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Biopsy-based optimization and calibration of a signal-intensity-ratio-based MRI method (1.5 Tesla) in a dextran-iron loaded mini-pig model, enabling estimation of very high liver iron concentrations. MAGNETIC RESONANCE MATERIALS IN PHYSICS, BIOLOGY AND MEDICINE 2022; 35:843-859. [PMID: 35038062 PMCID: PMC9463247 DOI: 10.1007/s10334-021-00998-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/26/2021] [Accepted: 12/28/2021] [Indexed: 11/15/2022]
Abstract
Objective Magnetic resonance imaging (MRI)-based techniques for non-invasive assessing liver iron concentration (LIC) in patients with iron overload have a limited upper measuring range around 35 mg/g dry weight, caused by signal loss from accelerated T1-, T2-, T2* shortening with increasing LIC. Expansion of this range is necessary to allow evaluation of patients with very high LIC. Aim To assess measuring range of a gradient-echo R2* method and a T1-weighted spin-echo (SE), signal intensity ratio (SIR)-based method (TE = 25 ms, TR = 560 ms), and to extend the upper measuring range of the SIR method by optimizing echo time (TE) and repetition time (TR) in iron-loaded minipigs. Methods Thirteen mini pigs were followed up during dextran-iron loading with repeated percutaneous liver biopsies for chemical LIC measurement and MRIs for parallel non-invasive estimation of LIC (81 examinations) using different TEs and TRs. Results SIR and R2* method had similar upper measuring range around 34 mg/g and similar method agreement. Using TE = 12 ms and TR = 1200 ms extended the upper measuring range to 115 mg/g and yielded good method of agreement. Discussion The wider measuring range is likely caused by lesser sensitivity of the SE sequence to iron, due to shorter TE, leading to later signal loss at high LIC, allowing evaluation of most severe hepatic iron overload. Validation in iron-loaded patients is necessary.
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Doyle EK, Thornton S, Toy KA, Powell AJ, Wood JC. Improving CPMG liver iron estimates with a T 1 -corrected proton density estimator. Magn Reson Med 2021; 86:3348-3359. [PMID: 34324729 DOI: 10.1002/mrm.28943] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 01/19/2023]
Abstract
PURPOSE CPMG spin echo acquisitions are attractive for diagnosing and monitoring liver iron concentration in iron overload disorders due to their time efficiency and potential to reveal unique information about tissue iron distribution. Clinical adoption remains low due to the insensitivity of CPMG-based R 2 estimates to liver iron concentration (LIC) when common fitting techniques are applied. In this work, we demonstrate that the inclusion of a proton density estimator (PDE) derived from the CPMG acquisition increase the sensitivity of CPMG R 2 estimates to LIC in both simulated and in-vivo human data. THEORY AND METHODS CPMG R 2 acquisitions from 50 clinically indicated MRI studies in patients with iron overload were analyzed with and without PDE constraints. Liver regions of interest were fit to monoexpontial and nonexponential signal decay equations. LIC by R 2 ∗ served as the reference standard. The observed calibration between CPMG R 2 values and LIC were compared to results predicted from a previously validated Monte Carlo model. RESULTS The sensitivity of CPMG-derived R 2 triples when a proton density constraint is applied. When compared with R 2 ∗ -LIC estimates, both monoexponential and nonexponential models were unbiased but demonstrated broad 95% confidence intervals particularly for LIC values below 12 mg/g. Absolute error did not increase with LIC. CONCLUSION A proton density constraint can increase the sensitivity of CPMG-based models to iron. CPMG acquisitions are time-efficient and could potentially improve the dynamic range of single spin echo techniques as well as providing insight into tissue iron distribution.
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Affiliation(s)
- Eamon K Doyle
- Cardiology, Children's Hospital of Los Angeles, Los Angeles, CA, USA.,Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Samuel Thornton
- Electrical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Kristin A Toy
- Cardiology, Children's Hospital of Los Angeles, Los Angeles, CA, USA
| | | | - John C Wood
- Cardiology, Children's Hospital of Los Angeles, Los Angeles, CA, USA.,Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
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Salama SA, Kabel AM. Taxifolin ameliorates iron overload-induced hepatocellular injury: Modulating PI3K/AKT and p38 MAPK signaling, inflammatory response, and hepatocellular regeneration. Chem Biol Interact 2020; 330:109230. [PMID: 32828744 DOI: 10.1016/j.cbi.2020.109230] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 07/30/2020] [Accepted: 08/18/2020] [Indexed: 02/06/2023]
Abstract
Although physiological levels of iron are essential for numerous biological processes, excess iron causes critical tissue injury. Under iron overload conditions, non-chelated iron generates reactive oxygen species that mediate iron-induced tissue injury with subsequent induction of apoptosis, necrosis, and inflammatory responses. Because liver is a central player in iron metabolism and storage, it is vulnerable to iron-induced tissue injury. Taxifolin is naturally occurring compound that has shown potent antioxidant and potential iron chelation competency. The aim of the current study was to investigate the potential protective effects of taxifolin against iron-induced hepatocellular injury and to elucidate the underlining mechanisms using rats as a mammalian model. The results of the current work indicated that taxifolin inhibited iron-induced apoptosis and enhanced hepatocellular survival as demonstrated by decreased activity of caspase-3 and activation of the pro-survival signaling PI3K/AKT, respectively. Western blotting analysis revealed that taxifolin enhanced liver regeneration as indicated by increased PCNA protein abundance. Taxifolin mitigated the iron-induced histopathological aberration and reduced serum activity of liver enzymes (ALT and AST), highlighting enhanced liver cell integrity. Mechanistically, taxifolin modulated the redox-sensitive MAPK signaling (p38/c-Fos) and improved redox status of the liver tissues as indicated by decreased lipid peroxidation and protein oxidation along with enhanced total antioxidant capacity. Interestingly, it decreased liver iron content and down-regulated the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. Collectively, these data highlight, for the first time, the ameliorating effects of taxifolin against iron overload-induced hepatocellular injury that is potentially mediated through anti-inflammatory, antioxidant, and potential iron chelation activities.
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Affiliation(s)
- Samir A Salama
- Division of Biochemistry, Department of Pharmacology and GTMR Unit, College of Pharmacy, Taif University, Taif, 21974, Saudi Arabia; Department of Biochemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, 11751, Egypt.
| | - Ahmed M Kabel
- Department of Clinical Pharmacy, College of Pharmacy, Taif University, Taif, Saudi Arabia; Department of Pharmacology, Faculty of Medicine, Tanta University, Tanta, Egypt
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Calle-Toro JS, Barrera CA, Khrichenko D, Otero HJ, Serai SD. R2 relaxometry based MR imaging for estimation of liver iron content: A comparison between two methods. Abdom Radiol (NY) 2019; 44:3058-3068. [PMID: 31161282 DOI: 10.1007/s00261-019-02074-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE To compare the reproducibility and accuracy of R2-relaxometry MRI for estimation of liver iron concentration (LIC) between in-house analysis and FDA-approved commercially available third party results. METHODS All MR studies were performed on a 1.5T scanner. Multi-echo spin-echo scans with a fixed TR and increasing TE values of 6 ms, 9 ms, 12 ms, 15 ms, and 18 ms (spaced at 3 ms intervals) were used. Post-processing of the images to calculate mean relaxivity, R2, included drawing of regions of interest to include the whole liver on mid-slice. The relationship between liver R2 values and estimated LIC calculated with in-house analysis and values reported by an external company (FerriScan®, Resonance Health, Australia) were assessed with correlation coefficients and Bland-Altman difference plots. Continuous variables are presented as mean ± standard deviation. Significance was set at p value < 0.05. RESULTS 474 studies from 175 patients were included in the study (mean age 10.4 ± 4.2 years (range 1-18 years); 254 studies from girls, 220 studies from boys). LIC ranged from 0.6 to 43 mg/g dry tissue, covering a broad range from normal levels to extremely high iron levels. Linearity between proprietary and in-house methods was excellent across the observed range for R2 (31.5 to 334.8 s-1); showing a correlation coefficient of r = 0.87, p < 0.001. Bland-Altman R2 difference plot between the two methods shows a mean bias of + 21.5 s-1 (range - 47.0 to + 90.0 s-1 between two standard deviations). LIC reported by FerriScan® compared with LIC estimated in-house with R2 as reported by FerriScan® agreed strongly, (r = 1.0, p < 0.001). CONCLUSION R2 relaxometry MR imaging for liver iron concentration estimation is reproducible between proprietary FDA-approved commercial software and in-house analysis methods.
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Affiliation(s)
- Juan S Calle-Toro
- Division of Body Imaging, Department of Radiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Christian A Barrera
- Division of Body Imaging, Department of Radiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Dmitry Khrichenko
- Division of Body Imaging, Department of Radiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Hansel J Otero
- Division of Body Imaging, Department of Radiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Suraj D Serai
- Division of Body Imaging, Department of Radiology, Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA.
