Edge Enhancement Optimization in Flexible Endoscopic Images to the Perception of Ear, Nose and Throat Professionals

OBJECTIVES

Digital endoscopes are connected to a video processor that applies various operations to process the image. One of those operations is edge enhancement that sharpens the image. The purpose of this study was to (1) quantify the level of edge enhancement, (2) measure the effect on sharpness and image noise, and (3) study the influence of edge enhancement on image quality perceived by ENT professionals.

METHODS

Three digital flexible endoscopic systems were included. The level of edge enhancement and the influence on sharpness and noise were measured in vitro, while systematically varying the levels of edge enhancement. In vivo images were captured at identical levels of one healthy larynx. Each series of in vivo images was presented to 39 ENT professionals according to a forced pairwise comparison test, to select the image with the best image quality for diagnostic purposes. The numbers of votes were converted to a psychometric scale of just noticeable differences (JND) according to the Thurstone V model.

RESULTS

The maximum level of edge enhancement varied per endoscopic system and ranged from 0.8 to 1.2. Edge enhancement increased sharpness and noise. Images with edge enhancement were unanimously preferred to images without edge enhancement. The quality difference with respect to zero edge enhancement reaches an optimum at levels between 0.7 and 0.9.

CONCLUSION

Edge enhancement has a major impact on sharpness, noise, and the resulting perceived image quality. We conclude that ENT professionals benefit from this video processing and should verify if their equipment is optimally configured.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:842-847, 2024.

Accelerated white matter lesion analysis based on simultaneous T 1 and T 2 ∗ quantification using magnetic resonance fingerprinting and deep learning

PURPOSE

To develop an accelerated postprocessing pipeline for reproducible and efficient assessment of white matter lesions using quantitative magnetic resonance fingerprinting (MRF) and deep learning.

METHODS

MRF using echo-planar imaging (EPI) scans with varying repetition and echo times were acquired for whole brain quantification of T 1 and T 2 ∗ in 50 subjects with multiple sclerosis (MS) and 10 healthy volunteers along 2 centers. MRF T 1 and T 2 ∗ parametric maps were distortion corrected and denoised. A CNN was trained to reconstruct the T 1 and T 2 ∗ parametric maps, and the WM and GM probability maps.

RESULTS

Deep learning-based postprocessing reduced reconstruction and image processing times from hours to a few seconds while maintaining high accuracy, reliability, and precision. Mean absolute error performed the best for T 1 (deviations 5.6%) and the logarithmic hyperbolic cosinus loss the best for T 2 ∗ (deviations 6.0%).

CONCLUSIONS

MRF is a fast and robust tool for quantitative T 1 and T 2 ∗ mapping. Its long reconstruction and several postprocessing steps can be facilitated and accelerated using deep learning.

Magnetic resonance fingerprinting for simultaneous renal T1 and T 2 * mapping in a single breath-hold

PURPOSE

To evaluate the use of magnetic resonance fingerprinting (MRF) for simultaneous quantification of T 1 and T 2 ∗ in a single breath-hold in the kidneys.

METHODS

The proposed kidney MRF sequence was based on MRF echo-planar imaging. Thirty-five measurements per slice and overall 4 slices were measured in 15.4 seconds. Group matching was performed for in-line quantification of T 1 and T 2 ∗ . Images were acquired in a phantom and 8 healthy volunteers in coronal orientation. To evaluate our approach, region of interests were drawn in the kidneys to calculate mean values and standard deviations of the T 1 and T 2 ∗ times. Precision was calculated across multiple repeated MRF scans. Gaussian filtering is applied on baseline images to improve SNR and match stability.

RESULTS

T 1 and T 2 ∗ times acquired with MRF in the phantom showed good agreement with reference measurements and conventional mapping methods with deviations of less than 5% for T 1 and less than 10% for T 2 ∗ . Baseline images in vivo were free of artifacts and relaxation times yielded good agreement with conventional methods and literature (deviation T 1 : 7 ± 4 % , T 2 ∗ : 6 ± 3 % ).

CONCLUSIONS

In this feasibility study, the proposed renal MRF sequence resulted in accurate T 1 and T 2 ∗ quantification in a single breath-hold.

