Tryggve Holck Storås

• Girelli, Alberto; Solheim, Andreas; Lian, Sofie Lysholm; Storås, Tryggve Holck; Nordengen, Kaja & Mardal, Kent-Andre (2026). Multiphasic transport in the human cranial dura: how meningeal lymphatic vessels drive waste clearance from brain cerebrospinal fluid. Fluids and Barriers of the CNS. doi: 10.1186/s12987-026-00861-y. Full text in Research Archive Show summary

  Background The discovery of meningeal lymphatic vessels (mLVs) has reshaped our understanding of brain waste clearance, positioning them as a very important clearance route. However, quantifying the precise hydrodynamics and solute transport mechanisms within the human dura mater in vivo remains highly challenging due to the multiscale nature of cranial fluid dynamics and imaging resolution limits. Methods We integrated patient-specific intrathecal contrast-enhanced MRI (gMRI) data from a single healthy subject with a novel anatomical segmentation of the cranial dura mater. By employing a hierarchy of inverse mathematical and micro-mechanical models, we estimated previously inaccessible physiological transport parameters. To ensure parameter identifiability, we deliberately modeled a scenario where the meningeal lymphatic vessels act as the sole fluid efflux route, thereby establishing an upper limit for their clearance capacity. These baseline estimates subsequently informed a spatially distributed, double-porosity 3D computational model of the human dura to simulate the fluid dynamics of cranial clearance. Results Our analysis suggests that purely diffusive macroscopic models fail to replicate in vivo tracer distribution. Conversely, a dual-porosity advection-diffusion framework successfully captures the tissue kinetics. The transport within the mLV compartment is characterized by highly convective clearance (with ), with macroscopic fluid velocities and effective lymphatic diffusion coefficients yielding an upper-bound advective capacity theoretically sufficient to clear the total albumin content in the Cerebrospinal Fluid (CSF). Conclusion Based on our findings on a single subject (Gonzo) solute clearance within the human cranial dura mater emerges as multiphasic, advection-dominated process. Rather than relying on passive Fickian diffusion, molecules appear to be actively and rapidly cleared through the meningeal lymphatic network via convective mechanisms. While our assumption of exclusively mLV-driven clearance provides a theoretical upper limit for their capacity, this hierarchical modeling approach successfully bridges clinical imaging and microscopic fluid dynamics, offering quantitative insights into the primary mechanical drivers of dural fluid clearance.

• Mossige, Ingrid; Valnes, Lars Magnus; Storås, Tryggve Holck; Emblem, Kyrre Eeg; Eide, Per Kristian & Ringstad, Geir Andre (2026). Comparing Glymphatic Function Measures: Diffusion Tensor Image Analysis Along Perivascular Spaces (DTI-ALPS) versus Intrathecal Contrast-Enhanced MRI. Radiology. ISSN 0033-8419. 318(2). doi: 10.1148/radiol.252070. Full text in Research Archive Show summary

  Background Diffusion-tensor image (DTI) analysis along the perivascular space (ALPS) is a noninvasive but not well-validated method proposed to evaluate glymphatic function. Purpose To assess ALPS indexes across participant groups and compare them with measures of cerebrospinal fluid (CSF) tracer enrichment and clearance obtained by intrathecal contrast-enhanced MRI (glymphatic MRI [gMRI]). Materials and Methods This secondary analysis of a prospective observational study included participants who underwent clinical work-up for CSF disorders from September 2015 to December 2019. MRI scans were acquired before injection and 24 and 48 hours after intrathecal injection of 0.5 mmol of gadobutrol. DTI scans were preprocessed and segmented using the FMRIB Software Library. Intrathecal contrast-enhanced MRI (ie, gMRI) scans were registered to the baseline T1-weighted image, and cortex and white matter (WM) were segmented with FreeSurfer. ALPS indexes were compared with relative changes in normalized T1-weighted signal intensity at 24 and 48 hours in regions of the cortex, subcortical WM, and deep WM where the ALPS regions of interest are located by using regression analysis. Results A total of 56 participants were included (mean age, 48 years ± 20 [SD]; 36 women): 16 with idiopathic normal pressure hydrocephalus (iNPH), 10 with arachnoid cysts, 11 with idiopathic intracranial hypertension, and 19 reference participants. The ALPS index was lower in the iNPH group than in the reference group (ALPS index, 1.26 and 1.68, respectively; P < .001). Across groups, the ALPS index and degree of CSF tracer enrichment at 24 hours in deep WM were negatively associated (β = −48; P < .001). However, mean tracer enrichment in the ALPS regions of interest was low (10%), in some participants close to 0, whereas enrichment in the cortex ranged from 68% to 81%. Across groups, there was no evidence of associations between the ALPS index and measures of CSF tracer dynamics at 48 hours in any region (|β| ≤ 8; P ≥ .55). Conclusion CSF tracer enhancement in the ALPS regions of interest was sparse across groups, and the association between the ALPS index and gMRI markers of glymphatic function was limited.

