Imagerie cardiaque multimodalités 2D et 3D (application à la coronarographie/tomoscintigraphie/TEP-CT)

La coronarographie et la tomoscintigraphie (SPECT, de l'anglais "Single Photon Emission Computed Tomography") sont deux techniques d'imagerie utilisées couramment pour diagnostiquer les maladies cardiovasculaires. La première modalité est constituée de séquences d'images à rayon X visualisant chacune, dans un même plan, les artères coronaires situées sur la face avant et la face arrière du cœur. Les images à rayons X fournissent des informations anatomiques liées à l'arbre artériel et mettent en évidence d'éventuels rétrécissements des artères (sténoses). La modalité SPECT (imagerie nucléaire) fournit une représentation 3D de la perfusion du volume myocardique. Cette information fonctionnelle permet la visualisation de régions myocardiques souffrant de défauts d'irrigations. Le but du travail présenté est de superposer, en 3D, les informations fonctionnelles et anatomiques pour établir un lien visuel entre des lésions artérielles et leurs conséquences en termes de défauts d'irrigation. Dans la représentation 3D choisie pour faciliter le diagnostic, la structure d'un arbre artériel schématique, comprenant les sténoses, est placée sur le volume de perfusion. Les données initiales sont constituées d'une liste de points représentatifs de l'arbre artériel (points d'arrivée et de départs de segments d'artères, bifurcations, sténoses, etc.) marqués par le coronarographiste dans les images à rayons X des différentes incidences. Le volume de perfusion est ensuite projeté sous les incidences des images de coronarographie. Un algorithme de recalage superposant les images à rayons X et les projections SPECT correspondantes fournit les paramètres des transformations géométriques ramenant les points marqués dans les images à rayons X dans une position équivalente dans les images SPECT. Un algorithme de reconstruction 3D permet ensuite de placer les points artériels et les sténoses sur le volume de perfusion et de former un arbre schématique servant de repère au clinicien. Une base de données formée de 28 patients a été utilisée pour effectuer 40 superpositions 3D de données anatomo-fonctionnelles. Ces reconstructions ont montré que la représentation 3D est suffisamment précise pour permettre d'établir visuellement un lien entre sténoses et défauts de perfusions. Nos algorithmes de superpositions 3D ont ensuite été complétés pour remplacer la modalité SPECT par les données de l'examen bimodal TEP/CT (Tomographie par Emission de Positons/Tomodensitométrie). Les données d'un cas clinique trimodal TEP/CT/coronarographie ont été utilisées pour vérifier l'adéquation de nos algorithmes à la nouvelle modalité d'imagerieCoronarography and tomoscintigraphy (SPECT, Single Photon Emission Tomography) are two imaging techniques used standardly for the diagnosis of cardiovascular diseases. The first modality consists of X-ray image sequences visualizing each, in a same plane, the coronary arteries located on the front and the back side of the heart. The X-ray images give anatomical information relating to the arterial tree and highlight eventual artery narrowings (stenoses). The SPECT modality (nuclear imaging) provide a 3D representation of the myocardial volume perfusion. This functional information authorizes the visualization of myocardial regions suffering from irrigation defaults. The aim of the presented work is to superimpose (in the 3D space) the functional and anatomical information in order to establish the visual link between arterial lesions and their consequence in terms of irrigation defaults. In the 3D representation chosen to facilitate the diagnosis, the structure of a schematic arterial tree and the stenoses are placed onto the perfusion volume. The initial data consist of a list of points representative for the arterial tree (start and end points of arterial segments, bifurcations, stenoses, etc) and marked by coronarographists on the X-ray images of the different incidences. The perfusion volume is then projected under the incidences of the coronarographic images. A registration algorithm superimposing the X-ray images and the corresponding SPECT projections provides the parameters of the geometrical transformations bringing the points marked in the X rays images in equivalent positions in the 2D SPECT images. A 3D reconstruction algorithm is then used to place the arterial points and the stenoses on the perfusion volume and build a schematic tree acting as landmark for the clinician. A 28 patient database was used to realize 40 3D superimposition of anatomo-functional data. These reconstructions have shown that the 3D representation is precise enough for the establishment of the visual relationship between stenoses and perfusion defaults. Our 3D superimposition algorithms were then be completed in order to replace the SPECT modality by data of the PET/CT (Positron Emission Tomography/Computed Tomography) bimodal examination. The data of a clinical trimodal PET/CT/coronarography case have been used to evaluate the adequacy of our algorithms to novel imaging modalitiesNANCY/VANDOEUVRE-INPL (545472102) / SudocSudocFranceF