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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5
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Krittayaphong R, Zhang S, Saiviroonporn P, Viprakasit V, Tanapibunpon P, Komoltri C, Wangworatrakul W. Detection of cardiac iron overload with native magnetic resonance T1 and T2 mapping in patients with thalassemia. Int J Cardiol 2017; 248:421-426. [DOI: 10.1016/j.ijcard.2017.06.100] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/08/2017] [Accepted: 06/26/2017] [Indexed: 12/15/2022]
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Masi B, Perles-Barbacaru TA, Laprie C, Dessein H, Bernard M, Dessein A, Viola A. In Vivo MRI Assessment of Hepatic and Splenic Disease in a Murine Model of Schistosomiasis [corrected]. PLoS Negl Trop Dis 2015; 9:e0004036. [PMID: 26394390 PMCID: PMC4578925 DOI: 10.1371/journal.pntd.0004036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/04/2015] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Schistosomiasis (or bilharzia), a major parasitic disease, affects more than 260 million people worldwide. In chronic cases of intestinal schistosomiasis caused by trematodes of the Schistosoma genus, hepatic fibrosis develops as a host immune response to the helminth eggs, followed by potentially lethal portal hypertension. In this study, we characterized hepatic and splenic features of a murine model of intestinal schistosomiasis using in vivo magnetic resonance imaging (MRI) and evaluated the transverse relaxation time T2 as a non-invasive imaging biomarker for monitoring hepatic fibrogenesis. METHODOLOGY/PRINCIPAL FINDINGS CBA/J mice were imaged at 11.75 T two, six and ten weeks after percutaneous infection with Schistosoma mansoni. In vivo imaging studies were completed with histology at the last two time points. Anatomical MRI allowed detection of typical manifestations of the intestinal disease such as significant hepato- and splenomegaly, and dilation of the portal vein as early as six weeks, with further aggravation at 10 weeks after infection. Liver multifocal lesions observed by MRI in infected animals at 10 weeks post infection corresponded to granulomatous inflammation and intergranulomatous fibrosis with METAVIR scores up to A2F2. While most healthy hepatic tissue showed T2 values below 14 ms, these lesions were characterized by a T2 greater than 16 ms. The area fraction of increased T2 correlated (rS = 0.83) with the area fraction of Sirius Red stained collagen in histological sections. A continuous liver T2* decrease was also measured while brown pigments in macrophages were detected at histology. These findings suggest accumulation of hematin in infected livers. CONCLUSIONS/SIGNIFICANCE Our multiparametric MRI approach confirms that this murine model replicates hepatic and splenic manifestations of human intestinal schistosomiasis. Quantitative T2 mapping proved sensitive to assess liver fibrogenesis non-invasively and may therefore constitute an objective imaging biomarker for treatment monitoring in diseases involving hepatic fibrosis.
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Affiliation(s)
- Brice Masi
- Génétique et Immunologie des Maladies Parasitaires-Unité Mixte de Recherche S_906, Aix-Marseille Université, Marseille, France
- Unité 906, Institut National de la Santé et de la Recherche Médicale, Marseille, France
| | - Teodora-Adriana Perles-Barbacaru
- Centre de Résonance Magnétique Biologique et Médicale-Unité Mixte de Recherche 7339, Aix-Marseille Université, Marseille, France
- Unité Mixte de Recherche 7339, Centre National de la Recherche Scientifique, Marseille, France
| | | | - Helia Dessein
- Génétique et Immunologie des Maladies Parasitaires-Unité Mixte de Recherche S_906, Aix-Marseille Université, Marseille, France
- Unité 906, Institut National de la Santé et de la Recherche Médicale, Marseille, France
| | - Monique Bernard
- Centre de Résonance Magnétique Biologique et Médicale-Unité Mixte de Recherche 7339, Aix-Marseille Université, Marseille, France
- Unité Mixte de Recherche 7339, Centre National de la Recherche Scientifique, Marseille, France
| | - Alain Dessein
- Génétique et Immunologie des Maladies Parasitaires-Unité Mixte de Recherche S_906, Aix-Marseille Université, Marseille, France
- Unité 906, Institut National de la Santé et de la Recherche Médicale, Marseille, France
- Laboratoire de Parasitologie-Mycologie, Centre Hospitalier Universitaire Timone, Assistance Publique des Hôpitaux de Marseille, Marseille, France
| | - Angèle Viola
- Centre de Résonance Magnétique Biologique et Médicale-Unité Mixte de Recherche 7339, Aix-Marseille Université, Marseille, France
- Unité Mixte de Recherche 7339, Centre National de la Recherche Scientifique, Marseille, France
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7
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Sarigianni M, Liakos A, Vlachaki E, Paschos P, Athanasiadou E, Montori VM, Murad MH, Tsapas A. Accuracy of magnetic resonance imaging in diagnosis of liver iron overload: a systematic review and meta-analysis. Clin Gastroenterol Hepatol 2015; 13:55-63.e5. [PMID: 24993364 DOI: 10.1016/j.cgh.2014.05.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 04/01/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Guidelines advocate use of magnetic resonance imaging (MRI) to estimate concentrations of iron in liver, to identify patients with iron overload, and to guide titration of chelation therapy. However, this recommendation was not based on a systematic synthesis and analysis of the evidence for MRI's diagnostic accuracy. METHODS We conducted a systematic review and meta-analysis to investigate the diagnostic accuracy of MRI in identifying liver iron overload in patients with hereditary hemochromatosis, hemoglobinopathy, or myelodysplastic syndrome; liver biopsy analysis was used as the reference standard. We searched MEDLINE and EMBASE databases, the Cochrane Library, and gray literature, and computed summary receiver operating curves by fitting hierarchical models. We assessed methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. RESULTS Our final analysis included 20 studies (819 patients, total). Sensitivity and specificity values varied greatly, ranging from 0.00 to 1.00 and from 0.50 to 1.00, respectively. Because of substantial heterogeneity and variable positivity thresholds, we calculated only summary receiver operating curves (and summary estimate points for studies that used the same MRI sequences). T2 spin echo and T2* gradient-recalled echo MRI sequences accurately identified patients without liver iron overload (liver iron concentration > 7 mg Fe/g dry liver weight) (negative likelihood ratios, 0.10 and 0.05 respectively). However, these MRI sequences are less accurate in establishing a definite diagnosis of liver iron overload (positive likelihood ratio, 8.85 and 4.86, respectively). CONCLUSIONS Based on a meta-analysis, measurements of liver iron concentration by MRI may be accurate enough to rule out iron overload, but not to definitely identify patients with this condition. Most studies did not use explicit and prespecified MRI thresholds for iron overload, therefore some patients may have been diagnosed inaccurately with this condition. More studies are needed of standardized MRI protocols and to determine the effects of MRI surveillance on the development of chronic liver disease and patient survival.
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Affiliation(s)
- Maria Sarigianni
- Clinical Research and Evidence-Based Medicine Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece; Knowledge and Evaluation Research Unit, College of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Aris Liakos
- Clinical Research and Evidence-Based Medicine Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece
| | - Efthymia Vlachaki
- Thalassemia Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece
| | - Paschalis Paschos
- Clinical Research and Evidence-Based Medicine Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece
| | - Eleni Athanasiadou
- Clinical Research and Evidence-Based Medicine Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece
| | - Victor M Montori
- Knowledge and Evaluation Research Unit, College of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Mohammad Hassan Murad
- Knowledge and Evaluation Research Unit, College of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Apostolos Tsapas
- Clinical Research and Evidence-Based Medicine Unit, Second Medical Department, Aristotle University Thessaloniki, Thessaloniki, Greece; Harris Manchester College, University of Oxford, Oxford, United Kingdom.
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8
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Alústiza JM, Emparanza JI, Castiella A, Casado A, Garrido A, Aldazábal P, San Vicente M, Garcia N, Asensio AB, Banales J, Salvador E, Moyua A, Arozena X, Zarco M, Jauregui L, Vicente O. Measurement of liver iron concentration by MRI is reproducible. BIOMED RESEARCH INTERNATIONAL 2015; 2015:294024. [PMID: 25874207 PMCID: PMC4385637 DOI: 10.1155/2015/294024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 09/14/2014] [Indexed: 02/08/2023]
Abstract
PURPOSE The objectives were (i) construction of a phantom to reproduce the behavior of iron overload in the liver by MRI and (ii) assessment of the variability of a previously validated method to quantify liver iron concentration between different MRI devices using the phantom and patients. MATERIALS AND METHODS A phantom reproducing the liver/muscle ratios of two patients with intermediate and high iron overload. Nine patients with different levels of iron overload were studied in 4 multivendor devices and 8 of them were studied twice in the machine where the model was developed. The phantom was analysed in the same equipment and 14 times in the reference machine. RESULTS FeCl3 solutions containing 0.3, 0.5, 0.6, and 1.2 mg Fe/mL were chosen to generate the phantom. The average of the intramachine variability for patients was 10% and for the intermachines 8%. For the phantom the intramachine coefficient of variation was always below 0.1 and the average of intermachine variability was 10% for moderate and 5% for high iron overload. CONCLUSION The phantom reproduces the behavior of patients with moderate or high iron overload. The proposed method of calculating liver iron concentration is reproducible in several different 1.5 T systems.
