| 6011. |
- Nocum, D. J., et al.
(författare)
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UTERINE ARTERY EMBOLISATION: CONTINUOUS QUALITY IMPROVEMENT REDUCES RADIATION DOSE WHILE MAINTAINING IMAGE QUALITY
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 196:3-4, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to introduce a continuous quality improvement (CQI) program for radiation dose optimisation during uterine artery embolisation (UAE) and assess its impact on dose reduction and image quality. The CQI program investigated the effects of optimising radiation dose parameters on the kerma-area product (KAP) and image quality when comparing a 'CQI intervention' group (n = 50) and 'Control' group (n = 50). Visual grading characteristics (VGC) analysis was used to assess image quality, using the 'Control' group as a reference. A significant reduction in KAP by 17% ( P = 0.041, d = 0.2) and reference air kerma (Ka, r) by 20% (P = 0.027, d = 0.2) was shown between the two groups. The VGC analysis resulted in an area under the VGC curve (AUCVGC) of 0.54, indicating no significant difference in image quality between the two groups (P = 0.670). The implementation of the CQI program and optimisation of radiation dose parameters improved the UAE radiation dose practices at our centre. The dose reduction demonstrated no detrimental effects on image quality.
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| 6012. |
- Nollet, Joeke L., et al.
(författare)
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Pharyngo-Esophageal Modulatory Swallow Responses to Bolus Volume and Viscosity Across Time
- 2022
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Ingår i: The Laryngoscope. - : John Wiley & Sons. - 0023-852X .- 1531-4995. ; 132:9, s. 1817-1824
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES/HYPOTHESIS: Modulation of the pharyngeal swallow to bolus volume and viscosity is important for safe swallowing and is commonly studied using high-resolution pharyngeal manometry (HRPM). Use of unidirectional pressure sensor technology may, however, introduce variability in swallow measures and a fixed bolus administration protocol may induce time and order effects. We aimed to overcome these limitations and to investigate the effect of time by repeating randomized measurements using circumferential pressure sensor technology.STUDY DESIGN: Sub-set analysis of data from the placebo arm of a randomized, repeated measures trial.METHODS: HRPM with impedance was recorded using a solid-state catheter with 36 circumferential pressure sensors and 18 impedance segments straddling from hypopharynx to stomach. Testing included triplicates of 5, 10, and 20 ml thin liquid and 10 ml thick liquid boluses, the order of the thin liquid boluses was randomized. The swallow challenges were repeated approximately 10 minutes after finishing the baseline measurement.RESULTS: We included 19 healthy adults (10/9 male/female; age 24.5 ± 4.1 year). Intrabolus pressure, all upper esophageal sphincter (UES) opening and relaxation metrics, and flow timing metrics increased with larger volumes. A thicker viscosity decreased UES relaxation time, UES basal pressure, and flow timing metrics, whereas UES opening extent increased. Pre-swallow UES basal pressure and post-swallow UES contractile integral decreased over time.CONCLUSION: Using circumferential pressure sensor technology, the effects of volume and viscosity were largely consistent with previous reports. UES contractile pressures reduced over time. The growing body of literature offers a benchmark for recognizing aberrant pharyngo-esophageal motor responses.LEVEL OF EVIDENCE: 3 Laryngoscope, 2021.
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| 6013. |
- Norbeck, Ola, et al.
(författare)
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Optimizing 3D EPI for rapid T1 -weighted imaging.
- 2020
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 84:3, s. 1441-1455
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the use of 3D EPI for rapid T1 -weighted brain imaging, focusing on the RF pulse's influence on the contrast between gray and white matter.METHODS: An interleaved 3D EPI sequence use partial Fourier and CAIPIRINHA sampling was used to acquire T1 -weighted brain volumes with isotropic resolution, low echo times, and low geometric distortions. Five different RF pulses were evaluated in terms of fat suppression performance and gray-white matter contrast. Two binomial RF pulses were compared to a single rectangular (WE-rect) RF pulse exciting only water, and two new RF pulses developed in this work, where one was an extension of the WE-rect, and the other was an SLR pulse. The technique was demonstrated in three clinical cases, where brain tumor patients were imaged before and after gadolinium administration.RESULTS: A fat-suppressed 3D EPI sequence with a phase encoding bandwidth of around 100 Hz was found to exhibit a good trade-off between geometrical distortions and scan duration. Whole-brain T1 -weighted 3D EPI images with 1.2 mm isotropic voxel size could be acquired in 24 seconds. The WE-rect, its extension, and the SLR RF pulses resulted in reduced magnetization transfer effects and provided a 20% mean increase in gray-white matter contrast.CONCLUSION: Using a high phase encoding bandwidth and RF pulses that reduce magnetization transfer effects, a fat-suppressed multi-shot 3D EPI sequence can be used to rapidly acquire isotropic T1 -weighted volumes.
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| 6014. |
- Norbeck, Ola, et al.
(författare)
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T1 -FLAIR imaging during continuous head motion : Combining PROPELLER with an intelligent marker.
- 2021
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 85:2, s. 868-882
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this work is to describe a T1 -weighted fluid-attenuated inversion recovery (FLAIR) sequence that is able to produce sharp magnetic resonance images even if the subject is moving their head throughout the acquisition.METHODS: The robustness to motion artifacts and retrospective motion correction capabilities of the PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) trajectory were combined with prospective motion correction. The prospective correction was done using an intelligent marker attached to the subject. This marker wirelessly synchronizes to the pulse sequence to measure the directionality and magnitude of the magnetic fields present in the MRI machine during a short navigator, thus enabling it to determine its position and orientation in the scanner coordinate frame. Three approaches to incorporating the marker-navigator into the PROPELLER sequence were evaluated. The specific absorption rate, and subsequent scan time, of the T1 -weighted FLAIR PROPELLER sequence, was reduced using a variable refocusing flip-angle scheme. Evaluations of motion correction performance were done with 4 volunteers and 3 types of head motion.RESULTS: During minimal out-of-plane movement, retrospective PROPELLER correction performed similarly to the prospective correction. However, the prospective clearly outperformed the retrospective correction when there was out-of-plane motion. Finally, the combination of retrospective and prospective correction produced the sharpest images even during large continuous motion.CONCLUSION: Prospective motion correction of a PROPELLER sequence makes it possible to handle continuous, large, and high-speed head motions with only minor reductions in image quality.