Time efficient whole-brain coverage with MR Fingerprinting using slice-interleaved echo-planar-imaging

Magnetic resonance fingerprinting (MRF) is a promising method for fast simultaneous quantification of multiple tissue parameters. The objective of this study is to improve the coverage of MRF based on echo-planar imaging (MRF-EPI) by using a slice-interleaved acquisition scheme. For this, the MRF-EPI is modified to acquire several slices in a randomized interleaved manner, increasing the effective repetition time of the spoiled gradient echo readout acquisition in each slice. Per-slice matching of the signal-trace to a precomputed dictionary allows the generation of T1 and T2* maps with integrated B1+ correction. Subsequent compensation for the coil sensitivity profile and normalization to the cerebrospinal fluid additionally allows for quantitative proton density (PD) mapping. Numerical simulations are performed to optimize the number of interleaved slices. Quantification accuracy is validated in phantom scans and feasibility is demonstrated in-vivo. Numerical simulations suggest the acquisition of four slices as a trade-off between quantification precision and scan-time. Phantom results indicate good agreement with reference measurements (Difference T1: -2.4 ± 1.1%, T2*: -0.5 ± 2.5%, PD: -0.5 ± 7.2%). In-vivo whole-brain coverage of T1, T2* and PD with 32 slices was acquired within 3:36 minutes, resulting in parameter maps of high visual quality and comparable performance with single-slice MRF-EPI at 4-fold scan-time reduction.

CO2 to methanol conversion using hydride terminated porous silicon nanoparticles

Porous silicon nanoparticles (Si-NPs) prepared via magnesiothermic reduction were used to convert carbon dioxide (CO₂) into methanol. The hydride surface of the silicon nanoparticles acted as a CO₂ reducing reagent without any catalyst at temperatures above 100 °C. The Si nanoparticles were reused up to four times without significant loss in methanol yields. The reduction process was monitored using in situ FT-IR and the materials were characterized using SEM, TEM, NMR, XPS, and powder XRD techniques. The influence of reaction temperature, pressure, and Si-NP concentration on CO₂ reduction were also investigated. Finally, Si particles produced directly from sand were used to convert CO₂ to methanol.

Wide-gamut lasing from a single organic chromophore

The development of wideband lasing media has deep implications for imaging, sensing, and display technologies. We show that a single chromophore can be engineered to feature wide-gamut fluorescence and lasing throughout the entire visible spectrum and beyond. This exceptional color tuning demonstrates a chemically controlled paradigm for light emission applications with precise color management. Achieving such extensive color control requires a molecular blueprint that yields a high quantum efficiency and a high solubility in a wide variety of liquids and solids while featuring a heterocyclic structure with good steric access to the lone pair electrons. With these requirements in mind, we designed a lasing chromophore that encloses a lasing color space twice as large as the sRGB benchmark. This record degree of color tuning can in principle be adapted to the solid state by incorporating the chromophore into polymer films. By appropriately engineering the base molecular structure, the widest range of lasing wavelengths observed for a conventional gain medium can be achieved, in turn establishing a possible route toward high-efficiency light emitters and lasers with near-perfect chromaticity.

Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): Dynamic myocardial T1 mapping using a cine steady-state look-locker approach

PURPOSE

To develop and evaluate a cardiac phase-resolved myocardial T₁ mapping sequence.

METHODS

The proposed method for temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ) is based on contiguous fast low-angle shot imaging readout after magnetization inversion from the pulsed steady state. Thereby, segmented k-space data are acquired over multiple heartbeats, before reaching steady state. This results in sampling of the inversion-recovery curve for each heart phase at multiple points separated by an R-R interval. Joint T₁ and B1+ estimation is performed for reconstruction of cardiac phase-resolved T₁ and B1+ maps. Sequence parameters are optimized using numerical simulations. Phantom and in vivo imaging are performed to compare the proposed sequence to a spin-echo reference and saturation pulse prepared heart rate-independent inversion-recovery (SAPPHIRE) T₁ mapping sequence in terms of accuracy and precision.

