UMR 1288 – Imagerie Translationnelle en Oncologie (LITO)

Publications de l’Unité

Année de publication : 2018

Jessica Goya-Outi, Fanny Orlhac, Raphael Calmon, Agusti Alentorn, Christophe Nioche, Cathy Philippe, Stéphanie Puget, Nathalie Boddaert, Irène Buvat, Jacques Grill, Vincent Frouin, Frederique Frouin (2018 Apr 11)

Computation of reliable textural indices from multimodal brain MRI: suggestions based on a study of patients with diffuse intrinsic pontine glioma.

Physics in medicine and biology : 105003 : DOI : 10.1088/1361-6560/aabd21 En savoir plus

Few methodological studies regarding widely used textural indices robustness in MRI have been reported. In this context, this study aims to propose some rules to compute reliable textural indices from multimodal 3D brain MRI. Diagnosis and post-biopsy MR scans including T1, post-contrast T1, T2 and FLAIR images from thirty children with diffuse intrinsic pontine glioma (DIPG) were considered. The hybrid white stripe method was adapted to standardize MR intensities. Sixty textural indices were then computed for each modality in different regions of interest (ROI), including tumor and white matter (WM). Three types of intensity binning were compared [Formula: see text]: constant bin width and relative bounds; [Formula: see text] constant number of bins and relative bounds; [Formula: see text] constant number of bins and absolute bounds. The impact of the volume of the region was also tested within the WM. First, the mean Hellinger distance between patient-based intensity distributions decreased by a factor greater than 10 in WM and greater than 2.5 in gray matter after standardization. Regarding the binning strategy, the ranking of patients was highly correlated for 188/240 features when comparing [Formula: see text] with [Formula: see text], but for only 20 when comparing [Formula: see text] with [Formula: see text], and nine when comparing [Formula: see text] with [Formula: see text]. Furthermore, when using [Formula: see text] or [Formula: see text] texture indices reflected tumor heterogeneity as assessed visually by experts. Last, 41 features presented statistically significant differences between contralateral WM regions when ROI size slightly varies across patients, and none when using ROI of the same size. For regions with similar size, 224 features were significantly different between WM and tumor. Valuable information from texture indices can be biased by methodological choices. Recommendations are to standardize intensities in MR brain volumes, to use intensity binning with constant bin width, and to define regions with the same volumes to get reliable textural indices.

Fanny Orlhac, Sarah Boughdad, Cathy Philippe, Hugo Stalla-Bourdillon, Christophe Nioche, Laurence Champion, Michaël Soussan, Frédérique Frouin, Vincent Frouin, Irène Buvat (2018 Jan 6)

A Postreconstruction Harmonization Method for Multicenter Radiomic Studies in PET.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine : 1321-1328 : DOI : 10.2967/jnumed.117.199935 En savoir plus

Several reports have shown that radiomic features are affected by acquisition and reconstruction parameters, thus hampering multicenter studies. We propose a method that, by removing the center effect while preserving patient-specific effects, standardizes features measured from PET images obtained using different imaging protocols. Pretreatment F-FDG PET images of patients with breast cancer were included. In one nuclear medicine department (department A), 63 patients were scanned on a time-of-flight PET/CT scanner, and 16 lesions were triple-negative (TN). In another nuclear medicine department (department B), 74 patients underwent PET/CT on a different brand of scanner and a different reconstruction protocol, and 15 lesions were TN. The images from department A were smoothed using a gaussian filter to mimic data from a third department (department A-S). The primary lesion was segmented to obtain a lesion volume of interest (VOI), and a spheric VOI was set in healthy liver tissue. Three SUVs and 6 textural features were computed in all VOIs. A harmonization method initially described for genomic data was used to estimate the department effect based on the observed feature values. Feature distributions in each department were compared before and after harmonization. In healthy liver tissue, the distributions significantly differed for 4 of 9 features between departments A and B and for 6 of 9 between departments A and A-S ( < 0.05, Wilcoxon test). After harmonization, none of the 9 feature distributions significantly differed between 2 departments ( > 0.1). The same trend was observed in lesions, with a realignment of feature distributions between the departments after harmonization. Identification of TN lesions was largely enhanced after harmonization when the cutoffs were determined on data from one department and applied to data from the other department. The proposed harmonization method is efficient at removing the multicenter effect for textural features and SUVs. The method is easy to use, retains biologic variations not related to a center effect, and does not require any feature recalculation. Such harmonization allows for multicenter studies and for external validation of radiomic models or cutoffs and should facilitate the use of radiomic models in clinical practice.


