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Selby NM, Francis ST. Assessment of Acute Kidney Injury using MRI. J Magn Reson Imaging 2024. [PMID: 38334370 DOI: 10.1002/jmri.29281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/10/2024] Open
Abstract
There has been growing interest in using quantitative magnetic resonance imaging (MRI) to describe and understand the pathophysiology of acute kidney injury (AKI). The ability to assess kidney blood flow, perfusion, oxygenation, and changes in tissue microstructure at repeated timepoints is hugely appealing, as this offers new possibilities to describe nature and severity of AKI, track the time-course to recovery or progression to chronic kidney disease (CKD), and may ultimately provide a method to noninvasively assess response to new therapies. This could have significant clinical implications considering that AKI is common (affecting more than 13 million people globally every year), harmful (associated with short and long-term morbidity and mortality), and currently lacks specific treatments. However, this is also a challenging area to study. After the kidney has been affected by an initial insult that leads to AKI, complex coexisting processes ensue, which may recover or can progress to CKD. There are various preclinical models of AKI (from which most of our current understanding derives), and these differ from each other but more importantly from clinical AKI. These aspects are fundamental to interpreting the results of the different AKI studies in which renal MRI has been used, which encompass different settings of AKI and a variety of MRI measures acquired at different timepoints. This review aims to provide a comprehensive description and interpretation of current studies (both preclinical and clinical) in which MRI has been used to assess AKI, and discuss future directions in the field. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 3.
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Affiliation(s)
- Nicholas M Selby
- Centre for Kidney Research and Innovation, Academic Unit for Translational Medical Sciences, School of Medicine, University of Nottingham, Nottingham, UK
- Department of Renal Medicine, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK
| | - Susan T Francis
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and The University of Nottingham, Nottingham, UK
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Lee SK, Lee J, Jang S, Lee E, Jeon CY, Lim KS, Jin YB, Choi J. Renal Diffusion-Weighted Imaging in Healthy Dogs: Reproducibility, Test-Retest Repeatability, and Selection of the Optimal b-value Combination. Front Vet Sci 2021; 8:641971. [PMID: 34277748 PMCID: PMC8282824 DOI: 10.3389/fvets.2021.641971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
Diffusion-weighted imaging (DWI) magnetic resonance imaging can evaluate alterations in the microstructure of the kidney. The purpose of this study was to assess the apparent diffusion coefficient (ADC) and the intravoxel incoherent motion model (IVIM) parameters of a normal kidney in healthy dogs, to evaluate the effect of b-value combinations on the ADC value, and the reproducibility and test-retest repeatability in monoexponential and IVIM analysis. In this experimental study, the ADC, pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f p) were measured from both kidneys in nine healthy beagles using nine b-values (b = 0, 50, 70, 100, 150, 200, 500, 800, and 1,000 s/mm2) twice with a 1-week interval between measurements. Interobserver and intraobserver reproducibility, and test-retest repeatability of the measurements were calculated. ADC values were measured using 10 different b-value combinations consisting of three b-values each, and were compared to the ADC obtained from nine b-values. All the ADC, D, D*, and f p values measured from the renal cortex, medulla, and the entire kidney had excellent interobserver and intraobserver reproducibility, and test-retest repeatability. The ADC obtained from a b-value combination of 0, 100, and 800 s/mm2 had the highest intraclass correlation coefficient with the ADC from nine b-values. The results of this study indicated that DWI MRI using multiple b-values is feasible for the measurement of ADC and IVIM parameters with high reproducibility and repeatability in the kidneys of healthy dogs. A combination of b = 0, 100, and 800 s/mm2 can be used for ADC measurements when multiple b-values are not available in dogs.
