[The potential of dual-energy virtual monochromatic imaging in reducing renal cyst pseudoenhancement: a phantom study].

Renal cyst pseudoenhancement, an artifactual increase of computed tomography (CT) attenuation for cysts with increased iodine concentrations in the renal parenchyma, complicates the classification of cysts and may thus lead to the mischaracterization of a benign non-enhancing lesion as an enhancing mass. The purpose of this study was to use a phantom model to assess the ability of dual-energy virtual monochromatic imaging to reduce renal pseudoenhancement. A water-filled cylindrical cyst model suspended in varying concentrations of iodine solution, to simulate varying levels of parenchymal enhancement, was scanned with a dual-energy CT scanner using the following three scanning protocols with different combinations of tube voltage: 80 and 140 kV; 80 and 140 kV with tin filter; and 100 and 140 kV with tin filter. Virtual monochromatic images were then synthesized for each dual-energy scan. Single-energy scan with a tube voltage of 120 kV was also performed to obtain polychromatic images as controls. Mean attenuation values (in Hounsfield units) of cyst proxies were measured on both polychromatic and virtual monochromatic images. Pseudoenhancement was considered to be present when the cyst attenuation level increased by more than 10 HU as the background iodine concentration increased from 0.0% to 0.4%, 1.5%, or 2.5%. Our results revealed that pseudoenhancement was not observed on any of the monochromatic images, but appeared on polychromatic images at a background iodine concentration of 2.5%. We thus conclude that dual-energy virtual monochromatic images have a potential to reduce renal pseudoenhancement.

Cognitive impairment as a strong predictor of incident disability in specific ADL-IADL tasks among community-dwelling elders: the Azuchi Study.

PURPOSE: We examined differential effects of cognitive impairment on each of the activities of daily living (ADL) and instrumental activities of daily living (IADL) tasks. DESIGN AND METHODS: In a 3-year follow-up of community-dwelling elderly persons in Azuchi, Japan, we assessed cognition by using the Hasegawa Dementia Scale. We examined (a) the cross-sectional association between cognitive impairment and functional disability in each ADL-IADL item; (b) cognitive impairment as a risk factor for incident disability in each ADL-IADL item, through logistic regression models; and (c) probabilities of incident loss of ADL-IADL abilities or death in 3 years, using multinomial logistic regression models. We also calculated the population attributable risk (PAR%) of cognitive impairment on incident loss of task-specific ADL-IADL abilities. RESULTS: Cross-sectionally, the severity of cognitive impairment was associated with disability in each ADL-IADL task, with larger effects shown for ADL items. Longitudinally, minimally or mildly cognitively impaired individuals had a significantly higher risk of losing functional abilities compared with those with intact cognition. The PAR% indicated that cognitive impairment accounts for 11% to 36% of incident disability in ADL-IADL tasks, with the highest PAR% shown for the ability to feed oneself. IMPLICATIONS: Cognitively impaired subjects are heterogeneous; the severity of cognitive impairment has a different impact on incident loss of task-specific ADL-IADL abilities, and comorbidities could affect disabilities differently. Consideration of these heterogeneities will enrich future studies on the impact of cognitive impairment on ADL-IADL abilities.

Influence of sound and light on heart rate variability.

The effects of acoustic and visual stimuli and their synergistic effects on heart rate variability including gender differences were investigated. Of particular interest was the influence of visual stimulus on heart rate variability during listening to simple sounds of different characters. Twelve male and 12 female university students were selected as subjects. The subjects listened at rest to 7 different figures of sound at loudness levels averaging 60 dB. Beat-to-beat R-R intervals were continuously recorded under the closed-eye condition (CEC) and the open-eye condition (OEC) prior to, during, and immediately after the exposure to acoustic stimuli. Low frequency (LF) power was defined over 0.04-0.15 Hz and high frequency (HF) power over 0.15-0.40 Hz. Cardiac autonomic function was estimated by plotting LF/HF in standard measure against HF in standard measure and by plotting LF/HF (%) against HF (%), accompanied by a demarcated central area. Values of LF/HF tended to be smaller under CEC than under OEC. Values of HF while listening to a 110 Hz sine wave under CEC were significantly greater than values for 880 Hz and 3520 Hz sine waves, or for 110 Hz or 880 Hz sawtooth waves, under OEC. Under CEC, values of HF for 7 figures of sound were greater in females than in males. The value of HF of sine wave for 110 Hz under CEC and OEC was significantly greater than that for white noise under the OEC. The results suggest that the cardiac parasympathetic nervous activity during auditory excitation increases with elimination of visual stimuli and tends to be greater in females than in males.