| 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. |
- Carlbom, Lina, et al.
(författare)
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Pre-transplantation ³¹P-magnetic resonance spectroscopy for quality assessment of human pancreatic grafts : A feasibility study
- 2017
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X .- 1873-5894. ; 39, s. 98-102
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the feasibility of using (31)P-MRS for objective non-invasive quality assessment of human pancreas grafts prior to transplantation or islet isolation.Materials and methods: Pancreata from 5 human donors, 3 males and 2 females, aged 49-78years, with body mass index (BMI) 22-31kg/m(2), were included. Pancreata were perfused with histidine-tryptophan-ketoglutarate solution during procurement and stored in hypothermic condition (4°C) for 21-44h. During the period of hypothermic storage repeated spectra were obtained for each graft by (31)P-MRS (1.5Tesla) to measure the cold ischemia time (CIT) dependent changes of the phosphorous metabolites adenosine triphosphate (ATP), phosphomonoesters (PME), phosphodiesters (PDE) and inorganic phosphate (Pi), in the grafts. Graft temperature was measured immediately before and after MR-examination. Reference spectrum for non-viable tissue was obtained after graft exposure to room temperature.Results: PME/Pi, PDE/Pi and ATP/Pi spectral intensities ratios decreased with increasing CIT, reflecting the decreased viability of the grafts. PME/Pi ratio was the most discriminatory variable at prolonged CIT. (31)P-MRS could be performed without significantly increasing graft temperature.Conclusions: (31)P-MRS may provide quantitative parameters for evaluating graft viability ex vivo, and is a promising tool for objective non-invasive assessment of the quality of human pancreas grafts prior to transplantation or islet isolation.
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| 3. |
- Covaciu, Lucian, 1964-, et al.
(författare)
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Brain temperature in healthy volunteers subjected to intranasal cooling
- 2011
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 37:8, s. 1277-1284
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: Intranasal cooling can be used to initiate therapeutic hypothermia. However, direct measurement of brain temperature is difficult and the intra-cerebral distribution of temperature changes with cooling is unknown. The purpose of this study was to measure the brain temperature of human volunteers subjected to intranasal cooling using non-invasive magnetic resonance (MR) methods.Methods: Intranasal balloons catheters circulated with saline at 20 °C were applied for 60 min in 10 healthy, unsedated volunteers. Brain temperature changes were measured and mapped using MR spectroscopic imaging (MRSI) and phase-mapping techniques. Heart rate and blood pressure were monitored throughout the experiment. Rectal temperature was measured before and after the cooling. Mini Mental State Examination (MMSE) test and nasal inspection were done before and after the cooling. Questionnaires about the subjects personal experience were filled after the experiment.Results: Brain temperature decrease measured by MRSI was -1.7 ± 0.8°C and by phase-mapping -1.8 ± 0.9°C at the end of cooling. Spatial distribution of temperature changes was relatively uniform. Rectal temperature decreased by -0.5 ± 0.3°C. The physiological parameters were stable and no shivering was reported. The volunteers remained alert during cooling and no cognitive dysfunctions were apparent at MMSE test. Postcooling nasal examination detected increased nasal secretion in 9 of the 10 volunteers. Volunteer’s acceptance of the method was good. Conclusion: Both MR techniques revealed brain temperature reductions after 60 min intranasal cooling with balloons circulated with saline at 20 °C in healthy and unsedated volunteers.
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| 4. |
- Covaciu, Lucian, et al.
(författare)
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Brain temperature in volunteers subjected to intranasal cooling
- 2011
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 37:8, s. 1277-1284
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Tidskriftsartikel (refereegranskat)abstract
- Intranasal cooling can be used to initiate therapeutic hypothermia. However, direct measurement of brain temperature is difficult and the intra-cerebral distribution of temperature changes with cooling is unknown. The purpose of this study was to measure the brain temperature of human volunteers subjected to intranasal cooling using non-invasive magnetic resonance (MR) methods. Intranasal balloons catheters circulated with saline at 20A degrees C were applied for 60 min in ten awake volunteers. No sedation was used. Brain temperature changes were measured and mapped using MR spectroscopic imaging (MRSI) and phase-mapping techniques. Heart rate and blood pressure were monitored throughout the experiment. Rectal temperature was measured before and after the cooling. Mini Mental State Examination (MMSE) test and nasal inspection were done before and after the cooling. Questionnaires about the subjects' personal experience were completed after the experiment. Brain temperature decrease measured by MRSI was -1.7 +/- A 0.8A degrees C and by phase-mapping -1.8 +/- A 0.9A degrees C (n = 9) at the end of cooling. Spatial distribution of temperature changes was relatively uniform. Rectal temperature decreased by -0.5 +/- A 0.3A degrees C (n = 5). The physiological parameters were stable and no shivering was reported. The volunteers remained alert during cooling and no cognitive dysfunctions were apparent in the MMSE test. Postcooling nasal examination detected increased nasal secretion in nine of the ten volunteers. Volunteers' acceptance of the method was good. Both MR techniques revealed brain temperature reductions after 60 min of intranasal cooling with balloons circulated with saline at 20A degrees C in awake, unsedated volunteers.
