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Dresselaers T, De Keyzer F, Claus P, Vande Berg B, Cernicanu A, De Bosscher R, Claessen G, Willems R, Bogaert J. Robustness of T1 and ECV mapping radiomics features: a between-session evaluation in young athletes. Eur Heart J Cardiovasc Imaging 2022. [DOI: 10.1093/ehjci/jeac141.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
Radiomics of cardiac MRI T1, T2 and extracellular volume (ECV) maps has the potential to add biomarkers that can aid in the detection and diagnosis of myocardial diseases. Recently, the feasibility of CMR mapping based radiomics to classify various myocardial diseases was demonstrated [1-6]. However, reproducibility studies have reported sensitivity of radiomics to acquisition parameters and processing steps involved concluding that only a limited number of features may be reproducible [7-8]. As CMR mapping guidelines recommend to use site-specific normal values [9], radiomics features derived likely also need careful site-specific evaluation to benchmark disease-related feature alterations.
Purpose
We aimed to assess the between-session reproducibility of radiomics features in a longitudinal dataset of MOLLI T1 and ECV maps obtained in young athletes at 1.5T.
Materials and methods
This study included data from 17 healthy subjects (15-20y; informed consent obtained) with data acquired two years apart [10] considered for this purpose as test-retest data since a prior standard analysis showed near identical average T1 (t1: 977±16 ms, t2: 982±20ms) and ECV (t1: 23.4±1.3%, t2: 23.4±1.5%). T1 mapping data was acquired on a 1.5T system (Ingenia, Philips) using MOLLI 5s(3s)3s. After motion correction and T1 and ECV map calculation [11], the left ventricular myocardium was manually delineated by two readers independently (3D Slicer [12]). In total 44 images (short and long axis) were included for each time point. The radiomics analysis resulted in 96 features per image (7 feature families, ‘shape’ excluded; no filters applied; Pyradiomics, [13]). The concordance correlation coefficient (CCC) was calculated to assess reproducibility, and features with CCCs ≥ 0.7 were considered reproducible. A coefficient of variation (CV) below 15% was considered low.
Results
Only a limited number of radiomics features had high CCC (T1: 6/96 ECV 0/96) or a low CV (T1: 32/96, ECV:30/96) in the between-session analysis. The inter-reader evaluation showed that the effect of the delineation on the results was limited. Features that were most robust in the between-session analysis were ‘first order (total)energy’ for T1 maps and ‘glcm_Autocorrelation’ for ECV maps (table 1). These results in young healthy subjects confirm previous test-retest reports [9-10]. Features with low CCC levels or high CV may however still be useful when discriminating between patient with myocardial diseases if the difference is larger than the confidence interval assessed via this reproducibility analysis.
Conclusion
In these healthy subjects, a strong variability in reproducibility of radiomics features of T1 and ECV mapping can be noted. Nonetheless, these variability measures are informative to determine features that are likely most robust when discriminating between health and disease and can be used as a benchmark towards radiomics AI-based diagnostic approaches. Top ranked features for either T1 or ECV
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Affiliation(s)
- T Dresselaers
- KU Leuven, Dept of Imaging and Pathology , Leuven , Belgium
| | - F De Keyzer
- KU Leuven, Dept of Imaging and Pathology , Leuven , Belgium
| | - P Claus
- KU Leuven, Dept of Cardiovascular Sciences , Leuven , Belgium
| | - B Vande Berg
- KU Leuven, Dept of Imaging and Pathology , Leuven , Belgium
| | - A Cernicanu
- Philips Benelux , Eindhoven , Netherlands (The)
| | - R De Bosscher
- KU Leuven, Dept of Imaging and Pathology , Leuven , Belgium
| | - G Claessen
- KU Leuven, Dept of Cardiovascular Sciences , Leuven , Belgium
| | - R Willems
- KU Leuven, Dept of Cardiovascular Sciences , Leuven , Belgium
| | - J Bogaert
- KU Leuven, Dept of Imaging and Pathology , Leuven , Belgium
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Rafouli-Stergiou P, Symons R, Droogne W, Dresselaers T, Masci PG, Bogaert J. Liver magnetic resonance relaxometry can provide useful markers for the assessment of right heart failure in dilated cardiomyopathy. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeab090.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
In dilated cardiomyopathy (DCM) patients at risk of developing right heart failure (RHF), early depiction of congestive heart failure (CHF) is pivotal to inform about the hemodynamic status and tailor medical therapy.
Purpose
We hypothesized that increased liver relaxation times measured at routine cardiovascular magnetic resonance (CMR), reflecting passive hepatic congestion, may be a valuable imaging biomarker to depict CHF.
Methods
The study cohort included DCM patients with (n = 48) and without (n = 46) right ventricular dysfunction (RVD), defined as a right ventricular ejection fraction <35%, and >45%, respectively, and a control group (n = 40). Native T1, T2, and extracellular volume (ECV) liver values were measured on routinely acquired cardiac maps.
Results
DCM with RVD patients had higher C-reactive protein, troponin I and NT-pro BNP values, and worse LV functional parameters than DCM without RVD patients (all p < 0.001). T1, T2 and ECV liver values were significantly higher in DCM with, compared to DCM without, RVD patients and also compared to controls [T1: 675 ± 88ms vs. 538 ± 39ms and 540 ± 34ms; T2: 54 ± 8ms vs. 45 ± 5ms and 46 ± 4ms; ECV: 36 ± 7% vs. 29 ± 4% and 30 ± 3%, respectively (all p < 0.001)]. Gamma glutamyltranspeptidase (γGT) correlated moderately but significantly with liver native T1 (r2 =0.34), T2 (r2 =0.27), and ECV (r2 =0.23) (all p < 0.001). Using right atrial pressure (RAP > 5 mmHg), as a surrogate measure of RHF, liver native T1 yielded at ROC analysis the highest AUC (0.906), significantly higher than liver ECV (0.813), γGT (0.806), liver T2 (0.797), total bilirubin (0.737) and alkaline phosphatase (0.561) [Figure 1]. A liver native T1 value of 617 ms showed a sensitivity of 79.5% and a specificity of 91.0% in identifying RHF. Density plots to discriminate between presence and absence of RHF are demonstrated at Figure 2. Excellent intra-/inter-observer agreement was found for assessment of native T1/T2/ECV liver values.