• Riseth, Jørgen Nilsen; Koch, Timo; Lian, Sofie Lysholm; Storås, Tryggve Holck; T., Zikatanov, Ludmil & Valnes, Lars Magnus [Show all 8 contributors for this article] (2026). Human brain MRI data of intrathecally injected tracer evolution over 72 hours for data-integrated simulations. Scientific Data. 13. doi: 10.1038/s41597-026-06564-1. Full text in Research Archive Show summary

  We present the Gonzo dataset: Brain MRI with processed and derivative data from one healthy male human volunteer ("Gonzo”) before and during the 72 hours after intrathecal injection of the contrast agent gadobutrol into the cerebrospinal fluid (CSF) of the spinal canal. The MRI data records include images highlighting the temporal and spatial evolution of the contrast agent in CSF, brain, and adjacent structures. In addition to raw MRI, we provide derivatives that enable numerical simulations of the transport process under study. Derivatives include T1 maps, tracer concentration maps, diffusion tensor maps, and unstructured triangulated volume meshes of the brain geometry. We also provide brain region markers obtained by image segmentation. A regional statistical analysis of the concentration data complements the image data. The presented data can be used to study the transport behavior and the underlying processes of a tracer in the brain. It is intended to contribute to and inspire new studies on the understanding of tracer transport, method development for image analysis, and simulation of brain fluid transport processes.

• Emblem, Kyrre E; Ringstad, Geir; Svensson, Siri Fløgstad; Vatnehol, Svein Are Sirirud; Storås, Tryggve Holck & Vik-Mo, Einar Osland [Show all 9 contributors for this article] (2025). Intrathecal contrast-enhanced MRI reveals an alternative route for drug delivery and brain tumor visualization. Cancer Letters. ISSN 0304-3835. 638. doi: 10.1016/j.canlet.2025.218152. Full text in Research Archive
• Valnes, Lars Magnus; Storås, Tryggve Holck; Vatnehol, Svein Are Sirirud; Ringstad, Geir Andre; Emblem, Kyrre Eeg & Eide, Per Kristian (2025). Optimized Magnetic Resonance T1 Mapping for Estimation of Intrathecal Contrast Concentrations in Human Brain and Ventricular Cerebrospinal Fluid. Magnetic Resonance in Medicine. ISSN 0740-3194. doi: 10.1002/mrm.70203. Full text in Research Archive
• Storås, Tryggve Holck; Lian, Sofie Lysholm; Mossige, Ingrid; Riseth, Jørgen Nilsen; Svensson, Siri Fløgstad & Løvland, Grethe [Show all 10 contributors for this article] (2025). T2-Weighted T1 Mapping and Automated Segmentation of CSF: Assessment of Solute Gradients in the Healthy Brain. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 0, p. 1–10. doi: 10.1002/jmri.70169. Full text in Research Archive Show summary

