Alain Seret

NEMA NU4-2008 Image Quality Performance Report for the microPET Focus 120 and for Various Transmission and Reconstruction Methods

This work aimed to evaluate the image quality and accuracy of attenuation and scatter corrections provided with the microPET Focus 120 scanner using the National Electrical Manufacturers Association NU4-2008 image quality phantom. Methods: Attenuation correction was obtained from transmission measurements using either a 68Ge or a 57Co point source. Fully corrected emission images were reconstructed using Fourier rebinning (FORE) and filtered backprojection (FBP). For attenuation data obtained with the 57Co source, fully corrected emission images were also reconstructed using FORE and 2-dimensional (2D) ordered-subset expectation maximization (OSEM), 3-dimensional (3D) filtered backprojection (3DRP), 3D OSEM, and 3D maximum a posteriori methods. The mean activity, the coefficients of variation (COVs) of the uniform slices, the recovery coefficients (RCs) for hot rods, and the spillover ratio (SOR) for nonemitting water and air compartments were measured. Results: For 57Co-based attenuation correction, the mean activity value differed by less than 3% from the true activity. Measuring the attenuation with 68Ge resulted in lower reconstructed activity and higher COV. On the basis of 57Co measurements, the SORs for air and water nonemitting compartments were the closest to zero for attenuation correction. The RC measured on emission images corrected for attenuation but not for scatter did not show any significant difference linked to the transmission method. However, higher RCs were noted for transmission measurement with 68Ge in coincidence with windowing when emission data were corrected for attenuation and scatter. This resulted from a lower mean value in the uniform area. 2D and 3DRP reconstruction methods showed little effect on the mean activity value, whereas iterative 3D methods gave 7% higher values. Higher RCs were found with iterative reconstruction than with FBP and 3DRP. However, the SOR seemed to be optimal with FBP. SORs were higher with iterative methods and decreased with the number of iterations. Conclusion: For studies of small rodents with the Focus 120, 57Co transmission seems to be the most suitable method for attenuation correction. FORE and 2D reconstruction methods appear to be a good compromise between overall image quality and reconstruction time: OSEM provides the largest contrasts, but FBP provides superior attenuation and scatter correction.

99mTc-MIBI pinhole SPECT in primary hyperparathyroidism: comparison with conventional SPECT, planar scintigraphy and ultrasonography

PurposeA pinhole collimator is routinely used to increase the resolution of scintigraphy. This prospective study was conducted to determine the interest of 99mTc-MIBI pinhole single-photon emission computed tomography (SPECT) for the preoperative localisation of parathyroid lesions in primary hyperparathyroidism.MethodsAll patients underwent a neck ultrasonography (US),

Median root prior and ordered subsets in Bayesian image reconstruction of single-photon emission tomography

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Clinical applications of pinhole single photon emission tomography

and 99mTc-MIBI planar images and two consecutive SPECT with a parallel (C-SPECT) and a pinhole collimator (P-SPECT). P-SPECT was performed with a tilted detector equipped with a pinhole collimator and reconstructed with a dedicated OSEM algorithm. A diagnostic confidence score (CS) was assigned to each procedure considering intensity and extra-thyroidal location of suspected lesions: 0u2009=u2009negative, 1u2009=u2009doubtful, 2u2009=u2009moderately positive, 3u2009=u2009positive. The results of these preoperative localisation studies were compared with surgical, pathological and 6-month biological findings.ResultsFifty-one patients cured after surgery were included. Surgery revealed 55 lesions (median weight 0.5xa0g, 11 in ectopy). Sensitivities of US, planar imaging, C-SPECT and P-SPECT were, respectively, 51, 76, 82 and 87%. Nine glands were only detected by tomography and five glands only by P-SPECT.

Spondylolyse bilatérale: intérêt de la tomoscintigraphie osseuse.

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Néoplasie mammaire plurifocale en généralisation osseuse

planar scans and P-SPECT were complementary and, when combined together, showed the highest sensitivity (93%). Compared with planar imaging and C-SPECT, P-SPECT increased CS for 42 and 53% of lesions, respectively, and contributed to markedly reduce the number of uncertain results.ConclusionsA combination of planar