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- Garpered, Sabine, et al.
(author)
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Measurement of airway inflammation in current smokers by positron emission tomography
- 2019
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In: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 39:6, s. 393-398
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Journal article (peer-reviewed)abstract
- Background Accumulation of activated neutrophilic leucocytes is known to increase uptake of F-18-fluorodeoxyglucose (F-18-FDG) into lung tissue. Available evidence suggests that smokers and subjects with chronic obstructive pulmonary disease (COPD) have neutrophilic inflammation in peripheral airways. The aim of this study was to examine whether current smokers have higher lung tissue uptake of F-18-FDG than never-smokers when correcting for air fraction of the lungs. Methods We prospectively recruited 33 current smokers and 33 never-smokers among subjects referred for diagnosis or staging of cancer, other than lung cancer, with combined positron emission tomography/computed tomography (PET/CT) with F-18-FDG. Subjects with focal F-18-FDG uptake or focal CT abnormalities in the lungs were excluded. The lungs were segmented in the CT image, and lung density measured. F-18-FDG uptake was measured in the corresponding volume and corrected for air fraction. Results Lung uptake of F-18-FDG, corrected for air fraction, was 12 center dot 5 and 8 per cent higher in the right and left lungs, respectively, in current smokers than in never-smokers (P<0 center dot 05). Conclusion Abnormal lung tissue uptake of F-18-FDG may be masked by reduced lung density if the uptake is not related to air fraction. Increased uptake of F-18-FDG in lung tissue in current smokers relative to never-smokers may reflect inflammation in peripheral airways. Measurements of F-18-FDG uptake in the lung tissue may be useful for animal and human studies of airways disease in COPD and the relation between airway and systemic inflammation.
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| 2. |
- Kollberg, Petter, et al.
(author)
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[F-18]Fluorodeoxyglucose - positron emission tomography/computed tomography improves staging in patients with high-risk muscle-invasive bladder cancer scheduled for radical cystectomy
- 2015
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In: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1813 .- 2168-1805. ; 49:4, s. 296-301
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Journal article (peer-reviewed)abstract
- Objective. The aim of this study was to evaluate the clinical use of [F-18]-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in addition to conventional preoperative radiological investigations in a defined group of patients with high-risk muscle-invasive bladder cancer. Materials and methods. In total, 103 patients with high-risk muscle-invasive bladder cancer defined as stage T3/T4 disease or as stage T2 with hydronephrosis or high-risk histological features, who were provisionally scheduled to undergo cystectomy, were prospectively recruited to the study. The patients were referred to FDG-PET/CT in addition to standard preoperative investigation with computed tomography (CT). The final treatment decision was reached at a multidisciplinary conference based on all available information including the FDG-PET/Cf findings. Results. Compared to CT alone, FDG-PET/CT provided more supplemental findings suggesting malignant manifestations in 48 (47%) of the 103 patients. The additional FDG-PET/CT findings led to an altered provisional treatment plan in 28 out of 103 patients (27%), detection of disseminated bladder cancer and subsequent cancellation of the initially intended cystectomy in 16 patients, and identification of disseminated disease and treatment with induction chemotherapy before radical cystectomy in 12 patients. Conclusions. Preoperative FDG-PET/CT changed the treatment plan for a considerable proportion (27%) of the present patients. Accordingly, such examination can potentially improve the preoperative staging of cystectomy patients with high-risk features, and may also reduce the number of futile operations in patients with advanced disease who are beyond cure.
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| 3. |
- Oddstig, Jenny, et al.
(author)
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Comparison of conventional and Si-photomultiplier-based PET systems for image quality and diagnostic performance
- 2019
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In: BMC Medical Imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 19:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: A new generation of positron emission tomography with computed tomography (PET-CT) was recently introduced using silicon (Si) photomultiplier (PM)-based technology. Our aim was to compare the image quality and diagnostic performance of a SiPM-based PET-CT (Discovery MI; GE Healthcare, Milwaukee, WI, USA) with a time-of-flight PET-CT scanner with a conventional PM detector (Gemini TF; Philips Healthcare, Cleveland, OH, USA), including reconstruction algorithms per vendor's recommendations. METHODS: Imaging of the National Electrical Manufacturers Association IEC body phantom and 16 patients was carried out using 1.5 min/bed for the Discovery MI PET-CT and 2 min/bed for the Gemini TF PET-CT. Images were analysed for recovery coefficients for the phantom, signal-to-noise ratio in the liver, standardized uptake values (SUV) in lesions, number of lesions and metabolic TNM classifications in patients. RESULTS: In phantom, the correct (> 90%) activity level was measured for spheres ≥17 mm for Discovery MI, whereas the Gemini TF reached a correct measured activity level for the 37-mm sphere. In patient studies, metabolic TNM classification was worse using images obtained from the Discovery MI compared those obtained from the Gemini TF in 4 of 15 patients. A trend toward more malignant, inflammatory and unclear lesions was found using images acquired with the Discovery MI compared with the Gemini TF, but this was not statistically significant. Lesion-to-blood-pool SUV ratios were significantly higher in images from the Discovery MI compared with the Gemini TF for lesions smaller than 1 cm (p < 0.001), but this was not the case for larger lesions (p = 0.053). The signal-to-noise ratio in the liver was similar between platforms (p = 0.52). Also, shorter acquisition times were possible using the Discovery MI, with preserved signal-to-noise ratio in the liver. CONCLUSIONS: Image quality was better with Discovery MI compared to conventional Gemini TF. Although no gold standard was available, the results indicate that the new PET-CT generation will provide potentially better diagnostic performance.
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| 4. |
- Trägårdh, Elin, et al.
(author)
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Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for 18F-FDG
- 2019
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In: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 9:1
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Journal article (peer-reviewed)abstract
- Background: Block-sequential regularized expectation maximization (BSREM), commercially Q. Clear (GE Healthcare, Milwaukee, WI, USA), is a reconstruction algorithm that allows for a fully convergent iterative reconstruction leading to higher image contrast compared to conventional reconstruction algorithms, while also limiting noise. The noise penalization factor β controls the trade-off between noise level and resolution and can be adjusted by the user. The aim was to evaluate the influence of different β values for different activity time products (ATs = administered activity × acquisition time) in whole-body 18F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET-CT) regarding quantitative data, interpretation, and quality assessment of the images. Twenty-five patients with known or suspected malignancies, referred for clinical 18F-FDG PET-CT examinations acquired on a silicon photomultiplier PET-CT scanner, were included. The data were reconstructed using BSREM with β values of 100–700 and ATs of 4–16 MBq/kg × min/bed (acquisition times of 1, 1.5, 2, 3, and 4 min/bed). Noise level, lesion SUVmax, and lesion SUVpeak were calculated. Image quality and lesion detectability were assessed by four nuclear medicine physicians for acquisition times of 1.0 and 1.5 min/bed position. Results: The noise level decreased with increasing β values and ATs. Lesion SUVmax varied considerably between different β values and ATs, whereas SUVpeak was more stable. For an AT of 6 (in our case 1.5 min/bed), the best image quality was obtained with a β of 600 and the best lesion detectability with a β of 500. AT of 4 generated poor-quality images and false positive uptakes due to noise. Conclusions: For oncologic whole-body 18F-FDG examinations on a SiPM-based PET-CT, we propose using an AT of 6 (i.e., 4 MBq/kg and 1.5 min/bed) reconstructed with BSREM using a β value of 500–600 in order to ensure image quality and lesion detection rate as well as a high patient throughput. We do not recommend using AT < 6 since the risk of false positive uptakes due to noise increases.
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