  Background Cerebrospinal fluid (CSF) serves as a medium for nutrient delivery and waste clearance. The T1 relaxation rate, R1, can be used to measure the concentration of intrinsic solutes and extrinsic contrast agents. Purpose To implement a method for R1 mapping and segmentation of CSF and to use this method to explore how R1 of CSF relates to protein content and gadobutrol after intrathecal administration. Study Type Prospective cohort study, complemented by phantom analysis. Population Ten healthy control subjects (mean age 65.5 ± 4.4 years, range 57–72 years; five males and five females) and protein‐ and gadobutrol‐gradient phantom. Field Strength/Sequence 3 T Philips Ingenia scanner; 3D T2W mixed inversion recovery spin‐echo (T2W‐mixed IRSE) sequence and 3D T1W turbo field echo (3D T1W‐TFE). Assessment R1 maps were calculated by combining IR and SE data. An automated segmentation method derived from FreeSurfer employed SE data for CSF segmentation and T1W‐TFE for anatomical reference. CSF was collected by lumbar puncture for protein measurements, and 0.25 mmol gadobutrol was injected intrathecally. Post‐contrast assessments were performed at 3, 24, 48, and 72 h. Statistical Tests One‐way ANOVA, followed by a post hoc Tukey HSD test, and simple and multiple linear regression analysis; significance level of 0.05. Results R1 of ventricular CSF 0.216 ± 0.001 s −1 was significantly lower than that surrounding the cerebellum 0.225 ± 0.001 and cerebrum 0.228 ± 0.002 and correlated with lumbar protein concentration ( R 2  = 0.56). Peak gadobutrol concentrations were 101 ± 84 μM in ventricles, 185 ± 89 μM in cerebellar SAS and 166 ± 91 μM in cerebral SAS. Corresponding concentrations were 6 ± 4, 17 ± 8, and 37 ± 18 μM at 72 h. Data Conclusion Intrinsic R1 of CSF in the subarachnoid space correlated with protein content. Intracranial CSF enrichment after intrathecal administration of gadobutrol showed a large variation among healthy volunteers. Evidence Level 2. Technical Efficacy 3.

• Ottesen, Jon André; Storås, Tryggve Holck; Vatnehol, Svein Are Sirirud; Løvland, Grethe; Vik-Mo, Einar Osland & Schellhorn, Till [Show all 11 contributors for this article] (2025). Deep learning-based Intraoperative MRI reconstruction. European Radiology Experimental. 9(1). doi: 10.1186/s41747-024-00548-9. Full text in Research Archive Show summary

  Background We retrospectively evaluated the quality of deep learning (DL) reconstructions of on-scanner accelerated intraoperative MRI (iMRI) during respective brain tumor surgery. Methods Accelerated iMRI was performed using dual surface coils positioned around the area of resection. A DL model was trained on the fastMRI neuro dataset to mimic the data from the iMRI protocol. The evaluation was performed on imaging material from 40 patients imaged from Nov 1, 2021, to June 1, 2023, who underwent iMRI during tumor resection surgery. A comparative analysis was conducted between the conventional compressed sense (CS) method and the trained DL reconstruction method. Blinded evaluation of multiple image quality metrics was performed by two neuroradiologists and one neurosurgeon using a 1-to-5 Likert scale (1, nondiagnostic; 2, poor; 3, acceptable; 4, good; and 5, excellent), and the favored reconstruction variant. Results The DL reconstruction was strongly favored or favored over the CS reconstruction for 33/40, 39/40, and 8/40 of cases for readers 1, 2, and 3, respectively. For the evaluation metrics, the DL reconstructions had a higher score than their respective CS counterparts for 72%, 72%, and 14% of the cases for readers 1, 2, and 3, respectively. Still, the DL reconstructions exhibited shortcomings such as a striping artifact and reduced signal. Conclusion DL shows promise in allowing for high-quality reconstructions of iMRI. The neuroradiologists noted an improvement in the perceived spatial resolution, signal-to-noise ratio, diagnostic confidence, diagnostic conspicuity, and spatial resolution compared to CS, while the neurosurgeon preferred the CS reconstructions across all metrics. Relevance statement DL shows promise to allow for high-quality reconstructions of iMRI, however, due to the challenging setting of iMRI, further optimization is needed. Key Points iMRI is a surgical tool with a challenging image setting. DL allowed for high-quality reconstructions of iMRI. Additional optimization is needed due to the challenging intraoperative setting. Graphical Abstract

• Svensson, Siri Fløgstad; Arcos, José De; Darwish, Omar Isam; Fraser-Green, Jorunn; Storås, Tryggve & Holm, Sverre [Show all 9 contributors for this article] (2021). Robustness of MR Elastography in the Healthy Brain: Repeatability, Reliability, and Effect of Different Reconstruction Methods. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 53(5), p. 1510–1521. doi: 10.1002/jmri.27475. Full text in Research Archive Show summary

