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7. A Novel Method for the Generation of Realistic Lung Nodules Visualized Under X-Ray Imaging.

Author

Peker, Ahmet, Sinha, Ayushi, King, Robert M., Minnaard, Jeffrey, Sterren, William van der, Bydlon, Torre, Bankier, Alexander A., and Gounis, Matthew J.

Subjects
SOLITARY pulmonary nodule, LUNG diseases, PULMONARY nodules, X-ray imaging, LUNG tumors, LUNGS
Abstract

Objective: Image-guided diagnosis and treatment of lung lesions is an active area of research. With the growing number of solutions proposed, there is also a growing need to establish a standard for the evaluation of these solutions. Thus, realistic phantom and preclinical environments must be established. Realistic study environments must include implanted lung nodules that are morphologically similar to real lung lesions under X-ray imaging. Methods: Various materials were injected into a phantom swine lung to evaluate the similarity to real lung lesions in size, location, density, and grayscale intensities in X-ray imaging. A combination of n -butyl cyanoacrylate (n-BCA) and ethiodized oil displayed radiopacity that was most similar to real lung lesions, and various injection techniques were evaluated to ensure easy implantation and to generate features mimicking malignant lesions. Results: The techniques used generated implanted nodules with properties mimicking solid nodules with features including pleural extensions and spiculations, which are typically present in malignant lesions. Using only n-BCA, implanted nodules mimicking ground glass opacity were also generated. These results are condensed into a set of recommendations that prescribe the materials and techniques that should be used to reproduce these nodules. Conclusions: Generated recommendations on the use of n-BCA and ethiodized oil can help establish a standard for the evaluation of new image-guided solutions and refinement of algorithms in phantom and animal studies with realistic nodules. [ABSTRACT FROM AUTHOR]

Published
2024
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8. The effect of carotid artery stenting on capillary transit time heterogeneity in patients with carotid artery stenosis.

Author

Arsava, Ethem, Hansen, Mikkel, Kaplan, Berkan, Peker, Ahmet, Gocmen, Rahsan, Arat, Anil, Oguz, Kader, Topcuoglu, Mehmet, Østergaard, Leif, and Dalkara, Turgay

Subjects
Atherosclerosis, capillary transit time, carotid artery stenting, flow heterogeneity, perfusion MRI
Abstract

INTRODUCTION: Carotid revascularisation improves haemodynamic compromise in cerebral circulation as an additional benefit to the primary goal of reducing future thromboembolic risk. We determined the effect of carotid artery stenting on cerebral perfusion and oxygenation using a perfusion-weighted MRI algorithm that is based on assessment of capillary transit-time heterogeneity together with other perfusion and metabolism-related metrics. PATIENTS AND METHODS: A consecutive series of 33 patients were evaluated by dynamic susceptibility contrast perfusion-weighted MRI prior to and within 24 h of the endovascular procedure. The level of relative change induced by stenting, and relationship of these changes with respect to baseline stenosis degree were analysed. RESULTS: Stenting led to significant increase in cerebral blood flow (p  2s decreased from 24 ml to 12 ml (p = 0.009), with CTH > 2s from 29 ml to 19 ml (p = 0.041), and with RTH

Published
2018

9. Quantitative reliability assessment of brain MRI volumetric measurements in type II GM1 gangliosidosis patients.

Author

Zoppo, Christopher, Kolstad, Josephine, Johnston, Jean, D'Souza, Precilla, Kühn, Anna Luisa, Vardar, Zeynep, Peker, Ahmet, Lindsay, Clifford, Rentiya, Zubir S., King, Robert, Gray-Edwards, Heather, Vachha, Behroze, Acosta, Maria T., Tifft, Cynthia J., and Shazeeb, Mohammed Salman

Subjects
CORPUS striatum, CAUDATE nucleus, CORPUS callosum, INTRACLASS correlation, DISEASE progression
Abstract

