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COVID-19 can cause life-threatening lung-inflammation that is suggested to be mediated by neutrophils, whose effector mechanisms in COVID-19 is inexplicit. The aim of the present work is to evaluate a novel PET tracer for neutrophil elastase in COVID-19 patients and healthy controls. METHODS: In this open-label, First-In-Man study, four patients with hypoxia due to COVID-19 and two healthy controls were investigated with positron emission tomography (PET) using the new selective and specific neutrophil elastase PET-tracer [11C]GW457427 and [15O]water for the visualization and quantification of NE and perfusion in the lungs, respectively. RESULTS: [11C]GW457427 accumulated selectively in lung areas with ground-glass opacities on computed tomography characteristic of COVID-19 suggesting high levels on NE in these areas. In the same areas perfusion was severely reduced in comparison to healthy lung tissue as measured with [15O]water. CONCLUSION: The data suggests that NE may be responsible for the severe lung inflammation in COVID-19 patients and that inhibition of NE could potentially reduce the acute inflammatory process and improve the condition., De två sista författarna delar sistaförfattarskapet

Ett gemensamt ämnesspråk mellan lärare och elev är en förutsättning för att kunna samtala med ämnesspecifika ord, begrepp och termer inom ett visst område. Svenskämnets specifika språk ligger till grund för undervisnings- och bedömningspraktiker. Tidigare forskning visar att ett gemensamt språk mellan lärare och elever ger meningsfullhet som i vidare utsträckning gynnar lärandet. För att undersöka lärares attityder till ämnesspråk används en kvalitativ metod genom intervjuer med tre gymnasielärare i kursen Svenska 3. Studien fokuserar på lärarnas uppfattningar om och attityder till ämnesspråk samt hur de säger att de implementerar ämnesspråk i svenskämnet. Resultatet visar att samtliga lärare har en gemensam inställning till ämnesspråk, men implementerar ämnesspråk på olika sätt. Ämnesspråket får olika utfall i de olika klassrummen hos respektive lärare beroende på elevgrupp och vilka förväntningar lärarna har på eleverna.

This interview study examined the religiosity of eight Ukrainian refugees. The aim of the bachelor thesis was to study how religiosity and religious commitment are affected as a result of war and flight. The data was collected through eight semi-structured interviews and then analyzed based on previous research and theories, like Charles Glock´s theory of deprivation and Peter L. Berger and Thomas Luckmanns theory of plausibility structure. The results of the study showed that no one lost their faith in God due to the war, the escape and the arrival in Sweden. For some of the refugees, faith in God had become stronger and religious commitment had increased. This can be explained by the theories about deprivation and change in plausibility structure. The distinguishing feature of the study was that the bomb shelters in Ukraine became a place for faith in God, even for people who had not been religious believers before. The confined place, the physical proximity to other people, the collective in prayer created an important community for the affected people. People who were not believers before the war did not develop a religious faith after the escape. The conclusion of the study was that faith in God becomes tangible in war-torn situations where people fear for their lives. Religious affiliation and community was important for the Ukrainian refugees and was shown for example through increased church involvement in Sweden to find comfort and meaning.

Syftet med denna studie är att undersöka hur förskollärare beskriver begreppet inkludering samt hur de arbetar med inkludering och olika anpassningar, för att skapa en inkluderande förskolemiljö för alla barn oavsett behov. Vidare undersöks förskollärares upplevelser kring möjligheter och utmaningar med inkludering samt hur reflektionstiden påverkar det inkluderande arbetssättet. Studien är uppbyggd på en kvalitativ metod där semistrukturerade intervjuer har använts för att få fram studiens resultat. Intervjuerna i studien har genomförts individuellt med fyra förskollärare samt två specialpedagoger som sedan blivit utgångspunkten i studiens resultat. Studiens metod och innehåll utgår från det sociokulturella perspektivet samt samspelsteorin. Studiens resultat visar att förskollärare samt specialpedagoger anser att inkludering är av stor vikt för utvecklingsarbetet i förskolan. Begreppet inkludering beskrivs som när alla barn är tillsammans men utifrån olika förutsättningar. Fysiska samt sociala anpassningar anses som viktiga för att skapa en inkluderande verksamhet för alla barn. Det har visat sig vara viktigt att använda konkreta föremål och sociala anpassningar för att skapa en helhet och kunna anpassa verksamheten på både grupp och individnivå. Förskollärare lyfter möjligheter med ett inkluderande arbetssätt och menar att det skapar ett öppet klimat där alla barn får möjlighet att utvecklas utifrån sina individuella behov. Genom ett öppet klimat och en tillåtande miljö skapas en inkluderande lärmiljö och möjligheter utifrån varje enskild individ. Vidare beskrivs vikten vid att utforma miljön utifrån barnets eget intresse och uttryckta åsikter för att skapa en delaktighet och gemenskap i förskolan. Utmaningar som tas upp och belyses är hur begreppet tolkas på olika sätt beroende på vem som arbetar med inkludering. Förskollärarna i studien lyfter vikten av reflektionstiden i arbetslaget för att skapa en samsyn kring inkluderingsperspektivet och möjlighet att analys

