly important role in cancer treatment, and medical imaging plays an increasingly important role in radiotherapy. Magnetic resonance imaging (MRI) is poised to be a major component in the development towards more effective radiotherapy treatments with fewer side effects. This thesis attempts to contribute in realizing this potential.Radiotherapy planning requires simulation of radiation transport. The necessary physical properties are typically derived from CT images, but in some cases only MR images are available. In such a case, a crude but common approach is to approximate all tissue properties as equivalent to those of water. In this thesis we propose two methods to improve upon this approximation. The first uses a machine learning approach to automatically identify bone tissue in MR. The second, which we refer to as atlas-based regression, can be used to generate a realistic, patient-specific, pseudo-CT directly from anatomical MR images. Atlas-based regression uses deformable registration to estimate a pseudo-CT of a new patient based on a database of aligned MR and CT pairs.Cancerous tissue has a different structure from normal tissue. This affects molecular diffusion, which can be measured using MRI. The prototypical diffusion encoding sequence has recently been challenged with the introduction of more general gradient waveforms. One such example is diffusional variance decomposition (DIVIDE), which allows non-invasive mapping of parameters that reflect variable cell eccentricity and density in brain tumors. To take full advantage of such more general gradient waveforms it is, however, imperative to respect the constraints imposed by the hardware while at the same time maximizing the diffusion encoding strength. In this thesis we formulate this as a constrained optimization problem that is easily adaptable to various hardware constraints. We demonstrate that, by using the optimized gradient waveforms, it is technically feasible to perform whole-brain diffusional variance decomposition at clinical MRI systems with varying performance.The last part of the thesis is devoted to estimation of diffusion MRI models from measurements. We show that, by using a machine learning framework called Gaussian processes, it is possible to perform diffusion spectrum imaging using far fewer measurements than ordinarily required. This has the potential of making diffusion spectrum imaging feasible even though the acquisition time is limited. A key property of Gaussian processes, which is a probabilistic model, is that it comes with a rigorous way of reasoning about uncertainty. This is pursued further in the last paper, in which we propose a Bayesian reinterpretation of several of the most popular models for diffusion MRI. Thanks to the Bayesian interpretation it possible to quantify the uncertainty in any property derived from these models. We expect this will be broadly useful, in particular in group analyses and in cases when the uncertainty is large.
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| 17. |
- Sjölund, Jens, 1987-, et al.
(författare)
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Bayesian uncertainty quantification in linear models for diffusion MRI
- 2018
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 175, s. 272-285
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion MRI (dMRI) is a valuable tool in the assessment of tissue microstructure. By fitting a model to the dMRI signal it is possible to derive various quantitative features. Several of the most popular dMRI signal models are expansions in an appropriately chosen basis, where the coefficients are determined using some variation of least-squares. However, such approaches lack any notion of uncertainty, which could be valuable in e.g. group analyses. In this work, we use a probabilistic interpretation of linear least-squares methods to recast popular dMRI models as Bayesian ones. This makes it possible to quantify the uncertainty of any derived quantity. In particular, for quantities that are affine functions of the coefficients, the posterior distribution can be expressed in closed-form. We simulated measurements from single- and double-tensor models where the correct values of several quantities are known, to validate that the theoretically derived quantiles agree with those observed empirically. We included results from residual bootstrap for comparison and found good agreement. The validation employed several different models: Diffusion Tensor Imaging (DTI), Mean Apparent Propagator MRI (MAP-MRI) and Constrained Spherical Deconvolution (CSD). We also used in vivo data to visualize maps of quantitative features and corresponding uncertainties, and to show how our approach can be used in a group analysis to downweight subjects with high uncertainty. In summary, we convert successful linear models for dMRI signal estimation to probabilistic models, capable of accurate uncertainty quantification. © 2018 Elsevier Inc.
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| 18. |
- Sjölund, Jens, et al.
(författare)
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Constrained optimization of gradient waveforms for generalized diffusion encoding
- 2015
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Ingår i: Journal of magnetic resonance. - : Elsevier. - 1090-7807 .- 1096-0856. ; 261, s. 157-168
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion MRI is a useful probe of tissue structure. The prototypical diffusion encoding sequence, the single pulsed field gradient, has recently been challenged with the introduction of more general gradient waveforms. Out of these, we focus on q-space trajecory imaging, which generalizes the scalar b-value to a tensor valued property. To take full advantage of its capabilities, it is imperative to respect the constraints imposed by the hardware, while at the same time maximizing the diffusion encoding strength. We formulate this as a constrained optimization problem that accomodates constraints on maximum gradient amplitude, slew rate, coil heating and positioning of radiofrequency pulses. The power of this approach is demonstrated by a comparison with previous work on optimization of isotropic diffusion sequences, showing possible gains in diffusion weighting or in heat dissipation, which in turn means increased signal or reduced scan-times.
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| 19. |
- Sjölund, Jens, et al.
(författare)
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Gaussian process regression can turn non-uniform and undersampled diffusion MRI data into diffusion spectrum imaging
- 2017
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Ingår i: IEEE 14th International Symposium on Biomedical Imaging (ISBI 2017), 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509011728 - 9781509011735 ; , s. 778-782
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Konferensbidrag (refereegranskat)abstract
- We propose to use Gaussian process regression to accurately estimate the diffusion MRI signal at arbitrary locations in qspace. By estimating the signal on a grid, we can do synthetic diffusion spectrum imaging: reconstructing the ensemble averaged propagator (EAP) by an inverse Fourier transform. We also propose an alternative reconstruction method guaranteeing a nonnegative EAP that integrates to unity. The reconstruction is validated on data simulated from two Gaussians at various crossing angles. Moreover, we demonstrate on nonuniformly sampled in vivo data that the method is far superior to linear interpolation, and allows a drastic undersampling of the data with only a minor loss of accuracy. We envision the method as a potential replacement for standard diffusion spectrum imaging, in particular when acquistion time is limited.