RESULTS

In phantom, TOPAZ T₁ values with integrated B1+ correction are in good agreement with spin-echo T₁ values (normalized root mean square error = 4.2%) and consistent across the cardiac cycle (coefficient of variation = 1.4 ± 0.78%) and different heart rates (coefficient of variation = 1.2 ± 1.9%). In vivo imaging shows no significant difference in TOPAZ T₁ times between the cardiac phases (analysis of variance: P = 0.14, coefficient of variation = 3.2 ± 0.8%), but underestimation compared with SAPPHIRE (T₁ time ± precision: 1431 ± 56 ms versus 1569 ± 65 ms). In vivo precision is comparable to SAPPHIRE T₁ mapping until middiastole (P > 0.07), but deteriorates in the later phases.

CONCLUSIONS

The proposed sequence allows cardiac phase-resolved T₁ mapping with integrated B1+ assessment at a temporal resolution of 40 ms. Magn Reson Med 79:2087-2100, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Diaryliodonium salts as hydrosilylation initiators for the surface functionalization of silicon nanomaterials and their collaborative effect as ring opening polymerization initiators

Diaryliodonium salts were found to initiate hydrosilylation reactions on the surface of silicon nanosheets as well as silicon nanocrystals of different sizes. A variety of different functional substrates can be used to stabilize the surface of the photoluminescent materials. Additionally, the combination of hydride terminated silicon nanomaterials with diaryliodonium salts was found to initiate cationic ring opening polymerization, demonstrating the potential of silicon based nanomaterials as coinitiators and enabling a mild, straightforward reaction method.

A Lewis acid β-diiminato-zinc-complex as all-rounder for co- and terpolymerisation of various epoxides with carbon dioxide

A β-diiminato-zinc-N(SiMe3)2 complex (1) was synthesised and fully characterised, including an X-ray diffraction study. The activity of catalyst 1 towards the coupling reaction of CO2 and various epoxides, including propylene oxide (PO), cyclohexene oxide (CHO), styrene oxide (SO), limonene oxide (LO), octene oxide (OO) and epichlorohydrin (ECH), was investigated. Terpolymerisation of CO2, PO and LO, as well as CO2, CHO and PO, was successfully realised, resulting in polymers with adjustable glass transition temperatures and transparencies. Reaction conditions such as temperature, pressure and catalyst concentration were varied to find the optimal reaction values, especially regarding LO/CO2. In situ IR experiments hinted that at 60 °C and a critical LO concentration, polymerisation and depolymerisation are in an equilibrium (ceiling effect). Pressurising catalyst 1 with carbon dioxide resulted in a dimeric catalyst (2) with a OSiMe3 group as a new initiator. Homopolymerisation of different epoxides was carried out in order to explain the reactivity concerning copolymerisation reaction of CO2 and epoxides.

Tilt series STEM simulation of a 25×25×25nm semiconductor with characteristic X-ray emission

The detection and quantification of fabrication defects is vital to the ongoing miniaturization of integrated circuits. The atomic resolution of HAADF-STEM combined with the chemical sensitivity of EDS could provide the means by which this is achieved for the next generation of semiconductor devices. To realize this, however, a streamlined acquisition and analysis procedure must first be developed. Here, we report the simulation of a HAADF-STEM and EDS tilt-series dataset of a PMOS finFET device which will be used as a testbed for such a development. The methods used to calculate the data and the details of the specimen model are fully described here. The dataset consists of 179 projections in 2° increments with HAADF images and characteristic X-ray maps for each projection. This unusually large calculation has been made possible through the use of a national supercomputer and will be made available for the development and assessment of reconstruction and analysis procedures for this highly significant industrial application.

[SENDS criteria from the diversification of MAST procedures. Implementation of preoperative simulation]

CLINICAL ISSUE

Minimal access spinal technologies (MAST) lead to a diversification of surgical procedures, which requires careful selection of the procedure and outcome monitoring. For a rational selection of the procedure simulation, endoscopy, navigation, decompression and stabilization (SENDS) criteria can be derived from the development of the MAST procedures. Preoperative simulation has diagnostic and therapeutic values. The SENDS criteria can be verified indirectly via outcome control.

STANDARD TREATMENT

Biomechanically meaningful diagnostic x-rays of the spinal segment to be surgically treated are currently carried out with the patient in inclination and reclination.