Positron emission tomography (PET) combined with computed tomography (CT) is a widely used noninvasive molecular imaging modality with a broad range of clinical applications in oncology, neurology, and cardiology. Producing imperative image quality and accurate quantification are important driving forces behind the technological advances within PET image reconstruction and system development. To ensure clinical quality and to understand how the modern state-of-the-art PET/CT systems and image reconstruction methods compare with older systems and reconstruction methods they need to be evaluated and assessed in a clinical setting. This thesis summarizes six studies assessing the effect of state-of-the-art image reconstruction methods and the introduction of digital PET on image quality and quantitative outcomes of clinical PET scans in oncology, neurology, and cardiology. The overall aim was to evaluate, optimize, and compare quantitative results of regularized image reconstruction with the current standard reconstruction method used in routine clinical practice, ordered subsets expectation maximization (OSEM). The optimal setting of regularized image reconstruction by block-sequential regularized expectation maximization (BSREM) was found to be tracer dependent, and a potential clinical benefit in terms of image quality measures of BSREM over OSEM was found when applied for whole-body 18F-FDG, 68Ga-DOTATOC, 18F-fluorde, 11C-acetate, and 68Ga-PSMA-11 PET imaging. Software-aided assessment of neurodegenerative disease evaluated with 18F-FDG and 18F-flutemetamol was affected by image reconstruction methods and should be used with caution when employing other image reconstruction methods than those used for acquisition of the normal database. In contrast, changes in reconstruction settings were shown to not implicate myocardial blood flow (MBF) based on 15O-water PET analyzed using automated software. This shows that diagnostic MBF cutoff values can be consistently used

Background F-18-NaF positron emission tomography/computed tomography (fluoride PET/CT) is considered the most sensitive technique to detect bone metastasis in prostate cancer (PCa). Ga-68-PSMA-11 (PSMA) PET/CT is increasingly used for staging of PCa. This study primarily aimed to compare the diagnostic performance of fluoride PET/CT and gallium-based PSMA PET/CT in identifying bone metastasis followed by a comparison of PSMA PET/CT with contrast-enhanced CT (CE-CT) in identifying soft tissue lesions as a secondary objective. Methods Twenty-eight PCa patients with high suspicion of disseminated disease following curative treatment were prospectively evaluated. PET/CT examinations using fluoride and PSMA were performed. All suspicious bone lesions were counted, and the tracer uptake was measured as standardized uptake values (SUV) for both tracers. In patients with multiple findings, ten bone lesions with highest SUVmax were selected from which identical lesions from both scans were considered for direct comparison of SUVmax. Soft tissue findings of local and lymph node lesions from CE-CT were compared with PSMA PET/CT. Results Both scans were negative for bone lesions in 7 patients (25%). Of 699 lesions consistent with skeletal metastasis in 21 patients on fluoride PET/CT, PSMA PET/CT identified 579 lesions (83%). In 69 identical bone lesions fluoride PET/CT showed significantly higher uptake (mean SUVmax: 73.1 +/- 36.8) compared to PSMA PET/CT (34.5 +/- 31.4; p < 0.001). Compared to CE-CT, PSMA PET/CT showed better diagnostic performance in locating local (96% vs 61%, p = 0.004) and lymph node (94% vs 46%, p < 0.001) metastasis. Conclusion In this prospective comparative study, PSMA PET/CT detected the majority of bone lesions that were positive on fluoride PET/CT. Further, this study indicates better diagnostic performance of PSMA PET/CT to locate soft tissue lesions compared to CE-CT.

