Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10–15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology

CESAR - Stundatöflugerðar kerfi fyrir HR

Verkefnið fólst í að betrumbæta kerfi Háskólans í Reykjavík þegar kemur að gerð stundatafla fyrir kennara og nemendur skólans. Fundinn var stundatöflugerðar hugbúnaður frá þriðja aðila sem sér um gerð stundatafla en forritaður var milliliður, sem fékk nafnið CESAR, sem sér um að nálgast nauðsynleg gögn fyrir stundatöflugerð og koma þeim á það form sem stundatöflugerðar hugbúnaður getur tekið við. Einnig sér CESAR um að taka við tilbúnni stundatöflu frá hugbúnaði á formi xml skráar og bókar stofur á gagnagrunn skólans sem sóst er eftir í stundatöflunni. Markmið verkefnisins var að finna leið til að auðvelda gerð stundatafla fyrir starfsfólk skólans. Gera viðbætur á kerfum skólans sem mundu að miklu leyti vélvæða stundatöflugerð. Fyrsta skref var að ákveða hvaða leið yrði farin til að framkvæma þessar viðbætur. Tvennt var í boði, annars vegar að hefjast handa við að forrita kerfi frá grunni sem mundi sjá um gerð stundatafla fyrir skólann. Hinsvegar að finna hugbúnað frá þriðja aðila sem mundi sjá um gerð stundataflanna og forritaður yrði milliliður (þáttari) sem sæi um að sækja nauðsynleg gögn frá gagnagrunni skólans og setja þau á það form sem stundatöflugerðar hugbúnaður þyrfti. Seinni kosturinn varð fyrir valinu þar sem talið var að sá fyrri væri full stórt verkefni fyrir tvo og yrði einungis upphaf af stóru framtíðar verkefni sem aðrir nemendur gætu tekið við og haldið áfram með. Aftur á móti er fyrri kosturinn verkefni sem vert væri fyrir skólann að skoða

Muisca culture artefacts, Museo del Oro, Bogota, Colombia, 1977, [2] [picture] /

Condition: Good.; Title devised by cataloguer based on inscription on reverse.; Part of Wolfgang Sievers photographic archive.; Sievers number: V4560-add32 (devised number).; Inscriptions: "Muisca-1263".; "Photograph by Wolfgang Sievers and Brian Hart"--Stamped in red ink on verso.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-vn4193539

External Beam Radiotherapy for Head and Neck Cancers Is Associated with Increased Variability in Retinal Vascular Oxygenation

BACKGROUND: Radiation retinopathy is a possible post-treatment complication of radiation therapy. The pathophysiologic mechanism is hypothesized to be microvascular in origin, but evidence is limited. In an effort to study retinal oxygenation in these patients, we herein evaluate the repeatability and variability of retinal oximetry measurements in subjects who had previously received radiation and make comparisons to a cohort of unirradiated subjects. METHODS: Using retinal oximetry, a non-invasive imaging modality, we performed in vivo measurements of arteriole (SaO(2)) and venule SO(2) (SvO(2)) in subjects (n = 9, 18 retinas) who had received incidental radiation to their retinas (≥ 45 Gy to one retina) and in healthy subjects (n = 20, 40 retinas). A total of 1367 SO(2) observations on 593 vessels in 29 persons were analyzed to assess three sources of variance in vessel SO(2): 1) variance in repeated measurements of the same vessel (“repeatability”), 2) variance in different vessels within the same subject (“within-subject variability”), and 3) variance between subjects (“between-subject variability”). RESULTS: Retinal oximetry measurements were highly repeatable in both irradiated patients and unirradiated subjects. The within-subject variability of SvO(2) and SaO(2) measurements constituted the highest component of variance in both groups and was significantly higher in venules vs. arterioles (relative effect size 1.8, p<0.001) and in irradiated subjects vs. unirradiated subjects (relative effect size 1.6, p<0.001). CONCLUSIONS: Retinal oximetry is a highly repeatable technology and can be reliably used to study vascular oxygenation in irradiated subjects. Different vessels within the same subject exhibit a high degree of variability, suggesting that pooled analyses of multiple vessels are most likely to be informative of regional retinal oxygenation. Finally, irradiated subjects exhibited significantly higher within-subject variability in SO(2) measurements, suggesting that radiation may cause regional alterations in retinal oxygen delivery and/or metabolism

A semantically flexible feature fusion network for retinal vessel segmentation

The automatic detection of retinal blood vessels by computer aided techniques plays an important role in the diagnosis of diabetic retinopathy, glaucoma, and macular degeneration. In this paper we present a semantically flexible feature fusion network that employs residual skip connections between adjacent neurons to improve retinal vessel detection. This yields a method that can be trained employing residual learning. To illustrate the utility of our method for retinal blood vessel detection, we show results on two publicly available data sets, i.e. DRIVE and STARE. In our experimental evaluation we include widely used evaluation metrics and compare our results with those yielded by alternatives elsewhere in the literature. In our experiments, our method is quite competitive, delivering a margin of sensitivity and accuracy improvement as compared to the alternatives under consideration