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- Dahlman, Pär
(författare)
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CT Urography : Efforts to Reduce the Radiation Dose
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computed tomography urography (CTU) is today the imaging method used to investigate patients with suspected urinary tract malignancy, replacing the old imaging method intravenous pyelography (IVP) about a decade ago. The downside of this shift was that the effective radiation dose to the examined patient was eight times higher for CTU compared to IVP. Based on four different studies, the present thesis focused on efforts to reduce the CTU radiation dose. In study I, the number of cysts and solid lesions in the separate scan phases was evaluated in 57 patients undergoing four-phase CTU 1997-98. The number of scans was reduced from four to three when the nephrographic scan was abolished following study I.Study II registered the diameter of renal cell carcinoma (RCC) and the presenting symptoms in the total number of patients (n=232) diagnosed with RCC between 1997 and 2003. The results from study II showed that the critical size for RCCs to cause macroscopic hematuria was ≥ 4 cm. Study III was a dose-escalation study aimed to decide the minimal possible tube load in the unenhanced and excretory phase scans if the low dose images are reviewed together with normal dose corticomedullary phase images. Study III showed that it is possible to reduce the mean effective dose in three phase CTU from 16.2 mSv to 9.4 mSv with a combined low and normal dose CTU protocol. Study IV investigated the changes in the CTU protocol between 1997 and 2008, and the development of the effective radiation dose. Study IV clarified how the CTU protocol has changed between 1997 and 2008 and as a result the mean effective radiation dose to patients undergoing CTU in 2008 is only 39% of the effective dose in 1997. In conclusion, the findings from the studies included in this thesis have contributed to a reduced radiation dose to patients undergoing CTU. The mean effective dose from CTU is at present only three times higher compared to that from the IVP.
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| 2. |
- Hennings, Joakim, 1969-, et al.
(författare)
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11C-metomidate positron emission tomography after dexamethasone suppression for detection of small adrenocortical adenomas in primary aldosteronism
- 2010
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Ingår i: Langenbeck's archives of surgery (Print). - : Springer Science and Business Media LLC. - 1435-2443 .- 1435-2451. ; 395:7, s. 963-967
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate whether dexamethasone suppression treatment can improve 11 C-metomidate positron emission tomography (MTO-PET) detection of small adrenocortical adenomas in primary aldosteronism (PA). Materials and Methods: Eleven patients with proven PA and two patients with non-hyperfunctioning adrenocortical incidentalomas and small adrenocortical tumours observed on CT underwent MTO-PET before and 3 days after administration of oral dexamethasone suppression treatment. Small “hot-spot” regions of interest (ROIs) comprising 4-pixels (SUVhs) and 1-pixel (SUVmax) were placed in the tumour area with the highest radioactivity concentration and their respective standardised uptake values (SUV) were recorded. Results: All tumours were detected and categorised as adrenocortical by MTO-PET. SUVhs as well as SUVmax were higher in PA compared to non-functional adenomas. Normal adrenal cortex was suppressed after dexamethasone (p<0.05) but tumour SUV was not significantly decreased after suppression in either PA or non-functional tumours (p>0.05). However, these changes caused no significant increase in the tumour-to-normal adrenal ratio (p>0.05). Conclusion: MTO-PET is a highly sensitive method for detecting and categorising even small adrenocortical tumours in PA. In this series dexamethasone-suppressed MTO-PET was ubable to increase the tumour-to-normal-adrenal ratio to further facilitate detection of small adenomas in PA as an alternative to adrenal venous sampling.
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| 3. |
- Hennings, Joakim, et al.
