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Lübeck, Germany

Von Gladiss A.,University of Lubeck | Ahlborg M.,University of Lubeck | Knopp T.,Thorlabs GmbH | Buzug T.M.,University of Lubeck
IEEE Transactions on Magnetics | Year: 2015

The reconstruction of a particle concentration in magnetic particle imaging is commonly based on using a system matrix, whose acquisition is time consuming and whose storing is challenging. It has been shown recently that the acquisition time can be reduced with methods of compressed sensing and storage requirements can be reduced by storing in sparse representation. To improve the reconstruction, signals of low signal-to-noise ratio (SNR) are discarded. The determination of the SNR is difficult for undersampled signals. In this paper, the mixing order of the acquired harmonics is calculated to estimate the SNR. The spatial resolution of a system matrix can be increased by compressed sensing. A system matrix of small spatial resolution can be fully acquired in the same amount of time as a high resoluted system matrix that is undersampled correspondingly. © 1965-2012 IEEE. Source

Kuck M.,Charite - Medical University of Berlin | Alawi S.A.,Charite - Medical University of Berlin | Meinke M.C.,Charite - Medical University of Berlin | Fluhr J.W.,Charite - Medical University of Berlin | And 4 more authors.
Laser Physics Letters | Year: 2014

Non-invasive skin analysis by optical coherence tomography (OCT) is limited because of the absorption and scattering properties of the tissue. There are several possibilities for enhancing OCT images. The purpose of this study was to demonstrate that image quality can be improved using the hyperosmolar agents glucose and glycerol while investigating human ridged and meshed skin areas, without causing damage to the tissue. The experiments were carried out on the palm and the forearm of ten volunteers. After application of the substances in the test area, the penetration depth and image contrast were measured at intervals of 5 min for a total duration of 60 min. Both agents clearly improved the OCT imaging depth in comparison to untreated human skin. The results demonstrated that glucose had a faster diffusion rate than glycerol. Consequently, it can be concluded that the treatment with glucose or glycerol for optical clearing of the skin tissue results in an improved image quality if applied 15-25 min prior to clinical testing. © 2014 Astro Ltd. Source

Kuck M.,Charite - Medical University of Berlin | Schanzer S.,Charite - Medical University of Berlin | Ulrich M.,Charite - Medical University of Berlin | Bartels N.G.,Charite - Medical University of Berlin | And 6 more authors.
Journal of Biomedical Optics | Year: 2012

Noninvasive diagnostic tools, such as Trichoscan® , reflectance confocal microscopy (RCM), and optical coherence tomography (OCT), are efficient methods of hair shaft and growth evaluation. The aim of this study was to carry out a comparative assessment of these three medical procedures by measuring the hair shaft and hair growth after hair removal for a defined period of five days. The application of these techniques was demonstrated by measuring hair growth on the lower leg of six female volunteers. After removal of the hair shaft with a shaving system, the hair follicle infundibula and the length of the growing hairs were measured with the Trichoscan® , RCM, and OCT method. All three methods are reliable hair measuring tools after hair removal. Trichoscan® is best suited in the implementation of hair growth measurement and RCM in the analysis of hair follicles, whereas the OCT system can be consulted as an additional measurement for the evaluation of the hair follicle and length. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Source

Kuck M.,Charite - Medical University of Berlin | Strese H.,Charite - Medical University of Berlin | Alawi S.A.,Charite - Medical University of Berlin | Meinke M.C.,Charite - Medical University of Berlin | And 5 more authors.
Skin Research and Technology | Year: 2014

Background: The monitoring of wound-healing processes is indispensable for the therapeutic effectiveness and improved care of chronic wounds. Histological sections provide the best morphological assessment of wound recovery, but cause further tissue destruction and increase the risk of infection. Therefore, it is reasonable to apply a diagnostic tool that allows a non-invasive and reliable observation of morphological changes in wound healing. Methods: Optical coherence tomography (OCT) is an imaging technique for in vivo evaluation of skin diseases with a resolution close to histopathology. The aim of this study was to investigate whether OCT is suited to display the phases of wound healing. For this purpose, six patients with chronic wounds were objectively characterized by OCT during a period of 2 weeks. Results: Comparable results between histological findings and OCT were achieved. OCT allowed the detection of partial loss of the epidermis, vasoconstriction, vasodilatation and epithelialization. Conclusion: Consequently, OCT could be a potential non-invasive diagnostic tool for the characterization and monitoring of cutaneous wound-healing processes over time. © 2013 John Wiley & Sons A/S. Source

A parallel detecting optical coherence tomography (OCT) setup and method, in which the light paths of the illumination of the sample and of the detection of the backscattered light do not use the same apertures. The separation of illumination and detection apertures filters these disturbing reflexes from the backscattered light of the sample and significantly increases image quality.

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