118 results on '"Seeliger E"'
Search Results
2. Low-dose nitrite improves renal tissue reoxygenation after ischemia: P278
- Author
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Arakelyan, K., Cantow, K., Ladwig, M., Flemming, B., and Seeliger, E.
- Published
- 2014
3. Early effects of an x-ray contrast medium on renal T2*/T2 MRI as compared to short-term hyperoxia, hypoxia and aortic occlusion in rats
- Author
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Arakelyan, K., Cantow, K., Hentschel, J., Flemming, B., Pohlmann, A., Ladwig, M., Niendorf, T., and Seeliger, E.
- Published
- 2013
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4. Linking non-invasive parametric MRI with invasive physiological measurements (MR-PHYSIOL): towards a hybrid and integrated approach for investigation of acute kidney injury in rats
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Pohlmann, A., Cantow, K., Hentschel, J., Arakelyan, K., Ladwig, M., Flemming, B., Hoff, U., Persson, P. B., Seeliger, E., and Niendorf, T.
- Published
- 2013
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5. The step response: a method to characterize mechanisms of renal blood flow autoregulation
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Wronski, T., Seeliger, E., Persson, P.B., Forner, C., Fichtner, C., Scheller, J., and Flemming, B.
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Furosemide -- Research ,Biological sciences - Abstract
Response of renal vasculature to changes in renal perfusion pressure (RPP) involves mechanisms with different frequency characteristics. Autoregulation of renal blood flow (RBF) is mediated by the rapid myogenic response, by the slower tubuloglomerular feedback (TGF) mechanism, and, possibly, by an even slower third mechanism. To evaluate the individual contribution of these mechanisms to RBF autoregulation, we analyzed the response of RBF to a step increase in RPP. In anesthetized rats, the suprarenal aorta was occluded for 30 s, and then the occlusion was released to induce a step increase in RPP. Three dampened oscillations were observed; their oscillation periods ranged from 9.5 to 13 s, from 34.2 to 38.6 s, and from 100.5 to 132.2 s, respectively. The two faster oscillations correspond with previously reported data on the myogenic mechanism and the TGF. In accordance, after furosemide, the amplitude of the intermediate oscillation was significantly reduced. Inhibition of nitric oxide synthesis by [N.sup.[omega]]-nitro-L-arginine methyl ester significantly increased the amplitude of the 10-s oscillation. It is concluded that the parameters of the dampened oscillations induced by the step increase in RPP reflect properties of autoregulatory mechanisms. The oscillation period characterizes the individual mechanism, the dampening is a measure for the stability of the regulation, and the square of the amplitudes characterizes the power of the respective mechanism. In addition to the myogenic response and the TGF, a third rather slow mechanism of RBF autoregulation exists. myogenic reaction; tubuloglomerular feedback; furosemide; [N.sup.[omega]]-nitro-L-arginine methyl ester.
- Published
- 2003
6. Influence of baroreflex on volume elasticity of heart and aorta in the rabbit
- Author
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Wronski, T., Seeliger, E., Persson, P.B., Harnath, A., and Flemming, B.
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Physiology -- Research ,Biological sciences - Abstract
Optimal ventriculoaortic coupling includes tuning of elastic properties. The ratio of effective arterial elastance and left ventricular endsystolic elastance is often taken as a measure for mechanical and energetical efficiency. The present study determined the time course of ventricular and aortic volume elasticity (VE = dp/dV) throughout a complete heartbeat. This was achieved by using changes of eigenfrequency of two catheter-transducer systems under closed chest conditions in rabbits. Short-term VE modulation was studied by a baroreflex response, as induced by pressure changes applied to the carotid sinus. Long-term changes were studied in atherosclerotic rabbits (12 wk of high-cholesterol feeding). The time course and mean values of ventricular and aortic VE were changed by the baroreflex stimulus. Cholesterol feeding diminished the response. The degree of ventriculoaortic coupling, as quantified by V[E.sub.Aorta]/V[E.sub.ventricle] ratio, varied during a single ejection period. The large span allows either maximal energetical efficiency or maximal stroke work. Although normal rabbits adjusted their ventriculoaortic coupling during baroreflex input, the cholesterol-fed rabbits failed to do so. compliance; ventriculoarterial coupling; eigenfrequency; cholesterol; atherosclerosis
- Published
- 2002
7. Nitric oxide and the role of blood pressure variability to the kidney
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Nafz, B., Seeliger, E., and Persson, P. B.
- Published
- 2001
8. Coupling of left ventricular and aortic volume elasticity in the rabbit
- Author
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WRONSKI, T., PERSSON, P. B., SEELIGER, E., HARNATH, A., and FLEMMING, B.
- Subjects
Heart ventricle, Left -- Physiological aspects ,Blood flow -- Physiological aspects ,Aorta -- Physiological aspects ,Rabbits -- Physiological aspects ,Heart -- Contraction ,Atherosclerosis -- Physiological aspects ,Cholesterol -- Physiological aspects ,Biological sciences - Abstract
Wronski, T., P. B. Persson, E. Seeliger, A. Harnath, and B. Flemming. Coupling of left ventricular and aortic volume elasticity in the rabbit. Am J Physiol Regulatory Integrative Comp Physiol 279: R539-R547, 2000.--Changes in volume elasticity (VE) of the left ventricle and aorta could be important for blood flow. A procedure is presented to rapidly assess VE of the left ventricle and aorta by analyzing changes in the eigenfrequency. Six control rabbits and 11 rabbits with atheromatosis (12 wk of high-cholesterol feeding) were studied. In control rabbits, during the first half of the systole, left ventricular VE continuously increased to +43% (P [is less than] 0.05). Then VE gradually declined to an end-diastolic minimum (20% of the average systolic levels, P [is less than] 0.05). Aortic VE changes were in the opposite direction to the ventricle. Aortic VE continuously decreased throughout the systole; the last value was 20% lower than at the beginning of the systole (P [is less than] 0.05). Conversely, diastolic VE of the aorta took on greater values. This inverse time course between ventricle and aorta may reduce energy requirements for conveying blood. High cholesterol-fed rabbits did not reveal the inverse behavior of ventricular and aortic VE, e.g., aortic VE increased during the systole (119%, P [is less than] 0.05). heart; aorta; compliance; left ventricular-arterial coupling; eigenfrequency; cholesterol; atherosclerosis
- Published
- 2000
9. Early effects of an x-ray contrast medium on renal T2*/T2 MRI as compared to short-term hyperoxia, hypoxia and aortic occlusion in rats.
- Author
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Arakelyan, K., Cantow, K., Hentschel, J., Flemming, B., Pohlmann, A., Ladwig, M., Niendorf, T., and Seeliger, E.
- Subjects
X-rays ,MAGNETIC resonance imaging ,HYPEROXIA ,HYPOXEMIA ,CONTRAST media ,ARTERIAL occlusions ,LABORATORY rats ,KIDNEY physiology - Abstract
Aim X-ray contrast media ( CM) can cause acute kidney injury ( AKI). Medullary hypoxia is pivotal in CM-induced AKI, as indicated by invasively and pin-point measured tissue oxygenation. MRI provides spatially resolved blood oxygenation level-dependent data using T
2 * and T2 mapping. We studied CM effects on renal T2 */T2 and benchmarked them against short periods of hyperoxia, hypoxia and aortic occlusion ( AO). Methods Rats were equipped with carotid artery catheters (tip towards aorta) and supra-renal aortic occluders. T2 */T2 mapping was performed using a 9.4-T animal scanner. CM (1.5 mL iodixanol) was injected into the thoracic aorta with the animal in the scanner followed by 2 h of T2 */T2 mapping. For T2 */T2 assessment, regions of interest in the cortex ( C), outer medulla ( OM), inner medulla ( IM) and papilla ( P) were determined according to morphological features. Results Hyperoxia increased T2 * in C (by 17%) and all medullary layers (25-35%). Hypoxia decreased T2 * in C (40%) and all medullary layers (55-60%). AO decreased T2 * in C (18%) and all medullary layers (30-40%). Upon injection of CM, T2 * increased transiently, then decreased, reaching values 10-20% below baseline in C and OM and 30-40% below baseline in IM and P. Conclusion T2 * mapping corroborates data previously obtained with invasive methods and demonstrates that CM injection affects renal medullary oxygenation. CM-induced T2 * decrease in OM was small vs. hypoxia and aortic occlusion. T2 * decrease obtained for hypoxia was more pronounced than for AO. This indicates that T2 * may not accurately reflect blood oxygenation under certain conditions. [ABSTRACT FROM AUTHOR]- Published
- 2013
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10. Myocardial T2* mapping at ultrahigh magnetic fields: in vivo myocardial tissue characteri-zation and assessment of cardiac physiology with magnetic resonance imaging
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Huelnhagen Till, Flemming Bert, Seeliger Erdmann, Schulz-Menger Jeanette, and Niendorf Thoralf
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magnetic resonance imaging ,myocardial tissue characterization ,physiology ,ultrahigh field mr ,Medicine - Abstract
Mapping the effective transverse relaxation time T2* represents an emerging MRI tool for non-invasive myocardial tissue characterization and holds the promise to provide means for assessing myocardial (patho)physiology in vivo. This work takes advantage of the linear increase of susceptibility effects with magnetic field strength which renders it appealing to perform T2* mapping at ultrahigh magnetic fields and enables temporally resolved T2* mapping. Recognizing this potential this study examines the applicability of myocardial CINE T2* mapping in healthy volunteers and hypertrophic cardiomyopathy (HCM) patients at 7.0 Tesla and investigates its capability to distinguish between healthy myocardium and myocardium affected by HCM.