Conclusion
In DCM patients, assessment of liver relaxation times acquired on a CMR exam, may provide valuable information with regard to the presence of RHF.
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Affiliation(s)
| | - R Symons
- University Hospitals (UZ) Leuven, Leuven, Belgium
| | - W Droogne
- University Hospitals (UZ) Leuven, Leuven, Belgium
| | | | - PG Masci
- University Hospitals (UZ) Leuven, Leuven, Belgium
| | - J Bogaert
- University Hospitals (UZ) Leuven, Leuven, Belgium
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Dresselaers T, Rafouli-Stergiou P, De Bosscher R, Tilborghs S, Dausin C, Cernicanu A, Claus P, Willems R, Claessen G, Bogaert J. T1 and ECV mapping texture analysis distinguishing hypertrophic cardiomyopathy from athletes heart better than median values. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeab090.085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ph.D fellowship of the Research Foundation Flanders (FWO). The Master@Heart trial is funded by the FWO.
Introduction
Differentiating intensive training induced hypertrophy from hyperthropic cardiomyopathy (HCM) is important to identify those young athletes at risk of sudden cardiac death. Swoboda and colleagues demonstrated that T1 and ECV mapping can aid such a differentiation between athletic and pathological hypertrophy, particularly in subjects with indeterminate wall thickness (1).
Recently texture analysis (TA) methods of CMR data have demonstrated improved diagnostic accuracy over conventional qualitative analysis in various heart diseases. Only few studies have applied TA to T1 and ECV mapping data (2-4). Here we aimed to demonstrate that a TA approach provides superior capacity to distinguish HCM from athlete’s heart over average native T1 and ECV values.
Purpose
It was our hypothesis that a texture analysis of T1 and ECV mapping images would identify features that could discriminate between a HCM and athlete’s heart with a higher classification accuracy (CA) than average T1 and ECV values.
Methods
This study included data from 97 subjects diagnosed with HCM (acc. to guidelines; 5) and 28 athletes that took part in the Master@Heart trial (an ongoing study assessing the beneficial effects of long-term endurance exercise for the prevention of coronary artery disease, 6). Long and short axis T1 mapping data was acquired on a 1.5T Philips Ingenia system using MOLLI (seconds scheme). After offline motion correction and T1 and ECV map calculation (7), the left ventricular myocardium was manually delineated (3D Slicer; 8). Texture analysis of the masked images resulted in 194 features (Pyradiomics, standard settings; 9). The dataset was then split (75/25%) for training and testing purposes keeping images from the same subject within the same set. A fast correlation based filter rank was applied to the training data to derive relevant features. A further reduction to only two features was based on the CA of a support vector machine (SVM) learning method (linear kernel; cost 0.9 regression loss epsilon 0.1; leave-one-out). Finally, ROC analysis on the test data was used to determine the diagnostic accuracy for the following predictors: (1) median T1 and ECV (2) two most relevant features (training) (3) combination of (1) and (2) (ROC AUC statistics (10)).
Results
The two most relevant features were the histogram feature ECV energy and the gray level size zone matrix (GLSZM) feature native T1 zone entropy, a measure of heterogeneity in the texture pattern.
A model to distinguish HCM from athletes based on these features outperformed the model using only median T1 and ECV values with both higher sensitivity and specificity (table 1) and a significantly higher AUC in the ROC analysis (p < 0.05, figure 1). Combining these two features with median values did not improve the CA further.
Conclusion
Texture analysis of motion-corrected T1 and ECV mapping images out-performs classical analysis based on average values in distinguishing HCM from athlete"s heart.
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Affiliation(s)
- T Dresselaers
- KU Leuven, Dept of Imaging and Pathology, Leuven, Belgium
| | | | - R De Bosscher
- KU Leuven, Dept of Cardiovascular Sciences, Leuven, Belgium
| | - S Tilborghs
- KU Leuven, Department of Electrical Engineering (ESAT), Leuven, Belgium
| | - C Dausin
- KU Leuven, Exercise Physiology Research Group, Leuven, Belgium
| | - A Cernicanu
- Philips Benelux, Eindhoven, Netherlands (The)
| | - P Claus
- KU Leuven, Dept of Cardiovascular Sciences, Leuven, Belgium
| | - R Willems
- KU Leuven, Dept of Cardiovascular Sciences, Leuven, Belgium
| | - G Claessen
- KU Leuven, Dept of Cardiovascular Sciences, Leuven, Belgium
| | - J Bogaert
- KU Leuven, Dept of Imaging and Pathology, Leuven, Belgium
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Moura-Ferreira S, Vandenberk B, Masci PG, Dresselaers T, Garweg C, Symons R, Willems R, Bogaert J. Left ventricular remodeling in mitral valve prolapse patients: implications of apical papillary muscle implantation. Eur Heart J Cardiovasc Imaging 2021. [DOI: 10.1093/ehjci/jeab090.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
BACKGROUND
Mitral valve prolapse (MVP) causes left ventricle (LV) remodeling even in the absence of significant mitral regurgitation.
PURPOSE
We sought to evaluate whether apical implantation of the papillary muscle (PM) has an influence on the pattern and severity of MVP-related LV remodeling.
METHODS
All MVP patients who underwent Cardiovascular Magnetic Resonance at our institution between December 2008 and December 2019 were included, thoroughly reviewed and grouped according to apical/non-apical PM implantation.