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Affiliation(s)
- José María Alústiza
- 1Osatek, Donostia Universitary Hospital, P. Dr. Beguiristain 109, 20014 Donostia/San Sebastián, Spain
- *José María Alústiza:
| | - José I. Emparanza
- 2Clinical Epidemiology, Donostia Universitary Hospital, P. Dr. Beguiristain 117, 20080 Donostia/San Sebastián, Spain
| | - Agustín Castiella
- 3Gastroenterology, Mendaro Hospital, Mendarozabal s/n, Mendaro, Spain
| | - Alfonso Casado
- 4Basque Country University, Avenida Tolosa 54, 20018 Donostia/San Sebastián, Spain
| | - Adolfo Garrido
- 5Biochemical Laboratory, Donostia Universitary Hospital, P. Dr. Beguiristain 117, 20080 Donostia/San Sebastián, Spain
| | - Pablo Aldazábal
- 6Experimental Department, Donostia Universitary Hospital, P. Dr. Beguiristain 117, 20080 Donostia/San Sebastián, Spain
| | - Manuel San Vicente
- 1Osatek, Donostia Universitary Hospital, P. Dr. Beguiristain 109, 20014 Donostia/San Sebastián, Spain
| | - Nerea Garcia
- 6Experimental Department, Donostia Universitary Hospital, P. Dr. Beguiristain 117, 20080 Donostia/San Sebastián, Spain
| | - Ana Belén Asensio
- 6Experimental Department, Donostia Universitary Hospital, P. Dr. Beguiristain 117, 20080 Donostia/San Sebastián, Spain
| | - Jesús Banales
- 7Liver Diseases Unit, Biodonostia Research Institute, P. Dr. Beguiristain s/n, 20014 Donostia/San Sebastián, Spain
| | - Emma Salvador
- 1Osatek, Donostia Universitary Hospital, P. Dr. Beguiristain 109, 20014 Donostia/San Sebastián, Spain
| | - Aranzazu Moyua
- 8Policlínica Gipúzkoa, Paseo Miramón 174, 20014 Donostia/San Sebastián, Spain
| | - Xabier Arozena
- 9Radiology, Quirón Donostia Hospital, Alkolea Parkea 7, 20012 Donostia/San Sebastián, Spain
| | - Miguel Zarco
- 9Radiology, Quirón Donostia Hospital, Alkolea Parkea 7, 20012 Donostia/San Sebastián, Spain
| | - Lourdes Jauregui
- 10Onkologikoa, P. Dr. Beguiristain s/n, 20011 Donostia/San Sebastián, Spain
| | - Ohiana Vicente
- 10Onkologikoa, P. Dr. Beguiristain s/n, 20011 Donostia/San Sebastián, Spain
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Sado DM, Maestrini V, Piechnik SK, Banypersad SM, White SK, Flett AS, Robson MD, Neubauer S, Ariti C, Arai A, Kellman P, Yamamura J, Schoennagel BP, Shah F, Davis B, Trompeter S, Walker M, Porter J, Moon JC. Noncontrast myocardial T1 mapping using cardiovascular magnetic resonance for iron overload. J Magn Reson Imaging 2014; 41:1505-11. [PMID: 25104503 DOI: 10.1002/jmri.24727] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/31/2014] [Indexed: 12/18/2022] Open
Abstract
PURPOSE To explore the use and reproducibility of magnetic resonance-derived myocardial T1 mapping in patients with iron overload. MATERIALS AND METHODS The research received ethics committee approval and all patients provided written informed consent. This was a prospective study of 88 patients and 67 healthy volunteers. Thirty-five patients underwent repeat scanning for reproducibility. T1 mapping used the shortened modified Look-Locker inversion recovery sequence (ShMOLLI) with a second, confirmatory MOLLI sequence in the reproducibility group. T2 * was performed using a commercially available sequence. The analysis of the T2 * interstudy reproducibility data was performed by two different research groups using two different methods. RESULTS Myocardial T1 was lower in patients than healthy volunteers (836 ± 138 msec vs. 968 ± 32 msec, P < 0.0001). Myocardial T1 correlated with T2 * (R = 0.79, P < 0.0001). No patient with low T2 * had normal T1 , but 32% (n = 28) of cases characterized by a normal T2 * had low myocardial T1 . Interstudy reproducibility of either T1 sequence was significantly better than T2 *, with the results suggesting that the use of T1 in clinical trials could decrease potential sample sizes by 7-fold. CONCLUSION Myocardial T1 mapping is an alternative method for cardiac iron quantification. T1 mapping shows the potential for improved detection of mild iron loading. The superior reproducibility of T1 has potential implications for clinical trial design and therapeutic monitoring.
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Affiliation(s)
- Daniel M Sado
- The Heart Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Viviana Maestrini
- Department of Cardiovascular, Respiratory, Nephrology and Geriatrics Sciences, La Sapienza, University of Rome, Rome, Italy
| | - Stefan K Piechnik
- Oxford Centre for Clinical Magnetic Resonance Research, Department of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Sanjay M Banypersad
- The Heart Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Steven K White
- The Heart Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | | | - Matthew D Robson
- Oxford Centre for Clinical Magnetic Resonance Research, Department of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Stefan Neubauer
- Oxford Centre for Clinical Magnetic Resonance Research, Department of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Cono Ariti
- Department of Statistics, London School of Hygiene and Tropical Medicine, London, UK
| | - Andrew Arai
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Peter Kellman
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jin Yamamura
- University Medical Centre Hamburg-Eppendorf, Department of Diagnostic and Interventional Radiology, Hamburg, Germany
| | - Bjoern P Schoennagel
- University Medical Centre Hamburg-Eppendorf, Department of Diagnostic and Interventional Radiology, Hamburg, Germany
| | | | | | | | - Malcolm Walker
- The Heart Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | | | - James C Moon
- The Heart Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
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10
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Feng Y, He T, Carpenter JP, Jabbour A, Alam MH, Gatehouse PD, Greiser A, Messroghli D, Firmin DN, Pennell DJ. In vivo comparison of myocardial T1 with T2 and T2* in thalassaemia major. J Magn Reson Imaging 2013; 38:588-93. [PMID: 23371802 DOI: 10.1002/jmri.24010] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 11/30/2012] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To compare myocardial T1 against T2 and T2* in patients with thalassemia major (TM) for myocardial iron characterization. MATERIALS AND METHODS A total of 106 TM patients (29 ± 10 years; 58 males) were studied on a 1.5 Tesla scanner using dedicated T1, T2*, and T2 relaxometry sequences. A single mid-ventricular short axis slice was acquired within a breath-hold. RESULTS In patients with myocardial iron overload (T2* < 20 ms; n = 52), there were linear correlations between T2 and T2* (r = 0.82; P = 0.0), and between T1 and T2* (r = 0.83; P = 0.0). In patients with no myocardial iron (n = 54), T2* values were scattered with no significant correlation against T2 or T1. For all patients (n = 106) there was a strong linear correlation (r = 0.93; P = 0.0) between myocardial T1 and T2. CONCLUSION In patients with iron overload, myocardial T2 and T1 are correlated with T2*. In patients with low or normal myocardial iron concentration, other factors become dominant in affecting T2* values as shown by scattered T2* data. Myocardial T1 correlates linearly with T2 measurements in all patients suggesting that these two relaxation parameters avoid extrinsic magnetic field inhomogeneity effects and may potentially provide improved myocardial tissue characterization.
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Affiliation(s)
- Yanqiu Feng
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
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Abstract
Magnetic resonance imaging (MRI) enables a noninvasive in vivo quantification of iron in various organs. Several techniques have been developed that detect signal alterations derived mainly from the magnetic properties of ferritin and hemosiderin, the major iron storage compounds. High magnetic susceptibility of ferritin shortens the transversal relaxation time of nearby water protons and thus induces a focal signal extinction of iron-rich areas in T2-weighted (T2w) MRI. T2w tissue contrast is additionally influenced by other factors such as water content, myelin density, and the presence of other metals. Therefore, more specific methods are needed with higher specificity to iron. These in vivo techniques can be divided into three groups: relaxometry, magnetic field correlation imaging and phase-based contrast covering susceptibility-weighted imaging, and quantitative susceptibility mapping. The differential diagnosis of various neurological disorders is aided by characteristic patterns of iron depositions. Reliable estimates of cerebral tissue iron concentration are equally important in studying physiological age-related as well as pathological conditions in neurodegenerative, neuroinflammatory, and vascular diseases. In the future, monitoring changes in iron storage and content may serve as sensitive biomarker for diagnosis as well as treatment monitoring.
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Affiliation(s)
- Petr Dusek
- Department of Neurology and Center of Clinical Neuroscience, Charles University in Prague, 1st Faculty of Medicine and General University Hospital, Prague, Czech Republic; Institut für interventionelle und diagnostische Neuroradiologie, Universitätsmedizin Göttingen, Göttingen, Germany.
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12
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A practical approach for a wide range of liver iron quantitation using a magnetic resonance imaging technique. Radiol Res Pract 2012; 2012:207391. [PMID: 23365743 PMCID: PMC3530181 DOI: 10.1155/2012/207391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/12/2012] [Accepted: 11/13/2012] [Indexed: 01/19/2023] Open
Abstract
The goal of this study is to demonstrate a practical magnetic resonance imaging technique for quantifying a wide range of hepatic iron concentration (HIC) for hematologic oncology patients with transfusion iron overload in a routine clinical setting. To cover a wide range of T2* values from hematologic patients, we used a dual-acquisition method with two clinically available acquisition protocols on a 1.5T MRI scanner with different ΔTEs to acquire data in two breath-holds. An in-house image postprocessing software tool was developed to generate T2*, iron maps, and water and fat images, when fat is presented in the liver. The resulting iron maps in DICOM format are transferred to the institutional electronic medical record system for review by radiologists. The measured liver T2* values for 28 patients ranged from 0.56 ± 0.13 to 25.0 ± 2.1 milliseconds. These T2* values corresponded to HIC values ranging from 1.2 ± 0.1 mg/g to 45.0 ± 10.0 mg/g (dry weight). A moderate correlation between overall serum ferritin levels and R2* was found with a correlation coefficient of 0.83. Repeated phantom scans confirmed that the precision of this method is better than 4% for T2* measurements. The dual- acquisition method also improved the ability to quantify HIC of the patients with hepatic steatosis.