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- 2017
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11. Ein neues, verbessertes Verfahren zur indirekten Messung des Blutdruckes.
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SEELIGER, E. M. and HOEBEL, P.
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- 1970
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12. CLINOCAR, ein neues Gerät für den klinischen Notfalleinsatz.
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SEELIGER, E.
- Published
- 1969
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13. Automatisierung von klinischen und biologischen Untersuchungsmethoden.
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SEELIGER, E.
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- 1962
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14. CMR2009: 4.02: Massive increase in urine viscosity by iso-osmolar contrast media in the rat.
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Seeliger, E., Becker, K., Ladwig, M., Wronski, T., Persson, P. B., and Flemming, B.
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- 2009
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15. MRI of kidney size matters.
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Niendorf T, Gladytz T, Cantow K, Klein T, Tasbihi E, Velasquez Vides JR, Zhao K, Millward JM, Waiczies S, and Seeliger E
- Abstract
Objective: To highlight progress and opportunities of measuring kidney size with MRI, and to inspire research into resolving the remaining methodological gaps and unanswered questions relating to kidney size assessment., Materials and Methods: This work is not a comprehensive review of the literature but highlights valuable recent developments of MRI of kidney size., Results: The links between renal (patho)physiology and kidney size are outlined. Common methodological approaches for MRI of kidney size are reviewed. Techniques tailored for renal segmentation and quantification of kidney size are discussed. Frontier applications of kidney size monitoring in preclinical models and human studies are reviewed. Future directions of MRI of kidney size are explored., Conclusion: MRI of kidney size matters. It will facilitate a growing range of (pre)clinical applications, and provide a springboard for new insights into renal (patho)physiology. As kidney size can be easily obtained from already established renal MRI protocols without the need for additional scans, this measurement should always accompany diagnostic MRI exams. Reconciling global kidney size changes with alterations in the size of specific renal layers is an important topic for further research. Acute kidney size measurements alone cannot distinguish between changes induced by alterations in the blood or the tubular volume fractions-this distinction requires further research into cartography of the renal blood and the tubular volumes., (© 2024. The Author(s).)
- Published
- 2024
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16. In vivo monitoring of renal tubule volume fraction using dynamic parametric MRI.
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Tasbihi E, Gladytz T, Millward JM, Periquito JS, Starke L, Waiczies S, Cantow K, Seeliger E, and Niendorf T
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- Rats, Animals, Magnetic Resonance Imaging methods, Kidney diagnostic imaging, Kidney Tubules diagnostic imaging, Renal Insufficiency, Chronic, Acute Kidney Injury
- Abstract
Purpose: The increasing incidence of kidney diseases is a global concern, and current biomarkers and treatments are inadequate. Changes in renal tubule luminal volume fraction (TVF) serve as a rapid biomarker for kidney disease and improve understanding of renal (patho)physiology. This study uses the amplitude of the long T
2 component as a surrogate for TVF in rats, by applying multiexponential analysis of the T2 -driven signal decay to examine micromorphological changes in renal tissue., Methods: Simulations were conducted to identify a low mean absolute error (MAE) protocol and an accelerated protocol customized for the in vivo study of T2 mapping of the rat kidney at 9.4 T. We then validated our bi-exponential approach in a phantom mimicking the relaxation properties of renal tissue. This was followed by a proof-of-principle demonstration using in vivo data obtained during a transient increase of renal pelvis and tubular pressure., Results: Using the low MAE protocol, our approach achieved an accuracy of MAE < 1% on the mechanical phantom. The T2 mapping protocol customized for in vivo study achieved an accuracy of MAE < 3%. Transiently increasing pressure in the renal pelvis and tubules led to significant changes in TVF in renal compartments: ΔTVFcortex = 4.9%, ΔTVFouter_medulla = 4.5%, and ΔTVFinner_medulla = -14.6%., Conclusion: These results demonstrate that our approach is promising for research into quantitative assessment of renal TVF in in vivo applications. Ultimately, these investigations have the potential to help reveal mechanism in acute renal injury that may lead to chronic kidney disease, which will support research into renal disorders., (© 2024 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)- Published
- 2024
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17. Noninvasive Assessment of Diabetic Kidney Disease With MRI: Hype or Hope?
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Zhao K, Seeliger E, Niendorf T, and Liu Z
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- Humans, Kidney diagnostic imaging, Kidney physiopathology, Magnetic Resonance Imaging methods, Diabetic Nephropathies complications, Diabetic Nephropathies diagnosis, Diabetic Nephropathies physiopathology, Kidney Function Tests methods, Renal Insufficiency, Chronic etiology, Renal Insufficiency, Chronic prevention & control
- Abstract
Owing to the increasing prevalence of diabetic mellitus, diabetic kidney disease (DKD) is presently the leading cause of chronic kidney disease and end-stage renal disease worldwide. Early identification and disease interception is of paramount clinical importance for DKD management. However, current diagnostic, disease monitoring and prognostic tools are not satisfactory, due to their low sensitivity, low specificity, or invasiveness. Magnetic resonance imaging (MRI) is noninvasive and offers a host of contrast mechanisms that are sensitive to pathophysiological changes and risk factors associated with DKD. MRI tissue characterization involves structural and functional information including renal morphology (kidney volume (TKV) and parenchyma thickness using T
1 - or T2 -weighted MRI), renal microstructure (diffusion weighted imaging, DWI), renal tissue oxygenation (blood oxygenation level dependent MRI, BOLD), renal hemodynamics (arterial spin labeling and phase contrast MRI), fibrosis (DWI) and abdominal or perirenal fat fraction (Dixon MRI). Recent (pre)clinical studies demonstrated the feasibility and potential value of DKD evaluation with MRI. Recognizing this opportunity, this review outlines key concepts and current trends in renal MRI technology for furthering our understanding of the mechanisms underlying DKD and for supplementing clinical decision-making in DKD. Progress in preclinical MRI of DKD is surveyed, and challenges for clinical translation of renal MRI are discussed. Future directions of DKD assessment and renal tissue characterization with (multi)parametric MRI are explored. Opportunities for discovery and clinical break-through are discussed including biological validation of the MRI findings, large-scale population studies, standardization of DKD protocols, the synergistic connection with data science to advance comprehensive texture analysis, and the development of smart and automatic data analysis and data visualization tools to further the concepts of virtual biopsy and personalized DKD precision medicine. We hope that this review will convey this vision and inspire the reader to become pioneers in noninvasive assessment and management of DKD with MRI. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 2., (© 2023 International Society for Magnetic Resonance in Medicine.)- Published
- 2024
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18. Dynamic parametric MRI and deep learning: Unveiling renal pathophysiology through accurate kidney size quantification.
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Klein T, Gladytz T, Millward JM, Cantow K, Hummel L, Seeliger E, Waiczies S, Lippert C, and Niendorf T
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- Animals, Rats, Kidney diagnostic imaging, Algorithms, Magnetic Resonance Imaging, Image Processing, Computer-Assisted, Deep Learning, Organophosphorus Compounds, Triazoles
- Abstract
Renal pathologies often manifest as alterations in kidney size, providing a valuable avenue for employing dynamic parametric MRI as a means to derive kidney size measurements for the diagnosis, treatment, and monitoring of renal disease. Furthermore, this approach holds significant potential in supporting MRI data-driven preclinical investigations into the intricate mechanisms underlying renal pathophysiology. The integration of deep learning algorithms is crucial in achieving rapid and precise segmentation of the kidney from temporally resolved parametric MRI, facilitating the use of kidney size as a meaningful (pre)clinical biomarker for renal disease. To explore this potential, we employed dynamic parametric T
2 mapping of the kidney in rats in conjunction with a custom-tailored deep dilated U-Net (DDU-Net) architecture. The architecture was trained, validated, and tested on manually segmented ground truth kidney data, with benchmarking against an analytical segmentation model and a self-configuring no new U-Net. Subsequently, we applied our approach to in vivo longitudinal MRI data, incorporating interventions that emulate clinically relevant scenarios in rats. Our approach achieved high performance metrics, including a Dice coefficient of 0.98, coefficient of determination of 0.92, and a mean absolute percentage error of 1.1% compared with ground truth. The DDU-Net enabled automated and accurate quantification of acute changes in kidney size, such as aortic occlusion (-8% ± 1%), venous occlusion (5% ± 1%), furosemide administration (2% ± 1%), hypoxemia (-2% ± 1%), and contrast agent-induced acute kidney injury (11% ± 1%). This approach can potentially be instrumental for the development of dynamic parametric MRI-based tools for kidney disorders, offering unparalleled insights into renal pathophysiology., (© 2023 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)- Published
- 2024
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19. Comprehensive Analysis of the Spatial Distribution of Gadolinium, Iron, Manganese, and Phosphorus in the Brain of Healthy Rats After High-Dose Administrations of Gadodiamide and Gadobutrol.
