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Baldelomar EJ, Morozov D, Wilson LD, Eldeniz C, An H, Charlton JR, Bauer A, Keilholz SD, Hulbert ML, Bennett KM. Resting state MRI reveals spontaneous physiological fluctuations in the kidney and tracks diabetic nephropathy in rats. Am J Physiol Renal Physiol 2024. [PMID: 38660712 DOI: 10.1152/ajprenal.00423.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Accepted: 04/16/2024] [Indexed: 04/26/2024] Open
Abstract
The kidneys maintain fluid-electrolyte balance and excrete waste in the presence of constant fluctuations in plasma volume and systemic blood pressure. The kidneys perform these functions to control capillary perfusion and glomerular filtration by modulating the mechanisms of autoregulation. An effect of these modulations are spontaneous, natural fluctuations in nephron perfusion. Numerous other mechanisms can lead to fluctuations in perfusion and flow. The ability to monitor these spontaneous physiological fluctuations in vivo could facilitate the early detection of kidney disease. The goal of this work was to investigate the use of resting- state magnetic resonance imaging (rsMRI) to detect spontaneous physiological fluctuations in the kidney. We performed rsMRI of rat kidneys in vivo over 10 minutes, applying motion correction to resolve time series in each voxel. We observed spatially variable, spontaneous fluctuations in rsMRI signal between 0-0.3 Hz, in frequency bands also associated with autoregulatory mechanisms. We further applied rsMRI to investigate changes in these fluctuations in a rat model of diabetic nephropathy. Spectral analysis was performed on time series of rsMRI signal in kidney cortex and medulla. Power from spectra in specific frequency bands from kidney cortex correlated with severity of glomerular pathology caused by diabetic nephropathy. Finally, we investigated the feasibility of using rsMRI of the human kidney in two participants, observing the presence of similar, spatially variable fluctuations. This approach may enable a range of preclinical and clinical investigations of kidney function, and facilitate the development of new therapies to improve outcomes in patients with kidney disease.
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Affiliation(s)
- Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, Saint Louis, MO, United States
| | - Darya Morozov
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Leslie D Wilson
- Department of Comparative Medicine, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States
| | - Cihat Eldeniz
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States
| | - Hongyu An
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, Saint Louis, MO, United States
| | - Jennifer R Charlton
- Department of Pediatrics, University of Virginia, Charlottesville, VA, United States
| | - Adam Bauer
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Shella D Keilholz
- Department of Pediatrics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Monica L Hulbert
- Division of Pediatric Hematology/Oncology, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
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Li T, Xu Y, Wu T, Charlton JR, Bennett KM, Al-Hindawi F. BlobCUT: A Contrastive Learning Method to Support Small Blob Detection in Medical Imaging. Bioengineering (Basel) 2023; 10:1372. [PMID: 38135963 PMCID: PMC10740534 DOI: 10.3390/bioengineering10121372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/19/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023] Open
Abstract
Medical imaging-based biomarkers derived from small objects (e.g., cell nuclei) play a crucial role in medical applications. However, detecting and segmenting small objects (a.k.a. blobs) remains a challenging task. In this research, we propose a novel 3D small blob detector called BlobCUT. BlobCUT is an unpaired image-to-image (I2I) translation model that falls under the Contrastive Unpaired Translation paradigm. It employs a blob synthesis module to generate synthetic 3D blobs with corresponding masks. This is incorporated into the iterative model training as the ground truth. The I2I translation process is designed with two constraints: (1) a convexity consistency constraint that relies on Hessian analysis to preserve the geometric properties and (2) an intensity distribution consistency constraint based on Kullback-Leibler divergence to preserve the intensity distribution of blobs. BlobCUT learns the inherent noise distribution from the target noisy blob images and performs image translation from the noisy domain to the clean domain, effectively functioning as a denoising process to support blob identification. To validate the performance of BlobCUT, we evaluate it on a 3D simulated dataset of blobs and a 3D MRI dataset of mouse kidneys. We conduct a comparative analysis involving six state-of-the-art methods. Our findings reveal that BlobCUT exhibits superior performance and training efficiency, utilizing only 56.6% of the training time required by the state-of-the-art BlobDetGAN. This underscores the effectiveness of BlobCUT in accurately segmenting small blobs while achieving notable gains in training efficiency.
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Affiliation(s)
- Teng Li
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ 85281, USA; (T.L.); (Y.X.); (F.A.-H.)
| | - Yanzhe Xu
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ 85281, USA; (T.L.); (Y.X.); (F.A.-H.)
| | - Teresa Wu
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ 85281, USA; (T.L.); (Y.X.); (F.A.-H.)
| | - Jennifer R. Charlton
- Division Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, VA 22903, USA;
| | - Kevin M. Bennett
- Department of Radiology, Washington University, St. Louis, MO 63130, USA;
| | - Firas Al-Hindawi
- School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ 85281, USA; (T.L.); (Y.X.); (F.A.-H.)
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3
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Charlton JR, Li T, Wu T, deRonde K, Xu Y, Baldelomar EJ, Bennett KM. Use of novel structural features to identify urinary biomarkers during acute kidney injury that predict progression to chronic kidney disease. BMC Nephrol 2023; 24:178. [PMID: 37331957 DOI: 10.1186/s12882-023-03196-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/09/2023] [Indexed: 06/20/2023] Open
Abstract
BACKGROUND A significant barrier to biomarker development in the field of acute kidney injury (AKI) is the use of kidney function to identify candidates. Progress in imaging technology makes it possible to detect early structural changes prior to a decline in kidney function. Early identification of those who will advance to chronic kidney disease (CKD) would allow for the initiation of interventions to halt progression. The goal of this study was to use a structural phenotype defined by magnetic resonance imaging and histology to advance biomarker discovery during the transition from AKI to CKD. METHODS Urine was collected and analyzed from adult C57Bl/6 male mice at four days and 12 weeks after folic acid-induced AKI. Mice were euthanized 12 weeks after AKI and structural metrics were obtained from cationic ferritin-enhanced-MRI (CFE-MRI) and histologic assessment. The fraction of proximal tubules, number of atubular glomeruli (ATG), and area of scarring were measured histologically. The correlation between the urinary biomarkers at the AKI or CKD and CFE-MRI derived features was determined, alone or in combination with the histologic features, using principal components. RESULTS Using principal components derived from structural features, twelve urinary proteins were identified at the time of AKI that predicted structural changes 12 weeks after injury. The raw and normalized urinary concentrations of IGFBP-3 and TNFRII strongly correlated to the structural findings from histology and CFE-MRI. Urinary fractalkine concentration at the time of CKD correlated with structural findings of CKD. CONCLUSIONS We have used structural features to identify several candidate urinary proteins that predict whole kidney pathologic features during the transition from AKI to CKD, including IGFBP-3, TNFRII, and fractalkine. In future work, these biomarkers must be corroborated in patient cohorts to determine their suitability to predict CKD after AKI.
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Affiliation(s)
- Jennifer R Charlton
- School of Medicine, Department of Pediatrics, Division Nephrology, University of Virginia, Box 800386, Charlottesville, VA, 22903, USA.
| | - Teng Li
- Department of Computer Science, School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ, USA
| | - Teresa Wu
- Department of Industrial Engineering, School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ, USA
| | - Kimberly deRonde
- School of Medicine, Department of Pediatrics, Division Nephrology, University of Virginia, Box 800386, Charlottesville, VA, 22903, USA
| | - Yanzhe Xu
- Department of Industrial Engineering, School of Computing and Augmented Intelligence, Arizona State University, Tempe, AZ, USA
| | - Edwin J Baldelomar
- Washington University in St. Louis, Mallinckrodt Institute of Radiology, St. Louis MO, USA
| | - Kevin M Bennett
- Washington University in St. Louis, Mallinckrodt Institute of Radiology, St. Louis MO, USA
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Baldelomar EJ, Emoto KC, Jordan MVC, Charlton JR, Reichert DE, Parvin N, Yokono C, Hann BD, Bennett KM. Synthesis and Expression of a Targeted, Ferritin-Based Tracer for PET Imaging of Kidney Glomeruli. Methods Mol Biol 2023; 2664:201-213. [PMID: 37423992 DOI: 10.1007/978-1-0716-3179-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Cationic ferritin (CF) has been developed as a multimodal, targeted imaging tracer to directly detect and map nephrons in the kidney in vivo. Direct detection of functional nephrons provides a unique, sensitive biomarker to predict or monitor kidney disease progression. CF has been developed to map functional nephron number from magnetic resonance imaging (MRI) or positron emission tomography (PET). Previous preclinical imaging studies have used non-human-derived ferritin and commercial formulations that must still be developed for translation to clinical use. Here we describe the reproducible formulation of CF (either derived from horse or from human recombinant ferritin) optimized for intravenous injection and radiolabeling by PET. The human recombinant heteropolymer ferritin is spontaneously assembled in liquid culture (Escherichia coli, E. coli) and modified to form human recombinant cationic ferritin (HrCF) to mitigate potential immunologic reactions for use in humans.
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Affiliation(s)
- Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Kasey C Emoto
- Department of Biology, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Maria Veronica Clavijo Jordan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA
| | - Jennifer R Charlton
- Department of Pediatrics, Division of Nephrology, University of Virginia, Charlottesville, VA, USA
| | - David E Reichert
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Neda Parvin
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Courtnie Yokono
- Department of Biology, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Bradley D Hann
- Department of Biology, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA.
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Baldelomar EJ, Charlton JR, Bennett KM. Mapping single-nephron filtration in the isolated, perfused rat kidney using magnetic resonance imaging. Am J Physiol Renal Physiol 2022; 323:F602-F611. [PMID: 36049066 PMCID: PMC9602809 DOI: 10.1152/ajprenal.00103.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 08/16/2022] [Accepted: 08/25/2022] [Indexed: 12/14/2022] Open
Abstract
The kidney has an extraordinary ability to maintain glomerular filtration despite natural fluctuations in blood pressure and nephron loss. This is partly due to local coordination between single-nephron filtration and vascular perfusion. An improved understanding of the three-dimensional (3-D) functional coordination between nephrons and the vasculature may provide a new perspective of the heterogeneity of kidney function and could inform targeted therapies and timed interventions to slow or prevent the progression of kidney disease. Here, we developed magnetic resonance imaging (MRI) tools to visualize single-nephron function in 3-D throughout the isolated perfused rat kidney. We used an intravenous slow perfusion of a glomerulus-targeted imaging tracer [cationized ferritin (CF)] to map macromolecular dynamics and to identify glomeruli in 3-D, followed by a bolus of a freely filtered tracer (gadolinium diethylenetriamine penta-acetic acid) to map filtration kinetics. There was a wide intrakidney distribution of CF binding rates and estimated single-nephron glomerular filtration rate (eSNGFR) between nephrons. eSNGFR and CF uptake rates did not vary significantly by distance from the kidney surface. eSNGFR varied from ∼10 to ∼100 nL/min throughout the kidney. Whole single-kidney GFR was similar across all kidneys, despite differences in the distributions eSNGFR of and glomerular number, indicating a robust adaptive regulation of individual nephrons to maintain constant single-kidney GFR in the presence of a natural variation in nephron number. This work provides a framework for future studies of single-nephron function in the whole isolated perfused kidney and experiments of single-nephron function in vivo using MRI.NEW & NOTEWORTHY We report MRI tools to measure and map single-nephron function in the isolated, perfused rat kidney. We used imaging tracers to identify nephrons throughout the kidney and to measure the delivery and filtration of the tracers at the location of the glomeruli. With this technique, we directly measured physiological parameters including estimated single-nephron glomerular filtration rate throughout the kidney. This work provides a foundation for new studies to simultaneously map the function of large numbers of nephrons.
