Tryggve H Storås - Academia.edu (original) (raw)

Papers by Tryggve H Storås

Acta Physica Hungarica A) Heavy Ion Physics, 1996

Circulation, 2016

Background: Anthracycline treatment may cause myocardial damage with myocyte death and expansion ... more Background: Anthracycline treatment may cause myocardial damage with myocyte death and expansion of the myocardial extracellular volume (ECV) fraction by edema and fibrosis. We tested the hypothese...

Tidsskrift for Den Norske Laegeforening, 2005

Journal of Magnetic Resonance Imaging, 2021

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

European Radiology, 2003

Our objective was to evaluate Gastrografin for MR bowel imaging. Twenty-three healthy volunteers ... more Our objective was to evaluate Gastrografin for MR bowel imaging. Twenty-three healthy volunteers in two randomised groups received 300 or 400 ml 50% Gastrografin, drunk continuously during 2 and 3 h, respectively. Images were applied during breath-hold in three orthogonal orientations. The balanced fast-field echo (BFFE) and balanced turbo field-echo (BTFE) sequences, with acquisition times from 13 to 25 s, were used before gadolinium (Gd) DTPA implying 1-to 2-mm-thick slices locally or 6-mm-thick slices through the entire gastrointestinal tract. The Gd-enhanced images were performed using a 3D T1-weighted FFE sequence with water selective excitation (Proset). Image quality, including bowel distention, homogeneity of opacification and wall conspicuity, were evaluated by two experienced reviewers, and the adverse reactions

European Heart Journal, 2016

Aims Contemporary adjuvant treatment for early breast cancer is associated with improved survival... more Aims Contemporary adjuvant treatment for early breast cancer is associated with improved survival but at the cost of increased risk of cardiotoxicity and cardiac dysfunction. We tested the hypothesis that concomitant therapy with the angiotensin receptor blocker candesartan or the b-blocker metoprolol will alleviate the decline in left ventricular ejection fraction (LVEF) associated with adjuvant, anthracycline-containing regimens with or without trastuzumab and radiation. Methods and results In a 2 × 2 factorial, randomized, placebo-controlled, double-blind trial, we assigned 130 adult women with early breast cancer and no serious co-morbidity to the angiotensin receptor blocker candesartan cilexetil, the b-blocker metoprolol succinate, or matching placebos in parallel with adjuvant anticancer therapy. The primary outcome measure was change in LVEF by cardiac magnetic resonance imaging. A priori, a change of 5 percentage points was considered clinically important. There was no interaction between candesartan and metoprolol treatments (P ¼ 0.530). The overall decline in LVEF was 2.6 (95% CI 1.5, 3.8) percentage points in the placebo group and 0.8 (95% CI 20.4, 1.9) in the candesartan group in the intention-to-treat analysis (P-value for between-group difference: 0.026). No effect of metoprolol on the overall decline in LVEF was observed.