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Hummel L, Frenzel T, Boyken J, Pietsch H, and Seeliger E
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- Rats, Male, Animals, Manganese, Iron, Phosphorus, Gadolinium DTPA, Contrast Media, Brain diagnostic imaging, Gadolinium, Organometallic Compounds
- Abstract
Objectives: After the administration of gadolinium-based contrast agents (GBCAs), residual gadolinium (Gd) has been detected in a few distinct morphological structures of the central nervous system (CNS). However, a systematic, comprehensive, and quantitative analysis of the spatial Gd distribution in the entire brain is not yet available. The first aim of this study is to provide this analysis in healthy rats after administration of high GBCA doses. The second aim is to assess the spatial distributions and possible Gd colocalizations of endogenous iron (Fe), manganese (Mn), and phosphorus (P). In addition, the presence of Gd in proximity to blood vessels was assessed by immunohistochemistry., Materials and Methods: Male rats were randomly assigned to 3 groups (n = 3/group): saline (control), gadodiamide (linear GBCA), and gadobutrol (macrocyclic GBCA) with cumulative Gd doses of 14.4 mmol/kg of body mass. Five weeks after the last administration, the brains were collected and cryosectioned. The spatial distributions of Gd, Fe, Mn, and P were analyzed in a total of 130 sections, each covering the brain in 1 of the 3 perpendicular anatomical orientations, using laser ablation coupled with inductively coupled plasma mass spectrometry. Quantitative spatial element maps were generated, and the concentrations of Gd, Fe, and Mn were measured in 31 regions of interest covering various distinct CNS structures. Correlation analyses were performed to test for possible colocalization of Gd, Fe, and Mn. The spatial proximity of Gd and blood vessels was studied using metal-tagged antibodies against von Willebrand factor with laser ablation coupled with inductively coupled plasma mass spectrometry., Results: After administration of linear gadodiamide, high Gd concentrations were measured in many distinct structures of the gray matter. This involved structures previously reported to retain Gd after linear GBCA, such as the deep cerebellar nuclei or the globus pallidus, but also structures that had not been reported so far including the dorsal subiculum, the retrosplenial cortex, the superior olivary complex, and the inferior colliculus. The analysis in all 3 orientations allowed the localization of Gd in specific subregions and layers of certain structures, such as the hippocampus and the primary somatosensory cortex. After macrocyclic gadobutrol, the Gd tissue concentration was significantly lower than after gadodiamide. Correlation analyses of region of interest concentrations of Gd, Fe, and Mn revealed no significant colocalization of Gd with endogenous Fe or Mn in rats exposed to either GBCA. Immunohistochemistry revealed a colocalization of Gd traces with vascular endothelium in the deep cerebellar nuclei after gadobutrol, whereas the majority of Gd was found outside the vasculature after gadodiamide., Conclusions: In rats exposed to gadodiamide but not in rats exposed to gadobutrol, high Gd concentrations were measured in various distinct CNS structures, and structures not previously reported were identified to contain Gd, including specific subregions and layers with different cytoarchitecture and function. Knowledge of these distinct spatial patterns may pave the way for tailored functional neurological testing. Signs for the localization of the remaining Gd in the vascular endothelium were prominent for gadobutrol but not gadodiamide. The results also indicate that local transmetalation with endogenous Fe or Mn is unlikely to explain the spatial patterns of Gd deposition in the brain, which argues against a general role of these metals in local transmetalation and release of Gd ions in the CNS., Competing Interests: Conflicts of interest and sources of funding: T.F., J.B., and H.P. are employees of Bayer AG. L.H. was an employee of Bayer AG during part of the investigations., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)
- Published
- 2024
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20. Assessment of rhabdomyolysis-induced acute kidney injury with chemical exchange saturation transfer magnetic resonance imaging.
- Author
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Zhang Q, Tao Q, Xie Y, Chen Z, Seeliger E, Niendorf T, Chen W, and Feng Y
- Abstract
Background: Rhabdomyolysis (RM)-induced acute kidney injury (AKI) is a common renal disease with low survival rate and inadequate prognosis. In this study, we investigate the feasibility of chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) for assessing the progression of RM-induced AKI in a mouse model., Methods: AKI was induced in C57BL/6J mice via intramuscular injection of 7.5 mL/kg glycerol (n=30). Subsequently, serum creatinine (SCr), blood urea nitrogen (BUN), and hematoxylin-eosin (HE) and Masson staining, were performed. Longitudinal CEST-MRI was conducted on days 1, 3, 7, 15, and 30 after AKI induction using a 7.0-T MRI system. CEST-MRI quantification parameters including magnetization transfer ratio (MTR), MTR asymmetric analysis (MTR
asym ), apparent amide proton transfer (APT*), and apparent relayed nuclear Overhauser effect (rNOE*) were used to investigate the feasibility of detecting RM-induced renal damage., Results: Significant increases of SCr and BUN demonstrated established AKI. The HE staining revealed various degrees of tubular damage, and Masson staining indicted an increase in the degree of fibrosis in the injured kidneys. Among CEST parameters, the cortical MTR presented a significant difference, and it also showed the best diagnostic performance for AKI [area under the receiver operating characteristic curve (AUC) =0.915] and moderate negative correlations with SCr and BUN. On the first day of renal damage, MTR was significantly reduced in cortex (22.7%±0.04%, P=0.013), outer stripe of outer medulla (24.7%±1.6%, P<0.001), and inner stripe of outer medulla (27.0%±1.5%, P<0.001) compared to the control group. Longitudinally, MTR increased steadily with AKI progression., Conclusions: The MTR obtained from CEST-MRI is sensitive to the pathological changes in RM-induced AKI, indicating its potential clinical utility for the assessment of kidney diseases., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-699/coif). The authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)- Published
- 2023
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21. Renal MRI: From Nephron to NMR Signal.
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Bane O, Seeliger E, Cox E, Stabinska J, Bechler E, Lewis S, Hickson LJ, Francis S, Sigmund E, and Niendorf T
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- Humans, Magnetic Resonance Imaging methods, Nephrons, Kidney Function Tests, Kidney diagnostic imaging, Kidney Diseases diagnostic imaging
- Abstract
Renal diseases pose a significant socio-economic burden on healthcare systems. The development of better diagnostics and prognostics is well-recognized as a key strategy to resolve these challenges. Central to these developments are MRI biomarkers, due to their potential for monitoring of early pathophysiological changes, renal disease progression or treatment effects. The surge in renal MRI involves major cross-domain initiatives, large clinical studies, and educational programs. In parallel with these translational efforts, the need for greater (patho)physiological specificity remains, to enable engagement with clinical nephrologists and increase the associated health impact. The ISMRM 2022 Member Initiated Symposium (MIS) on renal MRI spotlighted this issue with the goal of inspiring more solutions from the ISMRM community. This work is a summary of the MIS presentations devoted to: 1) educating imaging scientists and clinicians on renal (patho)physiology and demands from clinical nephrologists, 2) elucidating the connection of MRI parameters with renal physiology, 3) presenting the current state of leading MR surrogates in assessing renal structure and functions as well as their next generation of innovation, and 4) describing the potential of these imaging markers for providing clinically meaningful renal characterization to guide or supplement clinical decision making. We hope to continue momentum of recent years and introduce new entrants to the development process, connecting (patho)physiology with (bio)physics, and conceiving new clinical applications. We envision this process to benefit from cross-disciplinary collaboration and analogous efforts in other body organs, but also to maximally leverage the unique opportunities of renal physiology. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2., (© 2023 International Society for Magnetic Resonance in Medicine.)
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- 2023
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22. Diagnostic and prognostic performance of renal compartment volume and the apparent diffusion coefficient obtained from magnetic resonance imaging in mild, moderate and severe diabetic kidney disease.