Psykisk ohälsa har ökat bland barn och unga i samhället. Huvudvärk kan vara ett psykosomatiskt symtom som indikerar psykisk ohälsa. Skolsköterskans hälsofrämjande och sjukdomsförebyggande arbete har en avgörande betydelse för att uppmärksamma de elever som söker för återkommande huvudvärk. Syftet med studien var att beskriva vilka omvårdnadsåtgärder skolsköterskan utför till elever som söker för återkommande huvudvärk. Metoden som användes var en kvalitativ innehållsanalys med induktiv ansats. Intervjuer genomfördes med åtta skolsköterskor från fyra olika kommuner. Resultatet presenterades med tre kategorier med tillhörande underkategorier: Övergripande hälsobedömning, Arbeta elev fokuserat, och Samarbete inom elevhälsan och med vårdnadshavare. I mötet med eleven gjorde skolsköterskorna en bedömning av elevens hälsosituation, såväl de fysiska, psykiska som de sociala aspekterna. Eleven var i fokus för skolsköterskorna. Samarbetet med vårdnadshavare och elevhälsa kunde hjälpa skolsköterskorna att få en helhetsbild av elevens situation. Olika behandlingsmetoder användes för att lindra huvudvärken. Omvårdnadsåtgärderna syftade till att öka elevens välbefinnande samt minska elevens skolfrånvaro för att på sikt få en friskare befolkning. Sambandet mellan huvudvärksproblematik och psykisk ohälsa är av stor vikt för skolsköterskan att ha kunskap om. Det är önskvärt med forskning kring en nationell handlingsplan över vilka omvårdnadsåtgärder som tidigt kan sättas in för elever med huvudvärksproblematik., Mental illness has increased among children and adolescents in society. Headaches can be a psychosomatic symptom indicating mental illness. The school nurse's work on health promotion and disease prevention is crucial for giving attention to students with recurrent headaches. The aim of this study was to describe what nursing measures the school nurse performed for those students who sought care for recurrent headaches. The method used was a qualitative content analysis with an inductive approach. Interviews were made with eight school nurses from four different municipalities. The results were presented in four main themes with these following associated sub-themes: Overall Health Assessment, Student Focused Work and Collaboration within Student Health Care and with Parents or Legal Guardians. When meeting with the student, the school nurses assessed the student's health situation; both physical, mental and social aspects. The student was in focus for the school nurses. Collaboration with parents or legal guardians and student health care could help the school nurses get an overall picture of the student's situation. Different treatments were used to relieve headache. The nursing measures taken were aimed at increasing the well-being of the student and reducing the student’s absence from school to eventually gain a healthier population. The connection between problems with headaches and mental illness is of great importance for the school nurse to have knowledge of. Research on a national plan of action is desirable, stating which nursing measures to take on an early stage for students with headache problems.

Aim: The aim of this prospective study was to evaluate a data-driven gating software's performance, in terms of identifying the respiratory signal, comparing [Ga-68]Ga-DOTATOC and [F-18]FDG examinations. In addition, for the [Ga-68]Ga-DOTATOC examinations, tracer uptake quantitation and liver lesion detectability were assessed. Methods: Twenty-four patients with confirmed or suspected neuroendocrine tumours underwent whole-body [Ga-68]Ga-DOTATOC PET/CT examinations. Prospective DDG was applied on all bed positions and respiratory motion correction was triggered automatically when the detected respiratory signal exceeded a certain threshold (R value >= 15), at which point the scan time for that bed position was doubled. These bed positions were reconstructed with quiescent period gating (QPG), retaining 50% of the total coincidences. A respiratory signal evaluation regarding the software's efficacy in detecting respiratory motion for [Ga-68]Ga-DOTATOC was conducted and compared to [F-18]FDG data. Measurements of SUVmax, SUVmean, and tumour volume were performed on [Ga-68]Ga-DOTATOC PET and compared between gated and non-gated images. Results: The threshold of R >= 15 was exceeded and gating triggered on mean 2.1 bed positions per examination for [Ga-68]Ga-DOTATOC as compared to 1.4 for [F-18]FDG. In total, 34 tumours were evaluated in a quantitative analysis. An increase of 25.3% and 28.1%, respectively, for SUVmax (P < 0.0001) and SUVmean (P < 0.0001), and decrease of 21.1% in tumour volume (P < 0.0001) was found when DDG was applied. Conclusions: High respiratory signal was exclusively detected in bed positions where respiratory motion was expected, indicating reliable performance of the DDG software on [Ga-68]Ga-DOTATOC PET/CT. DDG yielded significantly higher SUVmax and SUVmean values and smaller tumour volumes, as compared to non-gated images.