Introduction MR signal from prostate tissue show a biexponential T2-decay (1). Prostatic acini co... more Introduction MR signal from prostate tissue show a biexponential T2-decay (1). Prostatic acini contain fluid that probably account for the slower decaying T2 component. Biexponential relaxation can only be observed if proton exchange between contributing compartments is slow (2). In commonly used tracer kinetic modeling it is assumed that all the tissue contribute to signal enhancement as predicted by a fast exchange model (3). The existence of a tissue component with slow proton exchange introduces an extra variable influencing signal enhancement. The existence of non-enhancing glandular lumen predicts an inverse correlation between tissue lumen and signal enhancement. This is not commonly acknowledged by the pharmacokinetic analysis performed in prostate imaging. The purpose of this work was to demonstrate the predicted inverse correlation between glandular lumen and contrast enhancement in prostate cancer. Methods Seventeen patients who had undergone DCE MRI of the prostate prior to prostatectomy were included in this study. The MR examinations were performed on a Philips ACS-NT (1.5T) system with Power Track 6000 gradients. An endorectal coil was applied. Transverse T2W TSE images were obtained with the following parameters: repetition time = 2776 ms, echo time = 140 ms, field of view=180x126 mm, matrix=512x256, number of slices=10, slice thickness=5–7 mm, turbo factor=24, number of samplings=6, scan time=4:42 min. The Dynamic 3D Multi-shot EPI sequence was implemented with the following parameters: repetition time=55 ms, echo time=8 ms, flip angle=27o, field of view=180x126mm, matrix=256x108, number of slices=10, slice thickness=5–7 mm, number of samplings=1, EPI factor=19 and spectral fat suppression (SPIR). A total of 100 dynamic frames were scanned with a time interval of 2.83 s, resulting in a total imaging time of 4:43 min. Radical perineal prostatectomy specimens were fixed in formalin before sampling. To facilitate orientation the apex, anterior and posterior parts of the glands were marked with different colors. The prostate was examined with serial sections cut at 5 mm starting perpendicular to the distal urethra. The slices were paraffin embedded, sectioned and stained with hematoxylin and eosin. All sections were evaluated microscopically for carcinoma. Tumor outlines were drawn with ink on the cover glass. Equidistant photomicrographs at 100X were obtained at 2.5 mm interval within the tumor outlines. A grid of 5 by 5 lines defining 25 points was superimposed on the photomicrographs. Tissue volume ratios of glandular lumen, epithelial tissue and stroma were assessed by point-counting. The histology slices with tumor outlines were macro-photographed to aid correlation with MRI images. MR image analysis was performed using in house developed software programmed in IDL (ITT Visual Information Solutions, Boulder, Colorado, USA). ROIs defining the tumors were drawn in the T2W TSE images since these were easiest to compare with the macro-photos. Corresponding enhancement curves were extracted from the DCE images and maximum enhancement relative to the baseline signal was calculated. Results One patient was excluded because the tumor was too small for reliable localization on the MRI images. Data on the remaining sixteen patients is shown in Figure 1. Correlation between lumen volume fraction and maximum enhancement was highly significant r=-0.86, p 0.2 and r=0.14, p>0.2 respectively.

Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism ... more Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism lipid stores in sedentary overweight dysglycemic subjects and normal-weight control subjects (n=18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal mRNA of lipid droplet-associated proteins. Insulin sensitivity and VO 2 LD parameters of the sub-sarcolemmal LD population demonstrated reductions in LD density and LD diameters. Lipid droplet volume in the sub-sarcolemmal LD population was reduced by ~80%, in both groups, while IMF LD volume was unchanged. Interestingly, the lipid droplet diameter (n=10,958) distribution was skewed, with a lack of small diameter lipid droplets (smaller than ~200 nm), both in the SS and IMF regions. Our results show that the SS LD lipid store was sensitive to Session 9 Poster 8

Physiological reports, 2014

Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism ... more Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism remains unclear. We investigated how a 12-week supervised combined endurance and strength exercise intervention influenced muscle lipid stores in sedentary overweight dysglycemic subjects and normal weight control subjects (n = 18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal (SS) and intramyofibrillar (IMF) regions, and indirectly, by deep sequencing and real-time PCR of mRNA of lipid droplet-associated proteins. Insulin sensitivity and VO2max increased significantly in both groups after 12 weeks of training. Muscle lipid stores were reduced according to MRS at baseline before and after the intervention, whereas EM point counting showed no change in LD stores post exercise, indicating a reduction in muscle adipocytes. Large-scale EM quantification of LD par...

Magnetic Resonance Materials in Physics, 2004

The purpose of this paper is to present a new pulse sequence for visualizing slow flow. The new s... more The purpose of this paper is to present a new pulse sequence for visualizing slow flow. The new sequence consists of an initial Stejskal-Tanner flow sensitization part followed by a DEFT pulse and a spoiler gradient. A single-shot TSE readout train is then applied to sample the NMR signal. The sequence was initially tested using a simple flow phantom. To verify potential clinical use, both flow-sensitive MRCP and cerebrospinal fluid (CSF) images were produced. The phantom study proved the sequence sensitivity to flow in the range 0-1 cm/s. bVE-factors 1.5, 3, 6 and 12 were chosen. Within this flow velocity range, the signal dropped as predicted theoretically. This indicates that the method can be used to quantify flow. All anatomical features seen in a standard MRCP sequence were identified and the methods sensitivity to CSF flow was demonstrated by sagital images of the head. A new pulse sequence sensitive to slow flow has been developed.