Purpose: GM1-gangliosidosis (GM1) leads to extensive neurodegenerative changes and atrophy that precludes the use of automated MRI segmentation techniques for generating brain volumetrics. We developed a standardized segmentation protocol for brain MRIs of patients with type II GM1 and then assessed the inter- and intra-rater reliability of thismethodology. The volumetric data may be used as a biomarker of disease burden and progression, and standardized methodology may support research into the natural history of the disease which is currently lacking in the literature. Approach: Twenty-five brain MRIs were included in this study from 22 type II GM1 patients of which 8 were late-infantile subtype and 14 were juvenile subtype. The following structures were segmented by two rating teams on a slice-by-slice basis: whole brain, ventricles, cerebellum, lentiform nucleus, thalamus, corpus callosum, and caudate nucleus. The inter- and intra-rater reliability of the segmentationmethod was assessed with an intraclass correlation coeffcient as well as Sorensen-Dice and Jaccard coeffcients. Results: Based on the Sorensen-Dice and Jaccard coeffcients, the inter- and intra-rater reliability of the segmentation method was significantly better for the juvenile patients compared to late-infantile (p < 0.01). In addition, the agreement between the two rater teams and within themselves can be considered good with all p-values < 0.05. Conclusions: The standardized segmentation approach described here has good inter- and intra-rater reliability and may provide greater accuracy and reproducibility for neuromorphological studies in this group of patients and help to further expand our understanding of the natural history of this disease. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Differentiation of Post-Polio Syndrome from Prior Poliomyelitis Sequela by Assessing Paraspinal Muscle Involvement in Magnetic Resonance Imaging.

Author

Topaloglu, Mahir, Sarikaya, Deniz, Peker, Ahmet, Senturk, Yunus Emre, Terlemez, Rana, Cetin, Burak Ugur, Oge, Ali Emre, and Ketenci, Aysegul

Subjects
MAGNETIC resonance imaging, POLIO, LUMBAR pain, MUSCLE weakness, POSTPOLIOMYELITIS syndrome, FATIGUE (Physiology)
Abstract

Background/Objectives: Post-polio syndrome (PPS) affects former polio patients, manifesting decades after initial infection with progressive symptoms like pain, fatigue, and muscle weakness. Diagnosis relies on the clinical criteria and exclusion of other probable causes. The purpose of this study is to determine the scope and new diagnostic value of magnetic resonance imaging (MRI) in identifying muscle involvement in PPS and distinguishing it from prior poliomyelitis (PPM). Methods: This study was approved by the Koç University Ethics Committee with Approval No. 2023.409.IRB2.090. Electronic medical archives from two academic institutions were searched for records tagged with ICD code B-91 for poliomyelitis sequalae. The resulting search query of 291 records was manually sorted for PPS and PPM, medical history, clinical examination findings, and lumbar MR images down to 32 patients. Two independent radiologists evaluated the paraspinal musculature in the MRIs using the Mercuri scale. Inter-rater agreement, comparison of the paraspinal musculatures between groups, and their relationship to leg involvement were assessed with the resulting data. Results: Inter-rater agreement was found to be almost perfect across all muscles, except for the multifidus muscle. When clinical examination findings were included for these muscles, quadratus lumborum (QL) degradation was found in both right-side (p = 0.017) and left-side (p = 0.002) leg involvement. Conclusions: QL muscle deterioration may serve as a diagnostic marker for PPS, potentially guiding lumbar pain treatment through rehabilitation. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Active drug-coated flow diverter in a preclinical model of intracranial stenting.