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Affiliation(s)
- Sang-Kwon Lee
- College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
| | - Juryeoung Lee
- College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
| | - Seolyn Jang
- College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
| | - Eunji Lee
- College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
| | - Chang-Yeop Jeon
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, South Korea
| | - Kyung-Seoub Lim
- Futuristic Animal Resource and Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, South Korea
| | - Yeung Bae Jin
- College of Veterinary Medicine, Gyeongsang National University, Jinju, South Korea
| | - Jihye Choi
- College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, South Korea
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Lee G, Jeon S, Lee SK, Cheon B, Moon S, Park JG, Cho KO, Choi J. Quantitative evaluation of renal parenchymal perfusion using contrast-enhanced ultrasonography in renal ischemia-reperfusion injury in dogs. J Vet Sci 2018; 18:507-514. [PMID: 28385013 PMCID: PMC5746444 DOI: 10.4142/jvs.2017.18.4.507] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 12/16/2022] Open
Abstract
This study evaluated whether renal perfusion changes can be noninvasively estimated by using contrast-enhanced ultrasonography (CEUS) in renal ischemia-reperfusion injury and investigated the correlation between renal perfusion measured by CEUS and necrosis and apoptosis of renal tubular epithelial cells. In six dogs with experimentally induced renal ischemia-reperfusion injury, changes in time to peak intensity, peak intensity, and area under the curve were measured on CEUS. Peak intensity and area under the curve of the renal cortex began to decrease on day 1 (about 20% lower than baseline) and reached the lowest levels (about 50% of baseline) on day 4. They then gradually increased until day 10, at which time peak intensity was about 87% and area under the curve was about 95% of baseline; neither fully recovered. Both parameters were strongly correlated with the necrosis scores on histopathologic examination on day 4 (r = −0.810 of peak intensity and r = −0.886 of area under the curve). CEUS allowed quantitative evaluation of perfusion changes in acute renal ischemia-reperfusion injury, and CEUS results were correlated with renal tubular damage on histopathologic examination. Thus, CEUS could be a noninvasive, quantitative diagnostic method for determining progress of renal ischemia-reperfusion injury.
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Affiliation(s)
- Gahyun Lee
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Sunghoon Jeon
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Sang-Kwon Lee
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Byunggyu Cheon
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Sohyeon Moon
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Jun-Gyu Park
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Kyoung-Oh Cho
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Jihye Choi
- College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
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Pan L, Chen J, Xing W, Xing Z, Zhang J, Peng Y, Zhang Z. Magnetic resonance imaging evaluation of renal ischaemia-reperfusion injury in a rabbit model. Exp Physiol 2017; 102:1000-1006. [PMID: 28470945 DOI: 10.1113/ep086203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 04/24/2017] [Indexed: 02/06/2023]
Abstract
NEW FINDINGS What is the central question of this study? Renal ischaemia-reperfusion injury occurs in various clinical settings. The clinical diagnosis of ischaemia-reperfusion injury is routinely based on biochemical and haematological tests, which cannot evaluate the function of a single kidney. New magnetic resonance imaging techniques to identify the pathophysiological changes in the renal outer medulla were evaluated. What is the main finding and its importance? This study demonstrated that susceptibility-weighted imaging is a feasible non-invasive tool for imaging and evaluating physipathological changes in the renal outer medulla after ischaemia-reperfusion injury. The aim was to evaluate the feasibility of susceptibility-weighted imaging (SWI) as a tool to identify the changes in the renal outer medulla (OM) in a rabbit model of renal ischaemia-reperfusion injury (IRI). New Zealand rabbits were used (control group n = 10; IRI group n = 40). The rabbits in the IRI group were subjected to left renal artery clamping for 60 min. T2-weighted (T2WI) and SWI examinations were performed at 1, 12, 24 or 48 h after reperfusion (each n = 10). After the examinations, the kidneys were submitted to histological evaluation. The contrast-to-noise ratio (CNR) for the left renal OM was measured using T2WI and SWI. The T2WI and SWI scores of the integrity of the renal OM were evaluated. There were significant differences between T2WI CNRs and SWI CNRs in the control group and the IRI 1, 12 and 48 h time points (all P < 0.05). No significant difference was found between T2WI and SWI CNRs at IRI 24 h (P > 0.05). The mean SWI scores of renal OM in the IRI 1 and 12 h subgroups were both significantly lower than that in the control group (all P < 0.05). The only significant difference in the mean T2WI scores of renal OM was observed between the control and IRI 1 h groups (P < 0.05). Susceptibility-weighted imaging has a significant advantage in evaluation of healthy renal OM over conventional magnetic resonance imaging, and it is a feasible non-invasive tool for imaging and evaluating changes in the renal OM after IRI.
