scholarly journals Analysis Protocols for MRI Mapping of the Blood Oxygenation–Sensitive Parameters T2* and T2 in the Kidney

2021 ◽  
pp. 591-610
Author(s):  
João S. Periquito ◽  
Ludger Starke ◽  
Carlota M. Santos ◽  
Andreia C. Freitas ◽  
Nuno Loução ◽  
...  
Keyword(s):  
Data Analysis ◽  
Model Fitting ◽  
Kidney Injury ◽  
Blood Oxygenation ◽  
The European Union ◽  
Contrast Mechanism ◽  
Oxygenation Level ◽  
Quality Checks ◽  
Renal Mri ◽  
Sensitive Parameters

AbstractRenal hypoxia is generally accepted as a key pathophysiologic event in acute kidney injury of various origins and has also been suggested to play a role in the development of chronic kidney disease. Here we describe step-by-step data analysis protocols for MRI monitoring of renal oxygenation in rodents via the deoxyhemoglobin concentration sensitive MR parameters T2* and T2—a contrast mechanism known as the blood oxygenation level dependent (BOLD) effect.This chapter describes how to use the analysis tools provided by vendors of animal and clinical MR systems, as well as how to develop an analysis software. Aspects covered are: data quality checks, data exclusion, model fitting, fitting algorithm, starting values, effects of multiecho imaging, and result validation.This chapter is based upon work from the PARENCHIMA COST Action, 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 two separate chapters describing the basic concept and data analysis.

scholarly journals Experimental Protocol for MRI Mapping of the Blood Oxygenation-Sensitive Parameters T2* and T2 in the Kidney

2021 ◽  
pp. 403-417
Author(s):  
Andreas Pohlmann ◽  
Kaixuan Zhao ◽  
Sean B. Fain ◽  
Pottumarthi V. Prasad ◽  
Thoralf Niendorf
Keyword(s):  
Kidney Injury ◽  
Absolute Quantification ◽  
Blood Oxygenation ◽  
The European Union ◽  
Experimental Protocol ◽  
Contrast Mechanism ◽  
Oxygenation Level ◽  
Fraction Of Inspired Oxygen ◽  
Renal Mri

AbstractRenal hypoxia is generally accepted as a key pathophysiologic event in acute kidney injury of various origins, and has also been suggested to play a role in the development of chronic kidney disease. Here we describe a step-by-step experimental protocol for indirect monitoring of renal blood oxygenation in rodents via the deoxyhemoglobin sensitive MR parameters T2* and T2—a contrast mechanism known as the blood oxygenation level dependent (BOLD) effect. Since an absolute quantification of renal oxygenation from T2*/T2 remains challenging, the effects of controlled and standardized variations in the fraction of inspired oxygen are used for bench marking. This MRI method may be useful for investigating renal blood oxygenation of small rodents in vivo under various experimental (patho)physiological conditions.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 experimental protocol chapter is complemented by two separate chapters describing the basic concept and data analysis.

scholarly journals MRI Mapping of the Blood Oxygenation Sensitive Parameter T2* in the Kidney: Basic Concept

2021 ◽  
pp. 171-185
Author(s):  
Lu-Ping Li ◽  
Bradley Hack ◽  
Erdmann Seeliger ◽  
Pottumarthi V. Prasad
Keyword(s):  
Data Acquisition ◽  
Blood Oxygenation ◽  
The European Union ◽  
Noninvasive Method ◽  
Bold Mri ◽  
Oxygenation Level ◽  
Technical Issues ◽  
Renal Mri ◽  
The Cost

AbstractThe 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 pO2 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.

scholarly journals Sodium (23Na) MRI of the Kidney: Basic Concept

2021 ◽  
pp. 257-266
Author(s):  
James T. Grist ◽  
Esben Søvsø Hansen ◽  
Frank G. Zöllner ◽  
Christoffer Laustsen
Keyword(s):  
Data Analysis ◽  
Renal Diseases ◽  
The European Union ◽  
Key Indicator ◽  
Sodium Gradient ◽  
Sodium Imaging ◽  
Renal Mri ◽  
The Cost ◽  
Sodium Handling ◽  
23Na Mri

AbstractThe handling of sodium by the renal system is a key indicator of renal function. Alterations in the corticomedullary distribution of sodium are considered important indicators of pathology in renal diseases. The derangement of sodium handling can be noninvasively imaged using sodium magnetic resonance imaging (23Na MRI), with data analysis allowing for the assessment of the corticomedullary sodium gradient. Here we introduce sodium imaging, describe the existing methods, and give an overview of preclinical sodium imaging applications to illustrate the utility and applicability of this technique for measuring renal sodium handling.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.

scholarly journals Quantitative Assessment of Renal Perfusion and Oxygenation by Invasive Probes: Basic Concepts

2021 ◽  
pp. 89-107
Author(s):  
Kathleen Cantow ◽  
Roger G. Evans ◽  
Dirk Grosenick ◽  
Thomas Gladytz ◽  
Thoralf Niendorf ◽  
...  
Keyword(s):  
Kidney Injury ◽  
Tissue Perfusion ◽  
Renal Perfusion ◽  
Renal Tissue ◽  
Acute Injury ◽  
The European Union ◽  
Advantages And Disadvantages ◽  
Tissue Hypoperfusion ◽  
Renal Mri ◽  
The Cost

AbstractRenal 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.

scholarly journals Reversible (Patho)Physiologically Relevant Test Interventions: Rationale and Examples