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13
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Hocq A, Brouette N, Saussez S, Luhmer M, Gillis P, Gossuin Y. Variable-field relaxometry of iron-containing human tissues: a preliminary study. CONTRAST MEDIA & MOLECULAR IMAGING 2009; 4:157-64. [PMID: 19572379 DOI: 10.1002/cmmi.275] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Excess iron is found in brain nuclei from neurodegenerative patients (with Parkinson's, Alzheimer's and Huntington's diseases) and also in the liver and spleen of cirrhosis, hemochromatosis and thalassaemia patients. Ferritin, the iron-storing protein of mammals, is known to darken T(2)-weighted MR images. Understanding NMR tissue behavior may make it possible to detect those diseases, to follow their evolution and finally to establish a protocol for non-invasive measurement of an organ's iron content using MRI methods. In this preliminary work, the MR relaxation properties of embalmed iron-containing tissues were studied as well as their potential correlation with the iron content of these tissues. Relaxometric measurements (T(1) and T(2)) of embalmed samples of brain nuclei (caudate nucleus, dentate nucleus, globus pallidus, putamen, red nucleus and substantia nigra), liver and spleen from six donors were made at different magnetic fields (0.00023-14 T). The influence of the inter-echo time on transverse relaxation was also studied. Moreover, iron content of tissues was determined by inductively coupled plasma atomic emission spectroscopy. In brain nuclei, 1/T(2) increases quadratically with the field and depends on the inter-echo time in CPMG sequences at high fields, both features compatible with an outer sphere relaxation theory. In liver and spleen, 1/T(2) increases linearly with the field and depends on the inter-echo time at all fields. In our study, a correlation between 1/T(2) and iron concentration is observed. Explaining the relaxation mechanism for these tissues is likely to require a combination of several models. The value of 1/T(2) at high field could be used to evaluate iron accumulation in vivo. In the future, confirmation of those features is expected to be achieved from measurements of fresh (not embalmed) human tissues.
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Affiliation(s)
- Aline Hocq
- Biological Physics Department, University of Mons-Hainaut, 7000 Mons, Belgium.
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14
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Nielsen P, Engelhardt R, Grosse R, Janka G, Harmatz P, Fischer R. Italian Society of Hematology guidelines for thalassemia and non-invasive iron measurements. Haematologica 2008; 94:294-5; author reply 295-6. [PMID: 19109216 DOI: 10.3324/haematol.13600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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15
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House MJ, St Pierre TG, McLean C. 1.4T study of proton magnetic relaxation rates, iron concentrations, and plaque burden in Alzheimer's disease and control postmortem brain tissue. Magn Reson Med 2008; 60:41-52. [PMID: 18523986 DOI: 10.1002/mrm.21586] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We measured proton magnetic longitudinal (R(1)) and transverse (R(2)) relaxation rates at 1.4T, iron concentrations, water contents, and amyloid plaque densities in postmortem brain tissue samples from three Alzheimer's disease (AD), two possible AD, and five control subjects. Iron concentrations and R(1) were significantly higher in the temporal cortex region of our AD group compared to the controls. Frequency analyses showed that the observed trends of higher iron, R(1), and R(2) in AD gray matter regions were statistically significant. Simple regression models indicated that for AD and control gray matter the iron concentrations and water contents have significant linear correlations with R(1) and R(2). Multiple regression models based on iron concentrations and water contents were highly significant for all groups and tissue types and suggested that the effects of iron become more important in determining R(1) and R(2) in the AD samples. At 1.4T R(1) and R(2) are strongly affected by water content and to a lesser extent by variations in iron concentrations. The AD plaque density did not correlate with iron concentrations, water contents, R(1), or R(2), suggesting that increases in AD brain iron are not strongly related to the accumulation of amyloid plaques.
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Affiliation(s)
- Michael J House
- School of Physics, University of Western Australia, Perth, WA 6009, Australia.
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16
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Song R, Lin W, Chen Q, Asakura T, Wehrli FW, Song HK. Relationships between MR transverse relaxation parameters R*(2), R(2) and R'(2) and hepatic iron content in thalassemic mice at 1.5 T and 3 T. NMR IN BIOMEDICINE 2008; 21:574-580. [PMID: 18041805 DOI: 10.1002/nbm.1227] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Assessment of hepatic iron concentration is important in the management of patients with thalassemia. The goal of this study was to investigate the relationships between the three MR transverse relaxation rates, R*(2), R(2) and R'(2), and hepatic iron content in a mouse model of thalassemia at 1.5 and 3 T field strengths. A GESFIDE (gradient-echo sampling of free induction decay and echo) pulse sequence was used to measure the three parameters efficiently in a single scan in a study examining the livers of normal and thalassemic mice, including a subgroup of the latter that were subjected to periodic transfusions. The results showed that R*(2), R(2) and R'(2) all correlated closely with liver iron concentration at both 1.5 T and 3 T, with correlation coefficients ranging from 0.72 to 0.79. High degrees of correlation (r = 0.93-0.99) were also observed among the three MR parameters at both field strengths. It can be concluded that the three rates could all be effective for assessing hepatic iron concentration and that imaging at higher fields may not offer any advantages over that at lower fields.
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Affiliation(s)
- Ruitian Song
- Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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17
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Gossuin Y, Gillis P, Muller RN, Hocq A. Relaxation by clustered ferritin: a model for ferritin-induced relaxation in vivo. NMR IN BIOMEDICINE 2007; 20:749-56. [PMID: 17330925 DOI: 10.1002/nbm.1140] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Ferritin, the iron-storing protein of mammals, is known to darken T(2)-weighted MR images. This darkening could be used for the non-invasive measurement of an organ's iron content. Unexplained discrepancies exist between T(2) data obtained in ferritin-containing tissues and aqueous solutions of ferritin. The clustering of the protein induced by trypsin is used to evaluate the effect of ferritin agglomeration on the relaxation rates. Although the longitudinal relaxation is not significantly influenced by clustering, T(2) depends greatly on the stage of agglomeration: the transverse relaxation rate is higher for a clustered sample than for an unclustered sample. Moreover, the field and inter-echo time dependences of the relaxation rate indicate that the relaxation mechanism may be different between small clusters -- where a linear dependence of 1/T(2) on B(0) is observed -- and large clusters -- where a quadratic dependence is observed. These results help to explain the relaxation induced by ferritin in tissues.
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Affiliation(s)
- Yves Gossuin
- Biological Physics Department, University of Mons-Hainaut, 7000, Mons, Belgium.
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18
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Gossuin Y, Muller RN, Gillis P, Bartel L. Relaxivities of human liver and spleen ferritin. Magn Reson Imaging 2006; 23:1001-4. [PMID: 16376184 DOI: 10.1016/j.mri.2005.10.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 10/24/2005] [Indexed: 10/25/2022]
Abstract
Ferritin, the iron-storing protein of mammals, is known to darken T2-weighted magnetic resonance images. This darkening can be used to noninvasively measure an organ's iron content. Significant discrepancies exist between T2 data obtained with ferritin-containing tissues and with aqueous solutions of horse spleen ferritin (HSF). The NMR properties of stable human ferritin have never been studied in aqueous solutions. Relaxometry results on human liver and spleen ferritin are reported here, showing that the relaxation induced in aqueous solutions by human ferritins is comparable to that induced by HSF. As a consequence, the differences between ferritin-containing human tissues and ferritin solutions cannot be attributed to different NMR properties of human and horse ferritins, but probably to a clustering of the protein in vivo.
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Affiliation(s)
- Yves Gossuin
- Biological Physics Department, University of Mons-Hainaut, 7000 Mons, Belgium.
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19
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St Pierre TG, Clark PR, Chua-Anusorn W. Measurement and Mapping of Liver Iron Concentrations Using Magnetic Resonance Imaging. Ann N Y Acad Sci 2005; 1054:379-85. [PMID: 16339686 DOI: 10.1196/annals.1345.046] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Measurement of liver iron concentration (LIC) is an important clinical procedure in the management of transfusional iron overload with iron chelation. LIC gives an indication of over- or underchelation. Although chemical assay of needle biopsy samples from the liver has been considered the "gold standard" of LIC measurement, needle biopsy sampling errors can be surprisingly large owing to the natural spatial variation of LIC throughout the liver and the small size of biopsy specimens. A magnetic resonance imaging technique has now been developed that enables safe noninvasive measurement and imaging of LIC with a known accuracy and precision. Measurements of LIC can be made over the range of LIC encountered in clinical practice. The technique is based on the measurement and imaging of proton transverse relaxation rates (R2) within the liver. The R2 imaging technique can be implemented on most clinical 1.5-T MRI instruments, making it readily available to the clinical community.