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Affiliation(s)
- Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Jennifer R Charlton
- Division of Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, Virginia
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
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6
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Anderson E, Bennett KM, Van Vuuren J, Soulsby LK. Partner bereavement when parenting dependent children: What factors influence adjustment? Death Stud 2022; 47:239-248. [PMID: 35298362 DOI: 10.1080/07481187.2022.2048281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Little is known about those who are widowed while raising dependent children. This study aimed to explore the factors which influence adjustment to partner death. Seven fathers and five mothers were interviewed, and constructivist grounded theory was used. Three interrelated themes were identified: Interpersonal influences, Intrapersonal influences, and Contextual influences. Dependent children meant sole responsibility and increased demands, yet ultimately provided widowed parents a purpose. Participants highlighted the need for increased awareness of young widowhood at a systemic and cultural level, to improve communication around death and young widowhood. Implications included social, financial and therapeutic interventions.
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Affiliation(s)
- E Anderson
- Department of Primary Care and Mental Health, University of Liverpool, Liverpool, United Kingdom
| | - K M Bennett
- Department of Psychology, University Liverpool, Liverpool, United Kingdom
| | - J Van Vuuren
- Department of Primary Care and Mental Health, University of Liverpool, Liverpool, United Kingdom
| | - L K Soulsby
- Department of Psychology, University Liverpool, Liverpool, United Kingdom
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7
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Bennett KM, Baldelomar EJ, Charlton JR. Delivering on the potential of measuring nephron number in the clinic. Nat Rev Nephrol 2022; 18:271-272. [PMID: 35264770 DOI: 10.1038/s41581-022-00560-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA.
| | - Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Jennifer R Charlton
- Division of Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
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8
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Morozov D, Parvin N, Conaway M, Oxley G, Baldelomar EJ, Cwiek A, deRonde K, Beeman SC, Charlton JR, Bennett KM. Estimating Nephron Number from Biopsies: Impact on Clinical Studies. J Am Soc Nephrol 2022; 33:39-48. [PMID: 34758983 PMCID: PMC8763172 DOI: 10.1681/asn.2021070998] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 10/15/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Accumulating evidence supports an association between nephron number and susceptibility to kidney disease. However, it is not yet possible to directly measure nephron number in a clinical setting. Recent clinical studies have used glomerular density from a single biopsy and whole kidney cortical volume from imaging to estimate nephron number and single nephron glomerular filtration rate. However, the accuracy of these estimates from individual subjects is unknown. Furthermore, it is not clear how sample size or biopsy location may influence these estimates. These questions are critical to study design, and to the potential translation of these tools to estimate nephron number in individual subjects. METHODS We measured the variability in estimated nephron number derived from needle or virtual biopsies and cortical volume in human kidneys declined for transplantation. We performed multiple needle biopsies in the same kidney, and examined the three-dimensional spatial distribution of nephron density by magnetic resonance imaging. We determined the accuracy of a single-kidney biopsy to predict the mean nephron number estimated from multiple biopsies from the same kidney. RESULTS A single needle biopsy had a 15% chance and virtual biopsy had a 60% chance of being within 20% of the whole-kidney nephron number. Single needle biopsies could be used to detect differences in nephron number between large cohorts of several hundred subjects. CONCLUSIONS The number of subjects required to accurately detect differences in nephron number between populations can be predicted on the basis of natural intrakidney variability in glomerular density. A single biopsy is insufficient to accurately predict nephron number in individual subjects.
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Affiliation(s)
- Darya Morozov
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Neda Parvin
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Mark Conaway
- Division of Translational Research and Applied Statistics in the Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia
| | - Gavin Oxley
- University of Virginia, Charlottesville, Virginia
| | - Edwin J. Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Aleksandra Cwiek
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia
| | - Kim deRonde
- Department of Pediatrics, University of Virginia, Charlottesville, Virginia
| | - Scott C. Beeman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona
| | | | - Kevin M. Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
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9
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Cwiek A, Suzuki M, deRonde K, Conaway M, Bennett KM, El Dahr S, Reidy KJ, Charlton JR. Premature differentiation of nephron progenitor cell and dysregulation of gene pathways critical to kidney development in a model of preterm birth. Sci Rep 2021; 11:21667. [PMID: 34737344 PMCID: PMC8569166 DOI: 10.1038/s41598-021-00489-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 10/05/2021] [Indexed: 12/31/2022] Open
Abstract
Preterm birth is a leading cause of neonatal morbidity. Survivors have a greater risk for kidney dysfunction and hypertension. Little is known about the molecular changes that occur in the kidney of individuals born preterm. Here, we demonstrate that mice delivered two days prior to full term gestation undergo premature cessation of nephrogenesis, resulting in a lower glomerular density. Kidneys from preterm and term groups exhibited differences in gene expression profiles at 20- and 27-days post-conception, including significant differences in the expression of fat-soluble vitamin-related genes. Kidneys of the preterm mice exhibited decreased proportions of endothelial cells and a lower expression of genes promoting angiogenesis compared to the term group. Kidneys from the preterm mice also had altered nephron progenitor subpopulations, early Six2 depletion, and altered Jag1 expression in the nephrogenic zone, consistent with premature differentiation of nephron progenitor cells. In conclusion, preterm birth alone was sufficient to shorten the duration of nephrogenesis and cause premature differentiation of nephron progenitor cells. These candidate genes and pathways may provide targets to improve kidney health in preterm infants.
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Affiliation(s)
- Aleksandra Cwiek
- Division of Nephrology, Department of Pediatrics, University of Virginia, Box 800386, Charlottesville, VA, 22903, USA
- Cell & Developmental Biology Graduate Program, University of Virginia School of Medicine, Charlottesville, VA, 22903, USA
| | - Masako Suzuki
- Department of Genetics, Albert Einstein College of Medicine, New York, NY, USA
| | - Kimberly deRonde
- Division of Nephrology, Department of Pediatrics, University of Virginia, Box 800386, Charlottesville, VA, 22903, USA
| | - Mark Conaway
- University of Virginia Health System, Charlottesville, VA, USA
- Division of Translational Research and Applied Statistics, Department of Public Health Sciences, University of Virginia School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Samir El Dahr
- Department of Pediatrics, Tulane University School of Medicine and Children's Hospital of New Orleans, New Orleans, LA, USA
| | - Kimberly J Reidy
- Division of Nephrology, Department of Pediatrics, Children's Hospital at Montefiore, New York, NY, USA
| | - Jennifer R Charlton
- Division of Nephrology, Department of Pediatrics, University of Virginia, Box 800386, Charlottesville, VA, 22903, USA.
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10
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Abstract
Recent advances in medical imaging technology bring great promises for medicine practices. Imaging biomarkers are discovered to inform disease diagnosis, prognosis, and treatment assessment. Detecting and segmenting objects from images are often the first steps in quantitative measurement of these biomarkers. The challenges of detecting objects in images, particularly small objects known as blobs, include low image resolution, image noise and overlap among the blobs. This research proposes a Bi-Threshold Constrained Adaptive Scale (BTCAS) blob detector to uncover the relationship between the U-Net threshold and the Difference of Gaussian (DoG) scale to derive a multi-threshold, multi-scale small blob detector. With lower and upper bounds on the probability thresholds from U-Net, two binarized maps of the distance are rendered between blob centers. Each blob is transformed to a DoG space with an adaptively identified local optimum scale. A Hessian convexity map is rendered using the adaptive scale, and the under-segmentation typical of the U-Net is resolved. To validate the performance of the proposed BTCAS, a 3D simulated dataset (n = 20) of blobs, a 3D MRI dataset of human kidneys and a 3D MRI dataset of mouse kidneys, are studied. BTCAS is compared against four state-of-the-art methods: HDoG, U-Net with standard thresholding, U-Net with optimal thresholding, and UH-DoG using precision, recall, F-score, Dice and IoU. We conclude that BTCAS statistically outperforms the compared detectors.
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Affiliation(s)
- Yanzhe Xu
- School of Computing, Informatics and Decision Systems Engineering, and ASU-Mayo Center for Innovative Imaging, Arizona State University, Tempe, AZ, 85281, USA
| | - Teresa Wu
- School of Computing, Informatics and Decision Systems Engineering, and ASU-Mayo Center for Innovative Imaging, Arizona State University, Tempe, AZ, 85281, USA
| | - Jennifer R. Charlton
- Department of Pediatrics, Division Nephrology, University of Virginia, Charlottesville, 22908-0386, USA
| | - Fei Gao
- School of Computing, Informatics and Decision Systems Engineering, and ASU-Mayo Center for Innovative Imaging, Arizona State University, Tempe, AZ, 85281, USA
| | - Kevin M. Bennett
- Department of Radiology, Washington University, St. Louis, MO, 63130, USA
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11
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Charlton JR, Xu Y, Parvin N, Wu T, Gao F, Baldelomar EJ, Morozov D, Beeman SC, Derakhshan J, Bennett KM. Image analysis techniques to map pyramids, pyramid structure, glomerular distribution, and pathology in the intact human kidney from 3-D MRI. Am J Physiol Renal Physiol 2021; 321:F293-F304. [PMID: 34282957 DOI: 10.1152/ajprenal.00130.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Kidney pathologies are often highly heterogeneous. To comprehensively understand kidney structure and pathology, it is critical to develop tools to map tissue microstructure in the context of the whole, intact organ. Magnetic resonance imaging (MRI) can provide a unique, three-dimensional view of the kidney and allows for measurements of multiple pathological features. Here, we developed a platform to systematically render and map gross and microstructural features of the human kidney based on three-dimensional MRI. These features include pyramid number and morphology as well as the associated medulla and cortex. In a subset of these kidneys, we also mapped individual glomeruli and glomerular volumes using cationic ferritin-enhanced MRI to report intrarenal heterogeneity in glomerular density and size. Finally, we rendered and measured regions of nephron loss due to pathology and individual glomerular volumes in each pyramidal unit. This work provides new tools to comprehensively evaluate the kidney across scales, with potential applications in anatomic and physiological research, transplant allograft evaluation, biomarker development, biopsy guidance, and therapeutic monitoring. These image rendering and analysis tools could eventually impact the field of transplantation medicine to improve longevity matching of donor allografts and recipients and reduce discard rates through the direct assessment of donor kidneys.NEW & NOTEWORTHY We report the application of cutting-edge image analysis approaches to characterize the pyramidal geometry, glomerular microstructure, and heterogeneity of the whole human kidney imaged using MRI. This work establishes a framework to improve the detection of microstructural pathology to potentially facilitate disease monitoring or transplant evaluation in the individual kidney.