(författare)
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Long-term effects of surgical correction of adrenal hyperplasia and adenoma causing primary aldosteronism
- 2010
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Ingår i: Langenbeck's archives of surgery (Print). - : Springer Science and Business Media LLC. - 1435-2443 .- 1435-2451. ; 395:2, s. 133-137
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this is to study long-time results of surgery for primary aldosteronism. MATERIALS AND METHODS: Thirty patients operated on for primary aldosteronism were followed for an average of 7 years. All but five required potassium substitution. Systolic as well as diastolic hypertension (mean 157/93 mmHg) was present necessitating one to five antihypertensive drugs daily (mean 2.33). Preoperative indications for surgery included presumed adenoma (aldosterone-producing adenoma (APA)) or in one case unilateral dominance of hyperplasia. RESULTS: Histopathology was classified into adenoma (n = 9), dominant nodule (n = 16), and general hyperplasia without dominating nodules (n = 5), demonstrating a higher frequency of hyperplasia than anticipated. Long-term results revealed well-controlled blood pressure (BP; mean 134/80 mmHg). Antihypertensive medication was reduced (average of 1.78 per day), but only 36% of the patients were taken off these drugs completely. S-Aldosterone was normalized. All but one (a recurrence) were normokalemic without potassium substitution at follow-up. The APA group needed less medication (median 0.5 vs. 1.5 and 2 per day) and more patients in this group were totally medication free (50%). Two recurrences occurred in the group with general hyperplasia without dominating nodules. CONCLUSION: Nodular hyperplasia is more common than anticipated. Hypersecretion of aldosterone may be released from a large nodule identified as an adenoma, as well as from a generally hyperplastic gland that has not been identified as such. Nevertheless, surgery for lateralized disease results in good long-term control of BP with less antihypertensive medication. However, patients with dominant nodule or general hyperplasia without dominating nodules need more postoperative treatment than patients with APA. The majority of patients do not achieve normotension without medications, but they do become normokalemic.
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| 4. |
- Norlén, Olov, et al.
(författare)
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11C-5-hydroxytryptophan positron emission tomography after radiofrequency ablation of neuroendocrine tumor liver metastases
- 2012
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Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 39:6, s. 883-890
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim was to assess the feasibility of C-11-5-hydroxy-tryptophan positron emission tomography ( C-11-5-HTP-PET) in the follow-up after radiofrequency ablation (RFA) of liver metastases from neuroendocrine tumors (NETS). Background: Contrast-enhanced computed tomography (CECT) and contrast-enhanced ultrasound (CEUS) are commonly used to evaluate the liver after RFA of NETs. In general, C-11-5-HTP-PET is more sensitive in the visualization of NETs, but no studies have investigated its role after RFA.Methods: Six consecutive patients with liver metastases from NETs were subjected to RFA treatment. All patients underwent baseline imaging before RFA and on two occasions (1-2 and 6-11 months) after RFA. The imaging consisted of C-11-5-HTP-PET, CEUS and CECT on all three occasions.Results: Thirty RFA areas were evaluated, and residual tumors (RTs) were depicted in eight areas (22%). C-11-5-HTP-PET depicted RTs after RFA with maximum sensitivity (100%) and specificity (100%), using radiological follow-up as the gold standard. C-11-5-HTP-PET detected five out of eight RTs earlier than CECT or CEUS. In general, the sensitivity of C-11-5-HTP-PET exceeded that of CECT and CEUS for early visualization of NET liver metastases.Conclusion: C-11-5-HTP-PET can be used in the follow-up after RFA for the purpose of detecting RT, and it provides additional information to CEUS and CECT by detecting new lesions.
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| 7. |
- Aronsen, T., et al.
(författare)
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The operational sex ratio and density influence spatial relationships between breeding pipefish
- 2013
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:4, s. 888-897
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Tidskriftsartikel (refereegranskat)abstract
- The operational sex ratio (ratio of sexually receptive males to females) has been extensively studied in behavioral ecology, whereas other demographic factors such as the effect of density on mating behavior have received less empirical attention. We manipulated mating competition by establishing breeding populations of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) at 2 sex ratios (male biased or female biased) and 2 densities. We used mean crowding (m*) and the index of association (X) to measure spatial distributions within and between the sexes, respectively, and investigated how these measures reflect the predicted strength of mating competition. In general, female m* increased as fewer males were available for mating, which suggests increased intrasexual competition in the most competitive sex. However, male m* also increased as the operational sex ratio became more female biased, suggesting that m* did not reflect mating competition for males. Association between the sexes (X) was higher under male bias than female bias, probably because males were still available for mating under male bias. In addition, X decreased in the female-biased treatment as the operational sex ratio became even more female biased. Higher density increased m* in both sex ratios and sexes, although for both sexes in the female-biased high-density treatment the operational sex ratio did not influence m*, probably because femalefemale competition inhibits further crowding in this treatment. In this study, we show that the use of m* and X can be a useful tool in behavioral studies but their interpretation requires detailed information about the mating system. Therefore, we recommend caution with their broadscale application.