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Affiliation(s)
- Timothy G St Pierre
- School of Physics, M013, University of Western Australia, Crawley, Western Australia 6009, Australia.
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20
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Abstract
MR imaging is establishing a role as a primary diagnostic technique, with increasing evidence showing MR imaging to have advantages over CT regarding diagnostic sensitivity and specificity for many pathologies of solid organs, bile and pancreatic ducts, bowel, peritoneum, and retroperitoneum. In addition, there are increasing concerns regarding the risks of radiation and iodinated contrast associated with CT imaging of the abdomen. The incidence of contrast-induced nephropathy associated with iodinated contrast used for CT scanning is difficult to ascertain because reporting is spurious and variable in interpretation.
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Affiliation(s)
- Diego R Martin
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road NE, Atlanta, GA 30322, USA.
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21
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Wood JC, Enriquez C, Ghugre N, Tyzka JM, Carson S, Nelson MD, Coates TD. MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients. Blood 2005; 106:1460-5. [PMID: 15860670 PMCID: PMC1895207 DOI: 10.1182/blood-2004-10-3982] [Citation(s) in RCA: 793] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Accepted: 04/15/2005] [Indexed: 12/13/2022] Open
Abstract
Measurements of hepatic iron concentration (HIC) are important predictors of transfusional iron burden and long-term outcome in patients with transfusion-dependent anemias. The goal of this work was to develop a readily available, noninvasive method for clinical HIC measurement. The relaxation rates R2 (1/T2) and R2* (1/T2*) measured by magnetic resonance imaging (MRI) have different advantages for HIC estimation. This article compares noninvasive iron estimates using both optimized R2 and R2* methods in 102 patients with iron overload and 13 controls. In the iron-overloaded group, 22 patients had concurrent liver biopsy. R2 and R2* correlated closely with HIC (r2 > or = .95) for HICs between 1.33 and 32.9 mg/g, but R2 had a curvilinear relationship to HIC. Of importance, the R2 calibration curve was similar to the curve generated by other researchers, despite significant differences in technique and instrumentation. Combined R2 and R2* measurements did not yield more accurate results than either alone. Both R2 and R2* can accurately measure hepatic iron concentration throughout the clinically relevant range of HIC with appropriate MRI acquisition techniques.
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Affiliation(s)
- John C Wood
- Department of Pediatrics, Children's Hospital Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027-0034, USA.
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22
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Abstract
This article discusses MR imaging sequences that are used for the evaluation of diffuse liver diseases, including processes that lead to abnormal lipid metabolization, iron de-position disease, and perfusion abnormalities.
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Affiliation(s)
- Raman Danrad
- Department of Radiology, Emory University School of Medicine, 1365 Clifton Road NE, Atlanta, GA 30322, USA
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23
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Carneiro AAO, Fernandes JP, de Araujo DB, Elias J, Martinelli ALC, Covas DT, Zago MA, Angulo IL, St Pierre TG, Baffa O. Liver iron concentration evaluated by two magnetic methods: magnetic resonance imaging and magnetic susceptometry. Magn Reson Med 2005; 54:122-8. [PMID: 15968652 DOI: 10.1002/mrm.20510] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Quantification of liver iron concentration (LIC) is crucial in the management of patients suffering from certain pathologies that can produce iron overload, such as Cooley's anemia and hemochromatosis. All of these patients must control the level of iron deposits in their organs to avoid the toxicity of high LIC, which is potentially lethal. This paper describes experimental protocols for LIC measurement using two magnetic techniques: magnetic resonance imaging (MRI) and biomagnetic liver susceptometry (BLS). MRI proton transverse relaxation rate (R2) and image intensity, evaluated pixel by pixel, were used as indicators of iron load in the tissue. LIC measurement by BLS was performed using an AC superconducting susceptometer system. A group of 23 patients with a large range of iron overload (0.9 to 34.5 mgFe/g(dry tissue)) was evaluated with both techniques (MRI x BLS). A significant linear correlation (r = 0.89-0.95) was found between the LIC by MRI and by BLS. These results show the feasibility of using two noninvasive methodologies to evaluate liver iron store in a large concentration range. Both methodologies represent an equivalent precision.
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Affiliation(s)
- Antonio Adilton O Carneiro
- Departamento de Física e Matemática, FFCLRP, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.
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24
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Martin DR, Semelka RC. Magnetic Resonance Imaging of the Liver: Review of Techniques and Approach to Common Diseases. Semin Ultrasound CT MR 2005; 26:116-31. [PMID: 15987062 DOI: 10.1053/j.sult.2005.02.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
MR imaging examination of the liver should use a combination of single-shot T2W and breath-hold T1W images, and include gadolinium enhancement with acquisition of multiple phases. MR provides superior characterization of liver masses than CT, and multi-phase gadolinium enhancement including a properly timed arterial phase is critical. The T1 weighted pre-contrast images must include in-phase/out-of-phase acquisitions, to assess hepatic lipid and or iron content, and dynamically enhanced post-gadolinium images. Timing of the arterial phase images is also critical for demonstration of acute hepatitis. The timing of the venous and equilibrium phase images are less critical, and are important for grading more severe acute hepatitis, demonstration of fibrosis, and for delineating vascular abnormalities. In cirrhosis, dynamic post-gadolinium images are critical for detection and characterization of regenerative or dysplastic nodules, and HCC. The same sequences useful for liver evaluation provide a comprehensive evaluation of all the soft tissues of the abdomen, and allow depiction of most of the important diseases, thus facilitating use of a universal protocol for abdominal imaging.
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Affiliation(s)
- Diego R Martin
- Department of Radiology, Emory University Hospital, Atlanta, GA 30322, USA.
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25
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Gossuin Y, Burtea C, Monseux A, Toubeau G, Roch A, Muller RN, Gillis P. Ferritin-induced relaxation in tissues: an in vitro study. J Magn Reson Imaging 2005; 20:690-6. [PMID: 15390148 DOI: 10.1002/jmri.20152] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To study in vitro the proton relaxation induced in tissues by ferritin, the iron-storing protein of mammals. MATERIALS AND METHODS Nuclear magnetic relaxation dispersion (NMRD) profiles of liver and spleen from control and iron-overloaded mice are compared with NMRD profiles of ferritin and Fercayl-a ferritin-like akaganeite particle-in aqueous solutions or in 1% agarose gel. RESULTS The relaxation of water protons induced by ferritin and Fercayl in 1% agarose gel is comparable with the relaxation of aqueous solutions of the same compounds, but slower than the relaxation of liver and spleen. The gel is not a good model of tissues containing ferritin. The longitudinal NMRD profiles of control and iron-overloaded liver and spleen are almost identical: ferritin accumulation has only a slight effect on longitudinal relaxation. The transverse NMRD profiles of liver and spleen tissues are linear, but the slope of the linear regression is larger for iron-loaded organs than for control ones, which is a consequence of a higher ferritin concentration in the former. However, the correlation between the slope of the transverse NMRD profiles and the iron concentration is not very good, probably because transverse relaxation is modified by the clustering of ferritin in cells. CONCLUSION It could be difficult to develop a general technique for the accurate quantification of ferritin-bound iron by nuclear magnetic resonance or magnetic resonance imaging.
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Affiliation(s)
- Yves Gossuin
- Biological Physics Department, Faculty of Medicine and Pharmacy, University of Mons-Hainaut, Mons, Belgium.
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26
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27
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Gambarota G, Veltien A, van Laarhoven H, Philippens M, Jonker A, Mook OR, Frederiks WM, Heerschap A. Measurements of T1 and T2 relaxation times of colon cancer metastases in rat liver at 7 T. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2004; 17:281-7. [PMID: 15580375 DOI: 10.1007/s10334-004-0068-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 08/26/2004] [Accepted: 09/16/2004] [Indexed: 10/26/2022]
Abstract
The purpose of this study was to investigate the magnetic resonance imaging (MRI) characteristics of colon cancer metastases in rat liver at 7 T. A dedicated RF microstrip coil of novel design was built in order to increase the signal-to-noise ratio and, in combination with respiratory triggering, to minimize motion artifacts. T1- and T2-weighted MR imaging was performed to follow tumor growth. T1-weighted images provided a good anatomical delineation of the liver structure, while the best contrast between metastases and normal liver tissue was achieved with T2-weighted images. Measurements of T1 and T2 relaxation times were performed with inversion recovery FLASH and Carr-Purcell-Meiboom-Gill and inversion recovery FLASH imaging sequences, respectively, for quantitative MR characterization of metastases. Both the T1 and T2 of the metastases were significantly higher than those of normal liver tissue. Further, an increase in the T1 relaxation time of the metastases was observed with tumor growth. These findings suggest that quantitative in vivo MR characterization provides information on tumor development and possibly response to therapy, though additional studies are needed to elucidate the correlation between the changes in relaxation times and tumor microenvironment.
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Affiliation(s)
- G Gambarota
- Department of Radiology, University Medical Center Nijmegen, Nijmegen, The Netherlands.