TREATMENT INNOVATIONS

Software-related preoperative simulation based on these x-ray images facilitates the selection and implementation of the MAST procedure.

DIAGNOSTIC WORK-UP

For preoperative simulation motion shots are needed in inclination, neutral position and reclination and the dimensions can be obtained using an x-ray ball or a computed tomography (CT) scan.

PERFORMANCE

The SENDS criteria are useful because established procedures based on these criteria reach a comparable outcome. Preoperative simulation appears to be a useful selection criterion.

ACHIEVEMENTS

Preoperatively it is necessary to collate patient and segment information in order to provide each patient with individualized treatment. So far there is no evidence for a better outcome after preoperative simulation but a reduction of surgery time and intraoperative radiation exposure could already be demonstrated.

PRACTICAL RECOMMENDATIONS

Minimally invasive methods should be preferred if there is a comparable outcome. The establishment of new procedures has to be accompanied by the maintenance of a spine register. Minimally invasive surgical procedures should be individualized for each patient and segment. Mobility X-ray images should be prepared for use with the preoperative simulation as the information content significantly increases with respect to the MAST procedure.

Multiresponsive micellar block copolymers from 2-vinylpyridine and dialkylvinylphosphonates with a tunable lower critical solution temperature

Tailor-made, multi-responsive micellar AB and ABB′ block copolymers show a pH-sensitivity and a tunable LCST within an expanded temperature range.

Stereospecific catalytic precision polymerization of 2-vinylpyridine via rare earth metal-mediated group transfer polymerization with 2-methoxyethylamino-bis(phenolate)-yttrium complexes

C ₁-Symmetric 2-methoxyethylamino-bis(phenolate)-yttrium complexes for the stereospecific polymerization of 2-vinylpyridine.

Dinuclear zinc catalysts with unprecedented activities for the copolymerization of cyclohexene oxide and CO2

New dinuclear zinc catalysts reveal by far the highest polymerization rates for the copolymerization of cyclohexene oxide and CO₂.

Synthesis of hydrocarbon-soluble, methyl-substituted highly branched polysilanes via the Wurtz-type reductive coupling of trifunctional trisilanes and their pyrolysis to silicon carbide

(ClMe₂Si)₂SiMeCl was successfully converted into a hydrocarbon-soluble, highly branched polymethylsilane, which is usable as soluble precursor for the pyrolytic preparation of SiC.

Synthesis and characterization of a trinuclear iridium(iii) based catalyst for the photocatalytic reduction of CO2

A trimetallic Ir(iii) based photocatalyst for the reduction of CO₂ was developed and investigated, regarding the influence of spatial proximity between the catalyst centers towards the catalytic performance.

Ageing Challenges the Results of any Outcome Study: How to Address the Effects of Ageing on Activities of Daily Living

OBJECTIVES: Clinical study results might be substantially biased by the effects of ageing, resulting in considerable underestimation of treatment efficacy, especially when assessing activities of daily living (ADL) in elderly people. This study aimed to define age- and comorbidity-related normative values in ADL. METHODS: In cross-sectional sampling, 23 763 German-speaking Swiss individuals were contacted. Valid questionnaires from 16 191 (68%) eligible individuals ≥ 18 years of age were included in the study. Age-related ADL reference values were calculated using questionnaire data. RESULTS: The sample was representative of the German-speaking Swiss population as determined by 2003 census data. Age- and pain-related ADL reference values were plotted and confirmed that disability increased with increasing age. CONCLUSIONS: The use of ADL scales that provide age- and comorbidity-related reference values for outcome studies or studies focusing on the elderly is recommended in order to reduce the effect of bias.

