| 1. |
- Weis, Jan, et al.
(författare)
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MR spectroscopy of the human prostate using surface coil at 3 T : Metabolite ratios, age-dependent effects, and diagnostic possibilities
- 2011
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 34:6, s. 1277-1284
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To measure prostate spectra of healthy volunteers using a surface coil, to demonstrate age-dependent effects, and to investigate diagnostic possibilities for prostate cancer detection. MATERIALS AND METHODS: Single-voxel and 2D magnetic resonance spectroscopic imaging (MRSI) spectra of 51 healthy volunteers with biopsy-proven prostate carcinoma of 20 patients for comparison were measured and processed using the LCModel. The mean normalized spectra and mean metabolite-to-citrate intensity ratios were computed. RESULTS: Metabolite-to-citrate ratios of healthy volunteers were lower in the older group (>51 years) than in the younger group (<45 years). The peripheral zone (PZ) revealed a lower metabolite-to-citrate intensity ratio than the central gland (CG). Age-related differences in metabolite-to-citrate ratio were insignificant in the voxels with predominantly CG tissue, whereas significant differences were found in the PZ. Sensitivity in detecting prostate cancer by single-voxel spectroscopy (SVS) and 2D MRSI was 75% and 80%, respectively. CONCLUSION: SVS and 2D MRSI of the prostate at 3 T, using a surface coil, are useful in situations when insertion of the endorectal coil into the rectum is difficult or impossible. Our findings of age-dependent effects may be of importance for the analysis of patient spectra.
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| 2. |
- Covaciu, Lucian, et al.
(författare)
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Human brain MR spectroscopy thermometry using metabolite aqueous-solution calibrations
- 2010
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 31:4, s. 807-814
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To estimate absolute brain temperature using proton MR spectroscopy ((1)H-MRS) and mean brain-body temperature difference of healthy human volunteers. MATERIALS AND METHODS: Chemical shift difference between temperature-dependent water spectral line position and temperature-stable metabolite spectral reference was used for the estimations of absolute brain temperature. Temperature calibrations constants were obtained from the spectra of the N-acetyl aspartate (NAA line at approximately 2.0 ppm), glycero-phosphocholine (GPC line at approximately 3.2 ppm), and creatine (Cr line at approximately 3.0 ppm) aqueous solutions with pH values within physiologically pertinent ranges. Single-voxel PRESS sequence (TR/TE 2000/80 ms) was used for this purpose. Brain temperature was determined by averaging the temperatures computed from water-Cho, water-Cr, and water-NAA chemical shift differences. RESULTS: The mean brain temperature of 18 healthy volunteers was 38.1 +/- 0.4 degrees C and mean brain-body (rectal) temperature difference was 1.3 +/- 0.4 degrees C. CONCLUSION: Improved accuracy of the temperature constants and averaging the temperatures computed from water-Cho, water-Cr, and water-NAA chemical shift differences increased the reliability of the brain temperature estimations.
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| 3. |
- Marchesi, Silvia, et al.
(författare)
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Abdominal organ perfusion and inflammation in experimental sepsis : a magnetic resonance imaging study
- 2019
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Ingår i: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 316:1, s. G187-G196
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Ortiz-Nieto, Francisco, et al.
(författare)
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Quantification of lipids in human lower limbs using yellow bone marrow as the internal reference : gender-related effects
- 2010
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X .- 1873-5894. ; 28:5, s. 676-682
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this study was to determine and compare extra- and intramyocellular (IMCL) lipids content in the calf and thigh muscles of normal male and female volunteers using high-spatial-resolution magnetic resonance spectroscopic imaging (MRSI). The study groups consisted of 10 females and 10 males. The subjects were healthy and normal-weight. Fat (yellow bone marrow) was used as the internal concentration reference. Total fat and IMCL content were computed for all muscles in the slice and for three muscle compartments in the thigh, whereas three muscles and three muscle compartments were evaluated in the calf. To avoid the confounding effects of physical activity and diet, measurements were performed in the same session. A common feature for both genders was that thigh muscles had approximately 2.5 times greater total fat content as compared to muscles of the calf. The mean IMCL level was, however, more than 3 times higher in the calf muscles compared with the thigh. No significant differences in lipid concentrations of correspondent regions of interest were found between genders. The high-spatial-resolution MRSI technique enables a more detailed study of muscle lipid distribution and can therefore improve understanding of muscle lipid metabolism in healthy volunteers and in studies of patients with metabolic disorders.
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| 5. |
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| 6. |
- Schiza, Aglaia, et al.
(författare)
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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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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Weis, Jan, et al.