PURPOSE: To assess how some of the new developments in brain positron emission tomography (PET) image reconstruction affect quantitative measures and software-aided assessment of pathology in patients with neurodegenerative diseases. METHODS: PET data were grouped into four cohorts: prodromal Alzheimer's disease patients and controls receiving [18F]flutemetamol, and neurodegenerative disease patients and controls receiving [18F]FDG PET scans. Reconstructed images were obtained by ordered-subsets expectation maximization (OSEM; 3 iterations (i), 16/34 subsets (s), 3/5-mm filter, ±time-of-flight (TOF), ±point-spread function (PSF)) and block-sequential regularized expectation maximization (BSREM; TOF, PSF, β-value 75-300). Standardized uptake value ratios (SUVR) and z-scores were calculated (CortexID Suite, GE Healthcare) using cerebellar gray matter, pons, whole cerebellum and whole brain as reference regions. RESULTS: In controls, comparable results to the normal database were obtained with OSEM 3i/16 s 5-mm reconstruction. TOF, PSF and BSREM either increased or decreased the relative uptake difference to the normal subjects' database within the software, depending on the tracer and chosen reference area, i.e. resulting in increased absolute z-scores. Normalizing to pons and whole brain for [18F]flutemetamol and [18F]FDG, respectively, increased absolute differences between reconstructions methods compared to normalizing to cerebellar gray matter and whole cerebellum when applying TOF, PSF and BSREM. CONCLUSIONS: Software-aided assessment of patient pathologies should be used with caution when employing other image reconstruction methods than those used for acquisition of the normal database.

The purpose of this essay is to analyse the Swedish legal situation regarding refusal to work and when employers can terminate an employment through notice of termination or dismissal based on analysed reasons. In both doctrine and case law a distinction is made between specific and general refusal. Specific refusal can lead to termination of notice, while general refusal can lead to dismissal. The Labor Court have in their assessment, if refusal to work has provided grounds for termination of notice or dismissal, considered whether there were extenuating circumstances and whether the employee has previously misbehaved. Furthermore, they have also considered the employee’s continued suitability based on what happened and how the employee has acted after a warning was received. Case law also indicates that religious freedom weighs heavily, and that the employer needs reasonable reasons to restrict it. Regarding distance work the Labour Court has expressed that the employee has received a special degree of trust which requires clear communication on the part of the employee. In case of absence without leave, the court has deemed that a longer absence usually should result in dismissal while a shorter absence usually should result in termination of notice. Refusal to work has been considered justified in cases where there was a danger to life and health or if an order was contrary to law or good practice. In these cases, it is required that the employee's subjective judgment have been based on reasonable grounds., Den här uppsatsen syftar till att analysera det svenska rättsläget avseende arbetsvägran och när arbetsgivare, utifrån de analyserade grunderna, kan avsluta en anställning genom uppsägning eller avsked. I såväl doktrin som praxis görs en uppdelning mellan specifik och allmän arbetsvägran. Specifik arbetsvägran kan leda till uppsägning medan allmän arbetsvägran kan leda till avsked. Arbetsdomstolen har i sin bedömning, huruvida arbetsvägran utgjort grund för uppsägning eller avsked, tagit hänsyn till om det funnits förmildrande omständigheter samt om arbetstagaren tidigare misskött sig. Vidare har den i sin bedömning vägt in arbetstagarens fortsatta lämplighet utifrån det inträffade och hur arbetstagaren har agerat efter att varning erhållits. Enligt praxis väger religionsfriheten tungt och det krävs att arbetsgivaren ha rimliga skäl för att kunna inskränka den. Vid distansarbete har Arbetsdomstolen uttryckt att arbetstagaren ålagts ett särskilt förtroende vilket ställer krav på tydlig kommunikation från arbetstagarens sida. Avseende olovlig frånvaro har domstolen ansett att en längre tids frånvaro utgjort allmän arbetsvägran, vilket i regel har lett till avsked, medan en kortare tids frånvaro lett till uppsägning. Arbetsvägran har ansetts rättfärdigad i de fall där det funnits fara för liv och hälsa eller om order stridit mot lag eller god sed. I dessa fall krävs det att arbetstagarens subjektiva bedömning är grundad på rimliga skäl.

