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- Marchesi, Silvia, et al.
(author)
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Abdominal organ perfusion and inflammation in experimental sepsis : a magnetic resonance imaging study
- 2019
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 316:1, s. G187-G196
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Journal article (peer-reviewed)abstract
- Diffusion-weighted magnetic resonance imaging (DW-MRI) uses water as contrast and enables the study of perfusion in many organs simultaneously in situ. We used DW-MRI in a sepsis model, comparing abdominal organs perfusion with global hemodynamic measurements and inflammation. Sixteen anesthetized piglets were randomized into 3 groups: HighMAP (mean arterial pressure, MAP > 65 mmHg), LowMAP (MAP between 50 and 60 mmHg) and Healthy Controls (HC). Sepsis was obtained with endotoxin and the desired MAP maintained with noradrenaline. After 6 hours DW-MRI was performed. Acute inflammation was assessed with IL-6 and TNFα in abdominal organs, ascites, and blood and by histology of intestine (duodenum). Perfusion of abdominal organs was reduced in the LowMAP group compared to the HighMAP group and HC. Liver perfusion was still reduced by 25% in the HighMAP group compared with HC. Intestinal perfusion did not differ significantly between the study groups. Cytokines concentration were generally higher in the LowMAP group but did not correlate with global hemodynamics. However, cytokines correlated with regional perfusion and, for liver and intestine, also with intra-abdominal pressure. Histopathology of intestine worsened with decreasing perfusion. In conclusion, although a low MAP (≤60 mmHg) indicated impeded abdominal perfusion in experimental sepsis, it did not predict inflammation, nor did other global measures of circulation. Decreased abdominal perfusion predicted partially inflammation but intestine, occupying most of the abdomen, and liver, were also affected by intra-abdominal pressure.
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| 2. |
- Schiza, Aglaia, et al.
(author)
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Evaluation of Diffusion-Weighted MRI and FDG-PET/CT to Assess Response to AdCD40L treatment in Metastatic Melanoma Patients
- 2019
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In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- The purpose was to evaluate the potential of diffusion-weighted-magnetic resonance imaging (DW-MRI) and F-18-fludeoxy-glucose-positron emission tomography integrated with CT (FDG-PET/CT) for prediction of overall survival (OS) following AdCD40L-immunotherapy in patients with metastatic malignant melanoma (MMM). Twenty-four patients with refractory MMM were treated with immunostimulatory AdCD40L gene therapy in a phase I/IIa study. Pre-therapeutic DW-MRI and FDG-PET/CT were performed and then repeated at 5 and 9 weeks post-treatment. Evaluation was conducted according to RECIST 1.1 and EORTC criteria. Apparent diffusion coefficient (ADC), true diffusion coefficient (D), maximum standardized uptake value (SUVmax) were measured in the injected lesions. Fold changes (F) in ADC (F ADC), D (FD), SUVmax (FSUVmax) were statistically assessed. F D >= 1 and F ADC >= 1 were associated with better OS in scans at week 5 and 9 respectively. F SUVmax was not correlated to OS. F ADC >= 1 in both post-treatment scans and F D >= 1 at week 5 were related to a significant decrease of size of the injected lesions. These results suggest that in patients with MMM treated with AdCD401, functional parameters of DW-MRI are better early predictors of OS than the established metabolic and morphologic criteria for FDG-PET/CT and MRI, respectively.
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| 4. |
- Weis, Jan, et al.
(author)
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High-resolution echo-planar spectroscopic imaging of the human calf
- 2014
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e87533-
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Journal article (peer-reviewed)abstract
- BACKGROUND: This study exploits the speed benefits of echo-planar spectroscopic imaging (EPSI) to acquire lipid spectra of skeletal muscle. The main purpose was to develop a high-resolution EPSI technique for clinical MR scanner, to visualise the bulk magnetic susceptibility (BMS) shifts of extra-myocellular lipid (EMCL) spectral lines, and to investigate the feasibility of this method for the assessment of intra-myocellular (IMCL) lipids.METHODS: The study group consisted of six healthy volunteers. A two dimensional EPSI sequence with point-resolved spectroscopy (PRESS) spatial localization was implemented on a 3T clinical MR scanner. Measurements were performed by means of 64×64 spatial matrix and nominal voxel size 3×3×15 mm(3). The total net measurement time was 3 min 12 sec for non-water-suppressed (1 acquisition) and 12 min 48 sec for water-suppressed scans (4 acquisitions).RESULTS: Spectra of the human calf had a very good signal-to-noise ratio and linewidths sufficient to differentiate IMCL resonances from EMCL. The use of a large spatial matrix reduces inter-voxel signal contamination of the strong EMCL signals. Small voxels enabled visualisation of the methylene EMCL spectral line splitting and their BMS shifts up to 0.5 ppm relative to the correspondent IMCL line. The mean soleus muscle IMCL content of our six volunteers was 0.30±0.10 vol% (range 0.18-0.46) or 3.6±1.2 mmol/kg wet weight (range: 2.1-5.4).CONCLUSION: This study demonstrates that high-spatial resolution PRESS EPSI of the muscle lipids is feasible on standard clinical scanners.