Journal of Magnetic Resonance Imaging, 2008

European Radiology, 2005

The aim of this study was to assess the quality of MR imaging and level of adverse effects with i... more The aim of this study was to assess the quality of MR imaging and level of adverse effects with increasing concentrations of gastrografin. This is a prospective study with 24 healthy volunteers which were randomised into four groups receiving 50%, 25%, 10% and 0% gastrografin. The endpoint was bowel image quality based on distension, signal homogeneity and wall delineation evaluated by three independent radiologists, and the maximum bowel diameter at three different levels. The subjects also scored any adverse events on a 1-5 scale. The interradiologist agreement was relatively good, with kappa values varying between 0.81 and 0.41. Improved bowel distension and image quality were achieved with increasing concentrations. But significant dose-response effects were found between increasing osmolalities and the bowel diameters and also versus the score of adverse events. The most frequent adverse reactions were diarrhea, nausea and lack of palatability. There is a gradient relationship between increasing osmolality of gastrografin and improved image quality and the score of adverse effects. The optimum concentration of gastrografin is dependent of the tolerance of the adverse events.

European Radiology, 2008

The purpose of this paper is to present a pulse sequence optimized to visualize human peripheral ... more The purpose of this paper is to present a pulse sequence optimized to visualize human peripheral vessels. The optimized MR technique is a 3D multi-shot balanced non-SSFP gradient echo pulse sequence with fat suppression. Several imaging parameters were adjusted to find the best compromise between the contrast of vascular structures and muscle, fat, and bone. Most of the optimization was performed in the knee and calf regions using multi-channel SENSE coils. To verify potential clinical use, images of both healthy volunteers and volunteers with varicose veins were produced. The balanced non-SSFP sequence can produce high-spatial-resolution images of the human peripheral vessels without the need for an intravenous contrast agent. Both arteries and veins are displayed along with other body fluids. Due to the high spatial resolution of the axial plane source or reconstructed images, the need for procedures to separate arteries from veins is limited. We demonstrate that high signals from synovial joint fluid and cystic structures can be suppressed by applying an inversion prepulse but at the expense of reduced image signal-to-noise and overall image quality.

Acta Radiologica, 2007

Magnetic resonance cholangiopancreaticography (MRCP) is commonly used to evaluate the pancreatic ... more Magnetic resonance cholangiopancreaticography (MRCP) is commonly used to evaluate the pancreatic (PD) and common bile duct (CBD), and the addition of secretin is used to obtain functional information (S-MRCP). Neither method gives any information on flow velocities within the ducts. To evaluate a new, MRI diffusion-based, slow-flow-sensitive sequence for the detection of slow flow changes in the PD and CBD. Seven healthy volunteers were examined. A modified single-shot turbo spin-echo sequence was used to detect slow flow changes. Three b factors (0, 6, and 12 s/mm(2)) were used. The flow sensitivity was applied in two directions, vertically and horizontally. Scanning was performed before and after glucagon was given, and again after an intravenous injection of secretin. The sequence gives signal loss from a duct when flow increases, and such changes were recorded. All images showed the PD with b = 0 (no flow sensitization). After administration of glucagon, artifacts from bowel movements were reduced and visibility of the PD was improved at both b = 6 and b = 12. Significant reduction of the visibility of the PD, indicating increased flow, was recorded both at b = 6 and b = 12 after the administration of secretin. There were no changes in the visibility of the CBD. This study shows that MRI-based detection of slow flow changes inside the PD is possible. Due to the sequence's high sensitivity to any motion, further studies are required before adopting the method for clinical use.