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| 20. |
- Sjölund, Jens, et al.
(författare)
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Generating patient specific pseudo-CT of the head from MR using atlas-based regression
- 2015
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 60:2, s. 825-839
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Tidskriftsartikel (refereegranskat)abstract
- Radiotherapy planning and attenuation correction of PET images require simulation of radiation transport. The necessary physical properties are typically derived from computed tomography (CT) images, but in some cases, including stereotactic neurosurgery and combined PET/MR imaging, only magnetic resonance (MR) images are available. With these applications in mind, we describe how a realistic, patient-specific, pseudo-CT of the head can be derived from anatomical MR images. We refer to the method as atlas-based regression, because of its similarity to atlas-based segmentation. Given a target MR and an atlas database comprising MR and CT pairs, atlas-based regression works by registering each atlas MR to the target MR, applying the resulting displacement fields to the corresponding atlas CTs and, finally, fusing the deformed atlas CTs into a single pseudo-CT. We use a deformable registration algorithm known as the Morphon and augment it with a certainty mask that allows a tailoring of the influence certain regions are allowed to have on the registration. Moreover, we propose a novel method of fusion, wherein the collection of deformed CTs is iteratively registered to their joint mean and find that the resulting mean CT becomes more similar to the target CT. However, the voxelwise median provided even better results; at least as good as earlier work that required special MR imaging techniques. This makes atlas-based regression a good candidate for clinical use.
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| 21. |
- Sjölund, Jens, 1987-
(författare)
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MRI based radiotherapy planning and pulse sequence optimization
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radiotherapy plays an increasingly important role in cancer treatment, and medical imaging plays an increasingly important role in radiotherapy. Magnetic resonance imaging (MRI) is poised to be a major component in the development towards more effective radiotherapy treatments with fewer side effects. This thesis attempts to contribute in realizing this potential.Radiotherapy planning requires simulation of radiation transport. The necessary physical properties are typically derived from CT images, but in some cases only MR images are available. In such a case, a crude but common approach is to approximate all tissue properties as equivalent to those of water. In this thesis we propose two methods to improve upon this approximation. The first uses a machine learning algorithm to automatically identify bone tissue in MR. The second, which we refer to as atlas-based regression, can be used to generate a realistic, patient-specific, pseudo-CT directly from anatomical MR images. Atlas-based regression uses deformable registration to estimate a pseudo-CT of a new patient based on a database of aligned MR and CT pairs.Cancerous tissue has a dierent structure from normal tissue. This affects molecular diusion, which can be measured using MRI. The prototypical diusion encoding sequence has recently been challenged with the introduction of more general waveforms. To take full advantage of their capabilities it is, however, imperative to respect the constraints imposed by the hardware while at the same time maximizing the diffusion encoding strength. In this thesis we formulate this as a constrained optimization problem that is easily adaptable to various hardware constraints.
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| 22. |
- Sjölund, Jens, et al.
(författare)
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Skull Segmentation in MRI by a Support Vector Machine Combining Local and Global Features
- 2014
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Ingår i: 22nd International Conference on Pattern Recognition (ICPR), 2014. - : IEEE. ; , s. 3274-3279
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Konferensbidrag (refereegranskat)abstract
- Magnetic resonance (MR) images lack information about radiation transport-a fact which is problematic in applications such as radiotherapy planning and attenuation correction in combined PET/MR imaging. To remedy this, a crude but common approach is to approximate all tissue properties as equivalent to those of water. We improve upon this using an algorithm that automatically identifies bone tissue in MR. More specifically, we focus on segmenting the skull prior to stereotactic neurosurgery, where it is common that only MR images are available. In the proposed approach, a machine learning algorithm known as a support vector machine is trained on patients for which both a CT and an MR scan are available. As input, a combination of local and global information is used. The latter is needed to distinguish between bone and air as this is not possible based only on the local image intensity. A whole skull segmentation is achievable in minutes. In a comparison with two other methods, one based on mathematical morphology and the other on deformable registration, the proposed method was found to yield consistently better segmentations.
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| 23. |
- Ybrandt, Helene, et al.
(författare)
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Clinical outcomes in the routine evaluation of psychotherapy given by trainees: Effects on clients’ inter-personal problems and psychological symptoms
- 2019
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Ingår i: International Journal of Psychotherapy. - 1356-9082. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- A significant proportion of the psychotherapy in Sweden is delivered by psychology trainees at special educational clinical departments within the universities. The aim of this study was to investigate the effectiveness of the treatments at three clinics measured by outcomes of psychiatric symptoms and functioning (Clinical Outcomes in Routine Evaluation – Outcome Measures) and interpersonal problems (Inventory of Interpersonal Problems). The study included within-group comparisons based on data from 734 clients collected before and after individually short-term psychotherapy. The results show quite large effect sizes for the pre-to post- changes for psychological symptoms and for interpersonal problems; and a medium effect size for functions in general. About 60% of the clients had clinically symptoms and functional problems before therapy and around 60% of these ‘recovered’. Therefore, trainee-given therapy is clinically effective and should be seen as a helpful complement to the treatment of common psychiatric health problems.
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| 24. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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