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Affiliation(s)
- Liang Pan
- Department of Radiology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China
| | - Jie Chen
- Department of Radiology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China.,Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, People's Republic of China
| | - Wei Xing
- Department of Radiology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China
| | - Zhaoyu Xing
- Department of Urology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China
| | - Jinggang Zhang
- Department of Radiology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China
| | - Yan Peng
- Department of Pathology, the Third Affiliated Hospital of Suzhou University, Changzhou, People's Republic of China
| | - Zhuoli Zhang
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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Dunn DP, Kelsey NR, Lee KS, Smith MP, Mortele KJ. Non-oncologic applications of diffusion-weighted imaging (DWI) in the genitourinary system. ACTA ACUST UNITED AC 2016; 40:1645-54. [PMID: 26109511 DOI: 10.1007/s00261-015-0471-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Diffusion-weighted imaging (DWI) has become an increasingly used tool in abdominal and pelvic magnetic resonance imaging (MRI), primarily in the oncologic setting. DWI sequences are being added to routine MRI protocols at many institutions, and as its use has spread, more non-oncologic applications have been explored. The purpose of this article is to provide a review of DWI applications in inflammatory, infectious, autoimmune-mediated, and ischemic processes affecting the genitourinary system.
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Affiliation(s)
- Dell P Dunn
- Department of Radiology, David Grant Medical Center, 101 Bodin Cir, Travis AFB, CA, 94535, USA,
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Rona G, Pasaoglu L, Ozkayar N, Ciliz D, Toprak U, Kaya T, Abat G. Functional evaluation of secondary renal amyloidosis with diffusion-weighted MR imaging. Ren Fail 2016; 38:249-55. [PMID: 26727603 DOI: 10.3109/0886022x.2015.1128252] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES This study evaluated whether diffusion-weighted magnetic resonance imaging (DW-MRI) can be used to diagnose secondary renal amyloidosis looking specifically at the diagnostic efficacy of two apparent diffusion coefficient (ADC) measurement methods as they were used with DW-MRI. METHODS The study included 24 amyloid nephropathy (AN) patients, 20 chronic kidney disease (CKD) patients, and 20 healthy volunteers (HV). ADC values were measured using two different methods: 1) the method of the region of interest indicators (ROIs) and 2) the method of drawing whole renal parenchyma (WP). The correlation between the two methods was evaluated. RESULTS ROIs could differentiate AN-CKD (p = 0.007). ROIs and WP could differentiate AN-HV (p < 0.05). However, none of the methods could differentiate CKD-HV (p > 0.05). The sensitivity and specificity of the ROIs method in differentiating AN from CKD patients for 1.8 × 10(-3) cutoff ADC values were 79% and 60% and for AN-HV patients 79% and 70%. ADC values of AN patients with GFR > 60 mL/min were lower than that of HV (p < 0.01). CONCLUSION DW-MRI is a useful and non-invasive diagnostic tool in diagnosing secondary renal amyloidosis and differentiating renal amyloidosis from other CKDs. ROIs had the highest sensitivity and specificity for assessing the involvement of renal amyloidosis. MRI diagnosis of AN may obviate a renal biopsy for diagnosis.
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Affiliation(s)
- Gunay Rona
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Lale Pasaoglu
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Nihal Ozkayar
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Deniz Ciliz
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Ugur Toprak
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Tunca Kaya
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
| | - Gizem Abat
- a Ankara Numune Egitim Ve Arastirma Hastanesi , Ankara , Turkey
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Hueper K, Peperhove M, Rong S, Gerstenberg J, Mengel M, Meier M, Gutberlet M, Tewes S, Barrmeyer A, Chen R, Haller H, Wacker F, Hartung D, Gueler F. T1-mapping for assessment of ischemia-induced acute kidney injury and prediction of chronic kidney disease in mice. Eur Radiol 2014; 24:2252-60. [DOI: 10.1007/s00330-014-3250-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 04/02/2014] [Accepted: 05/15/2014] [Indexed: 12/27/2022]
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Liss P, Cox EF, Eckerbom P, Francis ST. Imaging of intrarenal haemodynamics and oxygen metabolism. Clin Exp Pharmacol Physiol 2013; 40:158-67. [PMID: 23252679 DOI: 10.1111/1440-1681.12042] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/07/2012] [Accepted: 12/12/2012] [Indexed: 01/07/2023]
Abstract
The interruption of blood flow results in impaired oxygenation and metabolism. This can lead to electrophysiological changes, functional impairment and symptoms in quick succession. Quantitative measures of organ perfusion, perfusion reserve and tissue oxygenation are crucial to assess normal tissue metabolism and function. Magnetic resonance imaging (MRI) provides a number of quantitative methods to assess physiology in the kidney. Blood oxygenation level-dependent (BOLD) MRI provides a method for the assessment of oxygenation. Blood flow to the kidney can be assessed using phase contrast MRI. Dynamic contrast-enhanced MRI and arterial spin labelling (ASL) provide methods to assess tissue perfusion, ASL using the magnetization of endogenous water protons and thus providing a non-invasive method to assess perfusion. The application of diffusion-weighted MRI allows molecular motion in the kidney to be measured. Novel techniques can also be used to assess oxygenation in the renal arteries and veins and, combined with flow measures, provide an estimation of oxygen metabolism. Magnetic resonance imaging provides a synergy of non-invasive techniques to study renal function and the demand for these techniques is likely to be driven by the incentive to avoid the use of contrast media, to avoid radiation and to avoid complications with intervention procedures.