Acta Physica Hungarica A) Heavy Ion Physics, 1996

Circulation, 2016

Background: Anthracycline treatment may cause myocardial damage with myocyte death and expansion ... more Background: Anthracycline treatment may cause myocardial damage with myocyte death and expansion of the myocardial extracellular volume (ECV) fraction by edema and fibrosis. We tested the hypothese...

Tidsskrift for Den Norske Laegeforening, 2005

Journal of Magnetic Resonance Imaging, 2021

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

European Radiology, 2003

Our objective was to evaluate Gastrografin for MR bowel imaging. Twenty-three healthy volunteers ... more Our objective was to evaluate Gastrografin for MR bowel imaging. Twenty-three healthy volunteers in two randomised groups received 300 or 400 ml 50% Gastrografin, drunk continuously during 2 and 3 h, respectively. Images were applied during breath-hold in three orthogonal orientations. The balanced fast-field echo (BFFE) and balanced turbo field-echo (BTFE) sequences, with acquisition times from 13 to 25 s, were used before gadolinium (Gd) DTPA implying 1-to 2-mm-thick slices locally or 6-mm-thick slices through the entire gastrointestinal tract. The Gd-enhanced images were performed using a 3D T1-weighted FFE sequence with water selective excitation (Proset). Image quality, including bowel distention, homogeneity of opacification and wall conspicuity, were evaluated by two experienced reviewers, and the adverse reactions

European Heart Journal, 2016

Aims Contemporary adjuvant treatment for early breast cancer is associated with improved survival... more Aims Contemporary adjuvant treatment for early breast cancer is associated with improved survival but at the cost of increased risk of cardiotoxicity and cardiac dysfunction. We tested the hypothesis that concomitant therapy with the angiotensin receptor blocker candesartan or the b-blocker metoprolol will alleviate the decline in left ventricular ejection fraction (LVEF) associated with adjuvant, anthracycline-containing regimens with or without trastuzumab and radiation. Methods and results In a 2 × 2 factorial, randomized, placebo-controlled, double-blind trial, we assigned 130 adult women with early breast cancer and no serious co-morbidity to the angiotensin receptor blocker candesartan cilexetil, the b-blocker metoprolol succinate, or matching placebos in parallel with adjuvant anticancer therapy. The primary outcome measure was change in LVEF by cardiac magnetic resonance imaging. A priori, a change of 5 percentage points was considered clinically important. There was no interaction between candesartan and metoprolol treatments (P ¼ 0.530). The overall decline in LVEF was 2.6 (95% CI 1.5, 3.8) percentage points in the placebo group and 0.8 (95% CI 20.4, 1.9) in the candesartan group in the intention-to-treat analysis (P-value for between-group difference: 0.026). No effect of metoprolol on the overall decline in LVEF was observed.