Brachycephaly is a conformation in cats and dogs developed by man through breeding. It is characterised by a short muzzle and a flat skull. A breed standard describes the conformation for each breed. The cat breeds that are classified as brachycephalic is Persian and Exotic and for dogs they are for example Pug, French bulldog, English bulldog, Boston terrier and Boxer. In Sweden Pug and French bulldog are both among the top 20 most popular breeds. The brachycephalic cats are not as popular in Sweden as the dogs are. The brachycephalic conformation is associated with several health problems and has an unfavourable impact on the welfare of the animals. In Sweden the animal welfare legislation and an ordinance on cats and dogs govern breeding with pets. Additionally, cat and dog breeders in Sweden needs a permit to breed three or more litters a year. It is the regional County Administrative Board that issues these permits. The aim of this bachelor thesis was to investigate how the brachycephalic conformations in cats and dogs affects the welfare of the animals. This thesis is a literature study. Scientific articles about brachycephaly, problems and diseases that are associated with brachycephaly and articles about animal welfare form the basis for this study. With the brachycephalic conformation comes several anatomic deformations, for example an elongated soft palate, abnormal nasopharyngeal turbinates and stenotic nares. All of these deformations could affect the breathing. If the breathing is affected, the cat or dog could have Brachycephalic obstructive airway syndrome (BOAS). Clinical signs of BOAS are among others steror, stridor, dyspnoea, cyanosis and fainting. A cat or a dog could show one or more clinical signs and the severity varies. Brachycephaly can affect more than just the airways, for example dogs can suffer from heat and exercise intolerance, both cats and dogs have a higher risk for skin, teeth and eye problems. Dystocia is another problem for brach

Accurate localization of recurrent prostate cancer (PCa) is critical, especially if curative therapy is intended. With the aim to optimize target-to-background uptake ratio in Ga-68-PSMA-11 PET, we investigated the image quality and quantitative measures of regularized reconstruction by block-sequential regularized expectation maximization (BSREM). Methods: The study encompassed retrospective reconstruction and analysis of 20 digital time-of-flight (TOF) PET/CT examinations acquired 60 min post injection of 2 MBq/kg of Ga-68-PSMA-11 in PCa patients with biochemical relapse after primary treatment. Reconstruction by ordered-subsets expectation maximization (OSEM; 3 iterations, 16 subsets, 5 mm gaussian postprocessing filter) and BSREM (beta-values of 100-1600) were used, both including TOF and point spread function (PSF) recovery. Background variability (BV) was measured by placing a spherical volume of interest in the right liver lobe and defined as the standard deviation divided by the mean standardized uptake value (SUV). The image quality was evaluated in terms of signal-to-noise ratio (SNR) and signal-to-background ratio (SBR), using SUVmax of the lesions. A visual assessment was performed by four observers. Results: OSEM reconstruction produced images with a BV of 15%, whereas BSREM with a beta-value above 300 resulted in lower BVs than OSEM (36% with beta 100, 8% with beta 1300). Decreasing the acquisition duration from 2 to 1 and 0.5 min per bed position increased BV for both reconstruction methods, although BSREM with beta-values equal to or higher than 800 and 1200, respectively, kept the BV below 15%. In comparison of BSREM with OSEM, the mean SNR improved by 25 to 66% with an increasing beta-value in the range of 200-1300, whereas the mean SBR decreased with an increasing beta-value, ranging from 0 to 125% with a beta-value of 100 and 900, respectively. Decreased acquisition duration resulted in beta-values of 800 to 1000 and 1200 to 1400 for 1 and 0.5 mi