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Affiliation(s)
- Jennifer R Charlton
- Department of Pediatrics, University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Yanzhe Xu
- School of Computing, Informatics, Decision Systems Engineering, Arizona State University, Tempe, Arizona.,Mayo Center for Innovative Imaging, Arizona State University, Tempe, Arizona
| | - Neda Parvin
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Teresa Wu
- School of Computing, Informatics, Decision Systems Engineering, Arizona State University, Tempe, Arizona.,Mayo Center for Innovative Imaging, Arizona State University, Tempe, Arizona
| | - Fei Gao
- School of Computing, Informatics, Decision Systems Engineering, Arizona State University, Tempe, Arizona.,Mayo Center for Innovative Imaging, Arizona State University, Tempe, Arizona
| | - Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Darya Morozov
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Scott C Beeman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona
| | - Jamal Derakhshan
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
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12
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Charlton JR, Baldelomar EJ, Hyatt DM, Bennett KM. Nephron number and its determinants: a 2020 update. Pediatr Nephrol 2021; 36:797-807. [PMID: 32350665 PMCID: PMC7606355 DOI: 10.1007/s00467-020-04534-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/29/2020] [Accepted: 03/05/2020] [Indexed: 12/30/2022]
Abstract
Studies of human nephron number have been conducted for well over a century and have uncovered a large variability in nephron number. However, the mechanisms influencing nephron endowment and loss, along with the etiology for the wide range among individuals are largely unknown. Advances in imaging technology have allowed investigators to revisit the principles of renal structure and physiology and their roles in the progression of kidney disease. Here, we will review the latest data on the influences impacting nephron number, innovations made over the last 6 years to understand and integrate renal structure and function, and new developments in the tools used to count nephrons in vivo.
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Affiliation(s)
- Jennifer R. Charlton
- University of Virginia School of Medicine, Department of Pediatrics, Division of Nephrology, Charlottesville, VA, USA
| | - Edwin J. Baldelomar
- Washington University in St. Louis, Department of Radiology, St. Louis, MO, USA
| | - Dylan M. Hyatt
- University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Kevin M. Bennett
- Washington University in St. Louis, Department of Radiology, St. Louis, MO, USA
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13
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Bennett KM, Baldelomar EJ, Morozov D, Chevalier RL, Charlton JR. New imaging tools to measure nephron number in vivo: opportunities for developmental nephrology. J Dev Orig Health Dis 2021; 12:179-183. [PMID: 31983353 PMCID: PMC8765346 DOI: 10.1017/s204017442000001x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mammalian kidney is a complex organ, requiring the concerted function of up to millions of nephrons. The number of nephrons is constant after nephrogenesis during development, and nephron loss over a life span can lead to susceptibility to acute or chronic kidney disease. New technologies are under development to count individual nephrons in the kidney in vivo. This review outlines these technologies and highlights their relevance to studies of human renal development and disease.
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Affiliation(s)
- K M Bennett
- Department of Radiology, Washington University, Saint Louis, MO, USA
| | - E J Baldelomar
- Department of Radiology, Washington University, Saint Louis, MO, USA
| | - D Morozov
- Department of Radiology, Washington University, Saint Louis, MO, USA
| | - R L Chevalier
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | - J R Charlton
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
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14
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Abstract
Tubular pathologies are a common feature of kidney disease. Current metrics to assess kidney health, in vivo or in transplant, are generally based on urinary or serum biomarkers and pathological findings from kidney biopsies. Biopsies, usually taken from the kidney cortex, are invasive and prone to sampling error. Tools to directly and noninvasively measure tubular pathology could provide a new approach to assess kidney health. This study used diffusion magnetic resonance imaging (dMRI) as a noninvasive tool to measure the size of the tubular lumen in ex vivo, perfused kidneys. We first used Monte Carlo simulations to demonstrate that dMRI is sensitive to restricted tissue water diffusion at the scale of the kidney tubule. We applied dMRI and biophysical modeling to examine the distribution of tubular diameters in ex vivo, fixed kidneys from mice, rats, and a human donor. The biophysical model to fit the dMRI signal was based on a superposition of freely diffusing water and water diffusing inside infinitely long cylinders of different diameters. Tubular diameters measured by dMRI were within 10% of those measured by histology within the same tissue. Finally, we applied dMRI to investigate kidney pathology in a mouse model of folic-acid-induced acute kidney injury. dMRI detected heterogeneity in the distribution of tubules within the kidney cortex of mice with acute kidney injury compared with control mice. We conclude that dMRI can be used to measure the distribution of tubule diameters in the kidney cortex ex vivo and that dMRI may provide a new noninvasive biomarker of tubular pathology.NEW & NOTEWORTHY Tubular pathologies are a common feature of kidney disease. Current metrics to assess kidney health, in vivo or in transplant, are generally based on urinary or serum biomarkers and pathological findings from kidney biopsies. Diffusion MRI can be used to measure the distribution of tubule diameters in the kidney cortex ex vivo and may provide a new noninvasive biomarker of tubular pathology.
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Affiliation(s)
- Darya Morozov
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Neda Parvin
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | | | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
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15
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Baldelomar EJ, Reichert DE, Shoghi KI, Beeman SC, Charlton JR, Strong L, Fettig N, Klaas A, Bennett KM. Mapping nephron mass in vivo using positron emission tomography. Am J Physiol Renal Physiol 2021; 320:F183-F192. [PMID: 33283644 PMCID: PMC8091936 DOI: 10.1152/ajprenal.00418.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 12/03/2020] [Accepted: 12/04/2020] [Indexed: 01/19/2023] Open
Abstract
Nephron number varies widely in humans. A low nephron endowment at birth or a loss of functioning nephrons is strongly linked to increased susceptibility to chronic kidney disease. In this work, we developed a contrast agent, radiolabeled cationic ferritin (RadioCF), to map functioning glomeruli in vivo in the kidney using positron emission tomography (PET). PET radiotracers can be detected in trace doses (<30 nmol), making them useful for rapid clinical translation. RadioCF is formed from cationic ferritin (CF) and with a radioisotope, Cu-64, incorporated into the ferritin core. We showed that RadioCF binds specifically to kidney glomeruli after intravenous injection in mice, whereas radiolabeled noncationic ferritin (RadioNF) and free Cu-64 do not. We then showed that RadioCF-PET can distinguish kidneys in healthy wild-type (WT) mice from kidneys in mice with oligosyndactylism (Os/+), a model of congenital hypoplasia and low nephron mass. The average standardized uptake value (SUV) measured by PET 90 min after injection was 21% higher in WT mice than in Os/+ mice, consistent with the higher glomerular density in WT mice. The difference in peak SUV from SUV at 90 min correlated with glomerular density in male mice from both WT and Os/+ cohorts (R2 = 0.98). Finally, we used RadioCF-PET to map functioning glomeruli in a donated human kidney. SUV within the kidney correlated with glomerular number (R2= 0.78) measured by CF-enhanced magnetic resonance imaging in the same locations. This work suggests that RadioCF-PET appears to accurately detect nephron mass and has the potential for clinical translation.
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Affiliation(s)
- Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - David E Reichert
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Kooresh I Shoghi
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Scott C Beeman
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona
| | | | - Lori Strong
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Nikki Fettig
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Amanda Klaas
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri
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16
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Zöllner FG, Dastrù W, Irrera P, Longo DL, Bennett KM, Beeman SC, Bretthorst GL, Garbow JR. Analysis Protocol for Dynamic Contrast Enhanced (DCE) MRI of Renal Perfusion and Filtration. Methods Mol Biol 2021; 2216:637-653. [PMID: 33476028 PMCID: PMC9703217 DOI: 10.1007/978-1-0716-0978-1_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Here we present an analysis protocol for dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data of the kidneys. It covers comprehensive steps to facilitate signal to contrast agent concentration mapping via T1 mapping and the calculation of renal perfusion and filtration parametric maps using model-free approaches, model free analysis using deconvolution, the Toft's model and a Bayesian approach.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 analysis protocol chapter is complemented by two separate chapters describing the basic concept and experimental procedure.
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Affiliation(s)
- Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Walter Dastrù
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Pietro Irrera
- University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy.
| | - Kevin M Bennett
- Washington University School of Medicine, St. Louis, MO, USA
| | - Scott C Beeman
- Washington University School of Medicine, St. Louis, MO, USA
| | | | - Joel R Garbow
- Washington University School of Medicine, St. Louis, MO, USA
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Pedersen M, Irrera P, Dastrù W, Zöllner FG, Bennett KM, Beeman SC, Bretthorst GL, Garbow JR, Longo DL. Dynamic Contrast Enhancement (DCE) MRI-Derived Renal Perfusion and Filtration: Basic Concepts. Methods Mol Biol 2021; 2216:205-227. [PMID: 33476002 DOI: 10.1007/978-1-0716-0978-1_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dynamic contrast-enhanced (DCE) MRI monitors the transit of contrast agents, typically gadolinium chelates, through the intrarenal regions, the renal cortex, the medulla, and the collecting system. In this way, DCE-MRI reveals the renal uptake and excretion of the contrast agent. An optimal DCE-MRI acquisition protocol involves finding a good compromise between whole-kidney coverage (i.e., 3D imaging), spatial and temporal resolution, and contrast resolution. By analyzing the enhancement of the renal tissues as a function of time, one can determine indirect measures of clinically important single-kidney parameters as the renal blood flow, glomerular filtration rate, and intrarenal blood volumes. Gadolinium-containing contrast agents may be nephrotoxic in patients suffering from severe renal dysfunction, but otherwise DCE-MRI is clearly useful for diagnosis of renal functions and for assessing treatment response and posttransplant rejection.Here we introduce the concept of renal DCE-MRI, describe the existing methods, and provide an overview of preclinical DCE-MRI applications to illustrate the utility of this technique to measure renal perfusion and glomerular filtration rate in animal models.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 introduction is complemented by two separate publications describing the experimental procedure and data analysis.
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Affiliation(s)
- Michael Pedersen
- Department of Clinical Medicine - Comparative Medicine Lab, Aarhus University, Aarhus, Denmark
| | - Pietro Irrera
- University of Campania "Luigi Vanvitelli", Napoli, Italy
| | - Walter Dastrù
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Kevin M Bennett
- Washington University School of Medicine, St. Louis, MO, USA
| | - Scott C Beeman
- Washington University School of Medicine, St. Louis, MO, USA
| | | | - Joel R Garbow
- Washington University School of Medicine, St. Louis, MO, USA
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy.
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18
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Bamford JB, Ramirez JM, Prewit WA, Robinson WJ, Bennett KM. Genotyping of the Galactosemia GALT 591 A>G Mutation by Pyrosequencing. Am J Clin Pathol 2020. [DOI: 10.1093/ajcp/aqaa161.281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Introduction/Objective
This project aimed to design a pyrosequencing assay capable of genetically analyzing the presence of GALT 591 A>G mutation for the diagnosis of galactosemia. Galactosemia is an autosomal recessive disorder that affects enzyme activity of galactose-1-phosphate uridylytransferase (GALT). This enzyme is responsible for proper processing of galactose to glucose; if not broken down the accumulation of galactose in the body results in developmental delays, clouding of the eyes, speech difficulties, and intellectual disabilities. Pyrosequencing offers a valuable platform in assessing whether patients are wild type unaffected (A:A), heterozygous carrier (A:G), or homozygous affected (G:G) at the alleles within the GALT 591 locus by measuring percentage of the wild type A allele and the mutant G allele.
