Fiche publication
Date publication
mai 2008
Auteurs
Membres identifiés du Cancéropôle Est :
Pr KARCHER Gilles
Tous les auteurs :
Ben Mahmoud S, El Khawaja MS, Poussier S, Maillard L, Laurens MH, Koessler L, Naoui S, Vespignani H, Karcher G, Marie PY
Résumé
Introduction: When ictal and interictal brain SPECT are reconstructed with filtered backprojection (FBP), the noise level of subtraction images is frequently high and requires the use of thresholding methods. The aim of this study was to compare the subtraction images for cerebral SPECT reconstructed either with FBP or with a 3D iterative reconstruction method (OSEM-3D). Materials and methods: After optimisation of the reconstruction parameters on phantom, the subtraction SPECT images, which were obtained with FBP or with OSEM-3D and coregistered with MRI images, were analyzed in 15 patients with refractory temporal epilepsy. Results: On phantom and with the constrain of high enough spatial resolution (full width at half of maximum for a punctual source less or equal to 11 mm) were reached using: (i) a Butterworth filter with a cut-off frequency of 0.4 Nyquist at order 6 for FBP and (ii) iterations, 16 subsets and a 9 mm gaussian filter for OSEM-3D. On the subtraction images, which were obtained with these parameters, the temporal foci from patients were smaller with OSEM-3D than with FBP (11 +/- 6 cm(3) versus 17 +/- 10 cm(3), P = mean voxel activities were equivalent between the two methods within temporal foci (6.30 +/- 3.13 counts versus 6.34 +/- 4.93 counts) these activities were dramatically reduced by OSEM-3D within background regions (0.02 +/- 0.02 counts versus 0.19 +/- 0.12 P < 0.001). Conclusion: For the ictal-interictal subtraction SPECT images, which are obtained in patients with refractory temporal epilepsy, the use optimized OSEM-3D method leads to dramatically reduce the volume of temporal foci, as well as the background noise level, two properties are likely to facilitate the detection and localisation of epilepsy foci. (C) 2008 Elsevier Masson SAS. All rights reserved.
Référence
Med Nucl-imag Fonct Metab. 2008 May;32(5):291-9