Introduction MR signal from prostate tissue show a biexponential T2-decay (1). Prostatic acini co... more Introduction MR signal from prostate tissue show a biexponential T2-decay (1). Prostatic acini contain fluid that probably account for the slower decaying T2 component. Biexponential relaxation can only be observed if proton exchange between contributing compartments is slow (2). In commonly used tracer kinetic modeling it is assumed that all the tissue contribute to signal enhancement as predicted by a fast exchange model (3). The existence of a tissue component with slow proton exchange introduces an extra variable influencing signal enhancement. The existence of non-enhancing glandular lumen predicts an inverse correlation between tissue lumen and signal enhancement. This is not commonly acknowledged by the pharmacokinetic analysis performed in prostate imaging. The purpose of this work was to demonstrate the predicted inverse correlation between glandular lumen and contrast enhancement in prostate cancer. Methods Seventeen patients who had undergone DCE MRI of the prostate prior to prostatectomy were included in this study. The MR examinations were performed on a Philips ACS-NT (1.5T) system with Power Track 6000 gradients. An endorectal coil was applied. Transverse T2W TSE images were obtained with the following parameters: repetition time = 2776 ms, echo time = 140 ms, field of view=180x126 mm, matrix=512x256, number of slices=10, slice thickness=5–7 mm, turbo factor=24, number of samplings=6, scan time=4:42 min. The Dynamic 3D Multi-shot EPI sequence was implemented with the following parameters: repetition time=55 ms, echo time=8 ms, flip angle=27o, field of view=180x126mm, matrix=256x108, number of slices=10, slice thickness=5–7 mm, number of samplings=1, EPI factor=19 and spectral fat suppression (SPIR). A total of 100 dynamic frames were scanned with a time interval of 2.83 s, resulting in a total imaging time of 4:43 min. Radical perineal prostatectomy specimens were fixed in formalin before sampling. To facilitate orientation the apex, anterior and posterior parts of the glands were marked with different colors. The prostate was examined with serial sections cut at 5 mm starting perpendicular to the distal urethra. The slices were paraffin embedded, sectioned and stained with hematoxylin and eosin. All sections were evaluated microscopically for carcinoma. Tumor outlines were drawn with ink on the cover glass. Equidistant photomicrographs at 100X were obtained at 2.5 mm interval within the tumor outlines. A grid of 5 by 5 lines defining 25 points was superimposed on the photomicrographs. Tissue volume ratios of glandular lumen, epithelial tissue and stroma were assessed by point-counting. The histology slices with tumor outlines were macro-photographed to aid correlation with MRI images. MR image analysis was performed using in house developed software programmed in IDL (ITT Visual Information Solutions, Boulder, Colorado, USA). ROIs defining the tumors were drawn in the T2W TSE images since these were easiest to compare with the macro-photos. Corresponding enhancement curves were extracted from the DCE images and maximum enhancement relative to the baseline signal was calculated. Results One patient was excluded because the tumor was too small for reliable localization on the MRI images. Data on the remaining sixteen patients is shown in Figure 1. Correlation between lumen volume fraction and maximum enhancement was highly significant r=-0.86, p 0.2 and r=0.14, p>0.2 respectively.

Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism ... more Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism lipid stores in sedentary overweight dysglycemic subjects and normal-weight control subjects (n=18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal mRNA of lipid droplet-associated proteins. Insulin sensitivity and VO 2 LD parameters of the sub-sarcolemmal LD population demonstrated reductions in LD density and LD diameters. Lipid droplet volume in the sub-sarcolemmal LD population was reduced by ~80%, in both groups, while IMF LD volume was unchanged. Interestingly, the lipid droplet diameter (n=10,958) distribution was skewed, with a lack of small diameter lipid droplets (smaller than ~200 nm), both in the SS and IMF regions. Our results show that the SS LD lipid store was sensitive to Session 9 Poster 8

Physiological reports, 2014

Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism ... more Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism remains unclear. We investigated how a 12-week supervised combined endurance and strength exercise intervention influenced muscle lipid stores in sedentary overweight dysglycemic subjects and normal weight control subjects (n = 18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal (SS) and intramyofibrillar (IMF) regions, and indirectly, by deep sequencing and real-time PCR of mRNA of lipid droplet-associated proteins. Insulin sensitivity and VO2max increased significantly in both groups after 12 weeks of training. Muscle lipid stores were reduced according to MRS at baseline before and after the intervention, whereas EM point counting showed no change in LD stores post exercise, indicating a reduction in muscle adipocytes. Large-scale EM quantification of LD par...

Magnetic Resonance Materials in Physics, 2004

The purpose of this paper is to present a new pulse sequence for visualizing slow flow. The new s... more The purpose of this paper is to present a new pulse sequence for visualizing slow flow. The new sequence consists of an initial Stejskal-Tanner flow sensitization part followed by a DEFT pulse and a spoiler gradient. A single-shot TSE readout train is then applied to sample the NMR signal. The sequence was initially tested using a simple flow phantom. To verify potential clinical use, both flow-sensitive MRCP and cerebrospinal fluid (CSF) images were produced. The phantom study proved the sequence sensitivity to flow in the range 0-1 cm/s. bVE-factors 1.5, 3, 6 and 12 were chosen. Within this flow velocity range, the signal dropped as predicted theoretically. This indicates that the method can be used to quantify flow. All anatomical features seen in a standard MRCP sequence were identified and the methods sensitivity to CSF flow was demonstrated by sagital images of the head. A new pulse sequence sensitive to slow flow has been developed.