Methods
PCR primers were designed for the mutation locus, and PCR amplification was optimized for the target 77 bp product, with verification by gel electrophoresis. The pyrosequencing assay was designed and validated on the Qiagen PyroMark Q24 instrument. Control samples included commercially purchased DNA from the Coriell Cell Repository.
Results
One hundred and thirty-three reactions were utilized to establish the following assay validation parameters: accuracy (100% for G:G, 95% for A:G and A:A), precision (determined by mean and standard deviation with a standard deviation of 0.6 for G:G, 4.55 for A:G and 4.85 for A:A), and limit of detection (10 ng DNA pre-PCR and 2 µL of PCR product loaded). Twenty-six blinded samples were utilized to test assay clinical performance, as compared against a high resolution melt curve assay.
Conclusion
It was determined that detection of GALT 591 A>G via pyrosequencing is highly sensitive and specific with a clinical sensitivity of 100% and a clinical specificity of 95.83%. It was concluded that this assay could be applied in a clinical environment for GALT 591 A>G genotyping to aid in galactosemia diagnosis.
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Affiliation(s)
- J B Bamford
- Laboratory Sciences and Primary Care, Texas Tech University Health Sciences Center, Lubbock, Texas, UNITED STATES
| | - J M Ramirez
- Laboratory Sciences and Primary Care, Texas Tech University Health Sciences Center, Lubbock, Texas, UNITED STATES
| | - W A Prewit
- Laboratory Sciences and Primary Care, Texas Tech University Health Sciences Center, Lubbock, Texas, UNITED STATES
| | - W J Robinson
- Laboratory Sciences and Primary Care, Texas Tech University Health Sciences Center, Lubbock, Texas, UNITED STATES
| | - K M Bennett
- Laboratory Sciences and Primary Care, Texas Tech University Health Sciences Center, Lubbock, Texas, UNITED STATES
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Charlton JR, Tan W, Daouk G, Teot L, Rosen S, Bennett KM, Cwiek A, Nam S, Emma F, Jouret F, Oliveira JP, Tranebjærg L, Frykholm C, Mane S, Hildebrandt F, Srivastava T, Storm T, Christensen EI, Nielsen R. Beyond the tubule: pathological variants of LRP2, encoding the megalin receptor, result in glomerular loss and early progressive chronic kidney disease. Am J Physiol Renal Physiol 2020; 319:F988-F999. [PMID: 33103447 DOI: 10.1152/ajprenal.00295.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Pathogenic variants in the LRP2 gene, encoding the multiligand receptor megalin, cause a rare autosomal recessive syndrome: Donnai-Barrow/Facio-Oculo-Acoustico-Renal (DB/FOAR) syndrome. Because of the rarity of the syndrome, the long-term consequences of the tubulopathy on human renal health have been difficult to ascertain, and the human clinical condition has hitherto been characterized as a benign tubular condition with asymptomatic low-molecular-weight proteinuria. We investigated renal function and morphology in a murine model of DB/FOAR syndrome and in patients with DB/FOAR. We analyzed glomerular filtration rate in mice by FITC-inulin clearance and clinically characterized six families, including nine patients with DB/FOAR and nine family members. Urine samples from patients were analyzed by Western blot analysis and biopsy materials were analyzed by histology. In the mouse model, we used histological methods to assess nephrogenesis and postnatal renal structure and contrast-enhanced magnetic resonance imaging to assess glomerular number. In megalin-deficient mice, we found a lower glomerular filtration rate and an increase in the abundance of injury markers, such as kidney injury molecule-1 and N-acetyl-β-d-glucosaminidase. Renal injury was validated in patients, who presented with increased urinary kidney injury molecule-1, classical markers of chronic kidney disease, and glomerular proteinuria early in life. Megalin-deficient mice had normal nephrogenesis, but they had 19% fewer nephrons in early adulthood and an increased fraction of nephrons with disconnected glomerulotubular junction. In conclusion, megalin dysfunction, as present in DB/FOAR syndrome, confers an increased risk of progression into chronic kidney disease.
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Affiliation(s)
- Jennifer R Charlton
- Division of Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, Virginia
| | - Weizhen Tan
- Division of Nephrology, Massachusetts General Hospital for Children, Boston, Massachusetts
| | - Ghaleb Daouk
- Division of Nephrology, Massachusetts General Hospital for Children, Boston, Massachusetts
| | - Lisa Teot
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts
| | - Seymour Rosen
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts.,Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Kevin M Bennett
- Department of Radiology, Washington University in Saint Louis, St. Louis, Missouri
| | - Aleksandra Cwiek
- Division of Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, Virginia
| | - Sejin Nam
- Department of Physics, University of Hawai'i at Manoa, Manoa, Hawai'i
| | - Francesco Emma
- Division of Nephrology, Department of Pediatric Subspecialties, Bambino Gesù Children's Hospital- Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy
| | - François Jouret
- Groupe Interdisciplinaire de Génoprotéomique Appliquée, Unit of Cardiovascular Sciences, University of Liège, Liège, Belgium
| | - João Paulo Oliveira
- Service of Medical Genetics, São João University Hospital Centre and Faculty of Medicine, University of Porto and i3S-Institute for Health Research and Innovation, Porto, Portugal
| | - Lisbeth Tranebjærg
- Department of Clinical Genetics, Rigshospitalet/The Kennedy Centre, Copenhagen, Denmark.,Institute of Clinical Medicine, University of Copenhagen, The Panum Institute, Copenhagen, Denmark
| | - Carina Frykholm
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Tina Storm
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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20
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Parvin N, Charlton JR, Baldelomar EJ, Derakhshan JJ, Bennett KM. Mapping vascular and glomerular pathology in a rabbit model of neonatal acute kidney injury using MRI. Anat Rec (Hoboken) 2020; 303:2716-2728. [PMID: 32445514 PMCID: PMC7680718 DOI: 10.1002/ar.24419] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 01/30/2020] [Accepted: 03/03/2020] [Indexed: 12/27/2022]
Abstract
Acute kidney injury (AKI) in premature neonates is common due to the administration of life-saving therapies. The impact of AKI on renal morphology and susceptibility to further renal damage is poorly understood. Recent advances in radiological imaging have allowed integration of soft tissue morphology in the intact organ, facilitating a more complete understanding of changes in tissue microstructure associated with pathology. Here, we applied magnetic resonance imaging (MRI) to detect both glomerular and vascular changes in a rabbit model of neonatal AKI, induced by indomethacin and gentamicin. Using combined spin-echo MRI and cationic ferritin enhanced gradient-echo MRI (CFE-MRI), we observed (a) an increased cortical arterial diameter in the AKI cohort compared to healthy controls, and (b) focal loss of vascular density and glomerular loss in a circumferential band ~1 mm from the cortical surface. This combined use of vascular and glomerular imaging may give insight into the etiology of AKI and its impact on renal health later in life.
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Affiliation(s)
- Neda Parvin
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jennifer R Charlton
- University of Virginia Children's Hospital, Department of Pediatrics, Charlottesville, Virginia, USA
| | - Edwin J Baldelomar
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jamal J Derakhshan
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Kevin M Bennett
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
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21
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Charlton JR, Xu Y, Wu T, deRonde KA, Hughes JL, Dutta S, Oxley GT, Cwiek A, Cathro HP, Charlton NP, Conaway MR, Baldelomar EJ, Parvin N, Bennett KM. Magnetic resonance imaging accurately tracks kidney pathology and heterogeneity in the transition from acute kidney injury to chronic kidney disease. Kidney Int 2020; 99:173-185. [PMID: 32916180 DOI: 10.1016/j.kint.2020.08.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 08/07/2020] [Accepted: 08/20/2020] [Indexed: 01/09/2023]
Abstract
Acute kidney injury (AKI) increases the risk for chronic kidney disease (CKD). However, there are few tools to detect microstructural changes after AKI. Here, cationic ferritin-enhanced magnetic resonance imaging (CFE-MRI) was applied to examine the heterogeneity of kidney pathology in the transition from AKI to CKD. Adult male mice received folic acid followed by cationic ferritin and were euthanized at four days (AKI), four weeks (CKD-4) or 12 weeks (CKD-12). Kidneys were examined by histologic methods and CFE-MRI. In the CKD-4 and CKD-12 groups, glomerular number was reduced and atubular cortical lesions were observed. Apparent glomerular volume was larger in the AKI, CKD-4 and CKD-12 groups compared to controls. Glomerular hypertrophy occurred with ageing. Interglomerular distance and glomerular density were combined with other MRI metrics to distinguish the AKI and CKD groups from controls. Despite significant heterogeneity, the noninvasive (MRI-based) metrics were as accurate as invasive (histological) metrics at distinguishing AKI and CKD from controls. To assess the toxicity of cationic ferritin in a CKD model, CKD-4 mice received cationic ferritin and were examined one week later. The CKD-4 groups with and without cationic ferritin were similar, except the iron content of the kidney, liver, and spleen was greater in the CKD-4 plus cationic ferritin group. Thus, our study demonstrates the accuracy and safety of CFE-MRI to detect whole kidney pathology allowing for the development of novel biomarkers of kidney disease and providing a foundation for future in vivo longitudinal studies in mouse models of AKI and CKD to track nephron fate.
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Affiliation(s)
- Jennifer R Charlton
- Department of Pediatrics, Division Nephrology, University of Virginia, Charlottesville, Virginia, USA.
| | - Yanzhe Xu
- ASU-Mayo Center for Innovative Imaging, School of Computing, Informatics, Decision Systems Engineering, Arizona State University, Tempe, Arizona, USA
| | - Teresa Wu
- ASU-Mayo Center for Innovative Imaging, School of Computing, Informatics, Decision Systems Engineering, Arizona State University, Tempe, Arizona, USA
| | - Kim A deRonde
- Department of Pediatrics, Division Nephrology, University of Virginia, Charlottesville, Virginia, USA
| | | | - Shourik Dutta
- School of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Gavin T Oxley
- University of Virginia, Charlottesville, Virginia, USA
| | | | - Helen P Cathro
- Department of Pathology University of Virginia, Charlottesville, Virginia, USA
| | - Nathan P Charlton
- Department of Toxicology, University of Virginia, Virginia, Charlottesville, USA
| | - Mark R Conaway
- Division of Translational Research and Applied Statistics Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia, USA
| | - Edwin J Baldelomar
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Neda Parvin
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Kevin M Bennett
- Department of Radiology, Washington University in St. Louis, St. Louis, Missouri, USA
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22
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Xu Y, Wu T, Gao F, Charlton JR, Bennett KM. Improved small blob detection in 3D images using jointly constrained deep learning and Hessian analysis. Sci Rep 2020; 10:326. [PMID: 31941994 PMCID: PMC6962386 DOI: 10.1038/s41598-019-57223-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 12/20/2019] [Indexed: 12/23/2022] Open
Abstract
Imaging biomarkers are being rapidly developed for early diagnosis and staging of disease. The development of these biomarkers requires advances in both image acquisition and analysis. Detecting and segmenting objects from images are often the first steps in quantitative measurement of these biomarkers. The challenges of detecting objects in images, particularly small objects known as blobs, include low image resolution, image noise and overlap between the blobs. The Difference of Gaussian (DoG) detector has been used to overcome these challenges in blob detection. However, the DoG detector is susceptible to over-detection and must be refined for robust, reproducible detection in a wide range of medical images. In this research, we propose a joint constraint blob detector from U-Net, a deep learning model, and Hessian analysis, to overcome these problems and identify true blobs from noisy medical images. We evaluate this approach, UH-DoG, using a public 2D fluorescent dataset for cell nucleus detection and a 3D kidney magnetic resonance imaging dataset for glomerulus detection. We then compare this approach to methods in the literature. While comparable to the other four comparing methods on recall, the UH-DoG outperforms them on both precision and F-score.