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| 8. |
- Berglund, Anders, 1956-, et al.
(författare)
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The Development of Cooperation Between Al Baha University and Uppsala University, Sweden
- 2014
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Ingår i: International Exhibition and Conference on Higher Education, Riyadh, Saudi Arabia.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Developing new master level education is a complex task. Not only is the competence within the discipline crucial; teaching and as a consequence, learning, must also be research-focused and must aim to encourage the students to develop into independent scholars.In this collaborative, multi-facetted project Al Baha University, Saudi Arabia, (ABU) and Uppsala University, Sweden, (UU) work jointly to develop ABU into a leading actor in master level education with a corresponding research profile. The schools/departments take their own decisions on design and priorities of the activities. In this way the project profits from the local competencies at both sites and becomes locally situated and thus closer to the needs and expectations of the ABU staff.The partners entered into collaboration 2011. Among initial achievements was the common identification of the need of a bridging year for tentative master’s students, to complement the skills from the undergraduate (UG) level, and reinforce the command of English, which is a necessary tool in international education. In addition, computer science and mathematics were selected as the initial development areas.Within mathematics, the Department of Mathematics at UU was engaged in a discussion aiming primarily to develop the UG curriculum to match the needs of a future master programme, and secondly to develop the curriculum of a ABU master programme in mathematics to match UU standards, with the possibility in mind of student exchange targeting specific courses and thesis studies.Meanwhile, in the autumn 2013 a female staff member of ABU was admitted as PhD student in mathematics at UU, and has now started her second semester of full time studies.Within computer science (CS), the project tackles the significant challenges to encourage students, teachers and the formal university structures to embrace the ideas of Scholarship of Teaching and Learning (SoTL). The aim is to promote staff and students to broaden their perspective on what research and investigation means and to critically examine teaching and learning. As a consequence, the ways to relate to the students, the subject area, the teaching and the colleagues must be scrutinised, with the intent of finding new teaching and learning forms.The project implements these ideas in several ways. Currently a staff development course is given as a starting point for the project within CS. With a focus on the changes needed to implement the ideas of SoTL, the course participants make their own pedagogical development projects, and study their own practice and its outcomes using rigorous research-based methods. As a continuation, during the coming years, the two universities will run a set of workshops, mainly with a methodological focus, followed by a series of three conferences, with the first one serving the local area, and the last being an internationally recognised Institute of Electrical and Electronics Engineers (IEEE) sponsored conference.
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| 9. |
- Bjärtå, Anna, 1974-, et al.
(författare)
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The effect of using different distractor sets in visual search with spiders and snakes on spider-sensitive and nonfearful participants
- 2013
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Ingår i: Swiss Journal of Psychology. - Bern : Verlag Hans Huber. - 1421-0185 .- 1662-0879. ; 72:4, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- In two visual search experiments, we investigated the impact of distractor sets on fear-relevant stimuli by comparing a search set with spiders, snakes, flowers, and mushrooms to one with spiders, snakes, rabbits, and turtles. We found speeded responses to spider and snake targets when flowers and mushrooms, but not when rabbits and turtles served as distractors. In Experiment 2, we compared spider-sensitive to nonfearful participants. Spider-sensitive participants responded faster than nonfearful participants to spider targets when we used flowers and mushrooms as distractors, but not when we used rabbit and turtle distractors. These results indicate that behavioral responses to the visual search task not only depend on the individual’s relationship to the stimuli included in the search set, but also on the context in which the feared or fear-relevant objects are presented.
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