Minimizing light exposure with the programmable array microscope

The exposure of fluorophores to intense illumination in a microscope often results in photobleaching and phototoxicity, thus constituting a major limiting factor in time lapse live cell or single molecule imaging. Laser scanning confocal microscopes are particularly prone to this problem, inasmuch as they require high irradiances to compensate for the inherently low duty cycle of point scanning systems. In the attempt to maintain adequate speed and signal-to-noise ratios, the fluorophores are often driven into saturation, thereby generating a nonlinear response. One approach for reducing photodegradation in the laser scanning confocal microscope is represented by controlled light exposure microscopy, introduced by Manders and colleagues. The strategy is to reduce the illumination intensity in both background areas (devoid of information) as well as in bright foreground regions, for which an adequate signal-to-noise ratio can be achieved with lower excitation levels than those required for the less intense foreground pixels/voxels. Such a variable illumination scheme can also be exploited in widefield microscopes that employ lower irradiance but higher illumination duty cycles. We report here on the adaptation of the controlled light exposure microscopy principle to the programmable array microscope, which achieves optical sectioning by use of a spatial light modulator (SLM) in an image plane as a programmable mask for illumination and conjugate (and nonconjugate) detection. By incorporating the basic controlled light exposure microscopy concept for minimizing exposure, we have obtained a reduction in the rate of photobleaching of up to ~5-fold, while maintaining an image quality comparable to regular imaging with the programmable array microscope.

A toolkit for the characterization of CCD cameras for transmission electron microscopy

Charge-coupled devices (CCD) are nowadays commonly utilized in transmission electron microscopy (TEM) for applications in life sciences. Direct access to digitized images has revolutionized the use of electron microscopy, sparking developments such as automated collection of tomographic data, focal series, random conical tilt pairs and ultralarge single-particle data sets. Nevertheless, for ultrahigh-resolution work photographic plates are often still preferred. In the ideal case, the quality of the recorded image of a vitrified biological sample would solely be determined by the counting statistics of the limited electron dose the sample can withstand before beam-induced alterations dominate. Unfortunately, the image is degraded by the non-ideal point-spread function of the detector, as a result of a scintillator coupled by fibre optics to a CCD, and the addition of several inherent noise components. Different detector manufacturers provide different types of figures of merit when advertising the quality of their detector. It is hard for most laboratories to verify whether all of the anticipated specifications are met. In this report, a set of algorithms is presented to characterize on-axis slow-scan large-area CCD-based TEM detectors. These tools have been added to a publicly available image-processing toolbox for MATLAB. Three in-house CCD cameras were carefully characterized, yielding, among others, statistics for hot and bad pixels, the modulation transfer function, the conversion factor, the effective gain and the detective quantum efficiency. These statistics will aid data-collection strategy programs and provide prior information for quantitative imaging. The relative performance of the characterized detectors is discussed and a comparison is made with similar detectors that are used in the field of X-ray crystallography.

DNA deformations near charged surfaces: electron and atomic force microscopy views

DNA is a very important cell structural element, which determines the level of expression of genes by virtue of its interaction with regulatory proteins. We use electron (EM) and atomic force microscopy (AFM) to characterize the flexibility of double-stranded DNA ( approximately 150-950 nm long) close to a charged surface. Automated procedures for the extraction of DNA contours ( approximately 10-120 nm for EM data and approximately 10-300 nm for AFM data) combined with new statistical chain descriptors indicate a uniquely two-dimensional equilibration of the molecules on the substrate surface regardless of the procedure of molecule mounting. However, in contrast to AFM, the EM mounting leads to a noticeable decrease in DNA persistence length together with decreased kurtosis. Analysis of local bending on short length scales (down to 6 nm in the EM study) shows that DNA flexibility behaves as predicted by the wormlike chain model. We therefore argue that adhesion of DNA to a charged surface may lead to additional static bending (kinking) of approximately 5 degrees per dinucleotide step without impairing the dynamic behavior of the DNA backbone. Implications of this finding are discussed.

Lässt sich die Canadian CT Head Rule für das leichte Schädel-Hirn-Trauma auf Deutschland übertragen?

PURPOSE

To evaluate the applicability of the Canadian CT Head Rule (CCHR) on head trauma patients in a German university hospital.

METHODS

122 patients (m = 74; f = 48; 40 +/- 19 years) were examined with cranial CT due to minor head trauma. The need for cranial CT according to the CCHR was evaluated retrospectively.