The epidermal growth factor receptor (EGFR) is often overexpressed during prostate cancer (PCa) progression towards androgen-independence after hormone therapy, but the overexpression is lower than in other types of cancers. Despite the low expression, EGFR has emerged as a promising therapeutic target for patients with castration-resistant PCa. Non-invasive methods for determination of EGFR expression in PCa can serve for patient stratification and therapy response monitoring. Radionuclide imaging probes based on affibody molecules (7 kDa) provide high contrast imaging of cancer-associated molecular targets. We hypothesized that the anti-EGFR affibody molecule DOTA-Z(EGFR:2377) labeled with Co-55 (positron-emitter, T1/2=17.5 h) would enable imaging of EGFR expression in PCa xenografts. The human PCa cell line DU-145 was used for in vitro and in vivo experiments and Co-57 was used as a surrogate for Co-55 in the present study. Binding of Co-57-DOTA-Z(EGFR:2377) to EGFR-expressing xenografts was saturable with anti-EGFR monoclonal antibody cetuximab, which would motivate the use of this tracer for monitoring the receptor occupancy during treatment. A significant dose-dependent difference in radioactivity accumulation in tumors and normal organs was observed when the biodistribution was studied 3 h after the injection of 10 and 35 mu g of Co-57-DOTA-Z(EGFR:2377): At lower doses the tumor uptake was 2-fold higher although tumor-to-organ ratios were not altered. For clinically relevant organs for PCa, tumor-to-organ ratios increased with time, and at 24 h pi were 2.2 +/- 0.5 for colon, 7 +/- 2 for muscle, and 4.0 +/- 0.7 for bones. Small animal SPECT/CT images confirmed the capacity of radiocobalt labeled DOTA-Z(EGFR:2377) to visualize EGFR expression in PCa. In conclusion, the present study demonstrated the feasibility of using the radiocobalt labeled anti-EGFR affibody conjugate Z(EGFR:2377) as an imaging agent for in vivo visualization of low EGFR-expressing tumors

Vascular endothelial growth factor receptor-2 (VEGFR2) is a key mediator of angiogenesis and therefore a promising therapeutic target in malignancies including glioblastoma multiforme (GBM). Molecular imaging of VEGFR2 expression may enable patient stratification for antiangiogenic therapy. The goal of the current study was to evaluate the capacity of the novel anti-VEGFR2 biparatopic affibody conjugate (Z(VEGFR2)-Bp(2)) for in vivo visualization of VEGFR2 expression in GBM. Methods: Z(VEGFR2)-Bp(2) coupled to a NODAGA chelator was generated and radiolabeled with indium-111. The VEGFR2-expressing murine endothelial cell line MS1 was used to evaluate in vitro binding specificity and affinity, cellular processing and targeting specificity in mice. Further tumor targeting was studied in vivo in GL261 glioblastoma orthotopic tumors. Experimental imaging was performed. Results: [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) bound specifically to VEGFR2 (K-D=33 +/- 18 pM). VEGFR2-mediated accumulation was observed in liver, spleen and lungs. The tumor-to-organ ratios 2 h post injection for mice bearing MS1 tumors were approximately 11 for blood, 15 for muscles and 78 for brain. Intracranial GL261 glioblastoma was visualized using SPECT/CT. The activity uptake in tumors was significantly higher than in normal brain tissue. The tumor-to-cerebellum ratios after injection of 4 mu g [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were significantly higher than the ratios observed for the 40 mu g injected dose and for the non-VEGFR2 binding size-matched conjugate, demonstrating target specificity. Microautoradiography of cryosectioned CNS tissue was in good agreement with the SPECT/CT images. Conclusion: The anti-VEGFR2 affibody conjugate [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) specifically targeted VEGFR2 in vivo and visualized its expression in a murine GBM orthotopic model. Tumor-to-blood ratios for [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were higher compared to other VEGFR2 imaging probes. [In-111]In-NODAGA-Z(VE, De två första författarna delar förstaförfattarskapet.De två sista författarna delar sistaförfattarskapet