- Author
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Zhao K, Li S, Liu Y, Li Q, Lin H, Wu Z, Seeliger E, Niendorf T, Liu Z, and Wang W
- Abstract
Background: Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD). There are unmet needs for noninvasive diagnosis and prognosis prediction of DKD in clinical practice. This study examines the diagnostic and prognostic value of magnetic resonance (MR) markers of renal compartment volume and the apparent diffusion coefficient (ADC) for mild, moderate, and severe DKD., Methods: This study was registered at the Chinese Clinical Trial Registry Center (registration number: ChiCTR-RRC-17012687). Sixty-seven DKD patients were prospectively randomly enrolled and underwent clinical examination and diffusion-weighted magnetic resonance imaging (DW-MRI). Patients with comorbidities that affected renal volumes or components were excluded. Ultimately, 52 DKD patients were included in the cross-sectional analysis. The ADC in the renal cortex (ADC
cortex ), ADC in the renal medulla (ADCmedulla ) and difference between ADCcortex and ADCmedulla (ΔADC) were measured using a twelve-layer concentric objects (TLCO) approach. Renal compartment volumes of the parenchyma and pelvis were derived from T2-weighted MRI. Due to lost contact or ESRD diagnosed before follow-up (n=14), only 38 DKD patients remained for follow-up (median period =8.25 years) to investigate the correlations between MR markers and renal outcomes. The primary outcomes were the composite of doubling of the primary serum creatinine concentration or ESRD., Results: ADCcortex presented superior performance in discriminating DKD with normal and declined estimated glomerular filtration rate (eGFR) over ADCmedulla , ΔADC and renal compartment volumes with an AUC of 0.904 (sensitivity of 83% and specificity of 91%) and was moderately correlated with the clinical biomarkers eGFR and proteinuria (P<0.05). The Cox survival analysis demonstrated that ADCcortex rather than ΔADC is a predictor of renal outcomes with a hazard ratio of 3.4 (95% CI: 1.1-10.2, P<0.05) independent of baseline eGFR and proteinuria., Conclusions: ADCcortex is a valuable imaging marker for the diagnosis and prediction of renal function decline in DKD., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-149/coif). WW was supported by grants from the National Natural Science Foundation of China (Nos. 82170731 and 81470974) and the High-level Hospital Construction Project of Guangdong Province (No. DFJH201908). ZL was supported by grants from the Key Area Research and Development Program of Guangdong Province (No. 2021B0101420006), Regional Innovation and Development Joint Fund of National Natural Science Foundation of China (No. U22A20345), Guangdong Provincial Key Laboratory of Artificial Intelligence in Medical Image Analysis and Application (No. 2022B1212010011), and High-level Hospital Construction Project of Guangdong Province (No. DFJHBF202105). Erdmann Seeliger was supported by grants from the German Research Foundation (Deutsche Forschungsgemeinschaft) Collaborative Research Center (1365 “Renoprotection” Project B04). ZW reports being a full-time employee of Philips (2020-now) during the conduct of the study. The other authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)- Published
- 2023
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23. Monitoring kidney size to interpret MRI-based assessment of renal oxygenation in acute pathophysiological scenarios.
- Author
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Cantow K, Gladytz T, Millward JM, Waiczies S, Niendorf T, and Seeliger E
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- Rats, Humans, Animals, Magnetic Resonance Imaging methods, Furosemide pharmacology, Hypoxia, Oxygen, Kidney, Acute Kidney Injury diagnostic imaging, Acute Kidney Injury pathology
- Abstract
Aim: Tissue hypoxia is an early key feature of acute kidney injury. Assessment of renal oxygenation using magnetic resonance imaging (MRI) markers T
2 and T2 * enables insights into renal pathophysiology. This assessment can be confounded by changes in the blood and tubular volume fractions, occurring upon pathological insults. These changes are mirrored by changes in kidney size (KS). Here, we used dynamic MRI to monitor KS for physiological interpretation of T2 * and T2 changes in acute pathophysiological scenarios., Methods: KS was determined from T2 *, T2 mapping in rats. Six interventions that acutely alter renal tissue oxygenation were performed directly within the scanner, including interventions that change the blood and/or tubular volume. A biophysical model was used to estimate changes in O2 saturation of hemoglobin from changes in T2 * and KS., Results: Upon aortic occlusion KS decreased; this correlated with a decrease in T2 *, T2 . Upon renal vein occlusion KS increased; this negatively correlated with a decrease in T2 *, T2 . Upon simultaneous occlusion of both vessels KS remained unchanged; there was no correlation with decreased T2 *, T2 . Hypoxemia induced mild reductions in KS and T2 *, T2 . Administration of an X-ray contrast medium induced sustained KS increase, with an initial increase in T2 *, T2 followed by a decrease. Furosemide caused T2 *, T2 elevation and a minor increase in KS. Model calculations yielded physiologically plausible calibration ratios for T2 *., Conclusion: Monitoring KS allows physiological interpretation of acute renal oxygenation changes obtained by T2 *, T2 . KS monitoring should accompany MRI-oximetry, for new insights into renal pathophysiology and swift translation into human studies., (© 2022 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.)- Published
- 2023
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24. Parametric MRI Detects Aristolochic Acid Induced Acute Kidney Injury.
- Author
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Mei Y, Yang G, Guo Y, Zhao K, Wu S, Xu Z, Zhou S, Yan C, Seeliger E, Niendorf T, Xu Y, and Feng Y
- Subjects
- Rats, Male, Animals, Rats, Wistar, Magnetic Resonance Imaging, Kidney diagnostic imaging, Kidney pathology, Acute Kidney Injury chemically induced, Acute Kidney Injury diagnostic imaging, Acute Kidney Injury pathology
- Abstract
Exposure to aristolochic acid (AA) is of increased concern due to carcinogenic and nephrotoxic effects, and incidence of aristolochic acid nephropathy (AAN) is increasing. This study characterizes renal alterations during the acute phase of AAN using parametric magnetic resonance imaging (MRI). An AAN and a control group of male Wistar rats received administration of aristolochic acid I (AAI) and polyethylene glycol (PEG), respectively, for six days. Both groups underwent MRI before and 2, 4 and 6 days after AAI or PEG administration. T
2 relaxation times and apparent diffusion coefficients (ADCs) were determined for four renal layers. Serum creatinine levels (sCr) and blood urea nitrogen (BUN) were measured. Tubular injury scores (TIS) were evaluated based on histologic findings. Increased T2 values were detected since day 2 in the AAN group, but decreased ADCs and increased sCr levels and BUN were not detected until day 4. Significant linear correlations were observed between T2 of the cortex and the outer stripe of outer medulla and TIS. Our results demonstrate that parametric MRI facilitates early detection of renal injury induced by AAI in a rat model. T2 mapping may be a valuable tool for assessing kidney injury during the acute phase of AAN.- Published
- 2022
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25. Early Identification of Hearing Loss and Language Development at 32 Months of Age.
- Author
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Harris AB, Seeliger E, Hess C, Sedey AL, Kristensen K, Lee Y, and Chung W
- Abstract
This study examines the relationship between the early identification of hearing loss and language outcomes for deaf/hard of hearing (D/HH) children, with bilateral or unilateral hearing loss and with or without additional disabilities. It was hypothesized that hearing loss identified by 3 months of age would be associated with better language outcomes. Using a prospective, longitudinal design, 86 families completed developmental instruments at two time points: at an average age of 14.8 months and an average age of 32.1 months. Multiple regression examined how hearing loss identified by 3 months of age contributed to later language outcomes while controlling for developmental level at the first time point. Hearing loss identified by 3 months of age was positively associated with better language outcomes for D/HH children at 32 months of age; however, D/HH children still exhibited language delays, compared to normative scores for same-aged hearing peers for reported measures. Language outcomes of children with unilateral hearing loss were not better than those of children with mild-to-moderate bilateral hearing loss. Children with additional disabilities and more severe bilateral hearing loss had lower language scores than those without., Competing Interests: Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
- Published
- 2022
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26. Reliable kidney size determination by magnetic resonance imaging in pathophysiological settings.
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Gladytz T, Millward JM, Cantow K, Hummel L, Zhao K, Flemming B, Periquito JS, Pohlmann A, Waiczies S, Seeliger E, and Niendorf T
- Subjects
- Animals, Kidney diagnostic imaging, Rats, Magnetic Resonance Imaging, Vascular Diseases
- Abstract
Aim: Kidney diseases constitute a major health challenge, which requires noninvasive imaging to complement conventional approaches to diagnosis and monitoring. Several renal pathologies are associated with changes in kidney size, offering an opportunity for magnetic resonance imaging (MRI) biomarkers of disease. This work uses dynamic MRI and an automated bean-shaped model (ABSM) for longitudinal quantification of pathophysiologically relevant changes in kidney size., Methods: A geometry-based ABSM was developed for kidney size measurements in rats using parametric MRI (T
2 , T2 * mapping). The ABSM approach was applied to longitudinal renal size quantification using occlusion of the (a) suprarenal aorta or (b) the renal vein, (c) increase in renal pelvis and intratubular pressure and (d) injection of an X-ray contrast medium into the thoracic aorta to induce pathophysiologically relevant changes in kidney size., Results: The ABSM yielded renal size measurements with accuracy and precision equivalent to the manual segmentation, with >70-fold time savings. The automated method could detect a ~7% reduction (aortic occlusion) and a ~5%, a ~2% and a ~6% increase in kidney size (venous occlusion, pelvis and intratubular pressure increase and injection of X-ray contrast medium, respectively). These measurements were not affected by reduced image quality following administration of ferumoxytol., Conclusion: Dynamic MRI in conjunction with renal segmentation using an ABSM supports longitudinal quantification of changes in kidney size in pathophysiologically relevant experimental setups mimicking realistic clinical scenarios. This can potentially be instrumental for developing MRI-based diagnostic tools for various kidney disorders and for gaining new insight into mechanisms of renal pathophysiology., (© 2021 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.)- Published
- 2021
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27. Continuous diffusion spectrum computation for diffusion-weighted magnetic resonance imaging of the kidney tubule system.
