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    Use of the Color Spaces in Determining the Level of Hemolysis in Blood under Storage
    (Springer-Verlag Berlin, 2015) Can, Osman Melih; Ulgen, Yekta; Akin, Ata
    Quality of the transfused blood units are needed to be controlled, because severe storage lesion leads to clinical adverse effects on critically ill patients. Currently, visual assessment of hemolysis is used to control the quality of the blood units by inspecting the pink discoloration in blood bag. However, the color of blood units can be uniquely and more accurately defined by a set of tristimulus values or color coordinates in a color space. The objective of the study is to monitor daily changes in the color parameters of stored blood and relate them with the changes in hemolysis index. Red blood cell (RBC) suspensions collected from 7 male volunteers were used for the study. On each day of storage, 24 colorimetric parameters in various color spaces were measured. Besides, each week of storage, standard hemolysis measurements were performed by taking blood samples from blood bags. Colorimetric parameters: tristimulus X, u', u-v saturation, Hunter a, CIE a*, CIELAB chroma and the correlated color temperature (CCT) that mostly correspond to red contents of the color stimuli changed significantly (p<0.05) for each sample after the third week of storage. Except CCT, hemolysis showed good correlation (r>0.65) (p<0.005) with those parameters. However u', u-v saturation and CIE a* are not sensitive enough to detect hemolysis in the first two weeks of the storage.
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    Using a low-amplitude RF pulse at echo time (LARFET) for device localization in MRI
    (Springer Heidelberg, 2014) Tumer, Murat; Sarioglu, Baykal; Mutlu, Senol; Ulgen, Yekta; Yalcinkaya, Arda; Ozturk, Cengizhan
    We describe a new method for frequency down-conversion of MR signals acquired with the radio-frequency projections method for device localization. A low-amplitude, off-center RF pulse applied simultaneously with the echo signal is utilized as the reference for frequency down-conversion. Because of the low-amplitude and large offset from the Larmor frequency, the RF pulse minimally interfered with magnetic resonance of protons. We conducted an experiment with the coil placed at different positions to verify this concept. The down-converted signal was transformed into optical signal and transmitted via fiber-optic cable to a receiver unit placed outside the scanner room. The position of the coil could then be determined by the frequency analysis of this down-converted signal and superimposed on previously acquired MR images for comparison. Because of minimal positional errors (a parts per thousand currency sign0.8 mm), this new device localization method may be adequate for most interventional MRI applications.