In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Q: Context: To examine peripheral nerve stimulation (PNS) thresholds for normal human subjects in magnetic resonance imaging (MRI) gradient coils, and determine if observed thresholds could be predicted based on gross physiologic measurements.', 'PNS thresholds for 21 healthy normal subjects were measured using a whole-body gradient coil. Subjects were exposed to a trapezoidal echo-planar imaging (EPI) gradient waveform and the total change in gradient strength (DeltaG) required to cause PNS as a function of the duration of the gradient switching time (tau) were measured. Correlation coefficients and corresponding P values were calculated for the PNS threshold measurements against simple physiologic measurements taken of the subjects, including weight, height, girth, and average body fat percentage, in order to determine if there were any easily observable dependencies.', 'No convincing correlations between threshold parameters and gross physiologic measurements were observed.\Question: Do simple anatomical measurements correlate significantly to individual peripheral nerve stimulation thresholds as measured in MRI gradient coils?

A: These results suggest it is unlikely that a simple physiologic measurement of subject anatomy can be used to guide the operation of MRI scanners in a subject-specific manner in order to increase gradient system performance while avoiding PNS.
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Q: Context: Population-based studies of associations between subclinical hypercortisolism and risk for disease states, such as type 2 diabetes mellitus, have been difficult to assess because of imprecise measures of glucocorticoid exposure. Alternative measures (salivary cortisol and adrenal gland volume) have not been systematically compared with 24-h urine free cortisol (UFC) in a healthy population.', 'Our objectives were: 1) to determine whether 24-h UFC and total daily salivary cortisol correlated with each other, adrenal gland volume, and salivary cortisol after dexamethasone suppression and 2) to evaluate the association of adrenal gland volume with salivary cortisol after dexamethasone suppression.', 'This was a cross-sectional study of 20 healthy, premenopausal African-American women aged 18-45 yr.', 'Salivary cortisol was assessed at six time points throughout the day simultaneous with 24-h UFC collection. Adrenal gland volume was measured by computed tomography scan. Dexamethasone-suppressed salivary cortisol was measured at 0800 h after administration of 0.5 mg dexamethasone at 2300 h the prior evening.', 'Dexamethasone-suppressed salivary cortisol levels correlated strongly with individual, timed salivary cortisol measurements, total daily salivary cortisol (rs=0.75; P=0.0001; n=20), and adrenal gland volume (rs=0.66; P=0.004; n=17). Total daily salivary cortisol and adrenal gland volume also correlated (rs=0.46; P=0.04; n=19). In contrast, 24-h UFC levels did not correlate with any of the other hypothalamic-pituitary-adrenal axis measures.\Question: Do adrenal gland volume and dexamethasone-suppressed cortisol correlate with total daily salivary cortisol in African-American women?

A: A dexamethasone suppression test or adrenal gland volume may be alternative measures for characterizing subtle subclinical hypercortisolism in healthy adults.
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Q: Context: Neocortical atrophy reduces PET signal intensity, potentially affecting the diagnostic efficacy of β-amyloid (Aβ) brain PET imaging. This study investigated whether partial-volume effect correction (PVEC), adjusting for this atrophy bias, improves the accuracy of (18)F-florbetaben Aβ PET.', 'We analyzed (18)F-florbetaben PET and MRI data obtained from 3 cohorts. The first was 10 patients with probable Alzheimer disease (AD) and 10 age-matched healthy controls (HCs), the second was 31 subjects who underwent in vivo imaging and postmortem histopathology for Aβ plaques, and the third was 5 subjects who underwent PET and MRI at baseline and 1 y later. The imaging data were coregistered and segmented. PVEC was performed using the voxel-based modified Müller-Gärtner method (PVELab, SPM8). From the PET data, regional and composite SUV ratios (SUVRs) with and without PVEC were obtained. In the MRI data, mesial temporal lobe atrophy was determined by the Scheltens mesial temporal atrophy scale and gray matter volumes by voxel-based morphometry.', 'In cohort 1, PVEC increased the effect on AD-versus-HC discrimination from a Cohen d value of 1.68 to 2.0 for composite SUVRs and from 0.04 to 1.04 for mesial temporal cortex SUVRs. The PVEC-related increase in mesial temporal cortex SUVR correlated with the Scheltens score (r = 0.84, P < 0.001), and that of composite SUVR correlated with the composite gray matter volume (r = -0.75, P < 0.001). In cohort 2, PVEC increased the correlation coefficient between mesial temporal cortex SUVR and histopathology score for Aβ plaque load from 0.28 (P = 0.09) to 0.37 (P = 0.03). In cohort 3, PVEC did not affect the composite SUVR dynamics over time for the Aβ-negative subject. This finding was in contrast to the 4 Aβ-positive subjects, in 2 of whom PVEC changed the composite SUVR dynamics.\Question: Does partial-Volume Effect Correction improve Quantitative Analysis of 18F-Florbetaben β-Amyloid PET Scans?

A:
The influence of PVEC on (18)F-florbetaben PET data is associated with the degree of brain atrophy. Thus, PVEC increases the ability of (18)F-florbetaben PET to discriminate between AD patients and HCs, to detect Aβ plaques in the atrophic mesial temporal cortex, and potentially to evaluate changes in brain Aβ load over time. As such, the use of PVEC should be considered for quantitative (18)F-florbetaben PET scans, especially in assessing patients with brain atrophy.
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