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Periquito JS, Gladytz T, Millward JM, Delgado PR, Cantow K, Grosenick D, Hummel L, Anger A, Zhao K, Seeliger E, Pohlmann A, Waiczies S, and Niendorf T
- Abstract
Background: The use of rigid multi-exponential models (with a priori predefined numbers of components) is common practice for diffusion-weighted MRI (DWI) analysis of the kidney. This approach may not accurately reflect renal microstructure, as the data are forced to conform to the a priori assumptions of simplified models. This work examines the feasibility of less constrained, data-driven non-negative least squares (NNLS) continuum modelling for DWI of the kidney tubule system in simulations that include emulations of pathophysiological conditions., Methods: Non-linear least squares (LS) fitting was used as reference for the simulations. For performance assessment, a threshold of 5% or 10% for the mean absolute percentage error (MAPE) of NNLS and LS results was used. As ground truth, a tri-exponential model using defined volume fractions and diffusion coefficients for each renal compartment (tubule system: D
tubules , ftubules ; renal tissue: Dtissue , ftissue ; renal blood: Dblood , fblood ;) was applied. The impact of: (I) signal-to-noise ratio (SNR) =40-1,000, (II) number of b-values (n=10-50), (III) diffusion weighting (b-rangesmall =0-800 up to b-rangelarge =0-2,180 s/mm2 ), and (IV) fixation of the diffusion coefficients Dtissue and Dblood was examined. NNLS was evaluated for baseline and pathophysiological conditions, namely increased tubular volume fraction (ITV) and renal fibrosis (10%: grade I, mild) and 30% (grade II, moderate)., Results: NNLS showed the same high degree of reliability as the non-linear LS. MAPE of the tubular volume fraction ( ftubules ) decreased with increasing SNR. Increasing the number of b-values was beneficial for ftubules precision. Using the b-rangelarge led to a decrease in MAPEftubules compared to b-rangesmall . The use of a medium b-value range of b=0-1,380 s/mm2 improved ftubules precision, and further bmax increases beyond this range yielded diminishing improvements. Fixing Dblood and Dtissue significantly reduced MAPEftubules and provided near perfect distinction between baseline and ITV conditions. Without constraining the number of renal compartments in advance, NNLS was able to detect the (fourth) fibrotic compartment, to differentiate it from the other three diffusion components, and to distinguish between 10% vs. 30% fibrosis., Conclusions: This work demonstrates the feasibility of NNLS modelling for DWI of the kidney tubule system and shows its potential for examining diffusion compartments associated with renal pathophysiology including ITV fraction and different degrees of fibrosis., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-1360). TN, AP, TG, ES, SW, KC report funding provided by the German Research Foundation [Gefoerdert durch die Deutsche Forschungsgemeinschaft (DFG), Projektnummer 394046635, SFB 1365, RENOPROTECTION. Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Project number 394046635, SFB 1365, RENOPROTECTION]. The other authors have no conflicts of interest to declare., (2021 Quantitative Imaging in Medicine and Surgery. All rights reserved.)- Published
- 2021
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28. Quantitative Assessment of Renal Perfusion and Oxygenation by Invasive Probes: Basic Concepts.
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Cantow K, Evans RG, Grosenick D, Gladytz T, Niendorf T, Flemming B, and Seeliger E
- Subjects
- Animals, Electrodes, Lasers, Oxygen Consumption, Perfusion, Software, Biomarkers analysis, Hemodynamics, Kidney physiology, Monitoring, Physiologic methods, Oxygen analysis, Renal Circulation
- Abstract
Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe basic principles of methodology to quantify renal hemodynamics and tissue oxygenation by means of invasive probes in experimental animals. Advantages and disadvantages of the various methods are discussed in the context of the heterogeneity of renal tissue perfusion and oxygenation.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by a separate chapter describing the experimental procedure and data analysis.
- Published
- 2021
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29. Subsegmentation of the Kidney in Experimental MR Images Using Morphology-Based Regions-of-Interest or Multiple-Layer Concentric Objects.
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Riazy L, Milani B, Periquito JS, Cantow K, Niendorf T, Pruijm M, Seeliger E, and Pohlmann A
- Subjects
- Animals, Humans, Software, Image Processing, Computer-Assisted methods, Kidney anatomy & histology, Kidney physiology, Magnetic Resonance Imaging methods
- Abstract
Functional renal MRI promises access to a wide range of physiologically relevant parameters such as blood oxygenation, perfusion, tissue microstructure, pH, and sodium concentration. For quantitative comparison of results, representative values must be extracted from the parametric maps obtained with these different MRI techniques. To improve reproducibility of results this should be done based on regions-of-interest (ROIs) that are clearly and objectively defined.Semiautomated subsegmentation of the kidney in magnetic resonance images represents a simple but very valuable approach for the quantitative analysis of imaging parameters in multiple ROIs that are associated with specific anatomic locations. Thereby, it facilitates comparing MR parameters between different kidney regions, as well as tracking changes over time.Here we provide detailed step-by-step instructions for two recently developed subsegmentation techniques that are suitable for kidneys of small rodents: i) the placement of ROIs in cortex, outer and the inner medulla based on typical kidney morphology and ii) the division of the kidney into concentrically oriented layers.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
- Published
- 2021
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30. Animal Models of Renal Pathophysiology and Disease.
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Hosszu A, Kaucsar T, Seeliger E, and Fekete A
- Subjects
- Animals, Disease Progression, Humans, Kidney Diseases therapy, Reproducibility of Results, Biomarkers analysis, Disease Models, Animal, Kidney physiopathology, Kidney Diseases classification, Kidney Diseases pathology, Magnetic Resonance Imaging methods
- Abstract
Renal diseases remain devastating illnesses with unacceptably high rates of mortality and morbidity worldwide. Animal models are essential tools to better understand the pathomechanisms of kidney-related illnesses and to develop new, successful therapeutic strategies. Magnetic resonance imaging (MRI) has been actively explored in the last decades for assessing renal function, perfusion, tissue oxygenation as well as the degree of fibrosis and inflammation. This chapter aims to provide a comprehensive overview of animal models of acute and chronic kidney diseases, highlighting MRI-specific considerations, advantages, and pitfalls, and thus assisting the researcher in experiment planning.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
- Published
- 2021
- Full Text
- View/download PDF
31. Physiological system analysis of the kidney by high-temporal-resolution T 2 ∗ monitoring of an oxygenation step response.
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Zhao K, Pohlmann A, Feng Q, Mei Y, Yang G, Yi P, Feng Q, Chen W, Zhou L, Wu EX, Seeliger E, Niendorf T, and Feng Y
- Subjects
- Animals, Hypoxia, Kidney diagnostic imaging, Kidney Cortex diagnostic imaging, Kidney Medulla diagnostic imaging, Magnetic Resonance Imaging, Oxygen, Rats, Hyperoxia diagnostic imaging, Reperfusion Injury
- Abstract
Purpose: Examine the feasibility of characterizing the regulation of renal oxygenation using high-temporal-resolution monitoring of the T 2 ∗ response to a step-like oxygenation stimulus., Methods: For T 2 ∗ mapping, multi-echo gradient-echo imaging was used (temporal resolution = 9 seconds). A step-like renal oxygenation challenge was applied involving sequential exposure to hyperoxia (100% O
2 ), hypoxia (10% O2 + 90% N2 ), and hyperoxia (100% O2 ). In vivo experiments were performed in healthy rats (N = 10) and in rats with bilateral ischemia-reperfusion injury (N = 4). To assess the step response of renal oxygenation, a second-order exponential model was used (model parameters: amplitude [A], time delay [Δt], damping constant [D], and period of the oscillation [T]) for renal cortex, outer stripe of the outer medulla, inner stripe of the outer medulla, and inner medulla., Results: The second-order exponential model permitted us to model the exponential T 2 ∗ recovery and the superimposed T 2 ∗ oscillation following renal oxygenation stimulus. The in vivo experiments revealed a difference in Douter medulla between healthy controls (D < 1, indicating oscillatory recovery) and ischemia-reperfusion injury (D > 1, reflecting aperiodic recovery). The increase in Douter medulla by a factor of 3.7 (outer stripe of the outer medulla) and 10.0 (inner stripe of the outer medulla) suggests that this parameter might be rather sensitive to (patho)physiological oxygenation changes., Conclusion: This study demonstrates the feasibility of monitoring the dynamic oxygenation response of renal tissues to a step-like oxygenation challenge using high-temporal-resolution T 2 ∗ mapping. Our results suggest that the implemented system analysis approach may help to unlock questions regarding regulation of renal oxygenation, with the ultimate goal of providing imaging means for diagnostics and therapy of renal diseases., (© 2020 International Society for Magnetic Resonance in Medicine.)- Published
- 2021
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32. Reversible (Patho)Physiologically Relevant Test Interventions: Rationale and Examples.