RESULTS
Apical PM implantation was found in 53/92 patients (58%) and associated with mitral leaflet thickening (p < 0.01) and a trend toward higher prevalence of mitral annular disjunction (p = 0.05). Whereas there were no differences between groups concerning ventricular volumes and ejection fraction, mitral valve prolapse location or severity of mitral valve insufficiency, patients with apical PM implantation showed more lateral wall remodeling with mid lateral wall thinning (2.1 [1.8-2.5]mm vs. 4.0 [3.5-5.0]mm, p < 0.01), increased LV eccentricity and a lower Global Circumferential Strain at this level (15 ± 3% vs. 20 ± 3%, p < 0.01). In long-axis direction, increased end-diastolic mid lateral wall angulation was found (i.e., angle <155° measured in the thinnest point of the mid lateral wall in 4-chamber view) with a higher angle variation during systole (25 ± 11° vs. 17 ± 8° p < 0.01). Remarkably, PM fibrosis was significantly more frequent in patients with apical PM implantation (i.e., 66% vs. 28%, p < 0.01). Importantly, PM fibrosis was observed in the apically implanted PM in the vast majority of cases (86%), showing a strong association between PM fibrosis and its apical implantation. Finally, a higher burden of premature ventricular complexes (>5%) and non-sustained ventricular tachyarrhythmias was found in patients with apical PM implantation: 53% vs. 25% (p = 0.04) and 38% vs. 18% (p = 0.04), respectively.
CONCLUSIONS
Apical PM implantation is part of the phenotypic spectrum of MVP, significantly impacts LV remodeling and potentially may be related to increased ventricular arrhythmogenicity.
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Affiliation(s)
- S Moura-Ferreira
- University Hospitals (UZ) Leuven, Department of Radiology, Leuven, Belgium
| | - B Vandenberk
- University Hospitals (UZ) Leuven, Department of Cardiovascular Diseases, Leuven, Belgium
| | - PG Masci
- King"s College Hospital, School of Biomedical Engineering and Imaging Sciences, London, United Kingdom of Great Britain & Northern Ireland
| | - T Dresselaers
- University Hospitals (UZ) Leuven, Department of Radiology, Leuven, Belgium
| | - C Garweg
- University Hospitals (UZ) Leuven, Department of Cardiovascular Diseases, Leuven, Belgium
| | - R Symons
- University Hospitals (UZ) Leuven, Department of Radiology, Leuven, Belgium
| | - R Willems
- University Hospitals (UZ) Leuven, Department of Cardiovascular Diseases, Leuven, Belgium
| | - J Bogaert
- University Hospitals (UZ) Leuven, Department of Radiology, Leuven, Belgium
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Bordonaro V, Bivort D, Dresselaers T, De Langhe E, Bogaert J, Symons R. Myocardial T1 mapping and extracellular volume quantification as novel biomarkers in risk stratification of patients with systemic sclerosis. Clin Radiol 2020; 76:162.e1-162.e8. [PMID: 33109349 DOI: 10.1016/j.crad.2020.09.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 09/30/2020] [Indexed: 11/29/2022]
Abstract
AIM To study the prognostic value of myocardial native T1 and extracellular volume (ECV), measured by cardiovascular magnetic resonance (CMR), in patients with systemic sclerosis (SSc). MATERIALS AND METHODS Thirty-three SSc patients (16/33 male, 48.5%) were studied using multiparametric CMR including native T1 mapping with ECV calculation, T2 mapping, and late gadolinium enhancement (LGE). Patients were followed-up for cardiac death, haemodynamically significant arrhythmia, or heart failure. Results were compared with 33 age- and gender-matched healthy controls. RESULTS When compared with controls, SSc patients had higher myocardial native T1 (1,058.9±71 versus 989.4±21.4 ms, p<0.001), higher T2 (54.9±5.7 versus 50±2.5 ms, p<0.001), and ECV values (27.9±5.4% versus 24.8±2%, p<0.004). LGE was present in eight patients (24%), two subendocardial, five midwall, and four subepicardial. LGE, native T1, and ECV were significantly associated with adverse events during follow-up in multivariate Cox regression analysis. Kaplan-Meier analysis demonstrated significant divergence of the survival curves based on the presence of elevated native T1 (≥1,069 ms) or ECV (≥31.4%) values. CONCLUSION Cardiac involvement is frequent in SSc. Both native T1 mapping and ECV represent novel non-invasive markers of myocardial fibrosis and could be used in the risk stratification of patients with SSc. CMR mapping may provide a novel biomarker for disease monitoring and study of therapies aiming to reduce myocardial fibrosis in SSc.
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Affiliation(s)
- V Bordonaro
- Department of Imaging and Pathology, University Hospitals Leuven, Leuven, Belgium
| | - D Bivort
- Department of Rheumatology, University Hospitals Leuven, Leuven, Belgium
| | - T Dresselaers
- Department of Imaging and Pathology, University Hospitals Leuven, Leuven, Belgium
| | - E De Langhe
- Department of Rheumatology, University Hospitals Leuven, Leuven, Belgium
| | - J Bogaert
- Department of Imaging and Pathology, University Hospitals Leuven, Leuven, Belgium
| | - R Symons
- Department of Imaging and Pathology, University Hospitals Leuven, Leuven, Belgium.
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Weerasekera A, Sima DM, Dresselaers T, Van Huffel S, Van Damme P, Himmelreich U. Non-invasive assessment of disease progression and neuroprotective effects of dietary coconut oil supplementation in the ALS SOD1 G93A mouse model: A 1H-magnetic resonance spectroscopic study. Neuroimage Clin 2018; 20:1092-1105. [PMID: 30368196 PMCID: PMC6202692 DOI: 10.1016/j.nicl.2018.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/28/2018] [Accepted: 09/16/2018] [Indexed: 12/12/2022]
Abstract
Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disease primarily characterized by progressive degeneration of motor neurons in the motor cortex, brainstem and spinal cord. Due to relatively fast progression of ALS, early diagnosis is essential for possible therapeutic intervention and disease management. To identify potential diagnostic markers, we investigated age-dependent effects of disease onset and progression on regional neurochemistry in the SOD1G93A ALS mouse model using localized in vivo magnetic resonance spectroscopy (MRS). We focused mainly on the brainstem region since brainstem motor nuclei are the primarily affected regions in SOD1G93A mice and ALS patients. In addition, metabolite profiles of the motor cortex were also assessed. In the brainstem, a gradual decrease in creatine levels were detected starting from the pre-symptomatic age of 70 days postpartum. During the early symptomatic phase (day 90), a significant increase in the levels of the inhibitory neurotransmitter γ- aminobutyric acid (GABA) was measured. At later time points, alterations in the form of decreased NAA, glutamate, glutamine and increased myo-inositol were observed. Also, decreased glutamate, NAA and increased taurine levels were seen at late stages in the motor cortex. A proof-of-concept (PoC) study was conducted to assess the effects of coconut oil supplementation in SODG93A mice. The PoC revealed that the coconut oil supplementation together with the regular diet delayed disease symptoms, enhanced motor performance, and prolonged survival in the SOD1G93A mouse model. Furthermore, MRS data showed stable metabolic profile at day 120 in the coconut oil diet group compared to the group receiving a standard diet without coconut oil supplementation. In addition, a positive correlation between survival and the neuronal marker NAA was found. To the best of our knowledge, this is the first study that reports metabolic changes in the brainstem using in vivo MRS and effects of coconut oil supplementation as a prophylactic treatment in SOD1G93A mice.