  Background Changes in brain stiffness can be an important biomarker for neurological disease. Magnetic resonance elastography (MRE) quantifies tissue stiffness, but the results vary between acquisition and reconstruction methods. Purpose To measure MRE repeatability and estimate the effect of different reconstruction methods and varying data quality on estimated brain stiffness. Study Type Prospective. Subjects Fifteen healthy subjects. Field Strength/Sequence 3T MRI, gradient-echo elastography sequence with a 50 Hz vibration frequency. Assessment Imaging was performed twice in each subject. Images were reconstructed using a curl-based and a finite-element-model (FEM)-based method. Stiffness was measured in the whole brain, in white matter, and in four cortical and four deep gray matter regions. Repeatability coefficients (RC), intraclass correlation coefficients (ICC), and coefficients of variation (CV) were calculated. MRE data quality was quantified by the ratio between shear waves and compressional waves. Statistical Tests Median values with range are presented. Reconstruction methods were compared using paired Wilcoxon signed-rank tests, and Spearman's rank correlation was calculated between MRE data quality and stiffness. Holm–Bonferroni corrections were employed to adjust for multiple comparisons. Results In the whole brain, CV was 4.3% and 3.8% for the curl and the FEM reconstruction, respectively, with 4.0–12.8% for subregions. Whole-brain ICC was 0.60–0.74, ranging from 0.20 to 0.89 in different regions. RC for the whole brain was 0.14 kPa and 0.17 kPa for the curl and FEM methods, respectively. FEM reconstruction resulted in 39% higher stiffness than the curl reconstruction (P < 0.05). MRE data quality, defined as shear-compression wave ratio, was higher in peripheral regions than in central regions of the brain (P < 0.05). No significant correlations were observed between MRE data quality and stiffness estimates. Data Conclusion MRE of the human brain is a robust technique in terms of repeatability. Caution is warranted when comparing stiffness values obtained with different techniques.

• Vatnehol, Svein Are Sirirud; Hol, Per Kristian; Bjørnerud, Atle; Amiry-Moghaddam, Mahmood; Haglerød, Camilla & Storås, Tryggve (2020). Effect of drinking oxygenated water assessed by in vivo MRI relaxometry. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 52(3), p. 720–728. doi: 10.1002/jmri.27104. Full text in Research Archive Show summary

  Grant Support This project was funded by the Research Council of Norway. Background Oxygen uptake through the gastrointestinal tract after oral administration of oxygenated water in humans is not well studied and is debated in the literature. Due to the paramagnetic properties of oxygen and deoxyhemoglobin, MRI as a technique might be able to detect changes in relaxometry values caused by increased oxygen levels in the blood. Purpose To assess whether oxygen dissolved in water is absorbed from the gastrointestinal tract and transported into the bloodstream after oral administration. Study Type A randomized, double‐blinded, placebo‐controlled crossover trial. Population/Subjects Thirty healthy male volunteers age 20–35. Field Strength/Sequence 3T/Modified Look–Locker inversion recovery (MOLLI) T1‐mapping and multi fast field echo (mFFE) T2*‐mapping. Assessment Each volunteer was scanned in two separate sessions. T1 and T2* maps were acquired repeatedly covering the hepatic portal vein (HPV) and vena cava inferior (VCI, control vein) before and after intake of oxygenated or control water. Assessments were done by placing a region of interest in the HPV and VCI. Statistical Test A mixed linear model was performed to the compare control vs. oxygen group. Results Drinking caused a mean 1.6% 95% CI (1.1–2.0% P < 0.001) increase in T1 of HPV blood and water oxygenation attributed another 0.70% 95% confidence interval (CI) (0.07–1.3% P = 0.028) increase. Oxygenation did not change T1 in VCI blood. Mean T2* increased 9.6% 95% CI (1.7–17.5% P = 0.017) after ingestion of oxygenated water and 1.2% 95% CI (−4.3–6.8% P = 0.661) after ingestion of control water. The corresponding changes in VCI blood were not significant. Data Conclusion Ingestion of water caused changes in T1 and T2* of HPV blood compatible with dilution due to water absorption. The effects were enhanced by oxygen. Assessment of oxygen enrichment of HPV blood was not possible due to the dilution effect. Level of Evidence 2 Technical Efficacy Stage 2 J. Magn. Reson. Imaging 2020;52:720–728.