(författare)
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Assessment of lipids in skeletal muscle by high-resolution spectroscopic imaging using fat as the internal standard : comparison with water referenced spectroscopy
- 2008
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 59:6, s. 1259-1265
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of the study was to compare proton (1H) single-voxel MR spectroscopy (MRS) with high-spatial-resolution spectroscopic imaging (MRSI) to determine the lipid content in human skeletal muscle. Unsuppressed water line was used as a concentration reference in the processing of single-voxel spectra. The spectrum from yellow bone marrow with a 100% fat content and probe with the vegetable oil served as internal and external reference for high-spatial-resolution MRSI, respectively. Very good correlation was found between lipid concentrations measured by water referenced single-voxel MRS and high-spatial-resolution MRSI with yellow bone marrow as the internal standard. Excellent correlation was found between total lipid concentrations estimated by high-spatial-resolution MRSI with vegetable oil as the external fat standard and yellow bone marrow as the internal reference. From comparison of single-voxel MRS and MRSI approaches, it follows that relaxation correction of the reference water and methylene fat line is inevitable in processing the standard single-voxel spectra. The high-resolution MRSI approach is recommended to avoid the problem of relaxation corrections and enables using vegetable oil as the external fat standard.
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| 8. |
- Weis, Jan, et al.
(författare)
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Assessment of lipids in skeletal muscle by LCModel and AMARES
- 2009
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 30:5, s. 1124-1129
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To process single voxel spectra of the human skeletal muscle by using an advanced method for accurate, robust, and efficient spectral fitting (AMARES) and by linear combination of model spectra (LCModel). To determine absolute concentrations of extra- (EMCL) and intramyocellular lipids (IMCL). MATERIALS AND METHODS: Single-voxel proton magnetic resonance spectroscopy (PRESS) was used to obtain the spectra of the calf muscles. Unsuppressed water line was used as a concentration reference. A new prior knowledge for AMARES was proposed to estimate the concentrations of EMCL and IMCL. The prior knowledge was derived from the spectrum of vegetable oil. The results were compared with the values estimated by LCModel. Absolute concentrations of total lipid content in millimoles per kilogram wet weight were used for the comparisons. RESULTS: Absolute concentrations of total lipid content in skeletal muscle were estimated by AMARES and LCModel. Very good correlation of the total fat (EMCL + IMCL) and IMCL concentrations was achieved between both data processing approaches. CONCLUSION: Assessment the absolute concentrations of muscular lipids by AMARES and LCModel can be performed with comparable accuracy.
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| 9. |
- Weis, Jan, et al.
(författare)
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High-resolution echo-planar spectroscopic imaging of the human calf
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e87533-
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Tidskriftsartikel (refereegranskat)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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| 10. |
- Weis, Jan, et al.
(författare)
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MR Spectroscopy of the Prostate at 3T : Measurements of Relaxation Times and Quantification of Prostate Metabolites using Water as an Internal Reference
- 2013
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Ingår i: Magnetic resonance in medical sciences. - : Japanese Society for Magnetic Resonance in Medicine. - 1347-3182 .- 1880-2206. ; 12:4, s. 289-296
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Tidskriftsartikel (refereegranskat)abstract
- Purpose:We performed single-voxel magnetic resonance spectroscopy (MRS) of the human prostate at 3 tesla using a surface coil to measure prostate water, choline (Cho), creatine (Cr), and citrate (Cit) relaxation times T1, T2, and to estimate concentrations of Cho, Cr, and Cit in healthy volunteers.Methods:In nine of 17 healthy volunteers, we performed experiments to estimate relaxation time, and we used the spectra of the other eight to compute metabolite concentrations. Spectra were processed by LCModel and AMARES (advanced method for accurate, robust, and efficient spectral fitting) algorithms. T1 and T2 values were obtained by monoexponential fitting of the spectral intensities. Metabolite concentrations were estimated using prostate tissue water as an internal concentration reference.Results:Relaxation times are reported for prostate water (T1, 2163±166 ms; T2, 110±18 ms), Cho (T1, 987±71 ms; T2, 239±24 ms), Cr (T1, 1128±149 ms; T2, 188±20 ms), and Cit (T1, 476±70 ms; T2, 228±42 ms). Mean concentrations in healthy prostate were Cho, 2.6±0.3 mM, Cr, 5.8±1.3 mM, and Cit, 26.9±5.5 mM.Conclusion:We observed metabolite relaxation times and concentrations consistent with published values of healthy volunteers at 1.5 and 3T. T1 values increased and T2 slightly decreased with magnetic field strength. Our preliminary patient results indicate that water-referenced quantitative MRS of the human prostate is a promising tool for monitoring therapeutic effects and detecting tumor relapse, i.e., in situations when Cit intensity is small or undetectable.
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