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Affiliation(s)
- A Weerasekera
- Biomedical MRI Unit/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - D M Sima
- Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Leuven, Belgium; icometrix, R&D department, Leuven, Belgium
| | - T Dresselaers
- Radiology, Department of Imaging and Pathology, UZ Leuven, Leuven, Belgium
| | - S Van Huffel
- Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Leuven, Belgium
| | - P Van Damme
- Department of Neurology, University Hospitals Leuven, Laboratory of Neurobiology, Leuven, Belgium; Department of Neurosciences, KU Leuven, Center for Brain & Disease Research, VIB, Leuven, Belgium
| | - U Himmelreich
- Biomedical MRI Unit/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
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Muthuramu I, Singh N, Amin R, Postnov A, Dresselaers T, Gheysens O, De Geest B. Selective cholesterol lowering gene transfer attenuates the development of pressure overload-induced cardiomyopathy in mice. Atherosclerosis 2015. [DOI: 10.1016/j.atherosclerosis.2015.04.213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Struys T, Ketkar-Atre A, Gervois P, Leten C, Hilkens P, Martens W, Bronckaers A, Dresselaers T, Politis C, Lambrichts I, Himmelreich U. Magnetic Resonance Imaging of Human Dental Pulp Stem Cells in Vitro and in Vivo. Cell Transplant 2013; 22:1813-29. [DOI: 10.3727/096368912x657774] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Recent advances in stem cell research have shown the promising nature of mesenchymal stem cells as plausible candidates for cell-based regenerative medicine. Many studies reported the use of human dental pulp stem cells (hDPSCs), which possess self-renewal capacity, high proliferation potential, and the ability to undergo multilineage differentiation. Together with this therapeutic approach, development of effective, noninvasive and nontoxic imaging techniques for visualizing and tracking the cells in vivo is crucial for the evaluation and improvement of stem cell therapy. Magnetic resonance imaging (MRI) is one of the most powerful diagnostic imaging techniques currently available for in vivo diagnosis and has been proposed as the most attractive modality for monitoring stem cell migration. The aim of this study was to investigate the labeling efficiency of hDPSCs using superparamagnetic iron oxide (SPIO) particles in order to allow visualization using in vitro and in vivo MRI without influencing cellular metabolism. MRI and transmission electron microscopy (TEM) showed optimal uptake with low SPIO concentrations of 15 μg/ml in combination with 0.75 μg/ml poly-l-lysine (PLL) resulting in more than 13 pg iron/cell and an in vitro detection limit of 50 labeled cells/μl. Very low SPIO concentrations in the culture medium resulted in extremely high labeling efficiency not reported before. For these conditions, tetrazolium salt assays showed no adverse effects on cell viability. Furthermore, in vivo MRI was performed to detect labeled hDPSCs transplanted into the brain of Rag 2-γ C immune-deficient mice. Transplanted cells did not show any signs of tumorgenecity or teratoma formation during the studied time course. We have reported on a labeling and imaging strategy to visualize human dental pulp stem cells in vivo using MRI. These data provide a solid base to allow cell tracking in future regenerative studies in the brain longitudinally.
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Affiliation(s)
- T. Struys
- Biomedical MRI Unit-MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - A. Ketkar-Atre
- Biomedical MRI Unit-MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - P. Gervois
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - C. Leten
- Biomedical MRI Unit-MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - P. Hilkens
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - W. Martens
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - A. Bronckaers
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - T. Dresselaers
- Biomedical MRI Unit-MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - C. Politis
- Ziekenhuis Oost-Limburg (ZOL), Genk, Belgium
| | - I. Lambrichts
- Biomedical Research Institute, Lab of Histology, Hasselt University, Diepenbeek, Belgium
| | - U. Himmelreich
- Biomedical MRI Unit-MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
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Sepúlveda MR, Dresselaers T, Vangheluwe P, Everaerts W, Himmelreich U, Mata AM, Wuytack F. Evaluation of manganese uptake and toxicity in mouse brain during continuous MnCl2 administration using osmotic pumps. Contrast Media Mol Imaging 2012; 7:426-34. [DOI: 10.1002/cmmi.1469] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
| | - T. Dresselaers
- Biomedical NMR Unit/ MoSAIC, Department of Imaging and Pathology of Medical Diagnostic Sciences, Faculty of Medicine; Katholieke Universiteit Leuven; Leuven; Belgium
| | - P. Vangheluwe
- Laboratory of Cellular Transport Systems; Department of. Molecular Cell Biology; Faculty of Medicine; Katholieke Universiteit Leuven; Leuven; Belgium
| | - W. Everaerts
- Laboratory of Experimental Urology; Department of Surgery; Faculty of Medicine; Katholieke Universiteit Leuven; Leuven; Belgium
| | - U. Himmelreich
- Biomedical NMR Unit/ MoSAIC, Department of Imaging and Pathology of Medical Diagnostic Sciences, Faculty of Medicine; Katholieke Universiteit Leuven; Leuven; Belgium
| | - A. M. Mata
- Departamento de Bioquímica y Biología Molecular y Genética; Facultad de Ciencias; Universidad de Extremadura; Badajoz; Spain
| | - F. Wuytack
- Laboratory of Cellular Transport Systems; Department of. Molecular Cell Biology; Faculty of Medicine; Katholieke Universiteit Leuven; Leuven; Belgium
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10
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Radermacher KA, Magat J, Bouzin C, Laurent S, Dresselaers T, Himmelreich U, Boutry S, Mahieu I, Vander Elst L, Feron O, Muller RN, Jordan BF, Gallez B. Multimodal assessment of early tumor response to chemotherapy: comparison between diffusion-weighted MRI, 1H-MR spectroscopy of choline and USPIO particles targeted at cell death. NMR Biomed 2012; 25:514-522. [PMID: 21874657 DOI: 10.1002/nbm.1765] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 05/20/2011] [Accepted: 05/20/2011] [Indexed: 05/31/2023]