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| 5. |
- Weis, Jan, et al.
(author)
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Phase-difference and spectroscopic imaging for monitoring of human brain temperature during cooling
- 2012
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In: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 30:10, s. 1505-1511
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Journal article (peer-reviewed)abstract
- Decrease of the human brain temperature was induced by intranasal cooling. The main purpose of this study was to compare the two magnetic resonance methods for monitoring brain temperature changes during cooling: phase-difference and magnetic resonance spectroscopic imaging (MRSI) with high spatial resolution. Ten healthy volunteers were measured. Selective brain cooling was performed through nasal cavities using saline-cooled balloon catheters. MRSI was based on a radiofrequency spoiled gradient echo sequence. The spectral information was encoded by incrementing the echo time of the subsequent eight image records. Reconstructed voxel size was 1x1x5 mm(3). Relative brain temperature was computed from the positions of water spectral lines. Phase maps were obtained from the first image record of the MRSI sequence. Mild hypothermia was achieved in 15-20 min. Mean brain temperature reduction varied in the interval <-3.0; -0.6>degrees C and <-2.7; -0.7>degrees C as measured by the MRSI and phase-difference methods, respectively. Very good correlation was found in all locations between the temperatures measured by both techniques except in the frontal lobe. Measurements in the transversal slices were more robust to the movement artifacts than those in the sagittal planes. Good agreement was found between the MRSI and phase-difference techniques. (C) 2012 Elsevier Inc. All rights reserved.
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| 6. |
- Weis, Jan, 1956-, et al.
(author)
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Quantification of metabolite concentrations in benign and malignant prostate tissues using 3D proton MR spectroscopic imaging
- 2017
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 45:4, s. 1232-1240
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Journal article (peer-reviewed)abstract
- PURPOSE: To estimate concentrations of choline (Cho), spermine (Spm), and citrate (Cit) in prostate tissue using 3D proton magnetic resonance spectroscopic imaging (MRSI) with water as an internal concentration reference as well as to assess the relationships between the measured metabolites and also between the metabolites and apparent diffusion coefficient (ADC).MATERIALS AND METHODS: Forty-six prostate cancer patients were scanned at 3T. Spectra were acquired with the point-resolved spectroscopy (PRESS) localization technique. Single-voxel spectra of four healthy volunteers were used to estimate T1 relaxation time of Spm. Spm, Cho concentrations, and ADC values of benign prostate tissues were correlated with Cit content.RESULTS: The T1 value, 708 ± 132 msec, was estimated for Spm. Mean concentrations in the benign peripheral zone (PZ) were Cho, 4.5 ± 1 mM, Spm, 13.0 ± 4.4 mM, Cit, 64.4 ± 16.1 mM. Corresponding values in the benign central gland (CG) were Cho, 3.6 ± 1 mM, Spm, 13.3 ± 4.5 mM, Cit, 34.3 ± 12.9 mM. Concentrations of Cit and Spm were positively correlated in the benign PZ zone (r = 0.730) and CG (r = 0.664). Positive correlation was found between Cit and Cho in the benign CG (r = 0.705). Whereas Cit and ADC were positively correlated in the benign PZ (r = 0.673), only low correlation was found in CG (r = 0.265).CONCLUSION: We have shown that it is possible to perform water-referenced quantitative 3D MRSI of the prostate at the cost of a relatively short prolongation of the acquisition time. The individual metabolite concentrations provide additional information compared to the previously used metabolite-to-citrate ratios.
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