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Localization of temporal epilepsy foci by subtraction ictal perfusion single photon emission computed tomography is enhanced when using 3D-OSEM iterative reconstruction

2009; Lippincott Williams & Wilkins; Volume: 30; Issue: 11 Linguagem: Inglês

10.1097/mnm.0b013e32832ebb09

1473-5628

Sinan Ben Mahmoud, Louis Maillard, Sylvain Poussier, Laurent Koessler, Mohamed Safa El Khawaja, Marie-Hélène Laurens, Hervé Vespignani, Gilles Karcher, Pierre-Yves Marie,

Epilepsy research and treatment

Subtraction ictal single photon emission computed tomography (SPECT) images, provided by filtered back-projection (FBP), may exhibit a confusing high level of noise. This study was aimed at assessing an optimized three-dimensional ordered subset expectation maximization (3D-OSEM) iterative reconstruction in this setting.On phantom images, parameters of 3D-OSEM reconstruction were selected as those providing the higher signal/noise ratio but a high enough spatial resolution, equivalent to that of conventional FBP reconstruction (full width at half-maximum = 11 mm). Thereafter, subtraction ictal ethylene cysteine dimer-SPECT coregistered to MRI and reconstructed with either FBP or 3D-OSEM were compared in 21 patients with well-characterized temporal epilepsy foci (subsequent successful surgical treatment).On subtraction images, the use of the selected 3D-OSEM reconstruction (five iterations, 16 subsets and a 9 mm Gauss filter) instead of FBP was associated with: (i) marked reductions in background activity (0.05 ± 0.09 vs. 0.25 ± 0.18 cps, P < 0.001) and in the size of temporal foci (10 ± 7 vs. 14 ± 11 cm, P = 0.01) and (ii) a trend toward higher accuracy in identifying the involved temporal lobes (86 vs. 76%).Localization of temporal epilepsy foci by subtraction ictal SPECT is likely to be enhanced by using 3D-OSEM rather than FBP reconstruction because of marked reductions in background activity and in the size of detected foci.