2021 ◽  
pp. 57-73
Author(s):  
Kathleen Cantow ◽  
Mechthild Ladwig-Wiegard ◽  
Bert Flemming ◽  
Andrea Fekete ◽  
Adam Hosszu ◽  
...  
Keyword(s):  
Kidney Injury ◽  
Renal Tissue ◽  
Renal Hemodynamics ◽  
Acute Injury ◽  
The European Union ◽  
Tissue Hypoperfusion ◽  
Renal Mri ◽  
The Individual ◽  
The Cost ◽  
Specific Control

AbstractRenal 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.

scholarly journals Angiotensin II Decreases the Renal MRI Blood Oxygenation Level–Dependent Signal

Hypertension ◽  
2006 ◽  
Vol 47 (6) ◽  
pp. 1062-1066 ◽  
Author(s):  
Hartmut Schachinger ◽  
Markus Klarhöfer ◽  
Lilly Linder ◽  
Jürgen Drewe ◽  
Klaus Scheffler
Keyword(s):  
Angiotensin Ii ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Dependent Signal ◽  
Renal Mri

scholarly journals Functional mapping in the human brain using high magnetic fields

1999 ◽  
Vol 354 (1387) ◽  
pp. 1195-1213 ◽  
Author(s):  
Kamil Ugurbil ◽  
Hu Xiaoping ◽  
Chen Wei ◽  
Xiao-Hong Zhu ◽  
Seong-Gi Kim ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Human Brain ◽  
Ocular Dominance ◽  
Blood Oxygenation ◽  
Functional Mapping ◽  
High Magnetic Fields ◽  
Single Subjects ◽  
Contrast Mechanism ◽  
Oxygenation Level ◽  
Magnetic Resonance Imaging Mri

An avidly pursued new dimension in magnetic resonance imaging (MRI) research is the acquisition of physiological and biochemical information non–invasively using the nuclear spins of the water molecules in the human body. In this trial, a recent and unique accomplishment was the introduction of the ability to map human brain function non–invasively. Today, functional images with subcentimetre resolution of the entire human brain can be generated in single subjects and in data acquisition times of several minutes using 1.5 tesla (T) MRI scanners that are often used in hospitals for clinical purposes. However, there have been accomplishments beyond this type of imaging using significantly higher magnetic fields such as 4 T. Efforts for developing high magnetic field human brain imaging and functional mapping using MRI (fMRI) were undertaken at about the same time. It has been demonstrated that high magnetic fields result in improved contrast and, more importantly, in elevated sensitivity to capillary level changes coupled to neuronal activity in the blood oxygenation level dependent (BOLD) contrast mechanism used in fMRI. These advantages have been used to generate, for example, high resolution functional maps of ocular dominance columns, retinotopy within the small lateral geniculate nucleus, true single–trial fMRI and early negative signal changes in the temporal evolution of the BOLD signal. So far these have not been duplicated or have been observed as significantly weaker effects at much lower field strengths. Some of these high–field advantages and accomplishments are reviewed in this paper.

scholarly journals Monitoring Renal Hemodynamics and Oxygenation by Invasive Probes: Experimental Protocol

2021 ◽  
pp. 327-347
Author(s):  
Kathleen Cantow ◽  
Mechthild Ladwig-Wiegard ◽  
Bert Flemming ◽  
Andreas Pohlmann ◽  
Thoralf Niendorf ◽  
...  
Keyword(s):  
Small Animal ◽  
Kidney Injury ◽  
Renal Perfusion ◽  
Renal Tissue ◽  
Renal Hemodynamics ◽  
Acute Injury ◽  
The European Union ◽  
Experimental Protocol ◽  
Integrative Physiology ◽  
Renal Mri

AbstractRenal 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.

scholarly journals Sodium (23Na) MRI of the Kidney: Experimental Protocol

2021 ◽  
pp. 473-480
Author(s):  
James T. Grist ◽  
Esben Søvsø Hansen ◽  
Frank G. Zöllner ◽  
Christoffer Laustsen
Keyword(s):  
Kidney Injury ◽  
The European Union ◽  
Experimental Protocol ◽  
European Cooperation ◽  
Sodium Gradient ◽  
Renal Mri ◽  
The Individual ◽  
Sodium Handling ◽  
23Na Mri ◽  
Protocol Review

AbstractSodium handling is a key physiological hallmark of renal function. Alterations are generally considered a pathophysiologic event associated with kidney injury, with disturbances in the corticomedullary sodium gradient being indicative of a number of conditions. This experimental protocol review describes the individual steps needed to perform 23Na MRI; allowing accurate monitoring of the renal sodium distribution in a step-by-step experimental protocol for rodents.This chapter is based upon work from the PARENCHIMA COST Action, 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 two separate chapters describing the basic concept and data analysis.

scholarly journals Subsegmentation of the Kidney in Experimental MR Images Using Morphology-Based Regions-of-Interest or Multiple-Layer Concentric Objects

2021 ◽  
pp. 549-564
Author(s):  
Leili Riazy ◽  
Bastien Milani ◽  
João S. Periquito ◽  
Kathleen Cantow ◽  
Thoralf Niendorf ◽  
...  
Keyword(s):  
Sodium Concentration ◽  
Magnetic Resonance Images ◽  
Blood Oxygenation ◽  
Regions Of Interest ◽  
The European Union ◽  
Tissue Microstructure ◽  
Renal Mri ◽  
Anatomic Locations ◽  
The Cost ◽  
Changes Over Time

AbstractFunctional 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.

Sign in / Sign up

Export Citation Format

Share Document