• Carling, Johan Ulrik; Barkhatov, Leonid; Reims, Henrik Mikael; Storås, Tryggve; Courivaud, Fredric A A & Kazaryan, Airazat M. [Show all 10 contributors for this article] (2019). Can we ablate liver lesions close to large portal and hepatic veins with MR-guided HIFU? An experimental study in a porcine model. European Radiology. ISSN 0938-7994. 29(9), p. 5013–5021. doi: 10.1007/s00330-018-5996-8. Full text in Research Archive
• Vatnehol, Svein Are Sirirud; Hol, Per Kristian; Bjørnerud, Atle; Amiry-Moghaddam, Mahmood; Haglerød, Camilla Margrete & Storås, Tryggve (2019). Precision of T1-relaxation time measurements in the hepatic portal vein: influence of measurement technique and sequence parameters. Magnetic Resonance Materials in Physics, Biology and Medicine. ISSN 0968-5243. 32(3), p. 359–368. doi: 10.1007/s10334-018-00731-1. Full text in Research Archive
• Vatnehol, Svein Are Sirirud; Hol, Per Kristian; Bjørnerud, Atle; Amiry-Moghaddam, Mahmood; Haglerød, Camilla Margrete & Storås, Tryggve (2019). Determination of oxygen r1 at 3 Tesla using samples with a concentration range of dissolved oxygen. Magnetic Resonance Materials in Physics, Biology and Medicine. ISSN 0968-5243. p. 1–7. doi: 10.1007/s10334-019-00783-x. Full text in Research Archive Show summary

  Objective To investigate the sensitivity of modified Look–Locker inversion recovery (MOLLI) to measure changes in dissolved oxygen (DO) concentrations in water samples and to calculate sequence-specific relaxivity (r1m) and limit of detection (LOD). Materials and methods Ten water samples with a range of DO concentrations were scanned at 3 T using two variations of MOLLI schemes. Using linear regression the r1 of DO was estimated from the measured DO concentrations and T1 relaxation rates (R1). The results were combined with previously reported values on in vivo stability measures of the MOLLI sequences and used to estimate a LOD. Results DO concentrations ranged from 0.5 to 21.6 mg L−1. A linear correlation between DO and R1 was obtained with both MOLLI sequences, with an average correlation coefficient (R2) 0.9 and an average estimated r1 (r^1) of 4.45 × 10−3 s−1 mg−1 L. Estimated LOD was ≈ 10 mg L−1. Conclusion MOLLI T1-mapping sequences may be used for detecting dissolved oxygen in vivo at 3 T with an r^1 in the range 4.18–4.8 × 10−3 s−1 mg−1 L and a corresponding LOD for dissolved oxygen of approximately 10 mg L−1. MOLLI-based T1 mapping may be a useful non-invasive tool for quantification of in vivo changes of DO concentration during oxygen challenges.

• Heck, Siri Lagethon; Gulati, Geeta; HOFFMANN, PAVEL; Knobelsdorff-Brenkenhoff, Florian von; Storås, Tryggve & Ree, Anne Hansen [Show all 12 contributors for this article] (2017). Effect of candesartan and metoprolol on myocardial tissue composition during anthracycline treatment: The PRADA trial. European Heart Journal-Cardiovascular Imaging. ISSN 2047-2404. 19(5), p. 544–552. doi: 10.1093/ehjci/jex159. Full text in Research Archive Show summary

  Aims: Anthracycline treatment may cause myocyte loss and expansion of the myocardial extracellular volume (ECV) fraction by oedema and fibrosis. We tested the hypotheses that adjuvant treatment for early breast cancer with the anthracycline epirubicin is dose dependently associated with increased ECV fraction and total ECV, as well as reduced total myocardial cellular volume, and that these changes could be prevented by concomitant angiotensin or beta-adrenergic blockade. Methods and results: PRevention of cArdiac Dysfunction during Adjuvant breast cancer therapy (PRADA) was a 2 × 2 factorial, placebo-controlled, double-blinded trial of candesartan and metoprolol. Sixty-nine women had valid ECV measurements. ECV fraction, total ECV, and total cellular volume were measured by cardiovascular magnetic resonance before and at the completion of anthracycline therapy. ECV fraction increased from 27.5 ± 2.7% to 28.6 ± 2.9% (P = 0.002). A cumulative doxorubicin equivalent dose of 268 mg/m2 was associated with greater increase in ECV fraction than doses <268 mg/m2 (mean change 3.4% [95% confidence interval (CI) 1.2, 5.5] vs. 0.7% [95% CI 0.0, 1.5], P = 0.006), as well as greater increase in total ECV (1.9 mL [95% CI 0.4, 3.5] vs. 0.1 mL [95% CI -0.6, 0.8], P = 0.04). In patients receiving candesartan, total cellular volume decreased (-3.5 mL [95% CI - 4.7, -2.2], P < 0.001) while in patients not receiving candesartan, it remained unchanged (P = 0.45; between group difference P = 0.003). Conclusions: Anthracycline therapy is associated with dose-dependent increase in ECV fraction and total ECV. Concomitant treatment with candesartan reduces left ventricular total cellular volume.