Abstract
The aim of this study was to determine the value of different magnetic resonance (MR) protocols to assess early tumor response to chemotherapy. We used a murine tumor model (TLT) presenting different degrees of response to three different cytotoxic agents. As shown in survival curves, cyclophosphamide (CP) was the most efficient drug followed by 5-fluorouracil (5-FU), whereas the etoposide treatment had little impact on TLT tumors. Three different MR protocols were used at 9.4 Tesla 24 h post-treatment: diffusion-weighted (DW)-MRI, choline measurement by (1) H MRS, and contrast-enhanced MRI using ultrasmall iron oxide nanoparticles (USPIO) targeted at phosphatidylserine. Accumulation of contrast agent in apoptotic tumors was monitored by T(2) -weighted images and quantified by EPR spectroscopy. Necrosis and apoptosis were assessed by histology. Large variations were observed in the measurement of choline peak areas and could not be directly correlated to tumor response. Although the targeted USPIO particles were able to significantly differentiate between the efficiency of each cytotoxic agent and best correlated with survival endpoint, they present the main disadvantage of non-specific tumor accumulation, which could be problematic when transferring the method to the clinic. DW-MRI presents a better compromise by combining longitudinal studies with a high dynamic range; however, DW-MRI was unable to show any significant effect for 5-FU. This study illustrates the need for multimodal imaging in assessing tumor response to treatment to compensate for individual limitations.
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Affiliation(s)
- K A Radermacher
- Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium
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11
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Oosterlinck WW, Dresselaers T, Geldhof V, Van Santvoort A, Robberecht W, Herijgers P, Himmelreich U. Response of mouse brain perfusion to hypo- and hyperventilation measured by arterial spin labeling. Magn Reson Med 2011; 66:802-11. [DOI: 10.1002/mrm.23060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 04/06/2011] [Accepted: 05/25/2011] [Indexed: 11/10/2022]
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12
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Casteels C, Vandeputte C, Rangarajan JR, Dresselaers T, Riess O, Bormans G, Maes F, Himmelreich U, Nguyen H, Van Laere K. Metabolic and type 1 cannabinoid receptor imaging of a transgenic rat model in the early phase of Huntington disease. Exp Neurol 2011; 229:440-9. [PMID: 21459091 DOI: 10.1016/j.expneurol.2011.03.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/11/2011] [Accepted: 03/21/2011] [Indexed: 01/11/2023]
Abstract
Several lines of evidence imply early alterations in metabolic and endocannabinoid neurotransmission in Huntington disease (HD). Using [(18)F]MK-9470 and small animal PET, we investigated for the first time cerebral changes in type 1 cannabinoid (CB1) receptor binding in vivo in pre-symptomatic and early symptomatic rats of HD (tgHD), in relation to glucose metabolism, morphology and behavioral testing for motor and cognitive function. Twenty-three Sprague-Dawley rats (14 tgHD and 9 wild-types) were investigated between the age of 2 and 11 months. Relative glucose metabolism and parametric CB1 receptor images were anatomically standardized to Paxinos space and analyzed voxel-wise. Volumetric microMRI imaging was performed to assess HD neuropathology. Within the first 10 months, bilateral volumes of caudate-putamen and lateral ventricles did not significantly differ between genotypes. Longitudinal- and genotype evolution showed that relative [(18)F]MK-9470 binding progressively decreased in the caudate-putamen and lateral globus pallidus of tgHD rats (-8.3%, p≤1.1×10(-5) at 5 months vs. -10.9%, p<1.5×10(-5) at 10 months). In addition, relative glucose metabolism increased in the bilateral sensorimotor cortex of 2-month-old tgHD rats (+8.1%, p≤1.5×10(-5)), where it was positively correlated to motor function at that time point. TgHD rats developed cognitive deficits at 6 and 11 months of age. Our findings point to early regional dysfunctions in endocannabinoid signalling, involving the lateral globus pallidus and caudate-putamen. In vivo CB1 receptor measurements using [(18)F]MK-9470 may thus be a useful early biomarker for HD. Our results also provide evidence of subtle motor and cognitive deficits at earlier stages than previously described.
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Affiliation(s)
- C Casteels
- Division of Nuclear Medicine, KU Leuven and University Hospital Leuven, Belgium.
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13
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Vande Velde G, Rangarajan JR, Toelen J, Dresselaers T, Ibrahimi A, Krylychkina O, Vreys R, Van der Linden A, Maes F, Debyser Z, Himmelreich U, Baekelandt V. Evaluation of the specificity and sensitivity of ferritin as an MRI reporter gene in the mouse brain using lentiviral and adeno-associated viral vectors. Gene Ther 2011; 18:594-605. [PMID: 21346786 DOI: 10.1038/gt.2011.2] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of in vivo imaging protocols to reliably track transplanted cells or to report on gene expression is critical for treatment monitoring in (pre)clinical cell and gene therapy protocols. Therefore, we evaluated the potential of lentiviral vectors (LVs) and adeno-associated viral vectors (AAVs) to express the magnetic resonance imaging (MRI) reporter gene ferritin in the rodent brain. First, we compared the induction of background MRI contrast for both vector systems in immune-deficient and immune-competent mice. LV injection resulted in hypointense (that is, dark) changes of T(2)/T(2)(*) (spin-spin relaxation time)-weighted MRI contrast at the injection site, which can be partially explained by an inflammatory response against the vector injection. In contrast to LVs, AAV injection resulted in reduced background contrast. Moreover, AAV-mediated ferritin overexpression resulted in significantly enhanced contrast to background on T(2)(*)-weighted MRI. Although sensitivity associated with the ferritin reporter remains modest, AAVs seem to be the most promising vector system for in vivo MRI reporter gene imaging.
