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EEG feedback methods, which link the occurrence of alpha to the presentation of repeated visual stimuli, reduce the relative variability of subsequent, alpha-blocking event durations. The temporal association between electro-cortical field activation and regional cerebral blood flow (rCBF) led us to investigate whether the reduced variability of alpha-blocking durations with feedback is associated with a reduction in rCBF variability. Reduced variability in the rCBF response domain under EEG feedback control might have methodological implications for future brain-imaging studies. Visual stimuli were randomly presented to seven subjects, contingent upon the occurrence of alpha (alpha-contingent stimulation (ACS)) or alpha-blocking (not-alpha-blocking-contingent stimulation (NACS)) events. We employed a within-subjects design. rCBF was measured from multiple, cortical and sub-cortical regions. The primary dependent variables were the Mean, Standard Deviation and the ratio of Mean/Standard Deviation of: 1) the alpha-blocking response durations and 2) the temporally summated rCBF responses within the Visual Associative regions of interest (ROIs). Additional within-subjects rCBF measures were derived to quantify the variance-reducing effects of ACS across multiple, distributed areas of the brain. Both EEG and rCBF measures demonstrated decreased variability under ACS. This improved control was seen for localized as well as anatomically distributed rCBF measures.

Background: Dopamine transporter (DAT) imaging of striatum is clinically used in Parkinson's disease (PD) and neurodegenerative parkinsonian syndromes (PS) especially in the early disease stages. The aim of the present study was to evaluate the diagnostic performance of the recently developed tracer for DAT imaging [18F]FE-PE2I PET/CT to the reference standard [123I]FP-CIT SPECT. Methods: Ninety-eight unselected patients referred for DAT imaging were included prospectively and consecutively and evaluated with [18F]FE-PE2I PET/CT and [123I]FP-CIT SPECT on two separate days. PET and SPECT scans were categorized independently by two blinded expert readers as either normal, vascular changes, or mixed. Semiquantitative values were obtained for each modality and compared regarding effect size using Glass' delta. Results: Fifty-six of the [123I]FP-CIT SPECT scans were considered abnormal (52 caused by PS, 4 by infarctions). Using [18F]FE-PE2I PET/CT, 95 of the 98 patients were categorized identically to SPECT as PS or non-PS with a sensitivity of 0.94 [0.84–0.99] and a specificity of 1.00 [0.92–1.00]. Inter-reader agreement for [18F]FE-PE2I PET with a kappa of 0.97 [0.89–1.00] was comparable to the agreement for [123I]FP-CIT SPECT of 0.96 [0.76–1.00]. Semiquantitative values for short 10-min reconstructions of [18F]FE-PE2I PET/CT were comparable to longer reconstructions. The effect size for putamen/caudate nucleus ratio was significantly increased using PET compared to SPECT. Conclusions: The high correspondence of [18F]FE-PE2I PET compared to reference standard [123I]FP-CIT SPECT establishes [18F]FE-PE2I PET as a feasible PET tracer for clinical use with favourable scan logistics. [ABSTRACT FROM AUTHOR]

Rett syndrome, which has a prevalence of 1 in 10,000 girls, was first recognized as a distinct clinical entity in 1966. The etiology of this syndrome is unknown, and researchers have not identified a specific marker for the disease. The diagnosis must be made solely upon clinical characteristics. Curiously, the disorder occurs only in females. A child with Rett syndrome develops apparently normally during the first 6 to 18 months of life. After that, the growth of the head decelerates and the child experiences a loss of motor skills. She becomes withdrawn, severely mentally retarded, and might be mistaken for autistic. Despite the striking symptoms, upon examination, the brain shows only mild diffuse atrophy and small size, which is in keeping with the duration of the developmental defect. Now, however, researchers have used single photon emission tomography (SPECT) to demonstrate a defect in the blood flow in the brains of girls with Rett syndrome. This defect may provide insight into the etiology of the disorder. After inhalation of xenon 133, a radioactive isotope of the inert gas, the emission of gamma rays by the xenon 133 in the blood was used by the SPECT instrument to construct quantitative pictures of blood flow in various brain regions. The results showed that the overall blood flow through the brains of the Rett syndrome patients was 22 percent less than that of control subjects. More interesting, however, is the fact that some brain regions, such as the primary sensory and motor regions by the central sulcus, were essentially normal while the frontal regions were abnormally low. This pattern is also observed in healthy infants within the first six months of birth. As a child develops normally, the inactivity of the frontal and temporoparietal lobes disappears and an adult pattern of brain circulation is seen by about one year of age. The observed abnormalities of the Rett syndrome patients may represent an arrest of metabolic or circulatory development at an infantile stage. (Consumer Summary produced by Reliance Medical Information, Inc.)