• Grøvik, Endre; Redalen, Kathrine Røe; Storås, Tryggve; Negard, Anne; Holmedal, Stein Harald & Ree, Anne Hansen [Show all 9 contributors for this article] (2017). Dynamic multi-echo DCE- and DSC-MRI in rectal cancer: Low primary tumor Ktrans and ΔR2* peak are significantly associated with lymph node metastasis. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 46(1), p. 194–206. doi: 10.1002/jmri.25566. Full text in Research Archive Show summary

  Purpose: To implement a dynamic contrast-based multi-echo MRI sequence in assessment of rectal cancer and evaluate associations between histopathologic data and the acquired dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) -MRI parameters. Materials and Methods: This pilot study reports results from 17 patients with resectable rectal cancer. Dynamic contrast-based multi-echo MRI (1.5T) was acquired using a three-dimensional multi-shot EPI sequence, yielding both DCE- and DSC-data following a single injection of contrast agent. The Institutional Review Board approved the study and all patients provided written informed consent. Quantitative analysis was performed by pharmacokinetic modeling on DCE data and tracer kinetic modeling on DSC data. Mann-Whitney U-test and receiver operating characteristics curve statistics was used to evaluate associations between histopathologic data and the acquired DCE- and DSC-MRI parameters. Results: For patients with histologically confirmed nodal metastasis, the primary tumor demonstrated a significantly lower Ktrans and peak change in R 2, R 2-peakenh, than patients without nodal metastasis, showing a P-value of 0.010 and 0.005 for reader 1, and 0.043 and 0.019 for reader 2, respectively. Conclusion: This study shows the feasibility of acquiring DCE- and DSC-MRI in rectal cancer by dynamic multi-echo MRI. A significant association was found between both Ktrans and R 2-peakenh in the primary tumor and histological nodal status of the surgical specimen, which may improve stratification of patients to intensified multimodal treatment.

• Langleite, Torgrim Mikal; Jensen, Jørgen; Norheim, Frode; Gulseth, Hanne Løvdal; Tangen, Daniel S. & Kolnes, Kristoffer Jensen [Show all 19 contributors for this article] (2016). Insulin sensitivity, body composition and adipose depots following 12 w combined endurance and strength training in dysglycemic and normoglycemic sedentary men. Archives of Physiology and Biochemistry. ISSN 1381-3455. 122(4), p. 167–179. doi: 10.1080/13813455.2016.1202985. Full text in Research Archive
• Gulati, Geeta; Heck, Siri Lagethon; Ree, Anne Hansen; HOFFMANN, PAVEL; Schulz-Menger, Jeanette & Fagerland, Morten [Show all 15 contributors for this article] (2016). Prevention of cardiac dysfunction during adjuvant breast cancer therapy (PRADA): a 2 x 2 factorial, randomized, placebo-controlled, double-blind clinical trial of candesartan and metoprolol. European Heart Journal. ISSN 0195-668X. 37(21), p. 1671–1680. doi: 10.1093/eurheartj/ehw022. Full text in Research Archive
• Lee, Sindre; Norheim, Frode; Langleite, Torgrim Mikal; NORENG, HANS JØRGEN; Storås, Tryggve & Afman, Lydia A. [Show all 18 contributors for this article] (2016). Effect of energy restriction and physical exercise intervention on phenotypic flexibility as examined by transcriptomics analyses of mRNA from adipose tissue and whole body magnetic resonance imaging. Physiological Reports. 4(21). doi: 10.14814/phy2.13019. Full text in Research Archive Show summary

  Overweight and obesity lead to changes in adipose tissue such as inflammation and reduced insulin sensitivity. The aim of this study was to assess how altered energy balance by reduced food intake or enhanced physical activity affect these processes. We studied sedentary subjects with overweight/obesity in two intervention studies, each lasting 12 weeks affecting energy balance either by energy restriction (~20% reduced intake of energy from food) in one group, or by enhanced energy expenditure due to physical exercise (combined endurance‐ and strength‐training) in the other group. We monitored mRNA expression by microarray and mRNA sequencing from adipose tissue biopsies. We also measured several plasma parameters as well as fat distribution with magnetic resonance imaging and spectroscopy. Comparison of microarray and mRNA sequencing showed strong correlations, which were also confirmed using RT‐PCR. In the energy restricted subjects (body weight reduced by 5% during a 12 weeks intervention), there were clear signs of enhanced lipolysis as monitored by mRNA in adipose tissue as well as plasma concentration of free‐fatty acids. This increase was strongly related to increased expression of markers for M1‐like macrophages in adipose tissue. In the exercising subjects (glucose infusion rate increased by 29% during a 12‐week intervention), there was a marked reduction in the expression of markers of M2‐like macrophages and T cells, suggesting that physical exercise was especially important for reducing inflammation in adipose tissue with insignificant reduction in total body weight. Our data indicate that energy restriction and physical exercise affect energy‐related pathways as well as inflammatory processes in different ways, probably related to macrophages in adipose tissue.