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| 5. |
- 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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| 6. |
- Johansson, Lars, et al.
(författare)
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Lipid Mobilization Following Roux-en-Y Gastric Bypass Examined by Magnetic Resonance Imaging and Spectroscopy
- 2008
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Ingår i: Obesity Surgery. - : Springer Science and Business Media LLC. - 0960-8923 .- 1708-0428. ; 18:10, s. 1297-1304
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Recent developments of magnetic resonance imaging (MRI) and spectroscopy have made it possible to quantify lipid deposited in different tissues. To what extent an improvement of glucose tolerance shortly after Roux-en-Y gastric bypass surgery (RYGBP) is reflected in lipid levels in liver and skeletal muscle, markers of insulin resistance, has not been clarified. METHODS: Whole-body MRI and MR spectroscopy (MRS) of liver and muscle and measurements of biochemical markers of glucose and lipid metabolism were performed at baseline and 1, 6, and 12 months following surgery in seven morbidly obese women. Volumes of adipose tissue depots and liver and muscle lipids were assessed from the MRI/MRS data. RESULTS: At 1 month postoperatively, body mass index and visceral and subcutaneous adipose tissues were reduced by 9%, 26%, and 10%, respectively, whereas no reductions in intrahepatocellular or skeletal intramyocellular lipid concentrations were found. Free fatty acid and beta-hydroxybutyrate levels were elevated two- and sixfold, respectively; glucose and insulin levels were lowered, indicating increased insulin sensitivity. Further weight loss up to 1 year was associated with reductions in all investigated lipid depots investigated, with the exception of the intramyocellular compartment. CONCLUSION: RYGBP causes rapid lipid mobilization from visceral and subcutaneous adipose depots and enhanced free fatty acid flux to the liver. An exceptional disconnection between liver fat and insulin sensitivity occurs in the early dynamic phase after surgery. However, in the late phase, the energy restriction imposed by the surgical procedure also reduces the liver lipids, but not the intramyocellular lipids.
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| 7. |
- 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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| 8. |
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| 9. |
- Tammela, T L, et al.
(författare)
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An Intraprostatic Modified Release Formulation of Antiandrogen 2-Hydroxyflutamide for Localized Prostate Cancer
- 2017
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Ingår i: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 0022-5347 .- 1527-3792. ; 198:6, s. 1333-1339
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate tolerability, safety and antitumor effects of a novel intra-prostatic depot formulation of antiandrogen 2-hydroxyflutamide (2-HOF in NanoZolid(®)) in men with localized prostate cancer (PCa).MATERIALS AND METHODS: Two clinical trials, LPC-002 and LPC-003, were conducted on a total of 47 men. The formulation was injected transrectally into the prostate with ultrasound guidance. In LPC-002 the effects on prostate specific antigen (PSA) and prostate volume (PV) were measured over 6 months on 24 patients. In LPC-003, antitumor effects were evaluated with histopathology, magnetic resonance imaging (MRI) including spectroscopy (MRS) during 6 or 8 weeks on 23 patients. In both studies, testosterone and 2-HOF in plasma were measured, as well as quality-of-life parameters.RESULTS: In LPC-002 (mean dose 690 mg) a reduction in PSA and PV was observed. The nadir values for PSA and PV were on average 24.9 % and 14.0 % below baseline, respectively. When increasing the dose in LPC-003 (920 mg and 1740 mg), the average PSA dropped 16 % and 23 %, respectively, after 6 and 8 weeks. MRI/MRS showed morphological changes and a global drop in metabolite concentrations following treatment indicating an antitumor response. The injections did not result in hormone related side effects. In total, three serious adverse events were reported, all resolved by oral antibiotic treatment.CONCLUSIONS: The intraprostatic injections of 2-HOF depot formulations indicated anti-tumor effects and proved safe and tolerable. However, for better anti-cancer effects higher doses and better dose distribution are suggested.
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| 10. |
- Weis, Jan, et al.
(författare)
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A simple method for mapping the B(1) field distribution of linear RF coils
- 2005
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Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer Science and Business Media LLC. - 0968-5243 .- 1352-8661. ; 18:6, s. 283-287
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Tidskriftsartikel (refereegranskat)abstract
- Inhomogeneity of the radio frequency (RF) field B1 leads to intensity variations in MR images and to spatial dependence of spectral line amplitudes. In this paper, a simple method of measuring the B1 field components of an unsegmented linear coil is described. The method is designed for the coils operating up to 20 MHz. The B1 field distribution is replaced by the static magnetic field caused by DC current flowing through the coil. The technique involves rotating the coil 90° so that measured B1 component is aligned with B0 and measuring the shift of resonance frequency using a spectroscopic imaging sequence. Experimental results were in good agreement with the theoretical computations.
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