- Author
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Cantow K, Ladwig-Wiegard M, Flemming B, Fekete A, Hosszu A, and Seeliger E
- Subjects
- Animals, Disease Progression, Hemodynamics, Humans, Mice, Oxygen Consumption, Rats, Software, Biomarkers analysis, Image Processing, Computer-Assisted methods, Kidney physiopathology, Magnetic Resonance Imaging methods, Monitoring, Physiologic methods, Oxygen metabolism, Renal Circulation
- Abstract
Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe test interventions that are used to study the control of renal hemodynamics and oxygenation in experimental animals in the context of kidney-specific control of hemodynamics and oxygenation. The rationale behind the use of the individual tests, the physiological responses of renal hemodynamics and oxygenation, the use in preclinical studies, and the possible application in humans are discussed.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
- Published
- 2021
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33. Preparation and Monitoring of Small Animals in Renal MRI.
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Kaucsar T, Hosszu A, Seeliger E, Reimann HM, and Fekete A
- Subjects
- Animals, Kidney surgery, Mice, Rats, Biomarkers analysis, Image Processing, Computer-Assisted methods, Kidney physiology, Magnetic Resonance Imaging methods, Monitoring, Physiologic methods, Software
- Abstract
Renal diseases remain devastating illnesses with unacceptably high rates of mortality and morbidity worldwide. Animal models are essential tools to better understand the pathomechanism of kidney-related illnesses and to develop new, successful therapeutic strategies. Magnetic resonance imaging (MRI) has been actively explored in the last decades for assessing renal function, perfusion, tissue oxygenation as well as the degree of fibrosis and inflammation. This chapter aims to provide an overview of the preparation and monitoring of small animals before, during, and after surgical interventions or MR imaging. Standardization of experimental settings such as body temperature or hydration of animals and minimizing pain and distress are essential for diminishing nonexperimental variables as well as for conducting ethical research.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
- Published
- 2021
- Full Text
- View/download PDF
34. Recommendations for Preclinical Renal MRI: A Comprehensive Open-Access Protocol Collection to Improve Training, Reproducibility, and Comparability of Studies.
- Author
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Pohlmann A, Back SJ, Fekete A, Friedli I, Hectors S, Jerome NP, Ku MC, Longo DL, Meier M, Millward JM, Periquito JS, Seeliger E, Serai SD, Waiczies S, Sourbron S, Laustsen C, and Niendorf T
- Subjects
- Disease Progression, Humans, Kidney Diseases therapy, Reproducibility of Results, Biomarkers analysis, Kidney physiopathology, Kidney Diseases classification, Kidney Diseases pathology, Magnetic Resonance Imaging methods, Practice Guidelines as Topic standards
- Abstract
Renal MRI holds incredible promise for making a quantum leap in improving diagnosis and care of patients with a multitude of diseases, by moving beyond the limitations and restrictions of current routine clinical practice. Clinical and preclinical renal MRI is advancing with ever increasing rapidity, and yet, aside from a few examples of renal MRI in routine use, it is still not good enough. Several roadblocks are still delaying the pace of progress, particularly inefficient education of renal MR researchers, and lack of harmonization of approaches that limits the sharing of results among multiple research groups.Here we aim to address these limitations for preclinical renal MRI (predominantly in small animals), by providing a comprehensive collection of more than 40 publications that will serve as a foundational resource for preclinical renal MRI studies. This includes chapters describing the fundamental principles underlying a variety of renal MRI methods, step-by-step protocols for executing renal MRI studies, and detailed guides for data analysis. This collection will serve as a crucial part of a roadmap toward conducting renal MRI studies in a robust and reproducible way, that will promote the standardization and sharing of data.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
- Published
- 2021
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35. MRI Mapping of the Blood Oxygenation Sensitive Parameter T 2 * in the Kidney: Basic Concept.
- Author
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Li LP, Hack B, Seeliger E, and Prasad PV
- Subjects
- Animals, Blood Gas Analysis, Humans, Software, Biomarkers analysis, Image Processing, Computer-Assisted methods, Kidney physiology, Magnetic Resonance Imaging methods, Monitoring, Physiologic methods, Oxygen blood, Oxygen Consumption
- Abstract
The role of hypoxia in renal disease and injury has long been suggested but much work still remains, especially as it relates to human translation. Invasive pO
2 probes are feasible in animal models but not for human use. In addition, they only provide localized measurements. Histological methods can identify hypoxic tissue and provide a spatial distribution, but are invasive and allow only one-time point. Blood oxygenation level dependent (BOLD) MRI is a noninvasive method that can monitor relative oxygen availability across the kidney. It is based on the inherent differences in magnetic properties of oxygenated vs. deoxygenated hemoglobin. Presence of deoxyhemoglobin enhances the spin-spin relaxation rate measured using a gradient echo sequence, known as R2 * (= 1/T2 *). While the key interest of BOLD MRI is in the application to humans, use in preclinical models is necessary primarily to validate the measurement against invasive methods, to better understand physiology and pathophysiology, and to evaluate novel interventions. Application of MRI acquisitions in preclinical settings involves several challenges both in terms of logistics and data acquisition. This section will introduce the concept of BOLD MRI and provide some illustrative applications. The following sections will discuss the technical issues associated with data acquisition and analysis.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by two separate chapters describing the experimental procedure and data analysis.- Published
- 2021
- Full Text
- View/download PDF
36. Monitoring Renal Hemodynamics and Oxygenation by Invasive Probes: Experimental Protocol.
- Author
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Cantow K, Ladwig-Wiegard M, Flemming B, Pohlmann A, Niendorf T, and Seeliger E
- Subjects
- Animals, Kidney surgery, Male, Oxygen Consumption, Rats, Rats, Wistar, Software, Hemodynamics, Image Processing, Computer-Assisted methods, Kidney physiology, Magnetic Resonance Imaging methods, Monitoring, Physiologic methods, Oxygen metabolism
- Abstract
Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe methods to study control of renal hemodynamics and tissue oxygenation by means of invasive probes in anesthetized rats. Step-by-step protocols are provided for two setups, one for experiments in laboratories for integrative physiology and the other for experiments within small-animal magnetic resonance scanners.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by a separate chapter describing the basic concepts of quantitatively assessing renal perfusion and oxygenation with invasive probes.
- Published
- 2021
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- View/download PDF
37. Imagine physiology without imaging.
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Cantow K, Hummel L, Flemming B, Waiczies S, Niendorf T, and Seeliger E
- Published
- 2020
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38. Probing renal blood volume with magnetic resonance imaging.
- Author
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Niendorf T, Seeliger E, Cantow K, Flemming B, Waiczies S, and Pohlmann A
- Subjects
- Animals, Ferrosoferric Oxide blood, Hemodynamics, Humans, Oxygen blood, Oxygen Consumption physiology, Blood Volume physiology, Kidney blood supply, Kidney diagnostic imaging, Kidney Diseases diagnostic imaging, Magnetic Resonance Imaging methods
- Abstract
Damage to the kidney substantially reduces life expectancy. Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. In vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) is sensitive to changes in the effective transversal relaxation time (T
2 *) in vivo, and is non-invasive and indicative of renal tissue oxygenation. However, the renal T2 * to tissue pO2 relationship is not governed exclusively by renal blood oxygenation, but is affected by physiological confounders with alterations in renal blood volume fraction (BVf) being of particular relevance. To decipher this interference probing renal BVf is essential for the pursuit of renal MR oximetry. Superparamagnetic iron oxide nanoparticle (USPIO) preparations can be used as MRI visible blood pool markers for detailing alterations in BVf. This review promotes the opportunities of MRI-based assessment of renal BVf. Following an outline on the specifics of renal oxygenation and perfusion, changes in renal BVf upon interventions and their potential impact on renal T2 * are discussed. We also describe the basic principles of renal BVf assessment using ferumoxytol-enhanced MRI in the equilibrium concentration regimen. We demonstrate that ferumoxytol does not alter control of renal haemodynamics and oxygenation. Preclinical applications of ferumoxytol enhanced renal MRI as well as considerations for its clinical implementation for examining renal BVf changes are provided alongside practical considerations. Finally, we explore the future directions of MRI-based assessment of renal BVf., (© 2019 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.)- Published
- 2020
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39. Google maps for tissues: Multiscale imaging of biological systems and disease.