• Grøvik, Endre; Bjørnerud, Atle; Kurz, Kathinka Dæhli; Kingsrød, Magnus; Sandhaug, Merete & Storås, Tryggve [Show all 7 contributors for this article] (2015). Single bolus split dynamic MRI: Is the combination of high spatial and dual-echo high temporal resolution interleaved sequences useful in the differential diagnosis of breast masses? Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 42(1), p. 180–187. doi: 10.1002/jmri.24753. Full text in Research Archive
• Li, Yuchuan; Lee, Sindre; Langleite, Torgrim Mikal; Norheim, Frode; Pourteymour, Shirin & Jensen, Jørgen [Show all 13 contributors for this article] (2014). Subsarcolemmal lipid droplet responses to a combined endurance and strength exercise intervention. Physiological Reports. 2(11). doi: 10.14814/phy2.12187. Full text in Research Archive
• Grøvik, Endre; Bjørnerud, Atle; Storås, Tryggve & Gjesdal, Kjell-Inge (2014). Split dynamic MRI: Single bolus high spatial-temporal resolution and multi contrast evaluation of breast lesions. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 39(3), p. 673–682. doi: 10.1002/jmri.24206. Full text in Research Archive
• Storås, Tryggve; Gjesdal, Kjell-Inge; Gadmar, Øystein Bech; Geitung, Jonn Terje & Klow, Nils-Einar (2010). Three-Dimensional Balanced Steady State Free Precession Imaging of the Prostate: Flip Angle Dependency of the Signal Based on a Two Component T2-decay Model. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 31(5), p. 1124–1131. doi: 10.1002/jmri.22135. Full text in Research Archive
• Enden, Tone Rønnaug; Storås, Tryggve; Negård, Anne; HAIG, YLVA; Sandvik, Leiv & Gjesdal, Kjell-Inge [Show all 8 contributors for this article] (2010). Visualization of Deep Veins and Detection of Deep Vein Thrombosis (DVT) With Balanced Turbo Field Echo (b-TFE) and Contrast-Enhanced T1 Fast Field Echo (CE-FFE) Using a Blood Pool Agent (BPA). Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 31(2), p. 416–424. doi: 10.1002/jmri.22046. Full text in Research Archive Show summary

  Purpose: To assess image quality, vessel visualization, preliminary diagnostic properties, and interobserver variability of a novel balanced turbo field echo (b-TFE) sequence and contrast-enhanced T1 fast field echo (CE-FFE) sequence with blood pool agent (BPA). Materials and Methods: A total of 15 healthy volunteers and six patients with ultrasound-verified proximal deep vein thrombosis (DVT) were examined from the inferior vena cava (IVC) to the proximal calf veins. Results: The great majority of deep veins were completely visualized on both sequences. In healthy volunteers the IVC was completely visualized in five b-TFE and 11 CE-FFE scans, and partially in seven b-TFE and four CE-FFE scans (P = 0.008). Poorest image quality was in the pelvis. Contrast-to-noise ratio (CNR) was higher on b-TFE compared to CE-FFE, with significant difference in calf images (P = 0.036). Sensitivity was 100% for proximal DVT with both methods. Specificity was 70% (CE-FFE) and 80% (b-TFE) for proximal femoral DVT; 100% in distal femoral. Interobserver reliability was kappa 1.0 (b-TFE), 0.9 (CE-FFE) for proximal, and overall poor for distal DVT. Conclusion: Contrast-enhancement did not add valuable information in visualizing deep veins of the lower limbs compared to b-TFE, though the IVC was slightly better visualized. Diagnostic properties and interobserver reliability of both sequences were good for proximal DVT and poor for distal DVT.

