Development of auditory localization accuracy and auditory spatial discrimination in children and adolescents.

The present study investigated the development of two parameters of spatial acoustic perception in children and adolescents with normal hearing, aged 6-18 years. Auditory localization accuracy was quantified by means of a sound source identification task and auditory spatial discrimination acuity by measuring minimum audible angles (MAA). Both low- and high-frequency noise bursts were employed in the tests, thereby separately addressing auditory processing based on interaural time and intensity differences. Setup consisted of 47 loudspeakers mounted in the frontal azimuthal hemifield, ranging from 90° left to 90° right (-90°, +90°). Target signals were presented from 8 loudspeaker positions in the left and right hemifields (±4°, ±30°, ±60° and ±90°). Localization accuracy and spatial discrimination acuity showed different developmental courses. Localization accuracy remained stable from the age of 6 onwards. In contrast, MAA thresholds and interindividual variability of spatial discrimination decreased significantly with increasing age. Across all age groups, localization was most accurate and MAA thresholds were lower for frontal than for lateral sound sources, and for low-frequency compared to high-frequency noise bursts. The study also shows better performance in spatial hearing based on interaural time differences rather than on intensity differences throughout development. These findings confirm that specific aspects of central auditory processing show continuous development during childhood up to adolescence.

Three-dimensional volumetric spatially angle-corrected pixelwise fetal flow volume measurement.

PURPOSE: Early attempts to calculate fetal global perfusion used 2 D images. The results were not sufficiently reliable. That's why RI measurements are still in use despite the fact that they do not reflect the amount of blood passing through the fetus. We present a novel three-dimensional approach to overcome these limitations. MATERIALS AND METHODS: In 124 singleton pregnancies between the 23rd and 4st gestational week, a three-dimensional color Doppler sonographic record of the umbilical cord was made, resulting in 281 volume data sets. With dedicated software (PixelFlux) the spatial angle of the umbilical vein was calculated and the true global fetal perfusion was calculated from its horizontal transection as the product of the area of all pixels and the spatial angle-corrected velocity. To validate the PixelFlux technique, phantom flow measurements were carried out. RESULTS: Phantom flow measurements revealed a highly significant correlation of actual flow volumes and those measured by the PixelFlux technique (p < 0.001; rPearson = 0.987 - 0.991) with an even higher interobserver correlation (p < 0.001; rPearson = 0.997). We found a significant correlation of fetal volume flow to gestational age and weight (r = 0.529 at spatial angles below 30° to r = 0.724 at spatial angles below 5°) and a significant influence of the spatial angle on this correlation (p = 0.003; r = -0.865). CONCLUSION: Spatial angle-corrected global fetal perfusion measurement improves existing approaches to fetal perfusion evaluation, and is feasible, simple and fast. Thus, it can be recommended to explore the relationship of fetal perfusion and disturbances of fetal development.

Dynamic color Doppler sonography of intestinal wall in patients with Crohn disease compared with healthy subjects.

OBJECTIVE: Chronic inflammatory bowel diseases are characterized by inflammatory hyperperfusion of the intestinal wall in affected bowel segments. We applied a novel method to quantify color Doppler signals dynamically along a complete heart cycle inside the bowel wall. The aim was to describe bowel wall perfusion in Crohn disease patients in comparison with healthy probands and to compare a conventional activity index (Pediatric Crohn Disease Activity Index) with perfusion measurements as an indicator of inflammatory activity. METHOD: Color Doppler sonographic videos of bowel wall perfusion from 34 healthy children (aged 5 to 18 years) and from 14 patients with Crohn disease (aged 8.2 to 15.9 years) were recorded under defined conditions. Perfusion signals (color hue, color area) were automatically measured inside the bowel wall. Specific tissue perfusion was calculated as mean flow velocity of a region of interest during one full heart cycle. Bowel wall perfusion was compared using the Pediatric Crohn Disease Activity Index in 12 patients. RESULTS: Specific bowel wall perfusion was significantly elevated in bowel segments of Crohn disease patients compared with healthy subjects (P < 0.001). Specific flow in small bowel was 0.025 cm/s in healthy probands and 0.095 cm/s in patients with Crohn disease, whereas large bowel wall perfusion of 0.012 cm/s in healthy probands clearly differed from 0.082 cm/s in patients with Crohn disease. No differences of perfusion between moderate and high Pediatric Crohn Disease Activity Index levels could be demonstrated despite a weak significant overall correlation. CONCLUSION: The new method of dynamic, automatic noninvasive perfusion quantification is useful to describe local inflammatory activity in bowel segments affected by Crohn disease and adds new information to activity evaluation by Pediatric Crohn Disease Activity Index. Specific wall perfusion in intestines of Crohn patients is significantly elevated and reaches up to sevenfold intensity compared with healthy subjects.