Fully digital PET is unaffected by any deterioration in TOF resolution and TOF image quality in the wide range of routine PET count rates

International audienceAbstract Purpose Digital PET involving silicon photomultipliers (SiPM) provides an enhanced time-of-flight (TOF) resolution as compared with photomultiplier (PMT)-based PET, but also a better prevention of the count-related rises in dead time and pile-up effects mainly due to smaller trigger domains (i.e., the detection surfaces associated with each trigger circuit). This study aimed to determine whether this latter property could help prevent against deteriorations in TOF resolution and TOF image quality in the wide range of PET count rates documented in clinical routine. Methods Variations, according to count rates, in timing resolution and in TOF-related enhancement of the quality of phantom images were compared between the first fully digital PET (Vereos) and a PMT-based PET (Ingenuity). Single-count rate values were additionally extracted from the list-mode data of routine analog- and digital-PET exams at each 500-ms interval, in order to determine the ranges of routine PET count rates. Results Routine PET count rates were lower for the Vereos than for the Ingenuity. For Ingenuity, the upper limits were estimated at approximately 21.7 and 33.2 Mcps after injection of respectively 3 and 5 MBq.kg -1 of current 18 F-labeled tracers. At 5.8 Mcps, corresponding to the lower limit of the routine count rates documented with the Ingenuity, timing resolutions provided by the scatter phantom were 326 and 621 ps for Vereos and Ingenuity, respectively. At higher count rates, timing resolution was remarkably stable for Vereos but exhibited a progressive deterioration for Ingenuity, respectively reaching 732 and 847 ps at the upper limits of 21.7 and 33.2 Mcps. The averaged TOF-related gain in signal/noise ratio was stable at approximately 2 for Vereos but decreased from 1.36 at 5.8 Mcps to 1.14 and 1.00 at respectively 21.7 and 33.2 Mcps for Ingenuity. Conclusion Contrary to the Ingenuity PMT-based PET, the Vereos fully digital PET is unaffected by any deterioration in TOF resolution and consequently, in the quality of TOF images, in the wide range of routine PET count rates. This advantage is even more striking with higher count-rates for which the preferential use of digital PET should be further recommended (i.e., dynamic PET recording, higher injected activities)

Combination of Single-Photon Emission and X-Ray Computed Tomography to visualize aerosol deposition in pleated filter

International audienc

Tracheobronchitis signs observed on ventilation lung scintigraphy during the course of COVID-19 infection

International audienc

Fully automated radiosynthesis of [ 18 F]fluoro- C -glyco-c(RGDfC): exploiting all the abilities of the AllInOne synthesizer

International audienc

Head-to-head comparison of image quality between brain 18F-FDG images recorded with a fully digital versus a last-generation analog PET camera

International audienceBackground: The quality of phantom images was previously shown to be higher on digital (Vereos Philips®) compared to analog PET (Ingenuity Philips®) cameras. This study aimed to determine the extent to which this difference still remains significant on normal brain 18 F-FDG PET images. Methods: Relative noise and contrast as well as border sharpness (a spatial resolution index) of central (striata) and peripheral (occiput) gray-matter structures were compared between 10 sets of normal brain 18 F-FDG PET images recorded and reconstructed on digital and analog last-generation PET cameras, together with a subjective visual analysis of image quality provided by experienced physicians. Results: Compared with analog PET, digital PET provided marked improvements in image quality parameters. The median relative noise was decreased (− 22%), while gray/white-matter contrast was increased (+ 27%/+ 41% for central/peripheral gray-matter structures), with these results being consistent with visual analysis. In addition, a clear enhancement in image sharpness was further documented for digital PET owing to the possible use of a 1-mm 3 voxel size (+ 24%/+ 21%). Conclusions: On normal brain 18 F-FDG images and compared with a last-generation analog PET, the fully digital PET camera offers marked improvements in image noise and contrast, as well as significant potential for further enhancing spatial resolution