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BACKGROUND AND PURPOSE: Cognitively stimulating life experiences and activities are deemed to moderate the clinical impact of brain damage progressively building a neural and cognitive reserve (CR). CR has been studied extensively in various neurodegenerative disorders, but not in corticobasal degeneration (CBD). METHODS: Using Statistical Parametric Mapping 8, years of education, as a determinant of CR, was correlated with tracer uptake on positron emission tomography with 18 F-fluorodeoxyglucose, as a marker of neurodegeneration, in 35 patients with various phenotypes of CBD, including a cognitive-motor composite score or symptoms duration as covariates for controlling disease stage. RESULTS: A cluster of relative hypometabolism was found associated with higher education in the left inferior regions of pre- and post-rolandic gyri and insula, which represent typical loci of neurodegeneration in CBD regardless of clinical presentation. CONCLUSIONS: The present findings extend to CBD the evidence gathered in other neurodegenerative disorders that a higher CR has a protective effect against the clinical manifestations of brain degeneration.
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Enfermedades de los Ganglios Basales/diagnóstico por imagen , Reserva Cognitiva/fisiología , Degeneración Nerviosa/diagnóstico por imagen , Anciano , Anciano de 80 o más Años , Enfermedades de los Ganglios Basales/psicología , Femenino , Fluorodesoxiglucosa F18 , Humanos , Masculino , Degeneración Nerviosa/psicología , Tomografía de Emisión de Positrones/métodosRESUMEN
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Humanos , Femenino , Persona de Mediana Edad , Sarcoidosis/complicaciones , Sarcoidosis , Fluorodesoxiglucosa F18/análisis , Tomografía de Emisión de Positrones/métodos , Biopsia con Aguja Fina , Enfermedades del Sistema Nervioso/complicaciones , Enfermedades del Sistema Nervioso , Neoplasias de la Médula Espinal/complicaciones , Neoplasias de la Médula EspinalRESUMEN
OBJECTIVE: The aim of this work was to assess robustness and reliability of an adaptive thresholding algorithm for the biological target volume estimation incorporating reconstruction parameters. METHOD: In a multicenter study, a phantom with spheres of different diameters (6.5-57.4 mm) was filled with (18)F-FDG at different target-to-background ratios (TBR: 2.5-70) and scanned for different acquisition periods (2-5 min). Image reconstruction algorithms were used varying number of iterations and postreconstruction transaxial smoothing. Optimal thresholds (TS) for volume estimation were determined as percentage of the maximum intensity in the cross section area of the spheres. Multiple regression techniques were used to identify relevant predictors of TS. RESULTS: The goodness of the model fit was high (R(2): 0.74-0.92). TBR was the most significant predictor of TS. For all scanners, except the Gemini scanners, FWHM was an independent predictor of TS. Significant differences were observed between scanners of different models, but not between different scanners of the same model. The shrinkage on cross validation was small and indicative of excellent reliability of model estimation. CONCLUSIONS: Incorporation of postreconstruction filtering FWHM in an adaptive thresholding algorithm for the BTV estimation allows obtaining a robust and reliable method to be applied to a variety of different scanners, without scanner-specific individual calibration.
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Tomografía de Emisión de Positrones/estadística & datos numéricos , Algoritmos , Biología Computacional , Fluorodesoxiglucosa F18 , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Modelos Lineales , Modelos Estadísticos , Fantasmas de Imagen , Radiofármacos , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos XRESUMEN
PURPOSE: The aim of this study was to assess the performance measurements of the new PET/CT system Discovery-600 (D-600, GEMS, Milwaukee, WI). METHODS: Performance measures were obtained with the National Electrical Manufacturers Association (NEMA) NU 2-2007 procedures. RESULTS: The transverse (axial) spatial resolution FWHMs were 4.9 (5.6) mm and 5.6 (6.4) mm at 1 and 10 cm off axis, respectively. The sensitivity (average at 0 and 10 cm) was 9.6 cps/kBq. The scatter fraction was 36.6% (low energy threshold: 425 keV). The NEC peak rate (k=1) was 75.2 kcps at 12.9 kBq/cc. The hot contrasts for 10, 13, 17, and 22 mm spheres were 41%, 51%, 62%, and 73% and the cold contrasts for 28 and 37 mm spheres were 68% and 72%. CONCLUSIONS: The Discovery-600 has good performance for the NEMA NU 2-2007 parameters, particularly in improved sensitivity compared to the scanners of the same Discovery family, D-ST and D-STE.
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Electricidad , Tomografía de Emisión de Positrones/normas , Tomografía Computarizada por Rayos X/normas , Estándares de Referencia , Estados UnidosRESUMEN
AIM: To evaluate evolution for bone (EfB), one of the recent corrective collimator detector response (CDR) image reconstruction packages, resolution recovery and iterative reconstruction protocols were compared to the standard Filtered Back Projection (FBP) protocol and the possibility of time reduced acquisition (15 instead of 30 seconds/projection) was evaluated. METHODS: Tomographic spatial resolution, contrast, noise and signal-to-noise ratio (SNR) were analyzed in phantom studies. Patient studies were conducted on sixteen [99mTc]HMPAO labeled leukocyte patients with suspected local inflammation, submitted to SPECT/CT and conventional leukocyte scintigraphy. Target background ratio (TBR) and boundary of each lesion were calculated. Images were also analyzed by visual inspection by two blinded expert physicians. RESULTS: a) Phantom: resolution in phantom improves with the use of EfB mainly due to iterative reconstruction methods vs FBP. EfB shows a reduction in noise. No differences were found in contrast data, while SNR changes were mainly due to changes in noise. Time reduction, while increasing image noise, does not modify resolution; nevertheless, half-time EfB noise is the same as full-time FBP noise. b) PATIENTS: lesion boundary is better defined in patient studies using iterative reconstruction vs FBP; no changes were observed for CDR vs iterative OSEM, or for full-time vs half-time acquisition. TBR is comparable in iterative and FBP protocols, while it is improved by EfB. At visual inspection, a higher score is always associated with EfB. CONCLUSION: Resolution, noise, SNR and TBR improve when applying the resolution recovery. EfB permits reduction of acquisition time without compromising image quality.
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Algoritmos , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Leucocitos/diagnóstico por imagen , Osteomielitis/diagnóstico , Tomografía Computarizada de Emisión de Fotón Único/métodos , Adulto , Anciano , Células Cultivadas , Femenino , Humanos , Marcaje Isotópico , Masculino , Persona de Mediana Edad , Fantasmas de Imagen , Radiofármacos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Relación Señal-Ruido , Técnica de Sustracción , Tomografía Computarizada de Emisión de Fotón Único/instrumentación , Tomografía Computarizada por Rayos X/métodos , Adulto JovenRESUMEN
The production of no-carrier-added (NCA) alpha-emitter (211)At/(211g)Po radionuclides for high-LET targeted radiotherapy and immunoradiotherapy, through the (209)Bi(alpha,2n) reaction, together with the required wet radiochemistry and radioanalytical quality controls carried out at LASA is described, through dedicated irradiation experiments at the MC-40 cyclotron of JRC-Ispra. The amount of both the gamma-emitter (210)At and its long half-lived alpha-emitting daughter (210)Po is optimised and minimised by appropriate choice of energy and energy loss of alpha particle beam. The measured excitation functions for production of the main radioisotopic impurity (210)At-->(210)Po are compared with theoretical predictions from model calculations performed at ENEA.