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Niendorf T, Frydman L, Neeman M, and Seeliger E
- Subjects
- Humans, Artificial Intelligence, Diagnostic Imaging methods, Disease, Models, Biological, Search Engine
- Published
- 2020
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40. Consensus-based technical recommendations for clinical translation of renal BOLD MRI.
- Author
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Bane O, Mendichovszky IA, Milani B, Dekkers IA, Deux JF, Eckerbom P, Grenier N, Hall ME, Inoue T, Laustsen C, Lerman LO, Liu C, Morrell G, Pedersen M, Pruijm M, Sadowski EA, Seeliger E, Sharma K, Thoeny H, Vermathen P, Wang ZJ, Serafin Z, Zhang JL, Francis ST, Sourbron S, Pohlmann A, Fain SB, and Prasad PV
- Subjects
- Animals, Biomarkers metabolism, Consensus, Delphi Technique, Humans, Kidney metabolism, Magnetic Resonance Imaging standards, Reproducibility of Results, Signal-To-Noise Ratio, Surveys and Questionnaires, Translational Research, Biomedical trends, Kidney diagnostic imaging, Magnetic Resonance Imaging trends
- Abstract
Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.
- Published
- 2020
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41. Cardiorenal sodium MRI in small rodents using a quadrature birdcage volume resonator at 9.4 T.
- Author
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Boehmert L, Waiczies H, Kuehne A, Oezerdem C, Waiczies S, Starke L, Ku MC, Pohlmann A, Seeliger E, and Niendorf T
- Subjects
- Animals, Calibration, Equipment Design, Heart diagnostic imaging, Heart Ventricles diagnostic imaging, Myocardium, Phantoms, Imaging, Radio Waves, Rats, Signal-To-Noise Ratio, Transducers, Translational Research, Biomedical, Kidney diagnostic imaging, Magnetic Resonance Imaging instrumentation, Sodium Isotopes
- Abstract
Objective: Design, implementation, evaluation and application of a quadrature birdcage radiofrequency (RF) resonator tailored for renal and cardiac sodium (
23 Na) magnetic resonance imaging (MRI) in rats at 9.4 T., Materials and Methods: A low pass birdcage resonator (16 rungs, din = 62 mm) was developed. The transmission field (B1 + ) was examined with EMF simulations. The scattering parameter (S-parameter) and the quality factor (Q-factor) were measured. For experimental validation B1 + -field maps were acquired with the double-angle method. In vivo sodium imaging of the heart (spatial resolution: (1 × 1 × 5) mm3 ) and kidney (spatial resolution: (1 × 1 × 10) mm3 ) was performed with a FLASH technique., Results: The RF resonator exhibits RF characteristics, transmission field homogeneity and penetration that afford23 Na MR in vivo imaging of the kidney and heart at 9.4 T. For the renal cortex and medulla a SNRs of 8 and 13 were obtained and a SNRs of 14 and 15 were observed for the left and right ventricle., Discussion: These initial results obtained in vivo in rats using the quadrature birdcage volume RF resonator for23 Na MRI permit dedicated studies on experimental models of cardiac and renal diseases, which would contribute to translational research of the cardiorenal syndrome.- Published
- 2020
- Full Text
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42. Diffusion-weighted Renal MRI at 9.4 Tesla Using RARE to Improve Anatomical Integrity.
- Author
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Periquito JDS, Paul K, Huelnhagen T, Ku MC, Ji Y, Cantow K, Gladytz T, Grosenick D, Flemming B, Seeliger E, Waiczies S, Niendorf T, and Pohlmann A
- Abstract
Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive imaging technique sensitive to tissue water movement. By enabling a discrimination between tissue properties without the need of contrast agent administration, DWI is invaluable for probing tissue microstructure in kidney diseases. DWI studies commonly make use of single-shot Echo-Planar Imaging (ss-EPI) techniques that are prone to suffering from geometric distortion. The goal of the present study was to develop a robust DWI technique tailored for preclinical magnetic resonance imaging (MRI) studies that is free of distortion and sensitive to detect microstructural changes. Since fast spin-echo imaging techniques are less susceptible to B
0 inhomogeneity related image distortions, we introduced a diffusion sensitization to a split-echo Rapid Acquisition with Relaxation Enhancement (RARE) technique for high field preclinical DWI at 9.4 T. Validation studies in standard liquids provided diffusion coefficients consistent with reported values from the literature. Split-echo RARE outperformed conventional ss-EPI, with ss-EPI showing a 3.5-times larger border displacement (2.60 vs. 0.75) and a 60% higher intra-subject variability (cortex = 74%, outer medulla = 62% and inner medulla = 44%). The anatomical integrity provided by the split-echo RARE DWI technique is an essential component of parametric imaging on the way towards robust renal tissue characterization, especially during kidney disease.- Published
- 2019
- Full Text
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43. Cardiorenal sodium MRI at 7.0 Tesla using a 4/4 channel 1 H/ 23 Na radiofrequency antenna array.
- Author
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Boehmert L, Kuehne A, Waiczies H, Wenz D, Eigentler TW, Funk S, von Knobelsdorff-Brenkenhoff F, Schulz-Menger J, Nagel AM, Seeliger E, and Niendorf T
- Subjects
- Electromagnetic Fields, Feasibility Studies, Female, Humans, Male, Phantoms, Imaging, Protons, Radio Waves, Reproducibility of Results, Torso diagnostic imaging, Transducers, Heart diagnostic imaging, Image Processing, Computer-Assisted methods, Kidney diagnostic imaging, Magnetic Resonance Imaging, Cine, Sodium Isotopes chemistry
- Abstract
Purpose: Cardiorenal syndrome describes disorders of the heart and the kidneys in which a dysfunction of 1 organ induces a dysfunction in the other. This work describes the design, evaluation, and application of a 4/4-channel hydrogen-1/sodium (
1 H/23 Na) RF array tailored for cardiorenal MRI at 7.0 Tesla (T) for a better physiometabolic understanding of cardiorenal syndrome., Methods: The dual-frequency RF array is composed of a planar posterior section and a modestly curved anterior section, each section consisting of 2 loop elements tailored for23 Na MR and 2 loopole-type elements customized for1 H MR. Numerical electromagnetic field and specific absorption rate simulations were carried out. Transmission field ( B 1 + ) uniformity was optimized and benchmarked against electromagnetic field simulations. An in vivo feasibility study was performed., Results: The proposed array exhibits sufficient RF characteristics, B 1 + homogeneity, and penetration depth to perform23 Na MRI of the heart and kidney at 7.0 T. The mean B 1 + field for sodium in the heart is 7.7 ± 0.8 µT/√kW and in the kidney is 6.9 ± 2.3 µT/√kW. The suitability of the RF array for23 Na MRI was demonstrated in healthy subjects (acquisition time for23 Na MRI: 18 min; nominal isotropic spatial resolution: 5 mm [kidney] and 6 mm [heart])., Conclusion: This work provides encouragement for further explorations into densely packed multichannel transceiver arrays tailored for23 Na MRI of the heart and kidney. Equipped with this technology, the ability to probe sodium concentration in the heart and kidney in vivo using23 Na MRI stands to make a critical contribution to deciphering the complex interactions between both organs., (© 2019 International Society for Magnetic Resonance in Medicine.)- Published
- 2019
- Full Text
- View/download PDF
44. Kidney damage by iodinated contrast media.
- Author
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Seeliger E and Persson PB
- Subjects
- Animals, Contrast Media administration & dosage, Contrast Media pharmacology, Dose-Response Relationship, Drug, Humans, Contrast Media adverse effects, Kidney Diseases chemically induced