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Affiliation(s)
- G Vande Velde
- Laboratory for Neurobiology and Gene Therapy, Katholieke Universiteit Leuven, Leuven, Flanders, Belgium
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14
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Vande Velde G, Baekelandt V, Dresselaers T, Himmelreich U. Magnetic resonance imaging and spectroscopy methods for molecular imaging. Q J Nucl Med Mol Imaging 2009; 53:565-585. [PMID: 20016450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Magnetic resonance imaging (MRI), one of the most powerful imaging modalities available for clinical diagnosis, has contributed significantly to phenotyping of transgenic organisms and to cellular imaging and is now gaining importance in the field of molecular imaging. Its advantage is the ability to provide in vivo information with high resolution and good soft tissue contrast as compared to established other molecular imaging methods. MRI can non-invasively report on cell localisation and migration with detailed anatomical background information, which is of great interest in cellular therapies. Recent technological advances and contrast generation strategies aim to bring MRI beyond cellular imaging to the detection of functional changes in vivo. MR based monitoring of molecular processes, requires the development of contrast agents and targeting methods as well as improvements in the methods sensitivity. Here, an overview is provided on advanced MR technologies and contrast generation strategies for this purpose. This includes MRI and MR spectroscopic methods for molecular imaging and various approaches for targeted and responsive contrast generation to visualize functional changes of particular cells. A description of different methods is provided, as well as the potentials and challenges of MR techniques for the visualization of molecular processes in vivo.
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Affiliation(s)
- G Vande Velde
- Laboratory for Neurobiology and Gene Therapy, Catholic University of Leuven, Leuven, Belgium
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15
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Liu Q, Monbaliu D, Vekemans K, Peeters R, De Keyzer F, Dresselaers T, Ni Y, Van Hecke P, Komuta M, Brassil J, Marchal G, Pirenne J. Can apparent diffusion coefficient discriminate ischemic from nonischemic livers? A pilot experimental study. Transplant Proc 2007; 39:2643-6. [PMID: 17954198 DOI: 10.1016/j.transproceed.2007.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE Using magnetic resonance imaging, the apparent diffusion coefficient (ADC) is an indicator to assess cerebral ischemia. The aim of this porcine study was to evaluate whether ADC assessed hepatic ischemia during ex vivo hypothermic machine perfusion (HMP) as well as in vivo. METHODS Ex vivo: ADC of normal versus warm ischemic (WI) livers was assessed during HMP and subsequent rewarming to mimic ischemia-reperfusion injury. As the preservation solution, we used either an acellular solution or diluted blood. WI was induced in the left lobe or in the whole liver and compared 2-hour WI and non-WI. In vivo: One liver was scanned with the left lobe vessels occluded for 2-hour WI and subsequently for 3 hour reperfusion to compare with the right lobe without WI. Aspartate aminotransferase (AST) in the perfusate and morphology were used as surrogates of WI. RESULTS In all WI livers, AST reached high levels and histology showed severe injury. Ex vivo ADC during acellular perfusion showed negligible differences between the livers with versus without WI, namely, 0.75 x 10(-3) or 0.88 x 10(-3) mm(2)/s during HMP. Ex vivo ADC using sanguineous perfusion showed 1.11 x 10(-3) or 0.83 x 10(-3) mm(2)/s during HMP in regions with versus without WI, respectively, a difference that remained stable during the whole experiment. ADC in vivo decreased from the physiological level of 1.07 x 10(-3) mm(2)/s to 0.75 x 10(-3) mm(2)/s in the first 30 minutes of WI, whereas ADC in the non-WI liver remained constant. CONCLUSION ADC in vivo decreased during hepatic ischemia, as previously seen in cerebral ischemia. However, the effect of WI on ADC was less clear during ex vivo HMP.
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Affiliation(s)
- Q Liu
- Abdominal Transplant Surgery, Catholic University of Leuven, Herestraat 49, 3000 Leuven, Belgium.
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16
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De Bock K, Dresselaers T, Kiens B, Richter EA, Van Hecke P, Hespel P. Evaluation of intramyocellular lipid breakdown during exercise by biochemical assay, NMR spectroscopy, and Oil Red O staining. Am J Physiol Endocrinol Metab 2007; 293:E428-34. [PMID: 17426112 DOI: 10.1152/ajpendo.00112.2007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The study compared the net decline of intramyocellular lipids (IMCL) during exercise (n = 18) measured by biochemical assay (BIO) and Oil Red O (ORO) staining on biopsy samples from vastus lateralis muscle and by (1)H-MR spectroscopy (MRS) sampled in an 11 x 11 x 18-mm(3) voxel in the same muscle. IMCL was measured before and after a 2-h cycling bout ( approximately 75% V(.)(O(2) peak)). ORO and MRS measurements showed substantial IMCL use during exercise of 31 +/- 12 and 47 +/- 6% of preexercise IMCL content. In contrast, use of BIO for IMCL determination did not reveal an exercise-induced breakdown of IMCL (2 +/- 9%, P = 0.29) in young healthy males. Correlations between different measures of exercise-induced IMCL degradation were low. Coefficients were 0.48 for MRS vs. ORO (P = 0.07) and were even lower for BIO vs. MRS (r = 0.38, P = 0.13) or ORO (r = 0.08, P = 0.78). This study demonstrates that different methods to measure IMCL in human muscles can result in different conclusions with regard to exercise-induced IMCL changes. MRS has the advantage that it is noninvasive, however, not fiber type specific and hampered by an at least 30-min delay in measurements after exercise completion and may overestimate IMCL use. BIO is the only quantitative method but is subject to variation when biopsies have different fiber type composition. However, BIO yields lower IMCL breakdown compared with ORO and MRS. ORO has the major advantage that it is fiber type specific, and it therefore provides information that is not available with the other methods.