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Affiliation(s)
- Per Liss
- Department of Radiology, Center for Medical Imaging, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
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Rheinheimer S, Schneider F, Stieltjes B, Morath C, Zeier M, Kauczor HU, Hallscheidt P. IVIM-DWI of transplanted kidneys: reduced diffusion and perfusion dependent on cold ischemia time. Eur J Radiol 2012; 81:e951-6. [PMID: 22785337 DOI: 10.1016/j.ejrad.2012.06.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/15/2012] [Accepted: 06/17/2012] [Indexed: 12/28/2022]
Abstract
PURPOSE To evaluate the effect of cold ischemia time (CIT) of renal allografts on diffusion and perfusion using intravoxel incoherent motion (IVIM) derived parameters. MATERIAL AND METHODS A total of 37 patients with renal allografts (CIT: 27 <15 h, 10 ≥15 h) and 30 individuals with healthy kidneys were examined at 1.5 T using a single-shot echo-planar diffusion-weighted pulse sequence with nine b-values ranging from 0 to 800 s/mm(2). ADC, perfusion fraction f, and the diffusion coefficient D were calculated using the IVIM model. Parameters of allografts stratified by CIT were compared with healthy kidney groups using the Mann-Whitney U test for unpaired data. We computed the Spearman correlation coefficient for correlation with creatinine values. RESULTS ADC, D, and f of transplanted kidneys were significantly lower than in the healthy controls. The long-CIT group showed significantly lower diffusion parameters compared with the short-CIT group [mean±SD]: ADC: 1.63±0.14 μm(2)/ms, f: 11.90±5.22%, D: 1.55±0.25 μm(2)/ms versus ADC: 1.79±0.13 μm(2)/ms, f: 16.12±3.43%, D: 1.73±0.14 μm(2)/ms, P(ADC), (f), (D)<0.05. CONCLUSION Our results suggest that diffusion parameters, especially the ADC, depend on the CIT of the kidney allograft. Potentially, this stands for functional changes in renal allografts. Diffusion-weighted imaging could be used for follow-up examinations. Thus, diffusion parameters may help guide therapy in patients with delayed graft function.
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Affiliation(s)
- S Rheinheimer
- Diagnostic and Interventional Radiology, University of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany.
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Wang J, Zhang Y, Yang X, Wang X, Zhang J, Fang J, Jiang X. Time course study on the effects of iodinated contrast medium on intrarenal water transport function using diffusion-weighted MRI. J Magn Reson Imaging 2012; 35:1139-44. [DOI: 10.1002/jmri.23511] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 10/24/2011] [Indexed: 11/11/2022] Open
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Abstract
Applications of diffusion-weighted (DW) magnetic resonance (MR) imaging outside the brain have gained increasing importance in recent years. Owing to technical improvements in MR imaging units and faster sequences, the need for noninvasive imaging without contrast medium administration, mainly in patients with renal insufficiency, can be met successfully by applying this technique. DW MR imaging is quantified by the apparent diffusion coefficient (ADC), which provides information on diffusion and perfusion simultaneously. By using a biexponential fitting process of the DW MR imaging data, these two entities can be separated, because this type of fitting process can serve as an estimate of both the perfusion fraction and the true diffusion coefficient. DW MR imaging can be applied for functional evaluation of the kidneys in patients with acute or chronic renal failure. Impairment of renal function is accompanied by a decreased ADC. Acute ureteral obstruction leads to perfusion and diffusion changes in the affected kidney, and renal artery stenosis results in a decreased ADC. In patients with pyelonephritis, diffuse or focal changes in signal intensity are seen on the high-b-value images, with increased signal intensity corresponding to low signal intensity on the ADC map. The feasibility and reproducibility of DW MR imaging in patients with transplanted kidneys have already been demonstrated, and initial results seem to be promising for the assessment of allograft deterioration. Overall, performance of renal DW MR imaging, presuming that measurements are of high quality, will further boost this modality, particularly for early detection of diffuse renal conditions, as well as more accurate characterization of focal renal lesions.