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| 6015. |
- Norberg, Pernilla, et al.
(författare)
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Optimisation of quantitative lung SPECT applied to mild COPD : a software phantom simulation study
- 2015
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Ingår i: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 5:16
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The amount of inhomogeneities in a (99m)Tc Technegas single-photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT method, measuring these inhomogeneities was proposed in earlier work. To detect mild COPD, which is a difficult task, optimised parameter values are needed.METHODS: In this work, the CVT method was optimised with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximisation (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung software phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%.RESULTS: The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq (99m)Tc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm(-1). Sixty-four reconstruction updates and a small kernel size should be used when the whole lung is analysed, and for the reduced lung a greater number of updates and a larger kernel size are needed.CONCLUSIONS: A LEHR collimator and 125 (99m)Tc MBq together with an optimal combination of cutoff frequency, number of updates and kernel size, gave the best result. Suboptimal selections of either cutoff frequency, number of updates and kernel size will reduce the imaging system's ability to detect mild COPD in the lung phantom.
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| 6016. |
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| 6017. |
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| 6018. |
- Nordberg, Erika, et al.
(författare)
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Cellular uptake of radioiodine delivered by trastuzumab can be modified by the addition of epidermal growth factor.
- 2005
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 32:7, s. 771-7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this study was to analyse whether non-radiolabelled epidermal growth factor (EGF) can modify the cellular uptake of 125I when delivered as [125I]trastuzumab. 125I was used as a marker for the diagnostically and therapeutically more interesting isotopes 123I (SPECT), 124I (PET) and 131I (therapy). METHODS: The cell-associated radioactivity was measured in squamous carcinoma A431 cells following addition of [125I]trastuzumab. Different concentrations of [125I]trastuzumab and unlabelled EGF were used, and the total, membrane-bound and internalised radioactivity was measured. We also analysed how EGF and trastuzumab affected the cell growth. RESULTS: It was generally found that the cellular 125I uptake was decreased by the addition of EGF when [125I]trastuzumab was added for short incubation times. However, if the incubation times were longer, EGF increased the 125I uptake. This shift came earlier when higher [125I]trastuzumab concentrations were applied. The addition of EGF also influenced cell proliferation, and concentrations above 10 ng/ml reduced cell growth by approximately 20% after 24 h of incubation. CONCLUSION: By adding unlabelled EGF, it was possible to modify the cellular uptake of [125I]trastuzumab. This points towards new approaches for the modification of radionuclide uptake in EGFR- and HER2-positive tumours.
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| 6019. |
- Nordenskjöld, A. C., et al.
(författare)
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X-ray exposure in utero and school performance : a population-based study of X-ray pelvimetry
- 2015
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Ingår i: Clinical Radiology. - : Elsevier BV. - 0009-9260 .- 1365-229X. ; 70:8, s. 830-834
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To investigate the association between exposure to ionising radiation from pelvimetric examinations in utero and school performance. MATERIAL AND METHODS: This was a population-based cohort study comprising 46,066 children born in the county of Ostergotland, Sweden, from 1980 through 1990. Through record linkage between Swedish registers, children exposed in utero to X-ray pelvimetry examination were compared to other children born in the same county during the study period, as well as to their unexposed siblings. Outcome variable was primary school grades, expressed in centiles and calculated through linear regression. RESULTS: In the univariate analysis, children exposed to X-ray pelvimetry in utero had higher school grades compared to unexposed children (point estimate 3 centiles, 95% confidence interval [CI]: 1.5 to 4.6). When sex, mother's education and income, birth order, and birth position were included in the analysis; however, the difference was reduced and the association was no longer statistically significant (PE 1.4, 95% CI: -0.1 to 2.8). Comparing exposed children with their siblings showed no statistical difference in univariate analysis or in multivariate analysis. CONCLUSION: No suggestion was found of a negative effect on school performance from in utero exposure of diagnostic X-ray pelvimetry.
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| 6020. |
- Nordgren, Marie, et al.
(författare)
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The Effectiveness of Four Intervention Methods for Preventing Inadvertent Perioperative Hypothermia During Total Knee or Total Hip Arthroplasty
- 2020
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Ingår i: AORN Journal. - : John Wiley & Sons. - 0001-2092 .- 1878-0369. ; 111:3, s. 303-312
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Tidskriftsartikel (refereegranskat)abstract
- Inadvertent perioperative hypothermia (IPH) occurs when a patient experiences a core temperature below 36 degrees C (96.8 degrees F) in perioperative settings and is a preventable risk factor for anesthesia- and surgery-related complications. Forced-air warming is an effective method to maintain normothermia. This study compared four interventions for preventing IPH for 120 patients undergoing primary elective unilateral total knee or total hip arthroplasty. The study was based on a time series nonequivalent comparison group design to investigate whether the incidence of IPH differed among treatment groups. We also sought to determine whether the patients' preoperative perceptions of warmth or cold correlated with core body temperatures. Patients receiving convective warming and prewarming appeared to experience fewer IPH events than patients in the other study groups. This study suggests that hypothermia is a common issue for patients undergoing total knee or total hip arthroplasty and that it may be possible to reduce its frequency.
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