Journal of Magnetic Resonance Imaging, 2008

European Radiology, 2005

The aim of this study was to assess the quality of MR imaging and level of adverse effects with i... more The aim of this study was to assess the quality of MR imaging and level of adverse effects with increasing concentrations of gastrografin. This is a prospective study with 24 healthy volunteers which were randomised into four groups receiving 50%, 25%, 10% and 0% gastrografin. The endpoint was bowel image quality based on distension, signal homogeneity and wall delineation evaluated by three independent radiologists, and the maximum bowel diameter at three different levels. The subjects also scored any adverse events on a 1-5 scale. The interradiologist agreement was relatively good, with kappa values varying between 0.81 and 0.41. Improved bowel distension and image quality were achieved with increasing concentrations. But significant dose-response effects were found between increasing osmolalities and the bowel diameters and also versus the score of adverse events. The most frequent adverse reactions were diarrhea, nausea and lack of palatability. There is a gradient relationship between increasing osmolality of gastrografin and improved image quality and the score of adverse effects. The optimum concentration of gastrografin is dependent of the tolerance of the adverse events.

European Radiology, 2008

The purpose of this paper is to present a pulse sequence optimized to visualize human peripheral ... more The purpose of this paper is to present a pulse sequence optimized to visualize human peripheral vessels. The optimized MR technique is a 3D multi-shot balanced non-SSFP gradient echo pulse sequence with fat suppression. Several imaging parameters were adjusted to find the best compromise between the contrast of vascular structures and muscle, fat, and bone. Most of the optimization was performed in the knee and calf regions using multi-channel SENSE coils. To verify potential clinical use, images of both healthy volunteers and volunteers with varicose veins were produced. The balanced non-SSFP sequence can produce high-spatial-resolution images of the human peripheral vessels without the need for an intravenous contrast agent. Both arteries and veins are displayed along with other body fluids. Due to the high spatial resolution of the axial plane source or reconstructed images, the need for procedures to separate arteries from veins is limited. We demonstrate that high signals from synovial joint fluid and cystic structures can be suppressed by applying an inversion prepulse but at the expense of reduced image signal-to-noise and overall image quality.

Acta Radiologica, 2007

Magnetic resonance cholangiopancreaticography (MRCP) is commonly used to evaluate the pancreatic ... more Magnetic resonance cholangiopancreaticography (MRCP) is commonly used to evaluate the pancreatic (PD) and common bile duct (CBD), and the addition of secretin is used to obtain functional information (S-MRCP). Neither method gives any information on flow velocities within the ducts. To evaluate a new, MRI diffusion-based, slow-flow-sensitive sequence for the detection of slow flow changes in the PD and CBD. Seven healthy volunteers were examined. A modified single-shot turbo spin-echo sequence was used to detect slow flow changes. Three b factors (0, 6, and 12 s/mm(2)) were used. The flow sensitivity was applied in two directions, vertically and horizontally. Scanning was performed before and after glucagon was given, and again after an intravenous injection of secretin. The sequence gives signal loss from a duct when flow increases, and such changes were recorded. All images showed the PD with b = 0 (no flow sensitization). After administration of glucagon, artifacts from bowel movements were reduced and visibility of the PD was improved at both b = 6 and b = 12. Significant reduction of the visibility of the PD, indicating increased flow, was recorded both at b = 6 and b = 12 after the administration of secretin. There were no changes in the visibility of the CBD. This study shows that MRI-based detection of slow flow changes inside the PD is possible. Due to the sequence's high sensitivity to any motion, further studies are required before adopting the method for clinical use.