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28
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St Pierre TG, Clark PR, Chua-Anusorn W. Single spin-echo proton transverse relaxometry of iron-loaded liver. NMR IN BIOMEDICINE 2004; 17:446-458. [PMID: 15523601 DOI: 10.1002/nbm.905] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A single-spin-echo methodology is described for the measurement and imaging of proton transverse relaxation rates (R2) in iron-loaded and normal human liver tissue in vivo. The methodology brings together previously reported techniques dealing with (i) the changes in gain between each spin-echo acquisition, (ii) signal level offset due to background noise, (iii) estimation of signal intensities in decay curves at time zero to enable reliable extraction of relaxation times from tissues with very short T2 values, (iv) bi-exponential modelling of decay curves with a small number of data points, and (v) reduction of respiratory motion artefacts. The accuracy of the technique is tested on aqueous manganese chloride solutions yielding a relaxivity of 74.1+/-0.3 s-1 (mM)-1, consistent with previous reports. The precision of the in vivo measurement of mean liver R2 values is tested through duplicate measurements on 10 human subjects with mean liver R2 values ranging from 26 to 220 s-1. The random uncertainty on the measurement of mean liver R2 was found to be 7.7%.
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Affiliation(s)
- Timothy G St Pierre
- School of Physics, M013, The University of Western Australia, Crawley, WA 6009, Australia.
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29
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Gossuin Y, Muller RN, Gillis P. Relaxation induced by ferritin: a better understanding for an improved MRI iron quantification. NMR IN BIOMEDICINE 2004; 17:427-432. [PMID: 15526352 DOI: 10.1002/nbm.903] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Ferritin, the iron storing protein, is known to darken T2-weighted MRI. This darkening can be used to non-invasively measure iron content. However, ferritin's behavior is not the same in tissue as in solution, a discrepancy that remains unexplained by the recently developed theory matching the NMR properties of ferritin solutions. A better understanding of the relaxation induced by ferritin in tissue could help for the development of new MRI protocols of iron quantification. In this short review, the main relaxation properties of ferritin in solution and in tissue are presented together with a discussion of the possible reasons for the faster transverse relaxation observed in tissues.
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Affiliation(s)
- Yves Gossuin
- Biological Physics Department, Faculty of Medicine and Pharmacy, University of Mons-Hainaut, 7000 Mons, Belgium.
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30
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St Pierre TG, Clark PR, Chua-anusorn W, Fleming AJ, Jeffrey GP, Olynyk JK, Pootrakul P, Robins E, Lindeman R. Noninvasive measurement and imaging of liver iron concentrations using proton magnetic resonance. Blood 2004; 105:855-61. [PMID: 15256427 DOI: 10.1182/blood-2004-01-0177] [Citation(s) in RCA: 640] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Measurement of liver iron concentration (LIC) is necessary for a range of iron-loading disorders such as hereditary hemochromatosis, thalassemia, sickle cell disease, aplastic anemia, and myelodysplasia. Currently, chemical analysis of needle biopsy specimens is the most common accepted method of measurement. This study presents a readily available noninvasive method of measuring and imaging LICs in vivo using clinical 1.5-T magnetic resonance imaging units. Mean liver proton transverse relaxation rates (R2) were measured for 105 humans. A value for the LIC for each subject was obtained by chemical assay of a needle biopsy specimen. High degrees of sensitivity and specificity of R2 to biopsy LICs were found at the clinically significant LIC thresholds of 1.8, 3.2, 7.0, and 15.0 mg Fe/g dry tissue. A calibration curve relating liver R2 to LIC has been deduced from the data covering the range of LICs from 0.3 to 42.7 mg Fe/g dry tissue. Proton transverse relaxation rates in aqueous paramagnetic solutions were also measured on each magnetic resonance imaging unit to ensure instrument-independent results. Measurements of proton transverse relaxivity of aqueous MnCl2 phantoms on 13 different magnetic resonance imaging units using the method yielded a coefficient of variation of 2.1%.
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31
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Wood JC, Fassler JD, Meade T. Mimicking liver iron overload using liposomal ferritin preparations. Magn Reson Med 2004; 51:607-11. [PMID: 15004804 PMCID: PMC2892965 DOI: 10.1002/mrm.10735] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Close monitoring of liver iron content is necessary to prevent iron overload in transfusion-dependent anemias. Liver biopsy remains the gold standard; however, MRI potentially offers a noninvasive alternative. Iron metabolism and storage is complicated and tissue/disease-specific. This report demonstrates that iron distribution may be more important than iron speciation with respect to MRI signal changes. Simple synthetic analogs of hepatic lysosomes were constructed from noncovalent attachment of horse-spleen ferritin to 0.4 microm diameter phospholipid liposomes suspended in agarose. Graded iron loading was achieved by varying ferritin burden per liposome as well as liposomal volume fraction. T1 and T2 relaxation times were measured on a 60 MHz NMR spectrometer and compared to simple ferritin-gel combinations. Liposomal-ferritin had 6-fold stronger T2 relaxivity than unaggregated ferritin but identical T1 relaxivity. Liposomal-ferritin T2 relaxivity also more closely matched published results from hemosiderotic marmoset liver, suggesting a potential role as an iron-calibration phantom.
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Affiliation(s)
- John C Wood
- Divisions of Cardiology and Radiology, Children's Hospital Los Angeles, Los Angeles, California 90027-0034, USA
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Clark PR, Chua-anusorn W, St Pierre TG. Reduction of respiratory motion artifacts in transverse relaxation rate (R2) images of the liver. Comput Med Imaging Graph 2004; 28:69-76. [PMID: 15127751 DOI: 10.1016/j.compmedimag.2003.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
An empirical motion artifact suppression technique has been developed to reduce the respiratory motion artifacts in axial single spin-echo magnetic resonance (MR) images of the liver post-acquisition. The correction scheme is based on the observation that the dominant motion artifacts within abdominal MR images are ghosts that follow the profile and signal intensity of high signal intensity boundaries, such as those for the subcutaneous fat along the anterior abdominal wall. The technique is applied to the reduction of respiratory motion artifacts in a spin echo image series of the liver of an iron-loaded patient and of a manganese chloride phantom subject to respiratory motion. Subsequent improvements to transverse relaxation rate (R2) image analysis are then demonstrated on the motion-corrected spin echo images, illustrating the utility of the technique for application in the R2 image-based measurement and mapping of liver iron concentration.
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Affiliation(s)
- Paul R Clark
- School of Physics, The University of Western Australia, Mailbag Delivery Point M013, Crawley, Perth, WA 6009, Australia
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33
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Affiliation(s)
- Peter-D Jensen
- Department of Haematology, Arhus University Hospital, Amtssygehuset, DK 8000 Aarhus C, Tage Hansensgade 2, Denmark.
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34
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Clark PR, Chua-anusorn W, St Pierre TG. Bi-exponential proton transverse relaxation rate (R2) image analysis using RF field intensity-weighted spin density projection: potential for R2 measurement of iron-loaded liver. Magn Reson Imaging 2003; 21:519-30. [PMID: 12878262 DOI: 10.1016/s0730-725x(03)00080-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A bi-exponential proton transverse relaxation rate (R(2)) image analysis technique has been developed that enables the discrimination of dual compartment transverse relaxation behavior in systems with rapid transverse relaxation enhancement. The technique is particularly well suited to single spin-echo imaging studies where a limited number of images are available for analysis. The bi-exponential R(2) image analysis is facilitated by estimation of the initial proton spin density signal within the region of interest weighted by the RF field intensities. The RF field intensity-weighted spin density map is computed by solving a boundary value problem presented by a high spin density, long T(2) material encompassing the region for analysis. The accuracy of the bi-exponential R(2) image analysis technique is demonstrated on a simulated dual compartment manganese chloride phantom system with relaxation rates and relative population densities between the two compartments similar to the bi-exponential transverse relaxation behavior expected of iron loaded liver. Results from analysis of the phantoms illustrate the potential of bi-exponential R(2) image analysis with RF field intensity-weighted spin density projection for quantifying transverse relaxation enhancement as it occurs in liver iron overload.
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Affiliation(s)
- Paul R Clark
- School of Physics, The University of Western Australia, Crawley, Perth, Western Australia 6009, Australia
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35
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Fenzi A, Bortolazzi M, Marzola P. Comparison between signal-to-noise ratio, liver-to-muscle ratio, and 1/T2 for the noninvasive assessment of liver iron content by MRI. J Magn Reson Imaging 2003; 17:589-92. [PMID: 12720269 DOI: 10.1002/jmri.10306] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To compare different MRI-derived parameters, i.e., liver signal-to-noise ratio (LSNR), liver-to-muscle ratio (LMR) and liver transversal relaxation rate (R2), in terms of their correlation with the ex vivo determined iron content in an experimental model of liver iron overload. MATERIALS AND METHODS Multi-echo spin echo (SE) images of the liver were acquired at 4.7 T from a group of 33 male wistar rats subjected to a high iron content diet for feeding periods ranging from 2 to 50 days. Liver transversal relaxation time, liver signal-to-noise ratio, and liver-to-muscle ratio were measured over the same region of interest in order to get a direct comparison between these parameters. After MRI experiments, the rats were sacrificed and the liver iron content was measured ex vivo by atomic absorption spectroscopy. RESULTS The iron content is better correlated to the LSNR than to the other parameters (LMR, R2). CONCLUSION The finding that liver signal-to-noise ratio is better correlated to the iron content than the liver T2 relaxation rate is relevant for clinical applications of MRI because a T2 determination is more time-consuming, both for acquisition and postprocessing of images, than a simple SNR determination.
