Graph-based multimodal multi-lesion DLBCL treatment response prediction from PET images

Diffuse Large B-cell Lymphoma (DLBCL) is a lymphatic cancer involving one or more lymph nodes and extranodal sites. Its diagnostic and follow-up rely on Positron Emission Tomography (PET) and Computed Tomography (CT). After diagnosis, the number of nonresponding patients to standard front-line therapy remains significant (30-40%). This work aims to develop a computer-aided approach to identify high-risk patients requiring adapted treatment by efficiently exploiting all the information available for each patient, including both clinical and image data. We propose a method based on recent graph neural networks that combine imaging information from multiple lesions, and a cross-attention module to integrate different data modalities efficiently. The model is trained and evaluated on a private prospective multicentric dataset of 583 patients. Experimental results show that our proposed method outperforms classical supervised methods based on either clinical, imaging or both clinical and imaging data for the 2-year progression-free survival (PFS) classification accuracy

Where Do Neurologists Look When Viewing Brain CT Images? An Eye-Tracking Study Involving Stroke Cases

The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the “bottom-up salience” form of visual attention, although the neurologists more effectively used the “top-down instruction” form

Apport de la normalisation spatiale des tomoscintigraphies à un modèle de référence pour la mesure quantitative de la contraction et de la perfusion myocardiques

La possibilité de mesurer simultanément la contraction et la perfusion myocardiques en tomoscintigraphie synchronisée constitue une avancée majeure pour la prise en charge de l'insuffisance coronaire, tant diagnostique que pronostique. De nombreuses approches en traitement d'image ont été proposées depuis les années 1990 pour quantifier au mieux ces variables. Dans ce travail, nous avons d'abord analysé les performances et les limites des principales approches publiées dans la littérature. Nous avons ensuite proposé une approche alternative, reposant sur une normalisation spatiale des images à un modèle cardiaque de référence, développée au cours d'une collaboration de notre institution avec la société Quantificare. L'intérêt de la normalisation spatiale est double : 1) améliorer la segmentation du myocarde grâce à une référence anatomique a priori fournie par une population normale moyennée (pour l'analyse de la fraction d'éjection du ventricule gauche), et 2) mieux caractériser la distribution de la perfusion en effectuant une comparaison voxel-par-voxel avec la population normale moyennée (pour l'analyse de la taille et de la sévérité des hypoperfusions). Nous avons enfin validé cette approche sur des populations de patients adaptées, en termes de précision, exactitude et pertinence clinique. Nous présentons le texte original de quatre articles publiés dans des revues internationales dans le cadre de ce travail. Nous concluons que la normalisation spatiale permet non seulement d'obtenir des mesures reproductibles et exactes de la fraction d'éjection du ventricule gauche mais se prête par ailleurs à une analyse de l'évolution temporelle des pathologies ischémiques.The ability for gated SPECT to measure simultaneously myocardial contraction and perfusion constitutes a major step forward in the management of coronary artery disease, such diagnostically than prognostically. Numerous image processing approaches have been proposed since the 1990's to quantify as best as possible these variables. In the present work, we first have analyzed the performances and limitations of the main approaches proposed in the literature. Then, we have proposed an alternative approach, based on the spatial normalization of images to a reference heart template, which has been developed during a collaboration between our institution and the Quantificare company. The interest of spatial normalization is twofold : 1) to improve myocardial segmentation with help of an a priori anatomical reference provided by an averaged normal population (for the assessment of left ventricular ejection fraction), and 2) to better characterize perfusion distribution by performing a voxel-by-voxel comparison with the averaged normal population (for the assessment of extent and severity of hypoperfusions). Finally, we have validated this approach on appropriate patient populations, in terms of precision, accuracy and clinical pertinence. We provide the text of four original articles published in international journals in the scope of the present work. We conclude that spatial normalization not only allows to obtain reproducible and accurate measurements of left ventricular ejection fraction but also is adapted to monitor serial changes of ischemic pathologies.PARIS12-CRETEIL BU Multidisc. (940282102) / SudocSudocFranceF

Valeur pronostique du TEP / TDM au 18F-FDG dans la détection de la transformation sarcomateuse chez des patients atteints de Neurofibrose de type 1

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocSudocFranceF

MRI and PET in monitoring response in lymphoma: Wednesday 5 October 2005, 08:30–10:00

The potential of FDG-PET and MRI in monitoring response to treatment in lymphoma is reviewed. Both FDG-PET and MRI can provide whole body imaging. Both also share the advantage of combining functional and anatomical information. At present, hybrid FDG-PET and MDCT is the best technique for monitoring response to treatment, especially early response to treatment. Early assessment of response to treatment has the potential to tailor therapy. MR imaging is useful especially in assessing bone marrow and central nervous system involvement

Whole body MRI and PET/CT in haematological malignancies

The usefulness of whole body magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT) in haematological malignancies is reviewed. PET/CT combining functional and anatomical information is currently a valuable tool in the management of patients with lymphoma, especially in the assessment of early treatment response. MRI is advantageous in evaluating bone marrow involvement and therefore plays an important role in clinical decision making for patients with myeloma. The development of whole body functional MR studies is underway and can potentially complement the PET/CT for better patient care

Myocardial Tracking, A New Method to Calculate Ejection Fraction with Gated SPECT: Validation with 201 Tl Versus Planar Angiography

Left ventricular ejection fraction (LVEF) and viability are essential variables for the prognosis of myocardial infarction and can be measured simultaneously by 201Tl gated SPECT; however, most algorithms tend to underestimate LVEF. This study aimed to evaluate a new myocardial tracking algorithm, MyoTrack (MTK), for automatic LVEF calculation. Methods: A rest/redistribution (20 min/4 h) 201Tl gated SPECT protocol followed immediately by a 99mTc equilibrium radionuclide angiography (ERNA) was performed in 75 patients with history of myocardial infarction. Quality of myocardial uptake was evaluated from count statistics and automatic quantification of defect sizes and severities (CardioMatch). LVEFs were calculated both with Germano’s quantitative gated SPECT (QGS) algorithm and with MTK. Briefly, the originality of this algorithm resides in the unique end-diastole segmentation, matching to a template and motion field tracking throughout the cardiac cycle. Results: ERNA LVEF averaged 33 % � 14%. QGS significantly underestimated this value at 20 min (30 % � 13%, P � 0.001) and at 4 h (30 % � 13%, P � 0.0001). By contrast, MTK did not miscalculate LVEF at 20 min (34 % � 14%, probability value was not significant) though a similar underestimation occurred at 4 h (31 % � 13%, P � 0.02). Individual differences between early and late gated SPECT values and differences between gated SPECT and ERNA values did not correlate with the extension of perfusion defects, count statistics, or heart rate. Conclusion: The MTK algorithm calculates LVEF on early/high-count images more accurately than ERNA, even in patients with severe perfusion defects, but tends to underestimate LVEF on delayed/low-contrast images, as other algorithms do. Key Words: 201Tl; gated SPECT; ejection fraction; accuracy; precisio