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Affiliation(s)
- K De Bock
- Research Centre for Exercise and Health, FABER-K. U. Leuven, Tervuursevest 101, B-3001 Leuven, Belgium
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17
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Dubois L, Dresselaers T, Landuyt W, Paesmans K, Mengesha A, Wouters BG, Hecke PV, Theys J, Lambin P. Efficacy of gene therapy-delivered cytosine deaminase is determined by enzymatic activity but not expression. Br J Cancer 2007; 96:758-61. [PMID: 17311022 PMCID: PMC2360068 DOI: 10.1038/sj.bjc.6603624] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/10/2007] [Accepted: 01/12/2007] [Indexed: 11/29/2022] Open
Abstract
The potential utility of tumour-selective 5-fluorouracil treatment using attenuated Salmonella serovar typhimurium recombinant for cytosine deaminase (TAPET-CD) has been documented in experimental settings. The present data demonstrate that in vivo (19)F-magnetic resonance spectroscopy measurements allow the outcome prediction of this prokaryotic-based therapy, demonstrating the necessity of non-invasive real-time imaging techniques for treatment monitoring.
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Affiliation(s)
- L Dubois
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - T Dresselaers
- Biomedical NMR Unit, K.U. Leuven, Herestraat 49, PO Box 803, 3000 Leuven, Belgium
| | - W Landuyt
- Laboratory of Experimental Oncology/Radiobiology, K.U. Leuven, Gasthuisberg-CDG 8th floor, Herestraat 49, 3000 Leuven, Belgium
| | - K Paesmans
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - A Mengesha
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - B G Wouters
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - P Van Hecke
- Biomedical NMR Unit, K.U. Leuven, Herestraat 49, PO Box 803, 3000 Leuven, Belgium
| | - J Theys
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - P Lambin
- Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, 6200 MD, Maastricht, The Netherlands
- Laboratory of Experimental Oncology/Radiobiology, K.U. Leuven, Gasthuisberg-CDG 8th floor, Herestraat 49, 3000 Leuven, Belgium
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18
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Devos A, Bergans N, Dresselaers T, De Brabanter J, Sima DM, Vanhamme L, Vanstapel F, Van Hecke P, Van Huffel S. Model order selection for quantification of a multi-exponential magnetic resonance spectrum. Conf Proc IEEE Eng Med Biol Soc 2006; 2006:1299-1302. [PMID: 17945630 DOI: 10.1109/iembs.2006.260107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Magnetic resonance spectroscopic signals analyzed by time-domain models in order to retrieve estimates of the model parameters usually require prior knowledge about the model order. For multi-exponential signals where a superposition of peaks occurs at the same resonance frequency, but with different damping values, model order selection criteria from information theory can be used. In this study, several generalized versions of information criteria are compared using Monte-Carlo simulation signals. The best criterion is further applied for selecting the model order of experimental glycogen signals.
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Affiliation(s)
- A Devos
- Department of Electrical Engineering, SCD-SISTA, Katholieke University, Kasteelpark Arenberg 10, 3001 Heverlee, Leuven, Belgium
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19
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Dresselaers T, Theys J, Nuyts S, Wouters B, de Bruijn E, Anné J, Lambin P, Van Hecke P, Landuyt W. Non-invasive 19F MR spectroscopy of 5-fluorocytosine to 5-fluorouracil conversion by recombinant Salmonella in tumours. Br J Cancer 2003; 89:1796-801. [PMID: 14583786 PMCID: PMC2394413 DOI: 10.1038/sj.bjc.6601345] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The aim of this study was to evaluate the applicability of fluorine-19 magnetic resonance spectroscopy (19F MRS) for monitoring in vivo the conversion of 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) after using an attenuated Salmonella Typhimurium strain recombinant to provide cytosine deaminase (TAPET-CD). The 19F MRS measurements were done on mice bearing the human colon tumour xenograft (HCT116). The intratumoural conversion is greater when TAPET-CD/5-FC is delivered intratumourally (i.tu.) than when TAPET-CD is delivered intravenously (i.v.) and 5-FC intraperitoneally (i.p.). Repeat measurements of the same tumour also yielded important information on the tumour colonization by TAPET-CD through the correlated 5-FC to 5-FU conversion efficacy. The in vivo MRS spectra were confirmed by in vitro19F MRS of perchloric acid extracts of the tumour tissue. No 5-FU metabolites were detectable in vivo in the tumours. However, the in vitro measurements revealed, besides 5-FC and 5-FU, the presence of small amounts of catabolites. Finally, spectra obtained in vitro from liver extracts of tumour-bearing mice treated i.tu. with TAPET-CD/5-FC showed no 5-FU and only little amounts of catabolites. Our data illustrate most importantly the potential of 19F MRS to monitor biologically-based treatments involving cytosine deaminase.
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Affiliation(s)
- T Dresselaers
- Biomedical NMR Unit, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - J Theys
- MAASTRO Lab/GROW, University Maastricht, PO BOX 616, 6200 MD Maastricht, The Netherlands
| | - S Nuyts
- Experimental Radiobiology/LEO, KU Leuven, Gasthuisberg-CDG, Herestraat 49, 3000 Leuven, Belgium
| | - B Wouters
- MAASTRO Lab/GROW, University Maastricht, PO BOX 616, 6200 MD Maastricht, The Netherlands
| | - E de Bruijn
- Laboratory Experimental Oncology, KU Leuven, Gasthuisberg-CDG, Herestraat 49, 3000 Leuven, Belgium
| | - J Anné
- Laboratory of Bacteriology, KU Leuven, Rega Institute, Minderbroederstraat 10, 3000 Leuven, Belgium
| | - P Lambin
- MAASTRO Lab/GROW, University Maastricht, PO BOX 616, 6200 MD Maastricht, The Netherlands
- Experimental Radiobiology/LEO, KU Leuven, Gasthuisberg-CDG, Herestraat 49, 3000 Leuven, Belgium
| | - P Van Hecke
- Biomedical NMR Unit, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - W Landuyt
- Experimental Radiobiology/LEO, KU Leuven, Gasthuisberg-CDG, Herestraat 49, 3000 Leuven, Belgium
- Experimental Radiobiology/LEO, K.U.Leuven, Gasthuisberg-CDG 8th floor, Herestraat 49, B-3000 Leuven, Belgium. E-mail:
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20
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Lammertyn J, Dresselaers T, Van Hecke P, Jancsók P, Wevers M, Nicolaï BM. MRI and x-ray CT study of spatial distribution of core breakdown in ‘Conference’ pears. Magn Reson Imaging 2003; 21:805-15. [PMID: 14559346 DOI: 10.1016/s0730-725x(03)00105-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Two non-destructive tomographic techniques, X-ray CT imaging and magnetic resonance imaging (MRI), were applied to study the development of core breakdown disorder in 'Conference' pears (Pyrus communis cv. Conference). This disorder, which is characterized by brown discoloration of the tissue and development of cavities, is induced by elevated CO(2) and decreased O(2) levels during controlled atmosphere storage. Tomographic images of pears stored for 10 months under disorder inducing conditions, were acquired with both techniques and compared to the actual slices. Both X-ray and MRI were able to differentiate between unaffected tissue, brown tissue and cavities. A simple image-processing program, based on threshold values, was developed to determine the area percentage of affected and unaffected tissue as well as the cavity and core area per slice. For all three imaging techniques the area percentage brown tissue per slice increased with the diameter of the pear, but was systematically underestimated by 12% and 6% for, respectively, X-ray and MRI, compared to the actual slices. The area percentage cavity corresponded very well for all techniques. It was also found that the contours of the brown tissue were parallel to the fruit boundaries, suggesting a relation between the disorder symptoms and gas diffusion properties of the fruit. It was concluded that MRI is the most appropriate technique to study the development of core breakdown disorder during postharvest storage in future experiments.