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Affiliation(s)
- Alberto Fenzi
- Institute of Medical Physics, Department of Biomedical and Morphological Sciences, University of Verona, Verona, Italy.
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36
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Bilello JP, Cable EE, Isom HC. Expression of E-cadherin and other paracellular junction genes is decreased in iron-loaded hepatocytes. THE AMERICAN JOURNAL OF PATHOLOGY 2003; 162:1323-38. [PMID: 12651624 PMCID: PMC1851226 DOI: 10.1016/s0002-9440(10)63928-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Iron overload in the liver may occur in the clinical conditions hemochromatosis and transfusion-dependent thalassemia or by long-term consumption of large amounts of dietary iron. As iron concentrations increase in the liver, cirrhosis develops, and subsequently the normal architecture of the liver deteriorates. The underlying mechanisms whereby iron loading of hepatocytes leads to the pathology of the liver are not understood. Similarly, a direct relationship between the expression levels of paracellular junction genes and altered hepatocellular physiology has been reported; however, no relationship has been identified between iron loading and the expression of paracellular junction genes. Here, we report that the expression of numerous paracellular junction genes was decreased in iron-loaded hepatocytes, leading to increased cellular permeability, increased baculovirus-mediated gene transfer, and decreased gap junction communication. Iron loading of hepatocytes resulted in decreased E-cadherin promoter activity and subsequently decreased E-cadherin mRNA and protein expression. The data presented in this study describe a clear relationship between iron overload and decreased expression of paracellular junction genes in hepatic cells of rat and human origin.
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Affiliation(s)
- John P Bilello
- Department of Microbiology and Immunology, Milton S. Hershey Medical Center, The Penn State College of Medicine, Hershey, Pennsylvania 17033, USA
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37
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Pardoe H, Chua-anusorn W, St Pierre TG, Dobson J. Detection limits for ferrimagnetic particle concentrations using magnetic resonance imaging based proton transverse relaxation rate measurements. Phys Med Biol 2003; 48:N89-95. [PMID: 12699196 DOI: 10.1088/0031-9155/48/6/401] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R2) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either dextran or polyvinyl alcohol. The method of preparation resulted in loosely packed clusters (dextran) or branched chains (polyvinyl alcohol) of particles containing of the order of 600 and 400 particles, respectively. For both methods of particle preparation, concentrations of ferrimagnetic iron in agar gel less than 0.01 mg ml(-1) had no measurable effect on the value of R2 for the gel. The results indicate that MRI-based R2 measurements using 1.5 T clinical scanners are not quite sensitive enough to detect the very low concentrations of nanoparticulate biogenic magnetite reported in human brain tissue.
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Affiliation(s)
- H Pardoe
- School of Physics, The University of Western Australia, Crawley, Perth, WA 6009, Australia
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38
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Clark PR, Chua-Anusorn W, St Pierre TG. Proton transverse relaxation rate (R2) images of liver tissue; mapping local tissue iron concentrations with MRI [corrected]. Magn Reson Med 2003; 49:572-5. [PMID: 12594762 DOI: 10.1002/mrm.10378] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Proton transverse relaxation rate (R(2)) imaging measurements were made on post mortem iron-loaded human liver tissue samples (both intact and dissected into approximately 1-cm cubes) from a single subject. Iron concentrations for the dissected samples as measured by atomic absorption spectrometry varied from 10.8 to 23.3 mg Fe.g(-1) dry tissue. A significant linear correlation between the mean R(2) and iron concentration of each sample was found (r = 0.95). In addition, regions of liver tissue with micronodular cirrhosis exhibited lower R(2) values, corresponding to the displacement of iron by fibrotic septa. The cirrhotic tissue was clearly identified as a separate peak in the R(2) distribution of the tissue. The relaxivity of the iron did not appear to depend on the microarchitecture of the tissue.
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Affiliation(s)
- Paul R Clark
- School of Physics, University of Western Australia, Crawley, Australia
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39
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Fischer R, Engelhardt R. Deferiprone versus desferrioxamine in thalassaemia, and T2* validation and utility. Lancet 2003; 361:182-3; author reply 183-4. [PMID: 12531618 DOI: 10.1016/s0140-6736(03)12222-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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40
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Carneiro AAO, Baffa O, Fernandes JP, Zago MA. Theoretical evaluation of the susceptometric measurement of iron in human liver by four different susceptometers. Physiol Meas 2002; 23:683-93. [PMID: 12450269 DOI: 10.1088/0967-3334/23/4/308] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This paper is an evaluation of liver iron quantification using a simulated magnetic susceptibility measurement in the hepatic region. Susceptometers having homogeneous and non-homogeneous magnetizing fields coupled with axial second-order and planar first-order gradiometric magnetic detectors were considered. The intensity of magnetic flux threading the detector coils was evaluated considering samples with volume and susceptibility equivalent to liver iron, tissue and lung air individually. These volumes were represented by cylindrical and spherical geometries. The main sources of error in quantifying iron overload in susceptometric measurement of hepatic tissue were evaluated for four configurations of the susceptometer.
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Affiliation(s)
- A A O Carneiro
- Departamento de Física e Matemática-FFCLRP, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP, Brazil
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41
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Nielsen P, Engelhardt R, Düllmann J, Fischer R. Non-invasive liver iron quantification by SQUID-biosusceptometry and serum ferritin iron as new diagnostic parameters in hereditary hemochromatosis. Blood Cells Mol Dis 2002; 29:451-8. [PMID: 12547235 DOI: 10.1006/bcmd.2002.0583] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the HFE-gene era, precise diagnostic parameters remain important to characterize individual iron stores, because the indication for therapy and prognosis are mainly related to the extent of iron loading. The frequently used serum ferritin interferes with non-iron related factors such as inflammation and may produce falsely positive values. We used a SQUID-biosusceptometer in a large series of patients (n = 679) to measure liver iron concentration in the differential diagnosis and therapy control of hereditary hemochromatosis (SQUID = superconducting quantum interference device). This truly non-invasive technique is sensitive, reliable, fast (online results), and also cost-effective when compared to invasive liver biopsy. Recently, ferritin iron content was propagated as a better parameter than ferritin protein. However, we found a poor correlation between ferritin iron and individual liver iron concentrations in patients with iron overload. Ferritin iron saturation varied in a range between 3 and 10%, independent from liver iron concentration. No differences were found between patients with hemochromatosis and secondary iron overload disease. Only patients with liver cell damage had increased ferritin iron saturations. In conclusion the diagnostic values of serum ferritin protein and iron to assess iron overload are limited.
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Affiliation(s)
- Peter Nielsen
- Inst. Molekulare Zellbiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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42
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Abstract
The intrinsic soft tissue contrast and exquisite sensitivity to contrast agents are unique attributes of magnetic resonance imaging that are beneficial when evaluating diffuse liver disease. Much like a pathologist uses different tissue or cell marker stains, the magnetic resonance imager can use a variety of imaging strategies to elucidate pathologic liver processes in vivo, including processes leading to abnormal lipid metabolization, iron deposition, perfusion abnormalities related to inflammation, fibrosis, vascular occlusion, or infarction and hemorrhage. This article reviews the most important diffuse liver diseases and the corresponding magnetic resonance imaging features.
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Affiliation(s)
- Diego R Martin
- Department of Radiology, Robert C Byrd Health Sciences Center, West Virginia University, West Virginia 26506-9235, USA.
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43
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Moroz P, Pardoe H, Jones SK, St Pierre TG, Song S, Gray BN. Arterial embolization hyperthermia: hepatic iron particle distribution and its potential determination by magnetic resonance imaging. Phys Med Biol 2002; 47:1591-602. [PMID: 12043822 DOI: 10.1088/0031-9155/47/9/312] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Arterial embolization hyperthermia (AEH) consists of arterially embolizing liver tumours with ferromagnetic particles that generate hysteretic heating on exposure to an alternating magnetic field. A critical component of AEH is the concentration and distribution of ferromagnetic particles in the normal hepatic parenchyma (NHP), as well as in the tumour tissue. If the distribution of particles in NHP is heterogeneous, with areas of high concentration, then unwanted areas of necrosis may result during AEH. Using an in vivo rabbit liver tumour model, this study showed that hepatic arterial infusion of ferromagnetic particles does indeed result in a heterogeneous distribution of iron in NHP. The radiological technique of magnetic resonance imaging (MRI) was then evaluated as a potential tool for non-invasively and prospectively determining the concentration and distribution of particles within the hepatic tumour and NHP following hepatic arterial infusion. A preliminary in vitro experiment showed that although the concentration of iron within the tumour tissue (1.92-3.50 mg of iron per gram of tissue) was too great to measure, MRI was able to accurately determine the lower iron concentration (0.10-0.53 mg of iron per gram of tissue) in NHP. Further work is needed to evaluate MRI under in vivo conditions. If successful, MRI could become an important component of an emerging novel treatment for advanced hepatic malignancies.
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Affiliation(s)
- Paul Moroz
- Centre for Applied Cancer Studies, The University of Western Australia, Perth, Australia.
