Basic principles and new advances in kidney imaging

Caroli, Anna; Remuzzi, Andrea; Lerman, Lilach O.

doi:10.1016/j.kint.2021.04.032

Cited by 31 publications

(15 citation statements)

References 97 publications

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“…Recognizing these limitations, synergistic approaches that include magnetic resonance imaging (MRI) are called for 1,3,5,9–13 . MRI facilitates the non‐invasive assessment of several structural and functional kidney features 12–20 . Among these, kidney size (KS) has gained substantial interest as a marker to diagnose and stage kidney disorders since KS changes are associated with several renal pathologies 21–23 …”

Section: Introductionmentioning

confidence: 99%

“…1,3,5,[9][10][11][12][13] MRI facilitates the non-invasive assessment of several structural and functional kidney features. [12][13][14][15][16][17][18][19][20] Among these, kidney size (KS) has gained substantial interest as a marker to diagnose and stage kidney disorders since KS changes are associated with several renal pathologies. [21][22][23] What has not been considered, however, is that KS is also crucial for the interpretation of MRI-based assessments of renal tissue oxygenation obtained by blood oxygenation level-dependent (BOLD) MRI techniques.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring kidney size to interpret MRI‐based assessment of renal oxygenation in acute pathophysiological scenarios

et al. 2022

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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 T 2 * 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 T 2 * and T 2 changes in acute pathophysiological scenarios. Methods: KS was determined from T 2 *, T 2 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 O 2 saturation of hemoglobin from changes in T 2 * and KS.Results: Upon aortic occlusion KS decreased; this correlated with a decrease in T 2 *, T 2 . Upon renal vein occlusion KS increased; this negatively correlated with a decrease in T 2 *, T 2 . Upon simultaneous occlusion of both vessels KS remained unchanged; there was no correlation with decreased T 2 *, T 2 . Hypoxemia induced mild reductions in KS and T 2 *, T 2 . Administration of an X-ray contrast medium induced sustained KS increase, with an initial increase in T 2 *, T 2 followed by a decrease. Furosemide caused T 2 *, T 2 elevation and a minor increase in KS. Model calculations yielded physiologically plausible calibration ratios for T 2 *. Conclusion: Monitoring KS allows physiological interpretation of acute renal oxygenation changes obtained by T 2 *, T 2 . KS monitoring should accompany MRIoximetry, for new insights into renal pathophysiology and swift translation into human studies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Monitoring kidney size to interpret MRI‐based assessment of renal oxygenation in acute pathophysiological scenarios

et al. 2022

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“…First, cell density may need to increase to a certain level to be detected by ADC changes. Second, besides apparent water diffusion, ADC also reflects blood flow in the microcirculation and tubular fluid flow in the kidney [38,39]. Hence, more sophisticated DWI models that deal with water diffusion, microcirculation and tubular flow separately such as IVIM or less constrained, data-driven non-negative least squares (NNLS) continuum approaches for renal DWI analysis should be employed in future studies [56][57][58][59].…”

Section: Discussionmentioning

confidence: 99%

“…In a study of kidney transplantation, the abrogation of the physiological gradient of T 2 across the kidney reflected the loss of tubular function and identified kidney grafts with acute rejection [36]. Restricted water diffusion, which manifests itself in a reduction of the apparent diffusion coefficient (ADC), has been reported in AKI when the interstitial space was narrowed due to infiltration of inflammatory cells or fibrosis [37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Parametric MRI Detects Aristolochic Acid Induced Acute Kidney Injury

et al. 2022

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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. T2 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.

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“…As a result, imaging modalities are now increasingly used in nephrology. They allow in vivo assessment of physiological, pathophysiological, and pharmacological processes at kidney tissue level ( Caroli et al, 2021 ; Klinkhammer et al, 2021 ). As such, imaging is becoming a powerful tool to improve our understanding of SGLT2i-pharmacology and is therefore anticipated to result in more effective treatment of the individual patient.…”

Section: Introductionmentioning

confidence: 99%

Current Use and Complementary Value of Combining in Vivo Imaging Modalities to Understand the Renoprotective Effects of Sodium-Glucose Cotransporter-2 Inhibitors at a Tissue Level

Hoek

Stevens

2022

Front. Pharmacol.

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Sodium-glucose cotransporter-2 inhibitors (SGLT2i) were initially developed to treat diabetes and have been shown to improve renal and cardiovascular outcomes in patients with- but also without diabetes. The mechanisms underlying these beneficial effects are incompletely understood, as is the response variability between- and within patients. Imaging modalities allow in vivo quantitative assessment of physiological, pathophysiological, and pharmacological processes at kidney tissue level and are therefore increasingly being used in nephrology. They provide unique insights into the renoprotective effects of SGLT2i and the variability in response and may thus contribute to improved treatment of the individual patient. In this mini-review, we highlight current work and opportunities of renal imaging modalities to assess renal oxygenation and hypoxia, fibrosis as well as interaction between SGLT2i and their transporters. Although every modality allows quantitative assessment of particular parameters of interest, we conclude that especially the complementary value of combining imaging modalities in a single clinical trial aids in an integrated understanding of the pharmacology of SGLT2i and their response variability.

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Basic principles and new advances in kidney imaging

Cited by 31 publications

References 97 publications

Monitoring kidney size to interpret MRI‐based assessment of renal oxygenation in acute pathophysiological scenarios

Monitoring kidney size to interpret MRI‐based assessment of renal oxygenation in acute pathophysiological scenarios

Parametric MRI Detects Aristolochic Acid Induced Acute Kidney Injury

Current Use and Complementary Value of Combining in Vivo Imaging Modalities to Understand the Renoprotective Effects of Sodium-Glucose Cotransporter-2 Inhibitors at a Tissue Level

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