The resolution and quantitative accuracy of PET are highly influenced by the reconstruction method. Penalized-likelihood estimation algorithms allow for fully convergent iterative reconstruction, generating a higher image contrast than ordered-subsets expectation maximization (OSEM) while limiting noise. In this study, a type of penalized reconstruction known as block-sequential regularized expectation maximization (BSREM) was compared with time-of-flight OSEM (TOF OSEM). Various strengths of noise penalization factor β were tested along with various acquisition durations and transaxial fields of view (FOVs) with the aim of evaluating the performance and clinical use of BSREM for 18F-FDG PET/CT, both quantitatively and in a qualitative visual evaluation. Methods: Eleven clinical whole-body 18F-FDG PET/CT examinations acquired on a digital TOF PET/CT scanner were included. The data were reconstructed using BSREM with point-spread function recovery and β-factors of 133, 267, 400, and 533—and using TOF OSEM with point-spread function—for various acquisition times per bed position and various FOVs. Noise level, signal-to-noise ratio (SNR), signal-to-background ratio (SBR), and SUV were analyzed. A masked evaluation of visual image quality, rating several aspects, was performed by 2 nuclear medicine physicians to complement the analysis. Results: The lowest levels of noise were reached with the highest β-factor, resulting in the highest SNR, which in turn resulted in the lowest SBR. A β-factor of 400 gave noise equivalent to TOF OSEM but produced a significant increase in SUVmax (11%), SNR (22%), and SBR (12%). BSREM with a β-factor of 533 at a decreased acquisition duration (2 min/bed position) was comparable to TOF OSEM at a full acquisition duration (3 min/bed position). Reconstructed FOV had an impact on BSREM outcome measures; SNR increased and SBR decreased when FOV was shifted from 70 to 50 cm. The evaluation of visual image quality resulted in similar scores for

Objectives: The penalized likelihood estimation reconstruction algorithm Q.Clear (GE Healthcare) allows for full convergence and edge preservation through a block sequential regularized expectation maximization technique. In this study the performance of Q.Clear was investigated for different penalization factors (β) with the aim to optimize its clinical use for four different tracers. Methods: Q.Clear reconstructions with β values of 200, 400, 600 and 800 were compared to time-of-flight ordered subset expectation maximization (TF-OSEM) (3 iterations, 16 subsets and 5 mm Gaussian filter) with point spread function recovery. Clinical whole-body PET/CT (Discovery MI, GE Healthcare) scans with 68Ga-DOTATOC, 18F-FDG, 11C-acetate or 18F-fluoride were analyzed for level of noise in healthy liver tissue, signal to noise ratio (SNR), signal to background ratio (SBR) and maximum standardized uptake value (SUVmax). In addition, acquisition times per bed position and transaxial field of view (FOV) of the reconstructed images were varied. For each tracer, images from 10 patients were included, with a mean of 30 lesions per tracer. A spherical reference volume of interest (VOI) was placed in the liver and lesions were delineated employing a 41% threshold of the maximum voxel. Results: The lowest levels of noise were reached with the highest beta factor resulting in the highest SNR, but this in turn gave the lowest SBR. Noise equivalence to OSEM was found with β 600 for 68Ga-DOTATOC, 18F-FDG and 18F-fluoride, and β 400 for 11C-acetate with a resulting significant increase of SUVmax (19.4%, 9.7%, 22.5% and 19.0% respectively) (P < 0.0001, paired t-test), SNR (22.1%, 22.6%, 9.5% and 33.6%) and SBR (19.5%, 11.7%, 21.3% and 18.5%) compared to OSEM. SNR decreased while SBR increased for all tracers when extending FOV from 500 to 700 mm, but only significantly for 18F-fluoride. Decreasing image acquisition time gave no statistical difference of SUVmax for 68Ga-DOTATOC, 18F-fluoride