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  • 1
    In: Critical Care, Springer Science and Business Media LLC, Vol. 26, No. 1 ( 2022-09-01)
    Abstract: Renal hypoperfusion has been suggested to contribute to the development of acute kidney injury (AKI) in critical COVID-19. However, limited data exist to support this. We aim to investigate the differences in renal perfusion, oxygenation and water diffusion using multiparametric magnetic resonance imaging in critically ill COVID-19 patients with and without AKI. Methods A prospective case–control study where patients without prior kidney disease treated in intensive care for respiratory failure due to COVID-19 were examined. Kidney Disease: Improving Global Outcomes Creatinine criteria were used for group allocation. Main comparisons were tested using Mann–Whitney U test. Results Nineteen patients were examined, ten with AKI and nine without AKI. Patients with AKI were examined in median 1 [0–2] day after criteria fulfillment. Age and baseline Plasma-Creatinine were similar in both groups. Total renal blood flow was lower in patients with AKI compared with patients without (median 645 quartile range [423–753] vs. 859 [746–920] ml/min, p  = 0.037). Regional perfusion was reduced in both cortex (76 [51–112] vs. 146 [123–169] ml/100 g/min, p  = 0.015) and medulla (28 [18–47] vs. 47 [38–73] ml/100 g/min, p  = 0.03). Renal venous saturation was similar in both groups (72% [64–75] vs. 72% [63–84] , ns.), as was regional oxygenation ( R 2 *) in cortex (17 [16–19] vs. 17 [16–18] 1/s, ns.) and medulla (29 [24–39] vs. 27 [23–29] 1/s, ns.). Conclusions In critically ill COVID-19 patients with AKI, the total, cortical and medullary renal blood flows were reduced compared with similar patients without AKI, whereas no differences in renal oxygenation were demonstrable in this setting. Trial registration ClinicalTrials ID: NCT02765191 , registered May 6 2014 and updated May 7 2020. Graphic Abstract
    Type of Medium: Online Resource
    ISSN: 1364-8535
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2051256-9
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  • 2
    In: Physiology, American Physiological Society, Vol. 38, No. S1 ( 2023-05)
    Abstract: Study objective: To investigate if there are any differences in total renal blood flow, regional renal perfusion, renal oxygenation or renal tissue properties, studied by non-invasive MRI, in patients having recovered from severe COVID-19 with different grades of acute kidney injury (AKI). Hypothesis: We hypothesize that the decrease in renal blood flow and perfusion that our research group have previously found in severe COVID-19 patients with AKI 1 may persist together with possible renal edema and development of fibrosis. Material and methods: We identified patients with AKI grade 3 from a cohort of patients previously treated in the intensive care unit for severe COVID-19 with respiratory failure. These patients were matched to possible extent regarding age, sex, height, weight, body mass index (BMI) and body surface area (BSA) with patients from the same cohort that had AKI grade 1 and patients that did not have AKI. A total of 22 patients were included. Because of common occurrence of oliguria without a reduction of glomerular filtration, AKI grade was determined using the Kidney Disease Improving Global Outcome (KDIGO) creatinine criteria only. All patients had a record of a plasma creatinine inside normal range within two years prior to ICU care, and had no history of renal disease. Comorbidities were common in the study population. Follow up examination was performed approximately five months after the patients were admitted the ICU. Results: Significant differences in cortical and medullary ADC were demonstrated between the study groups. Both cortical and medullary ADC was significantly reduced in the ‘AKI grade 3’ group compared to the ‘no AKI’ group and the ‘AKI grade 1’ group. Total renal blood flow was significantly lower in the ‘AKI grade 3’ group compared to the ‘no AKI’ group and global renal perfusion was significantly lower in the ‘AKI grade 3’ group compared to the ‘no AKI’ and ‘AKI grade 1’ groups. No significant differences in either cortical or medullary perfusion were seen between the groups. Cortical and medullary oxygenation and renal vein oxygen saturation did not differ significantly between the groups. Conclusion: In this study we demonstrates that, approximately five months after intensive care for severe COVID-19, patients that had high grades of AKI during hospitalization have reduced cortical and medullary ADC together with reduced total renal blood flow and global renal perfusion compared to similar patients that did not have AKI. These findings might indicate development of renal fibrosis. No differences regarding renal oxygenation were observed between the studied groups. 1. Luther T, Eckerbom P, Cox E, Lipcsey M, Bulow S, Hultstrom M, et al. Decreased renal perfusion during acute kidney injury in critical COVID-19 assessed by magnetic resonance imaging: a prospective case control study. Crit Care. 2022;26(1):262. Public and private funding sources. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
    Type of Medium: Online Resource
    ISSN: 1548-9213 , 1548-9221
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2018
    In:  The FASEB Journal Vol. 32, No. S1 ( 2018-04)
    In: The FASEB Journal, Wiley, Vol. 32, No. S1 ( 2018-04)
    Type of Medium: Online Resource
    ISSN: 0892-6638 , 1530-6860
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 1468876-1
    SSG: 12
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  • 4
    In: The FASEB Journal, Wiley, Vol. 28, No. S1 ( 2014-04)
    Type of Medium: Online Resource
    ISSN: 0892-6638 , 1530-6860
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 1468876-1
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    American Physiological Society ; 2019
    In:  American Journal of Physiology-Renal Physiology Vol. 316, No. 4 ( 2019-04-01), p. F693-F702
    In: American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 316, No. 4 ( 2019-04-01), p. F693-F702
