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Master Thesis

La technique de contrastes synthétiques multiples basés sur le T I améliore l'imagerie de la sclérose en plaques et de l'épilepsie à ultra-haut-champ

Abstract : Background: Ultra-high field MRI (≥7T) is a unique opportunity to improve the clinical diagnosis of brain pathologies, such as multiple sclerosis or focal epilepsy. However, several shortcomings of 7T MRI could hamper image quality and disrupt radiological interpretation. An adaptation of radiological practices compared to lower fields is therefore required. Purpose: To present an original synthetic MRI method based on T1 mapping achieved with the MP2RAGE sequence and validate the radiological value of on-demand T1-based contrasts generated by this technique in multiple sclerosis or focal epilepsy imaging at 7T. Materials and Methods: This retrospective study was carried out from October 2017 to December 2019 and included 21 patients suffering from different phenotypes of multiple sclerosis and 35 patients suffering from focal epilepsy who underwent MRI brain exams using a whole-body investigative 7T MR system. The quality of two proposed synthetic contrast images were assessed and compared to conventional images acquired at 7T using the MP2RAGE sequence by four radiologists, evaluating three qualitative criteria: signal homogeneity, contrast intensity and lesion depiction. Statistical analyses were performed on reported quality scores using Wilcoxon rank tests and further multiple comparisons tests. Intra- and inter-observer reliabilities were calculated as well. Results: Radiological quality scores were reported higher for synthetic images when compared to original images, whatever contrast, pathologies or raters were considered, with significant differences found for all three criteria (p<0.0001, Wilcoxon rank test). None of the four radiologists ever rated a synthetic image ‘significantly worse’ than an original image. Only a handful of synthetic images were rated slightly less satisfying, without precluding lesion identification. Conclusion: By providing an improved image quality at 7T, T1-based synthetic contrast images built from the MP2RAGE sequence could facilitate lesion visualization in pathological brain, while reducing the MR exam total duration by removing an additional sequence.
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Submitted on : Thursday, August 27, 2020 - 4:02:15 PM
Last modification on : Friday, October 23, 2020 - 4:46:30 PM
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Charlotte Seiler. La technique de contrastes synthétiques multiples basés sur le T I améliore l'imagerie de la sclérose en plaques et de l'épilepsie à ultra-haut-champ. Sciences du Vivant [q-bio]. 2020. ⟨dumas-02923989⟩



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