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Affiliation(s)
- J Lammertyn
- Flanders Centre/Laboratory of Postharvest Technology, Catholic University Leuven, Leuven, Belgium.
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21
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Bergans N, Dresselaers T, Vanhamme L, Van Hecke P, Van Huffel S, Vanstapel F. Quantification of the glycogen 13C-1 NMR signal during glycogen synthesis in perfused rat liver. NMR Biomed 2003; 16:36-46. [PMID: 12577296 DOI: 10.1002/nbm.812] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We studied glycogen synthesis from glucose in perfused livers of fed (n = 4) and 24 h starved (n = 7) rats. Glycogenolysis was inhibited by BAY R3401 (150 microM) and proglycosyn (100 microM). After 60 min, we replaced 99% (13)C-1 glucose by natural abundance glucose. This pulse-chase design allowed us to recognize residual ongoing futile glycogen turnover from the release of initially deposited (13)C-label, into the (13)C-free chase medium. Net residual turnover was less than 2 +/- 0.7% and 0.6 +/- 0.2% of 1-(13)C glycogen deposition rates of 0.31 +/- 0.04 and 0.99 +/- 0.04 micromol glucose g(-1) min(-1), in starved and fed livers, respectively. The 1-(13)C glycogen signal was monitored throughout the experiment with proton-decoupled (13)C NMR spectroscopy and analyzed in the time domain using AMARES. We noticed progressive line-broadening in any single experiment in the chase phase. One or a sum of two to three overlapping Lorentzians, with different exponential damping factors, were fitted to the signal. When the S/N was better than 40, the fit always delivered a small and a broad component. In the chase phase, the fit with a single Lorentzian resulted in a decline of glycogen signal by about 15 +/- 4 and 12 +/- 2% in starved and fed rats, respectively. This apparent decline in 1-(13)C glycogen signal could not be accounted for by the appearance of equivalent amounts of (13)C-labeled metabolites in the perfusate. The fit with a sum of two Lorentzians resulted in a decline of glycogen signal intensity of 7 +/- 5 and 5 +/- 3% in starved and fed rats, respectively, which reduced the apparent turnover to 8 +/- 9% and 6 +/- 4%, respectively. Quantification of the growing (13)C-1 glycogen signal requires a model function that accommodates changes in line shape throughout the period under study.
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Affiliation(s)
- N Bergans
- Biomedische NMR Eenheid, Afdeling Röntgendiagnose, Katholieke Universiteit Leuven, Leuven, Belgium
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22
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Beauloye C, Bertrand L, Krause U, Marsin AS, Dresselaers T, Vanstapel F, Vanoverschelde JL, Hue L. No-flow ischemia inhibits insulin signaling in heart by decreasing intracellular pH. Circ Res 2001; 88:513-9. [PMID: 11249875 DOI: 10.1161/01.res.88.5.513] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glucose-insulin-potassium solutions exert beneficial effects on the ischemic heart by reducing infarct size and mortality and improving postischemic left ventricular function. Insulin could be the critical protective component of this mixture, although the insulin response of the ischemic and postischemic myocardium has not been systematically investigated. The aim of this work was to study the insulin response during ischemia by analyzing insulin signaling. This was evaluated by measuring changes in activity and/or phosphorylation state of insulin signaling elements in isolated perfused rat hearts submitted to no-flow ischemia. Intracellular pH (pH(i)) was measured by NMR. No-flow ischemia antagonized insulin signaling including insulin receptor, insulin receptor substrate-1, phosphatidylinositol 3-kinase, protein kinase B, p70 ribosomal S6 kinase, and glycogen synthase kinase-3. These changes were concomitant with intracellular acidosis. Perfusing hearts with ouabain and amiloride in normoxic conditions decreased pH(i) and insulin signaling, whereas perfusing at pH 8.2 counteracted the drop in pH(i) and the inhibition of insulin signaling by ischemia. Incubation of cardiomyocytes in normoxic conditions, but at pH values below 6.75, mimicked the effect of ischemia and also inhibited insulin-stimulated glucose uptake. Finally, the in vitro insulin receptor tyrosine kinase activity was progressively inhibited at pH values below physiological pH(i), being abolished at pH 6.0. Therefore, ischemic acidosis decreases kinase activity and tyrosine phosphorylation of the insulin receptor thereby preventing activation of the downstream components of the signaling pathway. We conclude that severe ischemia inhibits insulin signaling by decreasing pH(i).
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Affiliation(s)
- C Beauloye
- Division of Cardiology, Hormone and Metabolic Research Unit Christian de Duve Institute of Cellular Pathology, Université catholique de Louvain, Brussels, Belgium
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Affiliation(s)
- S Van Roy
- Vlaamse Instelling van Technologisch Onderzoek (VITO), Mol, Belgium
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