    Abstract: Noninvasive methods of magnetic resonance imaging (MRI) can quantify parameters of kidney function. The main purpose of this study was to determine baseline values of such parameters in healthy volunteers. In 28 healthy volunteers (15 women and 13 men), arterial spin labeling to estimate regional renal perfusion, blood oxygen level-dependent transverse relaxation rate (R 2 *) to estimate oxygenation, and apparent diffusion coefficient (ADC), true diffusion (D), and longitudinal relaxation time (T 1 ) to estimate tissue properties were determined bilaterally in the cortex and outer and inner medulla. Additionally, phase-contrast MRI was applied in the renal arteries to quantify total renal blood flow. The results demonstrated profound gradients of perfusion, ADC, and D with highest values in the kidney cortex and a decrease towards the inner medulla. R 2 * and T 1 were lowest in kidney cortex and increased towards the inner medulla. Total renal blood flow correlated with body surface area, body mass index, and renal volume. Similar patterns in all investigated parameters were observed in women and men. In conclusion, noninvasive MRI provides useful tools to evaluate intrarenal differences in blood flow, perfusion, diffusion, oxygenation, and structural properties of the kidney tissue. As such, this experimental approach has the potential to advance our present understanding regarding normal physiology and the pathological processes associated with acute and chronic kidney disease.
    Type of Medium: Online Resource
    ISSN: 1931-857X , 1522-1466
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2019
    detail.hit.zdb_id: 1477287-5
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  • 6
    Online Resource
    Online Resource
    American Physiological Society ; 2020
    In:  American Journal of Physiology-Renal Physiology Vol. 319, No. 6 ( 2020-12-01), p. F966-F978
    In: American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 319, No. 6 ( 2020-12-01), p. F966-F978
    Abstract: Circadian regulation of kidney function is involved in maintaining whole body homeostasis, and dysfunctional circadian rhythm can potentially be involved in disease development. Magnetic resonance imaging (MRI) provides reliable and reproducible repetitive estimates of kidney function noninvasively without the risk of adverse events associated with contrast agents and ionizing radiation. The purpose of this study was to estimate circadian variations in kidney function in healthy human subjects with MRI and to relate the findings to urinary excretions of electrolytes and markers of kidney function. Phase-contrast imaging, arterial spin labeling, and blood oxygen level-dependent transverse relaxation rate (R 2 *) mapping were used to assess total renal blood flow and regional perfusion as well as intrarenal oxygenation in eight female and eight male healthy volunteers every fourth hour during a 24-h period. Parallel with MRI scans, standard urinary and plasma parameters were quantified. Significant circadian variations of total renal blood flow were found over 24 h, with increasing flow from noon to midnight and decreasing flow during the night. In contrast, no circadian variation in intrarenal oxygenation was detected. Urinary excretions of electrolytes, osmotically active particles, creatinine, and urea all displayed circadian variations, peaking during the afternoon and evening hours. In conclusion, total renal blood flow and kidney function, as estimated from excretion of electrolytes and waste products, display profound circadian variations, whereas intrarenal oxygenation displays significantly less circadian variation.
    Type of Medium: Online Resource
    ISSN: 1931-857X , 1522-1466
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2020
    detail.hit.zdb_id: 1477287-5
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  • 7
    Online Resource
    Online Resource
    Wiley ; 2013
    In:  Clinical and Experimental Pharmacology and Physiology Vol. 40, No. 2 ( 2013-02), p. 158-167
    In: Clinical and Experimental Pharmacology and Physiology, Wiley, Vol. 40, No. 2 ( 2013-02), p. 158-167
    Type of Medium: Online Resource
    ISSN: 0305-1870
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2020033-X
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  • 8
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 55, No. 2 ( 2022-02), p. 323-335
    Abstract: Phase‐contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC‐MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC‐MRI as a clinically useful tool. Purpose To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC‐MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies. Study Type Systematic consensus process using a modified Delphi method. Population Not applicable. Sequence Field/Strength Renal fast gradient echo‐based 2D PC‐MRI. Assessment An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4–10) years of experience in 2D PC‐MRI formulated consensus statements on renal 2D PC‐MRI in two rounds of surveys. Starting from a recently published systematic review article, literature‐based and data‐driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated. Statistical Tests Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60–74% agreement among the experts. Results Among 60 statements, 57 (95%) achieved consensus after the second‐round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC‐MRI data acquisition, processing, and reporting. Data Conclusion These recommendations might promote a widespread adoption of renal PC‐MRI, and may help foster the set‐up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC‐MRI. Level of Evidence 1 Technical Efficacy Stage 1
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 1497154-9
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  • 9
    In: Magnetic Resonance Materials in Physics, Biology and Medicine, Springer Science and Business Media LLC, Vol. 33, No. 1 ( 2020-02), p. 199-215
    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.
    Type of Medium: Online Resource
    ISSN: 0968-5243 , 1352-8661
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 1502491-X
    SSG: 11
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