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Affiliation(s)
- Yanzhe Xu
- School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, 699S Mill Ave, Tempe, AZ, 85281, USA
| | - Teresa Wu
- School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, 699S Mill Ave, Tempe, AZ, 85281, USA.
| | - Fei Gao
- School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, 699S Mill Ave, Tempe, AZ, 85281, USA
| | - Jennifer R Charlton
- Department of Pediatrics, Division Nephrology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Kevin M Bennett
- Department of Radiology, Washington University, St. Louis, MO, 63130, USA
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23
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Baldelomar EJ, Charlton JR, deRonde KA, Bennett KM. In vivo measurements of kidney glomerular number and size in healthy and Os /+ mice using MRI. Am J Physiol Renal Physiol 2019; 317:F865-F873. [PMID: 31339774 DOI: 10.1152/ajprenal.00078.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The development of chronic kidney disease (CKD) is associated with the loss of functional nephrons. However, there are no methods to directly measure nephron number in living subjects. Thus, there are no methods to track the early stages of progressive CKD before changes in total renal function. In this work, we used cationic ferritin-enhanced magnetic resonance imaging (CFE-MRI) to enable measurements of glomerular number (Nglom) and apparent glomerular volume (aVglom) in vivo in healthy wild-type (WT) mice (n = 4) and mice with oligosyndactylism (Os/+; n = 4), a model of congenital renal hypoplasia leading to nephron reduction. We validated in vivo measurements of Nglom and aVglom by high-resolution ex vivo MRI. CFE-MRI measured a mean Nglom of 12,220 ± 2,028 and 6,848 ± 1,676 (means ± SD) for WT and Os/+ mouse kidneys in vivo, respectively. Nglom measured in all mice in vivo using CFE-MRI varied by an average 15% from Nglom measured ex vivo in the same kidney (α = 0.05, P = 0.67). To confirm that CFE-MRI can also be used to track nephron endowment longitudinally, a WT mouse was imaged three times by CFE-MRI over 2 wk. Values of Nglom measured in vivo in the same kidney varied within ~3%. Values of aVglom calculated from CFE-MRI in vivo were significantly different (~15% on average, P < 0.01) from those measured ex vivo, warranting further investigation. This is the first report of direct measurements of Nglom and aVglom in healthy and diseased mice in vivo.
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Affiliation(s)
- Edwin J Baldelomar
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri.,Department of Physics, University of Hawai'i at Mānoa, Honolulu, Hawaii
| | - Jennifer R Charlton
- University of Virginia Children's Hospital, Department of Pediatrics, Charlottesville, Virginia
| | - Kimberly A deRonde
- University of Virginia Children's Hospital, Department of Pediatrics, Charlottesville, Virginia
| | - Kevin M Bennett
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri.,Department of Biology, University of Hawai'i at Mānoa, Honolulu, Hawaii
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Abstract
PURPOSE OF REVIEW Despite abundant evidence in adults, the relationship between acute kidney injury (AKI) and chronic kidney disease (CKD) remains unanswered in pediatrics. Obstacles to overcome include the challenges defining these entities and the lack of long-term follow-up studies. This review focuses on pediatric populations at high-risk for AKI, the evidence of the long-term effect of AKI on renal health, and biomarkers to detect renal disease. RECENT FINDINGS AKI in critically ill children and neonates is common and independently associated with adverse outcomes. Patients with diabetes and sickle cell disease along with neonates with necrotizing enterocolitis have been identified as high-risk for AKI. Preterm birth and neonates with AKI have signs of renal dysfunction early in childhood. Urinary biomarkers may identify AKI and CKD earlier than traditional biomarkers, but more work is necessary to determine their clinical utility. Promising technological advances including the ability to determine nephron number noninvasively will expand our ability to characterize the AKI to CKD transition. SUMMARY AKI is common and associated with poor outcomes. It is probable that AKI is a harbinger to CKD in pediatric populations. However, we currently lack the tools to definitely answer this question and more research is needed.
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Affiliation(s)
- David T Selewski
- Department of Pediatrics & Communicable Diseases, University of Michigan Medical School, Ann Arbor, Michigan
| | - Dylan M Hyatt
- University of Virginia, School of Medicine, Charlottesville, Virginia
| | - Kevin M Bennett
- Department of Biology, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Jennifer R Charlton
- Division of Nephrology, Department of Pediatrics, University of Virginia, Charlottesville, Virginia, USA
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25
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Abstract
number is highly variable in humans and is thought to play an important role in renal health. Chronic kidney disease (CKD) is the result of too few nephrons to maintain homeostasis. Currently, nephron number can only be determined invasively or as a terminal assessment. Due to a lack of tools to measure and track nephron number in the living, the early stages of CKD often go unrecognized, preventing early intervention that might halt the progression of CKD. In this work, we present a technique to directly measure glomerular number ( Nglom) and volume in vivo in the rat kidney ( n = 8) using MRI enhanced with the novel contrast agent cationized ferritin (CFE-MRI). Adult male rats were administered intravenous cationized ferritin (CF) and imaged in vivo with MRI. Glomerular number was measured and each glomerulus was spatially mapped in 3D in the image. Mean apparent glomerular volume (a Vglom) and intrarenal distribution of the individual glomerular volume (IGV), were also measured. These metrics were compared between images of the same kidneys scanned in vivo and ex vivo with CFE-MRI. In vivo Nglom and a Vglom correlated to ex vivo metrics within the same kidneys and were within 10% of Nglom and a Vglom previously validated by stereologic methods. This is the first report of direct in vivo measurements of Nglom and a Vglom, introducing an opportunity to investigate mechanisms of renal disease progression and therapeutic response over time.
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Affiliation(s)
| | - Jennifer R Charlton
- University of Virginia , Department of Pediatrics, Charlottesville, Virginia
| | - Scott C Beeman
- Washington University School of Medicine , Mallinckrodt Institute of Radiology, St. Louis, Missouri
| | - Kevin M Bennett
- University of Hawaii at Manoa, Department of Biology , Honolulu, Hawaii
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26
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Abstract
Small structure segmentation from medical images is a challenging problem yet has important applications. Examples are labeling cell, lesion and glomeruli for disease diagnosis, just to name a few. Though extensive research has proposed various detectors for this type of problem, most are 2D detectors. Recently, we have developed a Hessian based 3D detector to segment small structures from medical images (e.g., MRI). In our detector, two 3D geometrical features: regional blobness and flatness, in conjunction with the intensity features are fully utilized to serve the segmentation purpose. The objective of this research is to further improve the 3D detector with additions of texture features. Medical images contain rich information which can be presented as texture, the local characteristics pattern of image intensity. We hypothesize the Hessian based detector extended with the 3D texture features is expected to have improved performance in segmenting small structures. To thoroughly evaluate the contributions from the textual features, 25 synthetic images and 6 real world rat MR images are studied. It is observed the combination of intensity, blobness, and two texture features: intensity standard deviation and entropy improves performance in synthetic dataset by about 19% in F-score, and performs as well as other detectors on rat MR images.
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Sahni JN, Czanner G, Gutu T, Taylor SA, Bennett KM, Wuerger SM, Grierson I, Murray-Dunning C, Holland MN, Harding SP. Safety and acceptability of an organic light-emitting diode sleep mask as a potential therapy for retinal disease. Eye (Lond) 2016; 31:97-106. [PMID: 27983728 DOI: 10.1038/eye.2016.259] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/13/2016] [Indexed: 11/09/2022] Open
Abstract
PurposeThe purpose of the study was to study the effect of an organic light-emitting diode sleep mask on daytime alertness, wellbeing, and retinal structure/function in healthy volunteers and in diabetic macular oedema (DMO).Patients and methodsHealthy volunteers in two groups, 18-30 yrs (A), 50-70 yrs (B) and people with DMO (C) wore masks (504 nm wavelength; 80 cd/m2 luminance; ≤8 h) nightly for 3 months followed by a 1-month recovery period. Changes from baseline were measured for (means): psychomotor vigilance task (PVT) (number of lapses (NL), response time (RT)), sleep, depression, psychological wellbeing (PW), visual acuity, contrast sensitivity, colour, electrophysiology, microperimetry, and retinal thickness on OCT.ResultsOf 60 participants, 16 (27%) withdrew, 8 (13%) before month 1, due to sleep disturbances and mask intolerance. About 36/55 (65%) who continued beyond month 1 reported ≥1 adverse event. At month 3 mean PVT worsened in Group A (RT (7.65%, P<0.001), NL (43.3%, P=0.005)) and mean PW worsened in all groups (A 28.0%, P=0.01, B 21.2%, P=0.03, C 12.8%, P<0.05). No other clinically significant safety signal was detected. Cysts reduced/resolved in the OCT subfield of maximal pathology in 67% Group C eyes. Thinning was greater at 3 and 4 months for greater baseline thickness (central subfield P<0.001, maximal P<0.05).ConclusionSleep masks showed no major safety signal apart from a small impairment of daytime alertness and a moderate effect on wellbeing. Masks were acceptable apart from in some healthy participants. Preliminary data suggest a beneficial effect on retinal thickness in DMO. This novel therapeutic approach is ready for large clinical trials.
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Affiliation(s)
- J N Sahni
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK.,Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - G Czanner
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.,Department of Biostatistics, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - T Gutu
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK
| | - S A Taylor
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK
| | - K M Bennett
- Department of Psychological Sciences, Institute of Psychology, Health and Society, Liverpool, UK
| | - S M Wuerger
- Department of Psychological Sciences, Institute of Psychology, Health and Society, Liverpool, UK
| | - I Grierson
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - C Murray-Dunning
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | | | - S P Harding
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK.,Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
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28
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Xie L, Bennett KM, Liu C, Johnson GA, Zhang JL, Lee VS. MRI tools for assessment of microstructure and nephron function of the kidney. Am J Physiol Renal Physiol 2016; 311:F1109-F1124. [PMID: 27630064 DOI: 10.1152/ajprenal.00134.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 09/08/2016] [Indexed: 12/13/2022] Open
Abstract
MRI can provide excellent detail of renal structure and function. Recently, novel MR contrast mechanisms and imaging tools have been developed to evaluate microscopic kidney structures including the tubules and glomeruli. Quantitative MRI can assess local tubular function and is able to determine the concentrating mechanism of the kidney noninvasively in real time. Measuring single nephron function is now a near possibility. In parallel to advancing imaging techniques for kidney microstructure is a need to carefully understand the relationship between the local source of MRI contrast and the underlying physiological change. The development of these imaging markers can impact the accurate diagnosis and treatment of kidney disease. This study reviews the novel tools to examine kidney microstructure and local function and demonstrates the application of these methods in renal pathophysiology.