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Affiliation(s)
- Harriet C Thoeny
- Department of Radiology, Neuroradiology and Nuclear Medicine, University of Bern, Inselspital, Freiburgstrasse 10, CH-3010 Bern, Switzerland.
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Cheung JS, Fan SJ, Chow AM, Zhang J, Man K, Wu EX. Diffusion tensor imaging of renal ischemia reperfusion injury in an experimental model. NMR IN BIOMEDICINE 2010; 23:496-502. [PMID: 20175152 DOI: 10.1002/nbm.1486] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Renal ischemia reperfusion injury (IRI) is a major cause of acute renal failure. It occurs in various clinical settings such as renal transplantation, shock and vascular surgery. Serum creatinine level has been used as an index for estimating the degree of renal functional loss in renal IRI. However, it only evaluates the global renal function. In this study, diffusion tensor imaging (DTI) was used to characterize renal IRI in an experimental rat model. Spin-echo echo-planar DTI with b-value of 300 s/mm(2) and 6 diffusion gradient directions was performed at 7 T in 8 Sprague-Dawley (SD) with 60-min unilateral renal IRI and 8 normal SD rats. Apparent diffusion coefficient (ADC), directional diffusivities and fractional anisotropy (FA) were measured at the acute stage of IRI. The IR-injured animals were also examined by diffusion-weighted imaging with 7 b-values up to 1000 s/mm(2) to estimate true diffusion coefficient (D(true)) and perfusion fraction (P(fraction)) using a bi-compartmental model. ADC of injured renal cortex (1.69 +/- 0.24 x 10(-3) mm(2)/s) was significantly lower (p < 0.01) than that of contralateral intact cortex (2.03 +/- 0.35 x 10(-3) mm(2)/s). Meanwhile, both ADC and FA of IR-injured medulla (1.37 +/- 0.27 x 10(-3) mm(2)/s and 0.28 +/- 0.04, respectively) were significantly less (p < 0.01) than those of contralateral intact medulla (2.01 +/- 0.38 x 10(-3) mm(2)/s and 0.36 +/- 0.04, respectively). The bi-compartmental model analysis revealed the decrease in D(true) and P(fraction) in the IR-injured kidneys. Kidney histology showed widespread cell swelling and erythrocyte congestion in both cortex and medulla, and cell necrosis/apoptosis and cast formation in medulla. These experimental findings demonstrated that DTI can probe both structural and functional information of kidneys following renal IRI.
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Affiliation(s)
- Jerry S Cheung
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Cheung JS, Fan SJ, Chow AM, Hui ES, Wu EX. In vivo DTI assessment of hepatic ischemia reperfusion injury in an experimental rat model. J Magn Reson Imaging 2009; 30:890-5. [PMID: 19787745 DOI: 10.1002/jmri.21917] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To investigate hepatic ischemia reperfusion injury (IRI) using diffusion tensor imaging (DTI). MATERIALS AND METHODS Ten Sprague-Dawley rats were scanned at 7 Tesla (T) with DTI using b-value of 1000 s/mm(2) and 6 gradient directions before, 2 h, and 1 day after 30-min total hepatic IRI. Apparent diffusion coefficient or mean diffusivity (MD), directional diffusivities and fractional anisotropy (FA) were measured. Seven of the animals were also examined with spin-echo echo-planar diffusion-weighted imaging (DWI) with seven b-values up to 2000 s/mm(2) to estimate the true diffusion coefficient (D), blood pseudodiffusion coefficient (D), and perfusion fraction (f) using a bi-compartmental model. RESULTS MD 2 h after IRI (0.77 +/- 0.07 x 10(-3) mm(2)/s) was significantly lower (P < 0.01) than that before (1.03 +/- 0.07 x 10(-3) mm(2)/s) and 1 day after IRI (1.01 +/- 0.05 x 10(-3) mm(2)/s). Meanwhile, FA 2 h after IRI (0.33 +/- 0.03) was significantly higher (P < 0.01) than that before (0.21 +/- 0.02) and 1 day after IRI (0.20 +/- 0.02). The bi-compartmental model analysis revealed the transient decrease in D, D and f 2 h after IRI. Liver histology showed the multifocal cell swelling 3 h after IRI and widespread cell necrosis/apoptosis 1 day after IRI. Sinusoidal narrowing and congestion of erythrocytes were also observed 3 h and 1 day after IRI. CONCLUSION DTI can characterize hepatic IRI by detecting the transient change in both MD and FA.