RESULTS

With a sensitivity of 98.9 % and a specificity of 46.6 % all patients with the need for neurosurgical intervention were detected by applying the major criteria of the CCHR. Also, every patient with severe brain injury was detected by the extended criteria with a sensitivity of 99.6 % and a specificity of 34.1 %. This would have led to a reduction in the rate of cranial CT examinations by 45.1 % for the major and 22.1 % for the extended criteria. No patient with severe brain injury would have been missed by application of the criteria.

CONCLUSION

The Canadian CT Head Rule for patients with minor head trauma is applicable with a very high sensitivity and the potential of significantly reducing the rate of cranial CT examinations in these patients.

Diffusion of microspheres in sealed and open microarrays

In several experiments, we study the diffusion of microspheres with different radii in microarrays filled with a variety of aqueous solutions of ethylene glycol. We study diffusion in open and closed (sealed) microarrays. In sealed nanoliter wells, the tracers show pure diffusion, whereas in open reactors, a radial outward-directed evaporation-induced liquid flow is superimposed onto the diffusion. In general, one of the following quantities can be calculated if the others are known: the temperature, the viscosity of the medium, the radius of the microbeads, or the diffusion constant. The estimated diffusion constants in closed microarrays are in good agreement with theoretical predictions based on the Brownian motion. We monitor the motion of the microbeads under a microscope and extract their paths in time from the digital recordings. Ambiguous paths due to the crossing of two trajectories can be detected. We show that low microsphere concentrations or high viscosities do not hamper a robust estimation of the diffusion parameters.

Alignment of the cell nucleus from labeled proteins only for 4D in vivo imaging

Studies of protein dynamics by 4D (3D + time) confocal microscopy in vivo are hampered by global cell motion. The time between the acquisitions of the 3D images is in the order of minutes. Therefore, it is not to be expected that the cell as a whole remains fixed in the water basin on the stage. This superimposes a motion on the protein dynamics that has to be removed. We present a robust registration technique to align the cell images that does not require the a priori establishment of point-to-point correspondences. Instead, it uses the distribution of the labeled proteins. After correction for the translation, the 3D rotation of the cell is estimated. A robust intrinsic body coordinate system is constructed via the inertia tensor from the intensity distribution. By combining basis transformation to this intrinsic coordinate system, we can calculated the rotation matrix in a conceptual and computational straightforward manner. We have evaluated the performance of this approach in three experiments with human osteaosarcoma cells (U-2 OS), where the nuclear proteins Histon H4 and PML were visualized. The PML is concentrated in several dozen nuclear spots. Expression of Histon H4 results in a total nuclear staining. The registration results for both channels computed independently are very similar. Practically, this means that only the labeled material needs to be observed and still registration of the cell as a whole can be achieved.

First night effect in children and adolescents undergoing polysomnography for sleep-disordered breathing

OBJECTIVE

To establish whether there is a first night effect (FNE) in children and adolescents with suspected obstructive sleep apnoea undergoing polysomnography (PSG) and whether this affects sleep and breathing, furthermore, to determine the extent to which age may influence the sleep and cardiorespiratory parameters.

METHODS

One hundred and thirty-one children and adolescents (age classes-A: 2-6 years n=37; B: 7-12 years n=60; C: 13-17 years n=34) underwent PSG on 2 consecutive nights (I and II) under identical conditions for suspected sleep-related respiratory disorders. One hundred and five patients including 3 patients with obstructive sleep apnoea syndrome (OSAS) treated by adenotonsillectomy and 18 OSAS patients receiving nCPAP-therapy had no PSG-abnormalities (Group 1-A: n=28; B: n=53; C: n=24). A further 26 patients (Group 2) had clinically and polysomnographically confirmed untreated OSAS (A: n=9; B: n=12; C: n=5).