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Affiliation(s)
- Luke Xie
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah;
| | - Kevin M Bennett
- Department of Biology, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Chunlei Liu
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, North Carolina; and.,Brain Imaging and Analysis Center, Duke University Medical Center, Durham, North Carolina
| | - G Allan Johnson
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, North Carolina; and
| | - Jeff Lei Zhang
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah
| | - Vivian S Lee
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah
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29
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Charlton JR, Pearl VM, Denotti AR, Lee JB, Swaminathan S, Scindia YM, Charlton NP, Baldelomar EJ, Beeman SC, Bennett KM. Biocompatibility of ferritin-based nanoparticles as targeted MRI contrast agents. Nanomedicine 2016; 12:1735-45. [PMID: 27071333 DOI: 10.1016/j.nano.2016.03.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Revised: 02/24/2016] [Accepted: 03/26/2016] [Indexed: 10/22/2022]
Abstract
Ferritin is a naturally occurring iron storage protein, proposed as a clinically relevant nanoparticle with applications as a diagnostic and therapeutic agent. Cationic ferritin is a targeted, injectable contrast agent to measure kidney microstructure with MRI. Here, the toxicity of horse spleen ferritin is assessed as a step to clinical translation. Adult male mice received cationic, native and high dose cationic ferritin (CF, NF, or HDCF) or saline and were monitored for 3weeks. Transient weight loss occurred in the ferritin groups with no difference in renal function parameters. Ferritin-injected mice demonstrated a lower serum iron 3weeks after administration. In ferritin-injected animals pre-treated with hydrocortisone, there were no structural or weight differences in the kidneys, liver, lung, heart, or spleen. This study demonstrates a lack of significant detrimental effects of horse-derived ferritin-based nanoparticles at MRI-detectable doses, allowing further exploration of these agents in basic research and clinical diagnostics.
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Affiliation(s)
- Jennifer R Charlton
- University of Virginia, Department of Pediatrics, Division of Nephrology, Charlottesville VA, USA.
| | - Valeria M Pearl
- University of Virginia, Department of Pediatrics, Division of Nephrology, Charlottesville VA, USA.
| | - Anna R Denotti
- Ospedale Regionale per le Microcitemie, University of Cagliari, Italy, Department of Pediatrics.
| | - Jonathan B Lee
- Eastern Virginia Medical School, Department of Pediatrics, Norfolk, VA, USA.
| | - Sundararaman Swaminathan
- University of Virginia, Center for Immunity, Inflammation and Regenerative Medicine and Department of Medicine, Division of Nephrology, Charlottesville VA, USA.
| | - Yogesh M Scindia
- University of Virginia, Center for Immunity, Inflammation and Regenerative Medicine and Department of Medicine, Division of Nephrology, Charlottesville VA, USA.
| | - Nathan P Charlton
- University of Virginia, Department of Emergency Medicine, Division of Medical Toxicology, Charlottesville, VA, USA.
| | - Edwin J Baldelomar
- University of Hawaii at Manoa, Department of Physics, Honolulu, HI, USA.
| | - Scott C Beeman
- Washington University School of Medicine, Department of Radiology, St. Louis, MO, USA.
| | - Kevin M Bennett
- University of Hawaii at Manoa, Department of Biology, Honolulu, HI.
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Zhang M, Wu T, Beeman SC, Cullen-McEwen L, Bertram JF, Charlton JR, Baldelomar E, Bennett KM. Efficient Small Blob Detection Based on Local Convexity, Intensity and Shape Information. IEEE Trans Med Imaging 2016; 35:1127-1137. [PMID: 26685229 PMCID: PMC6991892 DOI: 10.1109/tmi.2015.2509463] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The identification of small structures (blobs) from medical images to quantify clinically relevant features, such as size and shape, is important in many medical applications. One particular application explored here is the automated detection of kidney glomeruli after targeted contrast enhancement and magnetic resonance imaging. We propose a computationally efficient algorithm, termed the Hessian-based Difference of Gaussians (HDoG), to segment small blobs (e.g., glomeruli from kidney) from 3D medical images based on local convexity, intensity and shape information. The image is first smoothed and pre-segmented into small blob candidate regions based on local convexity. Two novel 3D regional features (regional blobness and regional flatness) are then extracted from the candidate regions. Together with regional intensity, the three features are used in an unsupervised learning algorithm for auto post-pruning. HDoG is first validated in a 2D form and compared with other three blob detectors from literature, which are generally for 2D images only. To test the detectability of blobs from 3D images, 240 sets of simulated images are rendered for scenarios mimicking the renal nephron distribution observed in contrast-enhanced, 3D MRI. The results show a satisfactory performance of HDoG in detecting large numbers of small blobs. Two sets of real kidney 3D MR images (6 rats, 3 human) are then used to validate the applicability of HDoG for glomeruli detection. By comparing MRI to stereological measurements, we verify that HDoG is a robust and efficient unsupervised technique for 3D blobs segmentation.
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Hann BD, Baldelomar EJ, Charlton JR, Bennett KM. Measuring the intrarenal distribution of glomerular volumes from histological sections. Am J Physiol Renal Physiol 2016; 310:F1328-36. [PMID: 26984953 DOI: 10.1152/ajprenal.00382.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 03/11/2016] [Indexed: 11/22/2022] Open
Abstract
Glomerular volume is an important metric reflecting glomerular filtration surface area within the kidney. Glomerular hypertrophy, or increased glomerular volume, may be an important marker for renal stress. Current stereological techniques report the average glomerular volume (AVglom) within the kidney. These techniques cannot assess the spatial or regional heterogeneity common in developing renal pathology. Here, we report a novel "unfolding" technique to measure the actual distribution of individual glomerular volumes in a kidney from the two-dimensional glomerulus profiles observed by optical microscopy. The unfolding technique was first developed and tested for accuracy with simulations and then applied to measure the number of glomeruli (Nglom), AVglom, and intrarenal distribution of individual glomerular volume (IVglom) in the oligosyndactyl (Os/(+)) mouse model compared with wild-type (WT) controls. The Os/(+) mice had fewer and larger glomeruli than WT mice: Nglom was 12,126 ± 1,658 (glomeruli/kidney) in the WT mice and 5,516 ± 899 in the Os/(+) mice; AVglom was 2.01 ± 0.28 × 10(-4) mm(3) for the WT mice and 3.47 ± 0.35 × 10(-4) mm(3) for the Os/(+) mice. Comparing the glomerular volume distributions in Os/(+) and WT kidneys, we observed that the Os/(+) distribution peaked at a higher value of IVglom than the WT distribution peak, and glomeruli with a radius greater than 55 μm were more prevalent in the Os/(+) mice (3.4 ± 1.6% of total glomeruli vs. 0.6 ± 1.2% in WT). Finally, the largest profiles were more commonly found in the juxtamedullary region. Unfolding is a novel stereological technique that provides a new quantitative view of glomerular volume distribution in the individual kidney.
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Affiliation(s)
- Bradley D Hann
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, Hawaii
| | | | - Jennifer R Charlton
- Department of Pediatrics, Division of Nephrology, University of Virginia, Charlottesville, Virginia; and
| | - Kevin M Bennett
- Department of Biology, University of Hawaii at Manoa, Honolulu, Hawaii
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Beeman SC, Mandarino LJ, Georges JF, Bennett KM. Cationized ferritin as a magnetic resonance imaging probe to detect microstructural changes in a rat model of non-alcoholic steatohepatitis. Magn Reson Med 2016; 70:1728-38. [PMID: 23390010 DOI: 10.1002/mrm.24619] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PURPOSE The goal of this work was to detect disease-related microstructural changes to the liver using magnetic resonance imaging. Chronic liver disease can cause microstructural changes in the liver that reduce plasma access to the perisinusoidal space--the site of exchange between the blood plasma and the hepatic parenchyma. The reduced plasma access to the perisinusoidal space inhibits hepatic function and contributes to the ∼30,000 chronic liver disease-related deaths per year. METHODS The extracellular matrix-specific cationized ferritin magnetic resonance imaging probe was injected intravenously into healthy rats and a rat model of the chronic liver disease non-alcoholic steatohepatitis. Rats were subsequently imaged with T2*-weighted magnetic resonance imaging. RESULTS This work demonstrates that the binding of cationized ferritin to the perisinusoidal extracellular matrix is reduced by 55% in a rat model of non-alcoholic steatohepatitis compared to healthy controls. This reduced binding is detectable in vivo with magnetic resonance imaging. Immunofluorescence and electron microscopy indicated that the reduced binding is due to inhibited macromolecular access to the perisinusoidal space caused by non-alcoholic steatohepatitis-related microstructural changes. CONCLUSIONS The reduced accumulation of intravenously injected cationized ferritin may report on changes in macromolecular access to the liver parenchyma in chronic liver disease.
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Affiliation(s)
- Scott C Beeman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee
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Baldelomar EJ, Charlton JR, Beeman SC, Hann BD, Cullen-McEwen L, Pearl VM, Bertram JF, Wu T, Zhang M, Bennett KM. Phenotyping by magnetic resonance imaging nondestructively measures glomerular number and volume distribution in mice with and without nephron reduction. Kidney Int 2016; 89:498-505. [PMID: 26535998 PMCID: PMC4854807 DOI: 10.1038/ki.2015.316] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/23/2015] [Accepted: 08/20/2015] [Indexed: 12/29/2022]
Abstract
Reduced nephron mass is strongly linked to susceptibility to chronic renal and cardiovascular diseases. There are currently no tools to identify nephropenia in clinical or preclinical diagnostics. Such new methods could uncover novel mechanisms and therapies for chronic kidney disease (CKD) and reveal how variation among traits can affect renal function and morphology. Here we used cationized ferritin (CF)–enhanced MRI (CFE-MRI) to investigate the relationship between glomerular number (Nglom) and volume (Vglom) in kidneys of healthy wild-type mice and mice with oligosyndactylism (Os/+), a model of congenital nephron reduction. Mice were injected with CF and perfused, and the resected kidneys were imaged with 7T MRI to detect CF-labeled glomeruli. CFE-MRI was used to measure the intrarenal distribution of individual glomerular volumes and revealed two major populations of glomeruli distinguished by size. Spatial mapping revealed that the largest glomeruli were located in the juxtamedullary region in both wild-type and Os/+ mice and the smallest population located in the cortex. Os/+ mice had about a 50% reduction and 35% increase of Nglom and Vglom, respectively, in both glomerular populations compared with wild type, consistent with glomerular hypertrophy in the Os/+ mice. Thus, we provide a foundation for whole-kidney, MRI-based phenotyping of mouse renal glomerular morphology and provide new potential for quantitative human renal diagnostics.