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Affiliation(s)
- Jerry S Cheung
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China
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Thoeny HC, Binser T, Roth B, Kessler TM, Vermathen P. Noninvasive Assessment of Acute Ureteral Obstruction with Diffusion-weighted MR Imaging: A Prospective Study. Radiology 2009; 252:721-8. [PMID: 19567650 DOI: 10.1148/radiol.2523082090] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Harriet C Thoeny
- Department of Radiology, Neuroradiology and Nuclear Medicine, University Hospital of Bern, Inselspital, Freiburgstrasse 10, CH-3010 Bern, Switzerland.
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Pei XL, Xie JX. Functional MRI: evaluation of chronic kidney disease with perfusion imaging. Acad Radiol 2009; 16:88-95. [PMID: 19064216 DOI: 10.1016/j.acra.2008.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 06/12/2008] [Accepted: 07/10/2008] [Indexed: 11/19/2022]
Abstract
RATIONALE AND OBJECTIVES To evaluate the functional alterations of chronic kidney disease (CKD) with magnetic resonance dynamic perfusion imaging. MATERIALS AND METHODS Twenty-one healthy subjects (42 kidneys) and 20 CKD patients (40 kidneys) underwent routine scans with fat-saturated T1-weighted fast low angle shot (FLASH) and true-fast imaging with steady-state precession (FISP) sequences followed by dynamic perfusion scans using a turbo-FLASH T1-weighted sequence. Signal intensity (SI) of the cortex and medulla on images was measured and plotted as a function of time. Peak height (P) and time to peak (T) of the cortex and medulla SI were estimated, and P/T ratio and the area under the time-intensity curves were calculated. We also tested the correlation between these data and serum creatinine (sCr) levels in patients. RESULTS P, P/T ratio, and the area under the curve of patients' cortex and medulla were significantly decreased compared to control subjects, and T was delayed. In patients, P and P/T ratio of the cortex and P of the medulla were negatively correlated with sCr levels (r = -0.469, r = -0.419, and r = -0.423, respectively; P < 0.01). CONCLUSION Renal dysfunction in CKD can be evaluated by magnetic resonance dynamic perfusion imaging.
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Affiliation(s)
- Xin-Long Pei
- Department of Radiology, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing, 100083, China
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Thoeny HC, De Keyzer F. Extracranial applications of diffusion-weighted magnetic resonance imaging. Eur Radiol 2007; 17:1385-93. [PMID: 17206421 DOI: 10.1007/s00330-006-0547-0] [Citation(s) in RCA: 224] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 11/03/2006] [Accepted: 11/28/2006] [Indexed: 12/11/2022]
Abstract
Diffusion-weighted MRI has become more and more popular in the last couple of years. It is already an accepted diagnostic tool for patients with acute stroke, but is more difficult to use for extracranial applications due to technical challenges mostly related to motion sensitivity and susceptibility variations (e.g., respiration and air-tissue boundaries). However, thanks to the newer technical developments, applications of body DW-MRI are starting to emerge. In this review, we aim to provide an overview of the current status of the published data on DW-MRI in extracranial applications. A short introduction to the physical background of this promising technique is provided, followed by the current status, subdivided into three main topics, the functional evaluation, tissue characterization and therapy monitoring.
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Affiliation(s)
- Harriet C Thoeny
- Department of Radiology, Neuroradiology and Nuclear Medicine, University Hospital of Bern, Inselspital, Freiburgstrasse 10, CH-3010 Bern, Switzerland.
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Affiliation(s)
- Jeffrey J Neil
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA.