RESULTS

There were no statistically significant differences between children with no PSG-abnormalities (Group 1) and those with OSAS (Group 2) in terms of sleep parameters (arousal indices excluded), oxygen saturation (SaO(2)) and heart rate (HR), and these parameters have, therefore, been pooled for the entire group (n=131) in the 3 age classes A, B and C. In the second and third age classes, sleep efficiency on the first night was reduced. In all age classes, there was significantly more wakefulness during the first night. In the second and third age ranges, the proportion of NREM 1 in the first night was significantly higher, with a correspondingly reduced proportion of NREM 4 in the third age group. In all age classes, REM sleep was significantly less during the first night, but REM latency was comparable on both nights. On the first night, the mean HR was higher. There were significant differences in apnoea/hypopnoea-index (AHI), electroencephalogram (EEG)-arousal-index (AI) and motoric arousal index (jerk index, JI) between Groups 1 and 2. In neither group, were there any significant differences in AHI, mean SaO(2) or number of EEG-arousals between nights 1 and 2. Only in the age class A, in Group 2 (n=9) was the number of motoric arousals significantly higher on the first night. Comparison of the age classes A, B, and C revealed that most polysomnographic parameters were age-dependent. Increasing age was found to correlate with a higher proportion of NREM 1, especially on the first night. Also, there was an age-dependent increase in NREM 2 on both nights, a decrease in NREM 3 on the first night, and a decrease in NREM 4 on both nights. In older children, we also found a lower proportion of REM sleep on the first night and a lower HR on both nights. In Group 1, we found a lowered AHI, AI and JI (for JI significant only on the first night) in older patients. No such age dependence of AHI, AI and JI was seen in OSAS patients (Group 2).

CONCLUSIONS

In children and adolescents, there is an FNE comparable with that described in adults. In OSAS children and also in children with no PSG-abnormalities, there is night-to-night-variability in sleep parameters, but not in respiratory parameters. An adaptation night is, therefore, necessary when sleep architecture is to be studied, but not when only the nocturnal respiratory pattern is investigated. Sleep parameters, HR and arousal indices are all age-dependent.

Plasma cell granuloma involving the brain and the lung

BACKGROUND

Symptomatic plasma cell granulomas (PCG) of the central nervous system (CNS) are a rare entity, especially in association with an extracranial manifestation.

CLINICAL PRESENTATION

A 13 years old boy was operated on for a symptomatic plasma cell granuloma of the lower lobe of the left lung. Four years later, he suffered his first generalized seizure. CT and MRI scans revealed a small hyperdense lesion, which was located in the right frontal lobe, adjacent to the motor strip. Intervention. Stereotactic guided surgery was performed. A plasma cell granuloma was found, which histopathologically resembled the intrapulmonary lesion, which had been removed four years ago.

CONCLUSION

Histological findings, differential diagnosis and specific treatment are reviewed and discussed. Patients with PCG should be radiologically staged. Long term prognosis of PCG is good in cases surgically resectable. Nevertheless, patients require lifelong follow up.

Ring formation in nanoliter cups: quantitative measurements of flow in micromachined wells

Drying of DNA spots on microarrays and spilled coffee yields ringlike stains, because the outward flow transports dissolved particles to the border. Contact line pinning and diffusion limited evaporation of a liquid sample are the two necessary conditions to induce an outward directed liquid flow during evaporation. In this paper we present quantitative measurements of this flow field visualized by microspheres which are injected into a liquid sample in circular wells with a radius of 100-150 micro m and a depth of 6 micro m. The motion, including Brownian motion, of these microspheres with a radius of 0.25 micro m is recorded using digital fluorescence microscopy. Our analysis, using optic flow, does not require object identification, nor tracking of the individual objects. The spatiotemporal measurement space is sparsely filled at only those space/time positions where a microsphere is present. A confidence measure is computed indicating the presence of microspheres in this measurement space. The circular well shape allows us to transform the sparse measurement space into a denser, averaged radial velocity field. In this transformation we "interpolate" the radial velocity between values with a high confidence, which results in quantitative measurements of this outward flow field during the complete time interval of the evaporation process and at all radial positions in the circular wells. This allows for a quantitative validation of the elegant theory of ring formation.

[Adeno-tonsillar hyperplasia and obstructive sleep related respiratory disorders]

The most common cause of obstructive apnoeas in children is adenotonsillar hyperplasia. Possibilities of therapy are surgical intervention (adeniodectomy, tonsillectomy) or nasal CPAP. The decision on the most appropriate therapy must be individual. 26 children aged 2-5 years were investigated polysomnographically before therapy, after operation or with nCPAP-therapy. Polygraphy is a helpful aid in making up one's mind in favour of one of the possibilities of therapy, but also for controlling the therapeutic effect.