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Affiliation(s)
- Edwin J. Baldelomar
- University of Hawaii at Manoa, Department of Physics, Honolulu, Hawaii, USA
- University of Hawaii at Manoa, Department of Biology, Honolulu, Hawaii, USA
| | | | - Scott C. Beeman
- Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Bradley D. Hann
- University of Hawaii at Manoa, Department of Molecular Biosciences and Bioengineering, Honolulu, Hawaii, USA
- University of Hawaii at Manoa, Department of Biology, Honolulu, Hawaii, USA
| | | | | | | | - Teresa Wu
- Arizona State University, Tempe, Arizona, USA
| | - Min Zhang
- Arizona State University, Tempe, Arizona, USA
| | - Kevin M. Bennett
- University of Hawaii at Manoa, Department of Biology, Honolulu, Hawaii, USA
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Bennett KM. MRI shines (radiofrequency) light on kidney physiology. Am J Physiol Renal Physiol 2016; 310:F41-2. [DOI: 10.1152/ajprenal.00462.2015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Kevin M. Bennett
- Department of Biology, University of Hawaii at Manoa, Honolulu, Hawaii
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35
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Abstract
Recent advances in medical imaging technology have greatly enhanced imaging-based diagnosis which requires computational effective and accurate algorithms to process the images (e.g., measure the objects) for quantitative assessment. In this research, we are interested in one type of imaging objects: small blobs. Examples of small blob objects are cells in histopathology images, glomeruli in MR images, etc. This problem is particularly challenging because the small blobs often have in homogeneous intensity distribution and an indistinct boundary against the background. Yet, in general, these blobs have similar sizes. Motivated by this finding, we propose a novel detector termed Hessian-based Laplacian of Gaussian (HLoG) using scale space theory as the foundation. Like most imaging detectors, an image is first smoothed via LoG. Hessian analysis is then launched to identify the single optimal scale on which a presegmentation is conducted. The advantage of the Hessian process is that it is capable of delineating the blobs. As a result, regional features can be retrieved. These features enable an unsupervised clustering algorithm for postpruning which should be more robust and sensitive than the traditional threshold-based postpruning commonly used in most imaging detectors. To test the performance of the proposed HLoG, two sets of 2-D grey medical images are studied. HLoG is compared against three state-of-the-art detectors: generalized LoG, Radial-Symmetry and LoG using precision, recall, and F-score metrics.We observe that HLoG statistically outperforms the compared detectors.
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Bennett KM, Jo JI, Cabral H, Bakalova R, Aoki I. MR imaging techniques for nano-pathophysiology and theranostics. Adv Drug Deliv Rev 2014; 74:75-94. [PMID: 24787226 DOI: 10.1016/j.addr.2014.04.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 03/02/2014] [Accepted: 04/20/2014] [Indexed: 11/25/2022]
Abstract
The advent of nanoparticle DDSs (drug delivery systems, nano-DDSs) is opening new pathways to understanding physiology and pathophysiology at the nanometer scale. A nano-DDS can be used to deliver higher local concentrations of drugs to a target region and magnify therapeutic effects. However, interstitial cells or fibrosis in intractable tumors, as occurs in pancreatic or scirrhous stomach cancer, tend to impede nanoparticle delivery. Thus, it is critical to optimize the type and size of nanoparticles to reach the target. High-resolution 3D imaging provides a means of "seeing" the nanoparticle distribution and therapeutic effects. We introduce the concept of "nano-pathophysiological imaging" as a strategy for theranostics. The strategy consists of selecting an appropriate nano-DDS and rapidly evaluating drug effects in vivo to guide the next round of therapy. In this article we classify nano-DDSs by component carrier materials and present an overview of the significance of nano-pathophysiological MRI.
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Clavijo Jordan MV, Beeman SC, Baldelomar EJ, Bennett KM. Disruptive chemical doping in a ferritin-based iron oxide nanoparticle to decrease r2 and enhance detection with T1-weighted MRI. Contrast Media Mol Imaging 2014; 9:323-32. [PMID: 24764110 DOI: 10.1002/cmmi.1578] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 10/03/2013] [Accepted: 10/10/2013] [Indexed: 01/26/2023]
Abstract
Inorganic doping was used to create flexible, paramagnetic nanoparticle contrast agents for in vivo molecular magnetic resonance imaging (MRI) with low transverse relaxivity (r2). Most nanoparticle contrast agents formed from superparamagnetic metal oxides are developed with high r2. While sensitive, they can have limited in vivo detection due to a number of constraints with T2 or T2*-weighted imaging. T1-weighted imaging is often preferred for molecular MRI, but most T1-shortening agents are small chelates with low metal payload or are nanoparticles that also shorten T2 and limit the range of concentrations detectable with T1-weighting. Here we used tungsten and iron deposition to form doped iron oxide crystals inside the apoferritin cavity to form a WFe nanoparticle with a disordered crystal and un-coupled atomic magnetic moments. The atomic magnetic moments were thus localized, resulting in a principally paramagnetic nanoparticle. The WFe nanoparticles had no coercivity or saturation magnetization at 5 K and sweeping up to ± 20,000 Oe, while native ferritin had a coercivity of 3000 Oe and saturation at ± 20,000 Oe. This tungsten-iron crystal paramagnetism resulted in an increased WFe particle longitudinal relaxivity (r1) of 4870 mm(-1) s(-1) and a reduced transverse relaxivity (r2) of 9076 mm(-1) s(-1) compared with native ferritin. The accumulation of the particles was detected with T1-weighted MRI in concentrations from 20 to 400 nm in vivo, both injected in the rat brain and targeted to the rat kidney glomerulus. The WFe apoferritin nanoparticles were not cytotoxic up to 700 nm particle concentrations, making them potentially important for targeted molecular MRI.
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Bertram JF, Cullen-McEwen LA, Egan GF, Gretz N, Baldelomar E, Beeman SC, Bennett KM. Why and how we determine nephron number. Pediatr Nephrol 2014; 29:575-80. [PMID: 24022365 DOI: 10.1007/s00467-013-2600-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/25/2013] [Accepted: 08/02/2013] [Indexed: 01/23/2023]
Abstract
The total number of glomeruli (nephrons) in a kidney is an important microanatomical parameter for at least three reasons: it provides an index of the success/extent of nephrogenesis and can thereby provide insights into the roles of specific genes and feto-maternal environmental factors in nephrogenesis; low nephron number has been linked to an increased risk of cardiovascular and renal disease in adulthood; and knowledge of quantitative kidney microanatomy can illuminate our understanding of physiological mechanisms in health and disease. A range of methods has been used to count glomeruli in kidneys over the past 100 years, with design-based stereology (the physical disector/fractionator combination) considered the gold standard. However, this approach is labor-intensive and expensive, and therefore is not utilized by most laboratories. A new method for counting and sizing every glomerulus in the kidney has recently been described. This method involves in vivo labeling of glomeruli with cationic ferritin, and then magnetic resonance imaging (MRI) of the ex vivo kidney. Values are obtained in one sixth of the time of disector-based approaches. This new MRI method holds great promise for studies of glomerular number and size ex vivo and in vivo.
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Beeman SC, Cullen-McEwen LA, Puelles VG, Zhang M, Wu T, Baldelomar EJ, Dowling J, Charlton JR, Forbes MS, Ng A, Wu QZ, Armitage JA, Egan GF, Bertram JF, Bennett KM. MRI-based glomerular morphology and pathology in whole human kidneys. Am J Physiol Renal Physiol 2014; 306:F1381-90. [PMID: 24647716 DOI: 10.1152/ajprenal.00092.2014] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Nephron number (N(glom)) and size (V(glom)) are correlated with risk for chronic cardiovascular and kidney disease and may be predictive of renal allograft viability. Unfortunately, there are no techniques to assess N(glom) and V(glom) in intact kidneys. This work demonstrates the use of cationized ferritin (CF) as a magnetic resonance imaging (MRI) contrast agent to measure N(glom) and V(glom) in viable human kidneys donated to science. The kidneys were obtained from patients with varying levels of cardiovascular and renal disease. CF was intravenously injected into three viable human kidneys. A fourth control kidney was perfused with saline. After fixation, immunofluorescence and electron microscopy confirmed binding of CF to the glomerulus. The intact kidneys were imaged with three-dimensional MRI and CF-labeled glomeruli appeared as punctate spots. Custom software identified, counted, and measured the apparent volumes of CF-labeled glomeruli, with an ~6% false positive rate. These measurements were comparable to stereological estimates. The MRI-based technique yielded a novel whole kidney distribution of glomerular volumes. Histopathology demonstrated that the distribution of CF-labeled glomeruli may be predictive of glomerular and vascular disease. Variations in CF distribution were quantified using image texture analyses, which be a useful marker of glomerular sclerosis. This is the first report of direct measurement of glomerular number and volume in intact human kidneys.
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Affiliation(s)
- Scott C Beeman
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri
| | - Luise A Cullen-McEwen
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Victor G Puelles
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Min Zhang
- School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, Arizona
| | - Teresa Wu
- School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, Arizona
| | - Edwin J Baldelomar
- Department of Physics, College of Natural Sciences, University of Hawaii at Manoa, Honolulu, Hawaii
| | - John Dowling
- Department of Anatomical Pathology, Monash Medical Centre, Clayton, Victoria, Australia
| | - Jennifer R Charlton
- Department of Pediatrics, Division of Nephrology, University of Virginia Medical Center, Charlottesville, Virginia
| | - Michael S Forbes
- Department of Pediatrics, Division of Nephrology, University of Virginia Medical Center, Charlottesville, Virginia
| | - Amanda Ng
- Monash Biomedical Imaging, Monash University, Melbourne, Australia; and
| | - Qi-zhu Wu
- Monash Biomedical Imaging, Monash University, Melbourne, Australia; and
| | - James A Armitage
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Gary F Egan
- Monash Biomedical Imaging, Monash University, Melbourne, Australia; and
| | - John F Bertram
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Kevin M Bennett
- Department of Biology, College of Natural Sciences, University of Hawaii at Manoa, Honolulu, Hawaii
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Charlton JR, Beeman SC, Bennett KM. MRI-detectable nanoparticles: the potential role in the diagnosis of and therapy for chronic kidney disease. Adv Chronic Kidney Dis 2013; 20:479-87. [PMID: 24206600 DOI: 10.1053/j.ackd.2013.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 05/23/2013] [Accepted: 06/03/2013] [Indexed: 12/30/2022]
Abstract
Chronic kidney disease (CKD) is a common, deadly, and expensive threat to public health. Patients susceptible to the development of CKD are difficult to identify because there are few noninvasive clinical techniques and markers to assess early kidney dysfunction. Noninvasive imaging techniques are being developed to quantitatively measure kidney morphology and function in preclinical research and in clinical trials. Magnetic resonance imaging (MRI) techniques in particular have the potential to provide structural and functional information in the kidney. Novel molecular imaging techniques, using targeted magnetic nanoparticles that exploit the characteristics of the endogenous protein, ferritin, have been developed in conjunction with MRI to count every perfused glomerulus in the kidney and measure their individual volumes. This technique could open the door to the possibility of prospectively assessing and eventually reducing a patient's risk for progression to CKD. This review highlights the potential clinical benefits of early detection in patients predisposed to CKD and discusses technologic and regulatory hurdles to the translation of these molecular MRI techniques to provide early diagnosis of CKD.