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Michaely HJ, Sourbron S, Dietrich O, Attenberger U, Reiser MF, Schoenberg SO. Functional renal MR imaging: an overview. ACTA ACUST UNITED AC 2006; 32:758-71. [PMID: 17151905 DOI: 10.1007/s00261-006-9150-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Due to its complementary information to standard morphological imaging, functional renal magnetic resonance imaging is a rapid growing field of radiology. This pictorial essay provides a comprehensive overview of state-of-the-art functional renal imaging techniques including renal magnetic resonance angiography, first pass renal perfusion, assessment of renal function, blood-oxygen level dependent imaging of the kidneys and diffusion-weighted imaging of the kidneys including diffusion-tensor imaging of the kidneys. Basic technical concepts for all sequences are laid out. As renal perfusion imaging becomes a clinical routine examination, particular attention is given to renal perfusion measurements and the potential postprocessing approaches. Advantages and drawbacks of the published methods are illustrated. Future applications of functional renal imaging are presented.
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Affiliation(s)
- Henrik J Michaely
- Department of Clinical Radiology, University Hospitals—Grosshadern, Ludwig-Maximilians-University Munich, Marchioninistr.15, 81377, Munich, Germany.
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Prasad PV. Functional MRI of the kidney: tools for translational studies of pathophysiology of renal disease. Am J Physiol Renal Physiol 2006; 290:F958-74. [PMID: 16601297 PMCID: PMC2919069 DOI: 10.1152/ajprenal.00114.2005] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Magnetic resonance imaging (MRI) provides exquisite anatomic detail of various organs and is capable of providing additional functional information. This combination allows for comprehensive diagnostic evaluation of pathologies such as ischemic renal disease. Noninvasive MRI techniques could facilitate translation of many studies performed in controlled animal models using technologies that are invasive to humans. Such a translation is being recognized as essential because many proposed interventions and drugs that prove efficacious in animal models fail to do so in humans. In this article, we review the state-of-the-art functional MRI technique as applied to the kidneys.
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Affiliation(s)
- Pottumarthi V Prasad
- Dept. of Radiology, Walgreen Jr. Bldg., Suite 507, Evanston Northwestern Healthcare, 2650 Ridge Ave., Evanston, IL 60201, USA.
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Thoeny HC, De Keyzer F, Oyen RH, Peeters RR. Diffusion-weighted MR imaging of kidneys in healthy volunteers and patients with parenchymal diseases: initial experience. Radiology 2005; 235:911-7. [PMID: 15845792 DOI: 10.1148/radiol.2353040554] [Citation(s) in RCA: 332] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To prospectively evaluate feasibility of diffusion-weighted (DW) magnetic resonance (MR) imaging in assessment of renal function in healthy volunteers and patients with various renal abnormalities and to prospectively evaluate reproducibility of DW MR imaging in volunteers. MATERIALS AND METHODS Study protocol was approved by local ethics committee; informed consent was obtained. Eighteen healthy volunteers and 15 patients underwent transverse fat-saturated echo-planar DW MR imaging of the kidneys during normal breathing. Freehand regions of interest were delineated in the cortex and medulla of the kidneys. The following apparent diffusion coefficient (ADC) values were calculated: ADC of all b values (ADC(avg)), ADC of low b values (b = 0, 50, 100 sec/mm2; ADC(low)), and ADC of high b values (b = 500, 750, 1000 sec/mm2; ADC(high)). These values were calculated to differentiate influence of perfusion and diffusion. Reproducibility was assessed by repeating the same protocol in five randomly selected volunteers after 6 months. For statistical analysis, Student t tests were used. RESULTS In all volunteers, ADC(avg) and ADC(high) were significantly higher in the cortex than in the medulla (P < .001). No difference between the cortex and medulla could be observed for ADC(low). Patients with renal failure had significantly lower ADC(avg) (P < .001, P = .004), ADC(low) (P = .02, P = .03), and ADC(high) (P = .02, P = .04) of cortex and medulla, respectively, than did volunteers. In the patient with pyelonephritis, all ADC values of cortex and medulla were substantially lower compared with the contralateral side, whereas patients with ureteral obstruction showed varying degrees of difference in all ADC values compared with the contralateral side. No statistically significant changes were found in the repeat study of the volunteers. CONCLUSION DW MR imaging is feasible and reproducible in the assessment of renal function, as shown in our initial experience with a small number of patients and volunteers.
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Affiliation(s)
- Harriet C Thoeny
- Department of Radiology, University Hospitals Leuven, Leuven, Belgium.
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