Année de publication : 2017

Florentin Kucharczak, Kevin Loquin, Irène Buvat, Olivier Strauss, Denis Mariano-Goulart (2017 Dec 2)

Interval-based reconstruction for uncertainty quantification in PET.

Physics in medicine and biology : 035014 : DOI : 10.1088/1361-6560/aa9ea6 En savoir plus

A new directed interval-based tomographic reconstruction algorithm, called non-additive interval based expectation maximization (NIBEM) is presented. It uses non-additive modeling of the forward operator that provides intervals instead of single-valued projections. The detailed approach is an extension of the maximum likelihood-expectation maximization algorithm based on intervals. The main motivation for this extension is that the resulting intervals have appealing properties for estimating the statistical uncertainty associated with the reconstructed activity values. After reviewing previously published theoretical concepts related to interval-based projectors, this paper describes the NIBEM algorithm and gives examples that highlight the properties and advantages of this interval valued reconstruction.

Wadad Saba, Sébastien Goutal, Sylvain Auvity, Bertrand Kuhnast, Christine Coulon, Virginie Kouyoumdjian, Irène Buvat, Claire Leroy, Nicolas Tournier (2017 Sep 26)

Imaging the neuroimmune response to alcohol exposure in adolescent baboons: a TSPO PET study using F-DPA-714.

Addiction biology : 1000-1009 : DOI : 10.1111/adb.12548 En savoir plus

The effects of acute alcohol exposure to the central nervous system are hypothesized to involve the innate immune system. The neuroimmune response to an initial and acute alcohol exposure was investigated using translocator protein 18 kDa (TSPO) PET imaging, a non-invasive marker of glial activation, in adolescent baboons. Three different alcohol-naive adolescent baboons (3-4 years old, 9 to 14 kg) underwent F-DPA-714 PET experiments before, during and 7-12 months after this initial alcohol exposure (0.7-1.0 g/l). The brain distribution of F-DPA-714 (V ; in ml/cm ) was estimated in several brain regions using the Logan plot analysis and the metabolite-corrected arterial input function. Compared with alcohol-naive animals (V  = 3.7 ± 0.7 ml/cm ), the regional V s of F-DPA-714 were significantly increased during alcohol exposure (V  = 7.2 ± 0.4 ml/cm ; p < 0.001). Regional V s estimated several months after alcohol exposure (V  = 5.7 ± 1.4 ml/cm ) were lower (p < 0.001) than those measured during alcohol exposure, but remained significantly higher (p < 0.001) than in alcohol-naive animals. The acute and long-term effects of ethanol exposure were observed globally across all brain regions. Acute alcohol exposure increased the binding of F-DPA-714 to the brain in a non-human primate model of alcohol exposure that reflects the ‘binge drinking’ situation in adolescent individuals. The effect persisted for several months, suggesting a ‘priming’ of glial cell function after initial alcohol exposure.

Antoine Schernberg, Sylvain Reuze, Fanny Orlhac, Irène Buvat, Laurent Dercle, Roger Sun, Elaine Limkin, Alexandre Escande, Christine Haie-Meder, Eric Deutsch, Cyrus Chargari, Charlotte Robert (2017 Sep 17)

A score combining baseline neutrophilia and primary tumor SUV measured from FDG PET is associated with outcome in locally advanced cervical cancer.

European journal of nuclear medicine and molecular imaging : 187-195 : DOI : 10.1007/s00259-017-3824-z En savoir plus

We investigated whether a score combining baseline neutrophilia and a PET biomarker could predict outcome in patients with locally advanced cervical cancer (LACC).