C Roche

Publications (4)0.8 Total impact

• Article: Multimodal imaging for the detection and characterization of liver lesions in a mouse model of neuroendocrine tumor.

  O Beuf, C Lartizien, L Milot, L Baboï, C Roche, J-B Langlois, J-Y Scoazec, F Pilleul
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  ABSTRACT: The aim of this study was to compare in vivo magnetic resonance imaging (MRI) and ex vivo autoradiography with histopathological results for the detection and characterization of liver lesions in an experimental model of human neuroendocrine tumors. Intestinal STC-1 endocrine tumor cells were injected into 30 nude mice to achieve hepatic dissemination. Seven to 30 days after injection, T2-weighted in vivo images covering the entire liver were acquired with a 7-T system. Autoradiographs were also obtained in 28 mice after injection of fluorodeoxyglucose (18F-FDG). The autoradiographic liver samples were then stained with an antichromogranin antibody before histological analysis. Tumor size and the hepatic tumor fraction were measured using the three imaging modalities. Metastatic tumors visualized on the histological liver sections ranged in size from 50 microm (day 7) to 3 mm (day 30). The hepatic tumor fraction increased with time, reaching 30% of the hepatic surface area on day 30. Visual analysis revealed variable tumor distribution and type (solid and/or cystic). On MRI, lesions were identified from day 12 (about 100 icrom in diameter) and the hepatic tumor fraction was up to 48% at day 30. The smallest lesions (350 microm in diameter) were also detected at day 12 on the autoradiographs. There was good correlation between tumor fractions determined from autoradiographic and histological data. In vivo, MRI appears to be well suited to the follow-up of liver lesions in a mouse model of neuroendocrine tumor. Preliminary results using 18F-FDG in this animal model are promising, showing differences in FDG uptake.
  Gastroentérologie Clinique et Biologique 02/2008; 32(1 Pt. 1):32-40. · 0.80 Impact Factor
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  Available from: Olivier Beuf

  Article: Synchronisation strategies in T2-weighted MR imaging for detection of liver lesions: Application on a nude mouse model.

  L Baboi, L Milot, C Lartizien, C Roche, J-Y Scoazec, F Pilleul, O Beuf
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  ABSTRACT: The objective of this work was to propose original synchronisation strategies based on T2-weighted sequence performed on a small animal MRI spectrometer in order to improve the image contrast and detect mouse liver lesions at high magnetic field. The experiments were performed in vivo at 7T using a 32 mm inner diameter cylindrical volumetric coil for both RF emission and reception. A sensitive pressure sensor was used to detect external movements due to both respiration and heart beats. The pressure sensor was interfaced with a commercial ECG Trigger Unit to use dedicated functionalities (trigger levels, delays and window). To enable T2-weighted imaging with minimised T1 effects, an acquisition strategy with controlled TR spanning over several respiratory cycles was developed. With this strategy, the slices were acquired over several respiratory periods. The acquisition, performed over several respiratory periods, enables a longer TR than the typical mouse respiratory period. The image contrast is controllable and independent of the respiratory period. The heavily T2-weighted images obtained with the developed strategy allow better visualisation of lesions at high magnetic field. Moreover, double respiratory and cardiac synchronisation, based on a unique sensitive pressure sensor, improves image quality with less motion artifacts, especially in the ventral liver region. The total slice number is independent of respiratory period and thin slices can be acquired to cover the whole liver. The developed strategy enables high quality pure T2-weighted imaging with minimal motion artifacts. This strategy improves T2-weighted image contrast and quality, especially at high magnetic field, on animals with short respiratory periods. The strategy was demonstrated using a mouse model of liver lesions at 7T. This protocol could be used to carry out a longitudinal follow-up.
  Biomedical Imaging and Intervention Journal 10/2007; 3(4):e53.
• Conference Proceeding: Characterization of neuro-endocrine tumors in an athymic nude mouse model using dedicated synchronization strategies for T2-weigted MR imaging at 7T

  L.M. Baboi, L. Milot, C. Lartizien, C. Roche, J.-Y. Scoazec, F. Pilleul, O. Beuf
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  ABSTRACT: Endocrine tumours, with digestive localization, are tumours with variable forecast which are independent of their invasive and metastatic extensions. The experimental model of endocrine tumors with liver dissemination is available for evaluation of new medical therapeutics such as antiangiogenic therapy. MRI is a non invasive modality allowing in vivo examinations and is suitable to follow liver lesion evolution during longitudinal study on animal models. The goal of this study was to assess the detection level and to characterize the liver lesions in an athymic nude mouse model, using a dedicated MRI protocol and an optimized synchronization strategy at high magnetic field strength. The experiments were performed at 7T. To detect liver lesions, respiratory-triggered T2-weighted MR images is the sequence of choice. With conventional acquisition strategies used on small animal MR systems, trigger signal is performed at each respiratory cycle and thus, the T2 contrast is not freely controlled. Additionally, the slice number is limited by the expiration delay. To overcome these drawbacks, we proposed an original strategy enabling true T2-weighted imaging with minimal movement artifacts, regardless of the respiratory period and the number of slices. This protocol was used to carry out a longitudinal follow-up of hepatic lesions in 8 nude mice at stages D7, D12, D17 and D24. The fraction of lesion over the total liver volume was quantified. Moreover, the characterization of cystic or non-cystic type of lesions was achieved using various TE leading to T2 maps. In conclusion, the level of lesion detection and characterization of liver lesions was performed using a devoted protocol with original synchronization strategy dedicated to high field MRI. MR imaging could be used with relevance in the evaluation of new therapeutics protocol for treatment of liver lesions in neuroendocrine tumors using small animal model.
  Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE; 09/2007
• Article: Characterization of neuro-endocrine tumors in an athymic nude mouse model using dedicated synchronization strategies for T2-weigted MR imaging at 7T.

  L M Baboi, L Milot, C Lartizien, C Roche, J-Y Scoazec, F Pilleul, O Beuf
  [show abstract] [hide abstract]
  ABSTRACT: Endocrine tumours, with digestive localization, are tumours with variable forecast which are independent of their invasive and metastatic extensions. The experimental model of endocrine tumors with liver dissemination is available for evaluation of new medical therapeutics such as antiangiogenic therapy. MRI is a non invasive modality allowing in vivo examinations and is suitable to follow liver lesion evolution during longitudinal study on animal models. The goal of this study was to assess the detection level and to characterize the liver lesions in an athymic nude mouse model, using a dedicated MRI protocol and an optimized synchronization strategy at high magnetic field strength. The experiments were performed at 7T. To detect liver lesions, respiratory-triggered T2-weighted MR images is the sequence of choice. With conventional acquisition strategies used on small animal MR systems, trigger signal is performed at each respiratory cycle and thus, the T2 contrast is not freely controlled. Additionally, the slice number is limited by the expiration delay. To overcome these drawbacks, we proposed an original strategy enabling true T2-weighted imaging with minimal movement artifacts, regardless of the respiratory period and the number of slices. This protocol was used to carry out a longitudinal follow-up of hepatic lesions in 8 nude mice at stages D7, D12, D17 and D24. The fraction of lesion over the total liver volume was quantified. Moreover, the characterization of cystic or non-cystic type of lesions was achieved using various TE leading to T2 maps. In conclusion, the level of lesion detection and characterization of liver lesions was performed using a devoted protocol with original synchronization strategy dedicated to high field MRI. MR imaging could be used with relevance in the evaluation of new therapeutics protocol for treatment of liver lesions in neuroendocrine tumors using small animal model.
  Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2007; 2007:2879-82.