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44
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Wang ZJ, Haselgrove JC, Martin MB, Hubbard AM, Li S, Loomes K, Moore JR, Zhao H, Cohen AR. Evaluation of iron overload by single voxel MRS measurement of liver T2. J Magn Reson Imaging 2002; 15:395-400. [PMID: 11948828 DOI: 10.1002/jmri.10080] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To overcome the difficulty of poor signal-to-noise ratio of magnetic resonance imaging (MRI) in evaluating heavy iron overload by using a single voxel magnetic resonance spectroscopy (MRS) technique. MATERIALS AND METHODS A single voxel STEAM pulse sequence with a minimum TE of 1.5 msec and a sampling volume of 36.6 cm(3) was developed and applied to 1/T2 measurement of the liver in 14 patients with thalassemia whose liver iron concentration was determined through biopsy. RESULTS The iron level ranged from 0.23 to 37.15 mg Fe/g dry tissue with a median value of 18.06. In all cases, strong MR signals were obtained. 1/T2 was strongly correlated with the liver iron concentration (r = 0.95, P < 0.00005). CONCLUSION The single voxel MRS measurement of T2 in liver iron overload overcomes the difficulty of lack of detectable signals in conventional MRI when the iron level is high. There is an excellent correlation between the iron level and 1/T2.
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Affiliation(s)
- Zhiyue J Wang
- Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
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45
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Chan YL, Li CK, Lam CW, Yu SC, Chik KW, To KF, Yeung DK, Howard R, Yuen PM. Liver iron estimation in beta-thalassaemia: comparison of MRI biochemical assay and histological grading. Clin Radiol 2001; 56:911-6. [PMID: 11603894 DOI: 10.1053/crad.2001.0777] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS The aims of the study were to compare the efficacy of magnetic resonance imaging (MRI), biochemical assay and histological grading in estimating liver iron content, and to evaluate the value of liver to muscle signal intensity ratio (L/M ratio) on spin-echo T1-weighted images in this role. MATERIALS AND METHODS Thirty-nine homozygous beta-thalassaemics had their L/M ratio measured on MRI, followed by ultrasound-guided liver biopsies with histological grading of iron storage and biochemical quantification of liver iron concentration (LIC-b) using atomic absorption spectrophotometry. RESULTS A significant difference in L/M ratios between the four grades of iron storage on histology was observed (P < 0.001). The coefficient of correlation was -0.67 between L/M ratio and LIC-b ranging from 2 to 21.6 mg/g dry weight. Specific values of L/M ratio reliably reflected liver iron content at clinically important levels. A L/M ratio of < 0.6 has 86% sensitivity and 100% specificity in the prediction of grade 3 or 4 iron storage histologically and 81% sensitivity and 81% specificity in predicting LIC-b > 15 mg/g. A L/M ratio of > 0.8 predicts a histological iron storage grading of 0 or 1 with a 100% sensitivity and 74% specificity. CONCLUSION L/M ratio on MRI is of value as a non-invasive alternative to repeated liver biopsies for estimating liver iron content at clinically important thresholds.
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Affiliation(s)
- Y L Chan
- Department of Diagnostic Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shaitin, NT, Hong Kong.
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46
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Fenzi A, Bortolazzi M, Marzola P, Colombari R. In vivo investigation of hepatic iron overload in rats using T2 maps: quantification at high intensity field (4.7-T). J Magn Reson Imaging 2001; 13:392-6. [PMID: 11241812 DOI: 10.1002/jmri.1056] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In vivo quantitation of hepatic iron content is useful in diagnosis and staging of several iron related diseases. We used an experimental model of hepatic iron overload to determine the correlation between iron content and T2 relaxation time in rat liver. Experiments were carried out at 4.7T for high signal-to-noise ratio (SNR) using a spin-echo multiecho sequence with six echoes and minimum echo-time of 5.5 msec. The liver iron content was determined ex vivo by atomic absorption spectrophotometry (AAS). T2 maps were calculated in order to evaluate the space distribution of the iron content. We found good linear correlation between the in vivo liver transversal relaxation rate and the iron content within the range explored (106-4538 microg Fe/g liver wet wt.). T2 maps revealed that the decrease in T2 is not homogeneous through the liver parenchyma. This finding represents a physiological limitation to obtaining better correlation between T2 and iron content.
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Affiliation(s)
- A Fenzi
- Institute of Medical Physics, Department of Morpho-Biomedical Science, University of Verona, 37134 Verona, Italy.
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47
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Brittenham GM, Sheth S, Allen CJ, Farrell DE. Noninvasive methods for quantitative assessment of transfusional iron overload in sickle cell disease. Semin Hematol 2001; 38:37-56. [PMID: 11206960 DOI: 10.1016/s0037-1963(01)90059-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Because optimal management of iron chelation therapy in patients with sickle cell disease and transfusional iron overload requires accurate determination of the magnitude of iron excess, a variety of techniques for evaluating iron overload are under development, including measurement of serum ferritin iron levels, x-ray fluorescence of iron, magnetic resonance imaging, computed tomography, and measurement of magnetic susceptibility. The most promising methods for noninvasive assessment of body iron stores in patients with sickle cell anemia and transfusional iron overload are based on measurement of hepatic magnetic susceptibility, either using superconducting quantum interference device (SQUID) susceptometry or, potentially, magnetic resonance susceptometry.
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Affiliation(s)
- G M Brittenham
- Department of Pediatrics and Medicine, Columbia University, New York, NY, USA
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48
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Clark PR, St Pierre TG. Quantitative mapping of transverse relaxivity (1/T(2)) in hepatic iron overload: a single spin-echo imaging methodology. Magn Reson Imaging 2000; 18:431-8. [PMID: 10788721 DOI: 10.1016/s0730-725x(00)00118-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent research into the non-invasive assessment of hepatic iron concentrations using magnetic resonance imaging has shown that the proton transverse relaxivity (1/T(2)) varies linearly with liver iron concentration. However, the development of an image-based system for the assessment of hepatic iron distribution has been confounded by the presence of motion induced artifacts in the T(2)-weighted images. We report on the development of a single spin-echo imaging methodology that enables the generation of transverse relaxivity maps over the liver. A simple smoothing technique is used to accommodate the image intensity perturbations caused by abdominal motion. The relaxivity maps are consistent with the variation of iron concentration throughout the liver. A Parzen density estimate and histogram of the relaxivity distribution are generated to assist in the visual assessment of the degree and variability of T(2) shortening with liver iron loading. It was found that one or two Gaussian functions could be used to characterize the relaxivity distributions with a small number of parameters. We propose that this methodology may be used in the clinical setting to monitor hepatic iron concentrations in the advent of an accurate transverse relaxivity calibration curve.
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Affiliation(s)
- P R Clark
- Department of Physics, The University of Western Australia, Nedlands, Western Australia, Australia
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49
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Asanuma T, Hirano Y, Yamamoto K, Kon Y, Shimokawa S, Kuwabara M. MR imaging of hepatic injury in the LEC rat under a high magnetic field (7.05 T). J Vet Med Sci 1999; 61:239-44. [PMID: 10331195 DOI: 10.1292/jvms.61.239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Visualization of copper-induced hepatitis (CuH) in LEC rats was performed by using an MRI apparatus equipped with a magnet producing a high magnetic field of 7.05 T. When three groups of LEC rats (6-16 [pre-hepatitis], 15-26 [acute hepatitis] and 40-77 [chronic hepatitis] weeks old) were examined by MRI under T2-weighted imaging conditions which are suitable for the diagnosis of human hepatitis, hypointense MR images of the livers were, as a whole, obtained in all groups, suggesting that these conditions were not adequate for imaging of CuH of LEC rats. The shortening of the T1 and T2 relaxation times of livers due to an excess amount of paramagnetic irons under the high magnetic field was responsible for the lowering of MR signal intensities of the livers, especially those of 15 to 26-week old rats showing acute hepatitis. However, theoretical calculation of the MR signal intensities using the T1 and T2 relaxation times of the livers indicated that their imaging might be possible under proton density-weighted conditions even with a high magnetic field. Experimental results showed that hepatic injury was visualized as hyperintense regions in the MR image of the liver in the acute-phase rat.
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Affiliation(s)
- T Asanuma
- Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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50
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Abstract
By combining nuclear magnetic relaxometry on 39 ferritin samples with different iron loading with magnetometry, results were obtained that suggest a new interpretation of the core structure and magnetic properties of ferritin. These studies provide evidence that, contrary to most earlier reports, the ferritin core is antiferromagnetic (AFM) even at body temperature and possesses a superparamagnetic (SPM) moment due to incomplete cancellation of antiparallel sublattices, as predicted by Néel's theory. This moment also provides a likely explanation for the anomalous T2 shortening in ferritin solution. However, the number of SPM moments derived from this model is less than the number of ferritin molecules determined chemically, and a similar discrepancy was found by retrospectively fitting previously published magnetometry data. In other words, only a fraction of the ferritin molecules seem to be SPM. The studies also provide evidence for paramagnetic (PM) Curie-Weiss iron ions at the core surface, where the local Néel temperature is lower; these ions are apparently responsible for the weaker T1 shortening. In fact, the conversion of uncompensated AFM lattice ions to PM ions could explain the small number of SPM particles. The apparent Curie Law behavior of ferritin thus appears to be a coincidental result of different temperature dependences of the PM and SPM components.
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Affiliation(s)
- R A Brooks
- Neuroimaging Branch, NINDS, National Institutes of Health, Bethesda, Maryland 20892, USA
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