• Gjesdal, Kjell-Inge; Storås, Tryggve & Geitung, Jonn Terje (2009). A noncontrast-enhanced pulse sequence optimized to visualize human peripheral vessels. European Radiology. ISSN 0938-7994. 19(1), p. 110–120. doi: 10.1007/s00330-008-1113-8. Full text in Research Archive
• Storås, Tryggve & Kløw, Nils-Einar (2008). Prostate magnetic resonance imaging: multiexponential T2 decay in prostate tissue. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. 28(5), p. 1166–1172. Full text in Research Archive
• Negård, Anne; Storås, Tryggve; Borthne, A & Kløw, Nils-Einar (2005). Magnetic resonance imaging of the small bowel. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 125(22), p. 3094–3097. Full text in Research Archive
• Gjesdal, Kjell-Inge; Hellund, Johan Castberg; Storås, Tryggve & Geitung, Jonn-Terje (2004). A new pulse sequence to visualize slow flow. Magma forskning og viten. ISSN 1500-0788. 17(2), p. 68–73. Full text in Research Archive
• Storås, Tryggve; Gjesdal, Kjell-Inge; Svindland, Aud; Viktil, Ellen & Geitung, John Terje (2004). Dynamic First Pass 3D EPI of the Prostate: Accuracy in Tumor Location. Acta Radiologica. ISSN 0284-1851. 45, p. 584–590. Full text in Research Archive
• Borthne, Arne; Gjesdal, Kjell-Inge & Storås, Tryggve (2003). Bowel MR imaging with oral Gastrografin: an experimental study with healthy volunteers. European Radiology. ISSN 0938-7994. 13(1), p. 100–106. Full text in Research Archive
• Borthne, Arne; Gjesdal, Kjell-Inge & Storås, Tryggve (2003). Pediatric excretory MR urography: comparative study of enhanced and non-enhanced techniques. European Radiology. ISSN 0938-7994. 13(6), p. 1423–1427. Full text in Research Archive

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• Girelli, Alberto; Solheim, Andreas; Lian, Sofie Lysholm; Storås, Tryggve Holck; Nordengen, Kaja & Mardal, Kent-Andre (2026). Exploring dura hydrodynamics: The Role of the Meningeal Lymphatic Vessels in Brain Clearance. Full text in Research Archive
• Solheim, Andreas; Girelli, Alberto; Lian, Sofie Lysholm; Storås, Tryggve Holck; Nordengen, Kaja & Mardal, Kent-Andre (2026). Exploring the brain dura: Estimating meningeal lymphatic clearance through mathematical models. Full text in Research Archive
• Girelli, Alberto; Solheim, Andreas; Lian, Sofie Lysholm; Nordengen, Kaja; Storås, Tryggve Holck & Mardal, Kent-Andre (2026). Exploring the brain dura: a multiscale framework for dural lymphatic transport. Full text in Research Archive
• Girelli, Alberto; Solheim, Andreas; Lian, Sofie Lysholm; Storås, Tryggve Holck; Nordengen, Kaja & Mardal, Kent-Andre (2026). Computational Modeling of transport in the human brain dura. Full text in Research Archive
• Grøvik, Endre; Lysvik, Elisabeth Kirkeby; Bugge, Robin Antony Birkeland; Emblem, Kyrre E; Hjornevik, Trine & Vatnehol, Svein Are Sirirud [Show all 7 contributors for this article] (2021). A novel MRI phantom to study the fluid dynamics of the glymphatic system: a proof-of-concept study. Full text in Research Archive
• Grøvik, Endre; Redalen, Kathrine Røe; Storås, Tryggve; Holmedal, Stein Harald; Negard, Anne & Ree, Anne Hansen [Show all 9 contributors for this article] (2017). Improved sensitivity for rectal cancer differentiation by T2*-correction in DCE-MRI. Full text in Research Archive
• Heck, Siri Lagethon; Gulati, Geeta; HOFFMANN, PAVEL; Knobelsdorff-Brenkenhoff, Florian von; Storås, Tryggve & Ree, Anne Hansen [Show all 11 contributors for this article] (2016). Effects of Candesartan and Metoprolol on Myocardial Mass, Edema, and Fibrosis During Anthracycline Treatment in Early Breast Cancer: APRADA-CMR substudy. Full text in Research Archive
• Storås, Tryggve & Gjesdal, Kjell-Inge (2010). MRI of the prostate gland. Universitetet i Oslo. Full text in Research Archive

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