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Background: The purpose of this study was to evaluate the image quality in cardiac 18 F-FDG PET using the time of flight (TOF) and/or point spread function (PSF) modeling in the iterative reconstruction (IR)., Methods: Three scanners and an anthropomorphic cardiac phantom with an insert simulating a transmural defect (TD) were used. Two sets of scans (with/without TD) were acquired, and four reconstruction schemes were considered: (1) IR; (2) IR + PSF, (3) IR + TOF, and (4) IR + TOF + PSF. LV wall thickness (FWHM), contrast between LV wall and inner chamber (C IC ), and TD contrast in LV wall (C TD ) were evaluated., Results: Tests of the reconstruction protocols showed a decrease in FWHM from IR (13 mm) to IR + PSF (11 mm); an increase in the C IC from IR (65%) to IR + PSF (71%) and from IR + TOF (72%) to IR + TOF + PSF (77%); and an increase in the C TD from IR + PSF (72%) to IR + TOF (75%) and to IR + TOF + PSF (77%). Tests of the scanner/software combinations showed a decrease in FWHM from Gemini_TF (13 mm) to Biograph_mCT (12 mm) and to Discovery_690 (11 mm); an increase in the C IC from Gemini_TF (65%) to Biograph_mCT (73%) and to Discovery_690 (75%); and an increase in the C TD from Gemini_TF/Biograph_mCT (72%) to Discovery_690 (77%)., Conclusion: The introduction of TOF and PSF increases image quality in cardiac 18 F-FDG PET. The scanner/software combinations exhibit different performances, which should be taken into consideration when making cross comparisons.

Myotonia congenita is an autosomal dominantly or recessively inherited muscle disorder causing impaired muscle relaxation and variable degrees of permanent muscle weakness, abnormal currents linked to the chloride channel gene (CLCN1) encoding the chloride channel on skeletal muscle membrane. We describe 12 novel mutations: c.1606G>C (p.Val536Leu), c.2533G>A (p.Gly845Ser), c.2434C>T (p.Gln812X), c.1499T>G (p.E500X), c.1012C>T (p.Arg338X), c.2403+1G>A, c.2840T>A (p.Val947Glu), c.1598C>T (p.Thr533Ile), c.1110delC, c.590T>A (p.Ile197Arg), c.2276insA Fs800X, c.490T>C (p.Trp164Arg) in 22 unrelated Italian patients. To further understand the functional outcome of selected missense mutations (p.Trp164Arg, p.Ile197Arg and p.Gly845Ser, and the previously reported p.Gly190Ser) we characterized the biophysical properties of mutant ion channels in tsA cell model. In the physiological range of muscle membrane potential, all the tested mutations, except p.Gly845Ser, reduced the open probability, increased the fast and slow components of deactivation and affected pore properties. This suggests a decrease in macroscopic chloride currents impairing membrane potential repolarization and causing hyperexcitability in muscle membranes. Detailed clinical features are given of the 8 patients characterized by cell electrophysiology. These data expand the spectrum of CLCN1 mutations and may contribute to genotype-phenotype correlations. Furthermore, we provide insights into the fine protein structure of ClC-1 and its physiological role in the maintenance of membrane resting potential., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Characterisation of the physical performance of the new integrated PET/CT system Discovery ST (GE Medical Systems) has been performed following the NEMA NU 2-1994 (N-94) and the NEMA NU 2-2001 (N-01) standards in both 2D and 3D acquisition configuration. The Discovery ST combines a four or eight multi-slice helical CT scanner with a PET tomograph which consists of 10,080 BGO crystals arranged in 24 rings. The crystal dimensions are 6.3 x 6.3 x 30 mm(3) and they are organised in blocks of 6 x 6 crystals, coupled to a single photomultiplier tube with four anodes. The 24 rings of the PET system allow 47 images to be obtained, spaced by 3.27 mm, and covering an axial field of view of 157 mm. The low- and high-energy thresholds are set to 375 and 650 keV, respectively. The coincidence time window is set to 11.7 ns. Using the NEMA N-94 standard, the main results were: (1) the average (radial and tangential) transverse spatial resolution (FWHM) at 1, 10 and 20 cm off axis was 6.28 mm, 7.09 mm and 7.45 mm in 2D, and 6.68 mm, 7.72 mm and 8.13 mm in 3D; (2) the sensitivity for true events was 8,567 cps/kBq/cc in 2D and 36,649 cps/kBq/cc in 3D; (3) the scatter fraction was 15% in 2D and 30% in 3D; (4) the peak true events rate, the true events rate at 50% of the system dead-time and the true events rate when equal to the random events rate were 750 kcps at 189.81 kBq/cc, 744 kcps at 186.48 kBq/cc and 686 kcps at 150.59 kBq/cc, respectively, in 2D, and 922 kcps at 44.03 kBq/cc, 834 kcps at 53.28 kBq/cc and 921 kcps at 44.03 kBq/cc in 3D; (5) the noise equivalent count (NEC) peak rate was 270 kcps at 34.38 kBq/cc in 3D, with random coincidences estimated by delayed events. Using the NEMA N-01 standards the main results were: (1) the average transverse and axial spatial resolution (FWHM) at 1 cm and 10 cm off axis was 6.28 (4.56) mm and 6.88 (6.11) mm in 2D, and 6.29 (5.68) mm and 6.82 (6.05) mm in 3D; (2) the average sensitivity for the two radial positions (r=0 cm and r=10 cm) was 1.93 cps/kBq in 2D and 9.12 cps/kBq in 3D; (3) the scatter fraction was 19% in 2D and 45% in 3D; (4) the NEC peak rate was 54 kcps at 46.99 kBq/cc in 2D and 45.5 kcps at 10.84 kBq/cc in 3D, when random coincidences were estimated by using k=2 in the NEC formula, while the NEC peak rate was 81 kcps at 64.43 kBq/cc and 66 kcps at 14.86 kBq/cc in 2D and 3D, respectively, when random coincidences were estimated by using k=1 in the NEC formula. The new integrated PET-CT system Discovery ST has good overall performances in both 2D and 3D, with in particular a high sensitivity and a very good 3D NEC response.