- Published
- 2019
- Full Text
- View/download PDF
45. A synthetic epoxyeicosatrienoic acid analogue prevents the initiation of ischemic acute kidney injury.
- Author
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Hoff U, Bubalo G, Fechner M, Blum M, Zhu Y, Pohlmann A, Hentschel J, Arakelyan K, Seeliger E, Flemming B, Gürgen D, Rothe M, Niendorf T, Manthati VL, Falck JR, Haase M, Schunck WH, and Dragun D
- Subjects
- 8,11,14-Eicosatrienoic Acid administration & dosage, 8,11,14-Eicosatrienoic Acid metabolism, Acute Kidney Injury pathology, Animals, Cardiac Surgical Procedures adverse effects, Fatty Acids chemistry, Humans, Hydroxyeicosatetraenoic Acids metabolism, Ischemia pathology, Kidney metabolism, Male, Postoperative Complications, Rats, Rats, Inbred Lew, Reperfusion Injury metabolism, Signal Transduction, 8,11,14-Eicosatrienoic Acid analogs & derivatives, Acute Kidney Injury prevention & control, Fatty Acids pharmacology, Hydroxyeicosatetraenoic Acids blood, Ischemia etiology
- Abstract
Aim: Imbalances in cytochrome P450 (CYP)-dependent eicosanoid formation may play a central role in ischemic acute kidney injury (AKI). We reported previously that inhibition of 20-hydroxyeicosatetraenoic acid (20-HETE) action ameliorated ischemia/reperfusion (I/R)-induced AKI in rats. Now we tested the hypothesis that enhancement of epoxyeicosatrienoic acid (EET) actions may counteract the detrimental effects of 20-HETE and prevent the initiation of AKI., Methods: Male Lewis rats underwent right nephrectomy and ischemia was induced by 45 min clamping of the left renal pedicle followed by up to 48 h of reperfusion. Circulating CYP-eicosanoid profiles were compared in patients who underwent cardiac surgery with (n = 21) and without (n = 38) developing postoperative AKI., Results: Ischemia induced an about eightfold increase of renal 20-HETE levels, whereas free EETs were not accumulated. To compensate for this imbalance, a synthetic 14,15-EET analogue was administered by intrarenal infusion before ischemia. The EET analogue improved renal reoxygenation as monitored by in vivo parametric MRI during the initial 2 h reperfusion phase. The EET analogue improved PI3K- as well as mTORC2-dependent rephosphorylation of Akt, induced inactivation of GSK-3β, reduced the development of tubular apoptosis and attenuated inflammatory cell infiltration. The EET analogue also significantly alleviated the I/R-induced drop in creatinine clearance. Patients developing postoperative AKI featured increased preoperative 20-HETE and 8,9-EET levels., Conclusions: Pharmacological interventions targeting the CYP-eicosanoid pathway could offer promising new options for AKI prevention. Individual differences in CYP-eicosanoid formation may contribute to the risk of developing AKI in clinical settings., (© 2019 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)
- Published
- 2019
- Full Text
- View/download PDF
46. Millimeter spatial resolution in vivo sodium MRI of the human eye at 7 T using a dedicated radiofrequency transceiver array.
- Author
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Wenz D, Kuehne A, Huelnhagen T, Nagel AM, Waiczies H, Weinberger O, Oezerdem C, Stachs O, Langner S, Seeliger E, Flemming B, Hodge R, and Niendorf T
- Subjects
- Adult, Equipment Design, Female, Humans, Male, Phantoms, Imaging, Eye diagnostic imaging, Magnetic Resonance Imaging instrumentation, Magnetic Resonance Imaging methods, Sodium chemistry
- Abstract
Purpose: The aim of this study was to achieve millimeter spatial resolution sodium in vivo MRI of the human eye at 7 T using a dedicated six-channel transceiver array. We present a detailed description of the radiofrequency coil design, along with electromagnetic field and specific absorption ratio simulations, data validation, and in vivo application., Methods: Electromagnetic field and specific absorption ratio simulations were performed. Transmit field uniformity was optimized by using a multi-objective genetic algorithm. Transmit field mapping was conducted using a phase-sensitive method. An in vivo feasibility study was carried out with 3-dimensional density-adapted projection reconstruction imaging technique., Results: Measured transmit field distribution agrees well with the one obtained from simulations. The specific absorption ratio simulations confirm that the radiofrequency coil is safe for clinical use. Our radiofrequency coil is light and conforms to an average human head. High spatial resolution (nominal 1.4 and 1.0 mm isotropic) sodium in vivo images of the human eye were acquired within scan times suitable for clinical applications (∼ 10 min)., Conclusions: Three most important eye compartments in the context of sodium physiology were clearly delineated in all of the images: the vitreous humor, the aqueous humor, and the lens. Our results provide encouragement for further clinical studies. The implications for research into eye diseases including ocular melanoma, cataract, and glaucoma are discussed. Magn Reson Med 80:672-684, 2018. © 2018 International Society for Magnetic Resonance in Medicine., (© 2018 International Society for Magnetic Resonance in Medicine.)
- Published
- 2018
- Full Text
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47. Gadolinium Deposition in the Brain after Contrast-enhanced MRI: Are the Data Valid?
- Author
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Boyken J, Niendorf T, Flemming B, and Seeliger E
- Subjects
- Brain, Contrast Media, Gadolinium, Magnetic Resonance Imaging
- Published
- 2018
- Full Text
- View/download PDF
48. Somatosensory BOLD fMRI reveals close link between salient blood pressure changes and the murine neuromatrix.
- Author
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Reimann HM, Todiras M, Hodge R, Huelnhagen T, Millward JM, Turner R, Seeliger E, Bader M, Pohlmann A, and Niendorf T
- Subjects
- Animals, Brain Mapping methods, Electric Stimulation, Evoked Potentials, Somatosensory physiology, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Mice, Mice, Inbred C57BL, Blood Pressure physiology, Brain physiopathology, Nociception physiology, Nociceptive Pain physiopathology
- Abstract
The neuromatrix, or "pain matrix", is a network of cortical brain areas which is activated by noxious as well as salient somatosensory stimulation. This has been studied in mice and humans using blood oxygenation level-dependent (BOLD) fMRI. Here we demonstrate that BOLD effects observed in the murine neuromatrix in response to salient somatosensory stimuli are prone to reflect mean arterial blood pressure (MABP) changes, rather than neural activity. We show that a standard electrostimulus typically used in murine somatosensory fMRI can induce substantial elevations in MABP. Equivalent drug-induced MABP changes - without somatosensory stimulation - evoked BOLD patterns in the neuromatrix strikingly similar to those evoked by electrostimulation. This constitutes a serious caveat for murine fMRI. The regional specificity of these BOLD patterns can be attributed to the co-localization of the neuromatrix with large draining veins. Based on these findings we propose a cardiovascular support mechanism whereby abrupt elevations in MABP provide additional energy supply to the neuromatrix and other essential brain areas in fight-or-flight situations., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
49. Interpretation of functional renal MRI findings: Where physiology and imaging sciences need to talk across domains.
- Author
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Brix S, Cantow K, Flemming B, Pohlmann A, Niendorf T, and Seeliger E
- Subjects
- Animals, Kidney Function Tests, Magnetic Resonance Imaging, Rats, Viscosity, Contrast Media, Kidney
- Published
- 2018
- Full Text
- View/download PDF
50. Myocardial Effective Transverse Relaxation Time T 2 * is Elevated in Hypertrophic Cardiomyopathy: A 7.0 T Magnetic Resonance Imaging Study.
- Author
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Huelnhagen T, Ku MC, Reimann HM, Serradas Duarte T, Pohlmann A, Flemming B, Seeliger E, Eichhorn C, A Ferrari V, Prothmann M, Schulz-Menger J, and Niendorf T
- Subjects
- Adult, Cardiomyopathy, Hypertrophic physiopathology, Diastole, Female, Heart physiopathology, Humans, Male, Middle Aged, Systole, Cardiomyopathy, Hypertrophic diagnostic imaging, Heart diagnostic imaging, Magnetic Resonance Imaging methods
- Abstract
Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the myocardium and bares the risk of progression to heart failure or sudden cardiac death. Identifying patients at risk remains an unmet need. Recognizing the dependence of microscopic susceptibility on tissue microstructure and on cardiac macromorphology we hypothesized that myocardial T
2 * might be altered in HCM patients compared to healthy controls. To test this hypothesis, myocardial T2 * -mapping was conducted at 7.0 Tesla to enhance T2 * -contrast. 2D CINE T2 * -mapping was performed in healthy controls and HCM patients. To ensure that T2 * is not dominated by macroscopic magnetic field inhomogeneities, volume selective B0 shimming was applied. T2 * changes in the interventricular septum across the cardiac cycle were analyzed together with left ventricular radius and ventricular septal wall thickness. The results show that myocardial T2 * is elevated throughout the cardiac cycle in HCM patients compared to healthy controls. A mean septal T2 * = 13.7 ± 1.1 ms (end-systole: T2 * ,systole = 15.0 ± 2.1, end-diastole: T2 * ,diastole = 13.4 ± 1.3 ms, T2 * ,systole /T2 * ,diastole ratio = 1.12) was observed in healthy controls. For HCM patients a mean septal T2 * = 17.4 ± 1.4 ms (end-systole: T2 * ,systole = 17.7 ± 1.2 ms, end-diastole: T2 * ,diastole = 16.2 ± 2.5 ms, T2 * ,systole /T2 * ,diastole ratio = 1.09) was found. Our preliminary results provide encouragement that assessment of T2 * and its changes across the cardiac cycle may benefit myocardial tissue characterization in HCM.- Published
- 2018
- Full Text
- View/download PDF
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