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Lee CY, Bennett KM, Debbins JP. Sensitivities of statistical distribution model and diffusion kurtosis model in varying microstructural environments: a Monte Carlo study. J Magn Reson 2013; 230:19-26. [PMID: 23428968 DOI: 10.1016/j.jmr.2013.01.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 01/12/2013] [Accepted: 01/19/2013] [Indexed: 06/01/2023]
Abstract
The aim of this study was to investigate the microstructural sensitivity of the statistical distribution and diffusion kurtosis (DKI) models of non-monoexponential signal attenuation in the brain using diffusion-weighted MRI (DWI). We first developed a simulation of 2-D water diffusion inside simulated tissue consisting of semi-permeable cells and a variable cell size. We simulated a DWI acquisition of the signal in a volume using a pulsed gradient spin echo (PGSE) pulse sequence, and fitted the models to the simulated DWI signals using b-values up to 2500 s/mm(2). For comparison, we calculated the apparent diffusion coefficient (ADC) of the monoexponential model (b-value=1000 s/mm(2)). In separate experiments, we varied the cell size (5-10-15 μm), cell volume fraction (0.50-0.65-0.80), and membrane permeability (0.001-0.01-0.1mm/s) to study how the fitted parameters tracked simulated microstructural changes. The ADC was sensitive to all the simulated microstructural changes except the decrease in membrane permeability. The ADC increased with larger cell size, smaller cell volume fraction, and larger membrane permeability. The σstat of the statistical distribution model increased exclusively with a decrease in cell volume fraction. The Kapp of the DKI model was exclusively increased with decreased cell size and decreased with increasing membrane permeability. These results suggest that the non-monoexponential models of water diffusion have different, specific microstructural sensitivity, and a combination of the models may give insights into the microstructural underpinning of tissue pathology.
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Affiliation(s)
- Chu-Yu Lee
- Keller Center for Imaging Innovation, Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, USA
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Abstract
Techniques to measure morphological parameters, such as glomerular (and thereby nephron) number, glomerular size, and kidney volume, have been vital to understanding factors contributing to chronic kidney disease (CKD). These techniques have also been important to understanding the associations between CKD and other systemic and cardiovascular diseases and have led to the identification of developmental risk factors for these pathologies. However, existing techniques in quantitative kidney morphology are resource- and time-consuming and are destructive to the organ. This review discusses the emerging generation of techniques to study kidney morphology quantitatively using magnetic resonance imaging (MRI) using the intravenous injection of the superparamagnetic nanoparticle cationic ferritin, which binds to the glomerular basement membrane. A primary advantage of MRI over previously established techniques is the ability to quantify morphology in the intact organ with minimal sample preparation. We highlight areas of research where MRI-based morphological measurements will be helpful in animal models and possibly diagnostic clinical nephrology, discuss technical challenges in light of the progress in MRI techniques to date, and identify novel measurements that may be possible using MRI, both ex vivo and in vivo.
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Affiliation(s)
- K M Bennett
- Department of Biology, College of Natural Sciences, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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Beeman SC, Georges JF, Bennett KM. Toxicity, biodistribution, and ex vivo MRI detection of intravenously injected cationized ferritin. Magn Reson Med 2012; 69:853-61. [DOI: 10.1002/mrm.24301] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 03/27/2012] [Accepted: 03/28/2012] [Indexed: 01/12/2023]
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Clavijo-Jordan V, Kodibagkar VD, Beeman SC, Hann BD, Bennett KM. Principles and emerging applications of nanomagnetic materials in medicine. Wiley Interdiscip Rev Nanomed Nanobiotechnol 2012; 4:345-65. [PMID: 22488879 DOI: 10.1002/wnan.1169] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The development of nanometer-scale magnetic materials for biomedical applications spans the interface between the physical sciences and biology. Applications of these materials are rapidly becoming important in medicine and enable targeted therapies and diagnostics. At the same time, specific applications add focus to the development of novel magnetic materials and facilitate a deeper understanding of the physical mechanisms behind their function. This review presents a broad, nontechnical overview of the basis of magnetism in materials at the nanometer scale and describes how these materials are created, characterized, and used. Specific emerging applications in medical diagnostics and therapies are discussed, including cancer cell targeting for thermal ablation, tissue engineering, and three-dimensional noninvasive molecular imaging. Challenges in these fields are discussed, including the toxicity and delivery of magnetic nanomaterials and the sensitivity of imaging and therapeutic techniques. The development of novel nanomagnetic nanomaterials should continue to accelerate as new applications are identified and researchers uncover new mechanisms to increase and modulate magnetism at the nanometer scale.
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Affiliation(s)
- Veronica Clavijo-Jordan
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
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Beeman SC, Zhang M, Gubhaju L, Wu T, Bertram JF, Frakes DH, Cherry BR, Bennett KM. Measuring glomerular number and size in perfused kidneys using MRI. Am J Physiol Renal Physiol 2011; 300:F1454-7. [DOI: 10.1152/ajprenal.00044.2011] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The goal of this work was to nondestructively measure glomerular (and thereby nephron) number in the whole kidney. Variations in the number and size of glomeruli have been linked to many renal and systemic diseases. Here, we develop a robust magnetic resonance imaging (MRI) technique based on injection of cationic ferritin (CF) to produce an accurate measurement of number and size of individual glomeruli. High-field (19 Tesla) gradient-echo MR images of perfused rat kidneys after in vivo intravenous injection of CF showed specific labeling of individual glomeruli with CF throughout the kidney. We developed a three-dimensional image-processing algorithm to count every labeled glomerulus. MRI-based counts yielded 33,786 ± 3,753 labeled glomeruli ( n = 5 kidneys). Acid maceration counting of contralateral kidneys yielded an estimate of 30,585 ± 2,053 glomeruli ( n = 6 kidneys). Disector/fractionator stereology counting yielded an estimate of 34,963 glomeruli ( n = 2). MRI-based measurement of apparent glomerular volume of labeled glomeruli was 4.89 × 10−4mm3( n = 5) compared with the average stereological measurement of 4.99 × 10−4mm3( n = 2). The MRI-based technique also yielded the intrarenal distribution of apparent glomerular volume, a measurement previously unobtainable in histology. This work makes it possible to nondestructively measure whole-kidney glomerular number and apparent glomerular volumes to study susceptibility to renal diseases and opens the door to similar in vivo measurements in animals and humans.
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Affiliation(s)
| | - Min Zhang
- School of Computing, Informatics, and Decision Systems Engineering, and
| | - Lina Gubhaju
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Teresa Wu
- School of Computing, Informatics, and Decision Systems Engineering, and
| | - John F. Bertram
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | | | - Brian R. Cherry
- Magnetic Resonance Research Center, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona; and
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Abstract
Magnetoferritin nanoparticles have been developed as high-relaxivity, functional contrast agents for MRI. Several previous techniques have relied on unloading native ferritin and re-incorporation of iron into the core, often resulting in a polydisperse sample. Here, a simplified technique is developed using commercially available horse spleen apoferritin to create monodisperse magnetoferritin. Iron oxide atoms were incorporated into the protein core via a step-wise Fe(II)Chloride addition to the protein solution under low O(2) conditions; subsequent filtration steps allow for separation of completely filled and superparamagnetic magnetoferritin from the partially filled ferritin. This method yields a monodisperse and homogenous solution of spherical particles with magnetic properties that can be used for molecular magnetic resonance imaging. With a transverse per-iron and per-particle relaxivity of 78 mM(-1) sec(-1) and 404,045 mM(-1) sec(-1), respectively, it is possible to detect ∼ 10 nM nanoparticle concentrations in vivo.
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Affiliation(s)
- Veronica Clavijo Jordan
- School of Biological and Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State University, Tempe, Arizona 85287-9709, USA
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Colomb J, Louie K, Massia SP, Bennett KM. Self-degrading, MRI-detectable hydrogel sensors with picomolar target sensitivity. Magn Reson Med 2010; 64:1792-9. [PMID: 20648680 DOI: 10.1002/mrm.22570] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 05/14/2010] [Accepted: 06/16/2010] [Indexed: 11/10/2022]
Abstract
Nanostructured hydrogels have been developed as synthetic tissues and scaffolds for cell and drug delivery, and as guides for tissue regeneration. A fundamental problem in the development of synthetic hydrogels is that implanted gel structure is difficult to monitor noninvasively. This work demonstrates that the aggregation of magnetic nanoparticles, attached to specific macromolecules in biological and synthetic hydrogels, can be controlled to detect changes in gel macromolecular structure with MRI. It is further shown that the gels can be made to self-degrade when they come into contact with a target molecule in as low as pM concentrations. The sensitivity of the gels to the target is finely controlled using an embedded zymogen cascade amplifier. These "MRI reporter gels" may serve as smart, responsive polymer implants, as tissue scaffolds to deliver drugs, or to detect specific pathogens in vivo.
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Affiliation(s)
- Jason Colomb
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, USA
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Affiliation(s)
- Nikolay L. Martirosyan
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Kevin M. Bennett
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona
| | - Nicholas Theodore
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Mark C. Preul
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
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Bennett KM, Zhou H, Sumner JP, Dodd SJ, Bouraoud N, Doi K, Star RA, Koretsky AP. MRI of the basement membrane using charged nanoparticles as contrast agents. Magn Reson Med 2009; 60:564-74. [PMID: 18727041 DOI: 10.1002/mrm.21684] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The integrity of the basement membrane is essential for tissue cellular growth and is often altered in disease. In this work a method for noninvasively detecting the structural integrity of the basement membrane, based on the delivery of cationic iron-oxide nanoparticles, was developed. Cationic particles accumulate due to the highly negative charge of proteoglycans in the basement membrane. The kidney was used to test this technique because of its highly fenestrated endothelia and well-established disease models to manipulate the basement membrane charge barrier. After systemic injection of cationic or native ferritin (CF or NF) in rats, ex vivo and in vivo MRI showed selective accumulation of CF, but not NF, causing a 60% reduction in signal intensity in cortex at the location of individual glomeruli. Immunofluorescence and electron microscopy demonstrated that this CF accumulation was localized to the glomerular basement membrane (GBM). In a model of GBM breakdown during focal and segmental glomerulosclerosis, MRI showed reduced single glomerular accumulation of CF, but a diffuse accumulation of CF in the kidney tubules caused by leakage of CF through the glomerulus. Cationic contrast agents can be used to target the basement membrane and detect the breakdown of the basement membrane in disease.
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Affiliation(s)
- Kevin M Bennett
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
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Bennett KM, Hyde JS, Schmainda KM. Water diffusion heterogeneity index in the human brain is insensitive to the orientation of applied magnetic field gradients. Magn Reson Med 2006; 56:235-9. [PMID: 16929466 DOI: 10.1002/mrm.20960] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The alpha diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The alpha-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, alpha-DWI was performed with magnetic field gradients applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the alpha-DWI method must take this into account to be complete. In this work the relationship between the applied magnetic field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of applied gradients, while the heterogeneity index alpha is relatively direction-insensitive. It is proposed that in clinical use, maps of alpha can be created using diffusion-weighting gradients applied in a single direction that reflect the tissue heterogeneity.
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Affiliation(s)
- Kevin M Bennett
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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