Texture analysis of magnetic resonance images of rat muscles during atrophy and regeneration

OBJECTIVES: The goals of the current study were (i) to introduce texture analysis on magnetic resonance imaging (MRI-TA) as a noninvasive method of muscle investigation that can discriminate three muscle conditions in rats; these are normal, atrophy and regeneration; and (ii) to show consistency between MRI-TA results and histological results of muscle type 2 fibers\u27 cross-sectional area. METHOD: Twenty-three adult female Wistar rats were randomized into (i) control (C), (ii) immobilized (I) and (iii) recovering (R) groups. For the last two groups, the right hind limb calf muscles were immobilized against the abdomen for 14 days; then, the hind limb was remobilized only for the R group for 40 days. At the end of each experimental period, MRI was performed using 7-T magnet Bruker Avance DRX 300 (Bruker, Wissembourg); T1-weighted MRI acquisition parameters were applied to show predominantly muscle fibers. Rats were sacrificed, and the gastrocnemius muscle (GM) was excised immediately after imaging. (A) Histology: GM type 2 fibers (fast twitch) were selectively stained using the adenosine triphosphatase (ATPase) technique. The mean cross-sectional areas were compared between the three groups. (B) Image analysis: regions of interest (ROIs) were selected on GM MR images where statistical methods of texture analysis were applied followed by linear discriminant analysis (LDA) and classification. RESULTS: Histological analysis showed that the fibers\u27 mean cross-sectional areas on GM transversal sections represented a significant statistical difference between I and C rats (ANOVA, P<.001) as well as between R and I rats (ANOVA, P<.01), but not between C and R rats. Similarly, MRI-TA on GM transversal images detected different texture for each group with the highest discrimination values (Fisher F coefficient) between the C and I groups, as well as between I and R groups. The lowest discrimination values were found between C and R groups. LDA showed three texture classes schematically separated. CONCLUSION: Quantitative results of MRI-TA were statistically consistent with histology. MRI-TA can be considered as a potentially interesting, reproducible and nondestructive method for muscle examination during atrophy and regeneration

From in-vitro genetic alteration to in-vivo NMR imaging, a unique animal model of depression

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Is magnetic resonance imaging texture analysis a useful tool for cell therapy in vivo monitoring?

Assessment of anti-tumor treatment efficiency is usually done by measuring tumor size. Treatment may however induce changes in the tumor other than tumor size. Magnetic Resonance Imaging Texture Analysis (MRI-TA) is presently used to follow activated lymphocyte cell therapy. We used a 7T microimager to acquire high-resolution MR images of an experimental liver metastasis from colon carcinoma in rats treated (n = 4) or not (n = 3) with a cell therapy product. MRI-TA was then performed with Linear Discriminant Analysis and showed: i) a significant variation of tumor texture with tumor growth and ii) a significant modification in the texture of tumors treated with activated lymphocytes compared with untreated tumors. T2-weighted images or volume calculation did not evidence any difference. MRI-TA appears as a promising method for early detection and follow-up of response to cell therapy

Diabète insulino-dépendant et parachutisme

Définition des règles de dérogation autorisant la pratique du parachutisme chez les sujets diabétiques insulino-dépendants

Assignment of heme mythyl 1H-NMR resonances of high-spin and low-spin ferric complexes of cytochrome P450cam using one-dimensional and two-dimensional paramagnetic signals enhancement (PASE) magnetization transfer experiments

An 1H-NMR study of ferric cytochrome P450cam in different paramagnetic states was performed. Assignment of three heme methyl resonances of the isocyanide adduct of cytochrome P450 in the ferric low-spin state was recently performed using electron exchange in the presence of putidaredoxin [Mouro, C., Bondon, A., Jung, C., Hui Bon Hoa, G., De Certaines, J.D., Spencer, R.G.S. and Simonneaux, G. (1999) FEBS Lett. 455, 302-306]. In this study, heme methyl protons of cytochrome P450 in the native high-spin and low-spin states were assigned through one-dimensional and two-dimensional magnetization transfer spectroscopy using the paramagnetic signals enhancement (PASE) method. The order of the methyl proton chemical shifts is inverted between high-spin and low-spin states. The methyl order observed in the ferric low-spin isocyanide complexes is related to the orientation of the cysteinate ligand

Ex-vivo magnetic resonance image texture analysis can discriminate genotypic origin in bovine meat

International audienceTexture analysis (TA) combined with dedicated gradient echo magnetic resonance imaging (MRI) at high field provides specific parametric T-2* maps of connective tissue and allows statistical analysis of the resulting texture. The present study clearly demonstrates that MRI-TA of bovine meat can discriminate between muscle types Gluteo biceps and Pectoralis profundus, and between genotype origins corresponding to the mutation on the myostatin gene: normal +/+, heterozygous mhl+ or homozygous double-muscled mh/mh Belgian White Blue bulls. Values of interclass separations reflect the significantly different collagen and fat contents in these genotypes. To our knowledge, no previous study has demonstrated such a correlation between MRI texture and genetics-related modifications

MRI texture analysis of GRMD dogs using orthogonal moments : a preliminary study.

International audienceMagnetic resonance image texture analysis (MRI-TA) has been already demonstrated as a powerful tool to extract image information better than visual examination of grey levels. Human muscular dystrophy is a disease of which diagnosis is rather easy but it remains a lack of atraumatic methods for its follow-up as well as for the management of treatments presently in progress. MRI appears to be a potential tool for disease follow-up and treatment monitoring. The present study is part of the European project MYO-MRI (http://myo-mri.eu/) aimed at improving diagnosis and understanding of muscle pathology. This paper focuses on the use of Legendre and Zernike moment-based texture analysis of MRI T2-weighted images to follow from 2 to 14 months 5 healthy and 5 Golden Retriever Muscular Dystrophy Dogs (GRMD), acknowledged to be the most accurate animal model available for human Duchenne Muscular Dystrophy. Regions-Of-Interest (ROIs) were characterized by moments and the features so extracted were analyzed by Principal Component Analysis and classified by means of Support Vector Machine. The preliminary results show relevant discriminations between dogs populations in reference to disease status and evolution