Author

King, Robert M., Peker, Ahmet, Epshtein, Mark, Arends, Jennifer M., Brochu, Alice B., Raskett, Christopher M., Slazas, Kimiko J., Puri, Ajit S., Arthur, Adam S., Fiorella, David, Gounis, Matthew J., and Anagnostakou, Vania

Subjects
PREVENTION of surgical complications, NEUROLOGIC examination, STATISTICAL correlation, BASILAR artery, T-test (Statistics), STATISTICAL significance, HEPARIN, OPTICAL coherence tomography, BRAIN, DOGS, MAGNETIC resonance imaging, MANN Whitney U Test, DESCRIPTIVE statistics, THROMBOEMBOLISM, ANIMAL experimentation, NEURORADIOLOGY, DATA analysis software, DRUG-eluting stents
Abstract

Background Flow diverters carry the risk of thromboembolic complications (TEC). We tested a coating with covalently bound heparin that activates antithrombin to address TEC by locally downregulating the coagulation cascade. We hypothesized that the neuroimaging evidence of TEC would be reduced by the coating. Methods 16 dogs were implanted with overlapping flow diverters in the basilar artery, separated into two groups: heparin-coated (n=9) and uncoated (n=7). Following implantation, high-frequency optical coherence tomography (HF-OCT) was acquired to quantify acute thrombus (AT) formation on the flow diverters. MRI was performed postoperatively and repeated at 1, 2, 3, 4, and 8 weeks, consisting of T1-weighted imaging, time-0f-flight (ToF), diffusion weighted imaging (DWI), susceptibility weighted imaging (SWI), and fluid attenuated inversion recovery (FLAIR) sequences. Neurological examinations were performed throughout the 8-week duration of the study. Results The mean AT volume on coated devices was lower than uncoated (0.014 vs 0.018 mm³); however, this was not significant (P=0.3). The mean number of foci of magnetic susceptibility artifacts (MSAs) on SWI was significantly different between the uncoated and coated groups at the 1-week follow-up (P<0.02), and remained statistically different throughout the duration of the study. The AT volume showed a direct linear correlation with the MSA count and 80% of the variance in the MSA could be explained by the AT volume (P<0.001). Pathological analysis showed evidence of ischemic injury at locations of MSA. Conclusions Heparin-coated flow diverters significantly reduced the number of new MSAs after 1 week follow-up, showing the potential to reduce TEC. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Extracting the collective wisdom in probabilistic judgments

Author

Peker, Ahmet Cem and Peker, Ahmet Cem

Abstract

How should we combine disagreeing expert judgments on the likelihood of an event? A common solution is simple averaging, which allows independent individual errors to cancel out. However, judgments can be correlated due to an overlap in their information, resulting in a miscalibration in the simple average. Optimal weights for weighted averaging are typically unknown and require past data to estimate reliably. This paper proposes an algorithm to aggregate probabilistic judgments under shared information. Experts are asked to report a prediction and a meta-prediction. The latter is an estimate of the average of other individuals’ predictions. In a Bayesian setup, I show that if average prediction is a consistent estimator, the percentage of predictions and meta-predictions that exceed the average prediction should be the same. An “overshoot surprise” occurs when the two measures differ. The Surprising Overshoot algorithm uses the information revealed in an overshoot surprise to correct for miscalibration in the average prediction. Experimental evidence suggests that the algorithm performs well in moderate to large samples and in aggregation problems where individuals disagree in their predictions.

Published
2023

18. Guess what I think:Essays on the wisdom in meta-predictions

Author

Peker, Ahmet Cem and Peker, Ahmet Cem

Abstract

People’s self-reported beliefs, judgments and experiences are highly subjective and can be unreliable. However, such information is also very valuable. Researchers would like to know the true motives of people to understand their behavior. Practitioners can use subjective data to make better decisions. Furthermore, subjective judgments are useful in forecasting. Previous work suggests that the “Wisdom of Crowds” is an effective solution for predicting uncertain quantities. This dissertation develops novel methods to elicit and aggregate subjective information effectively. All methods are based on the following idea: What people think about other people’s judgments (“meta-prediction”) is related to their own judgment on the matter. Chapter 2 proposes a new forecast aggregation algorithm that improves the “Wisdom of Crowds” on the likelihood of an event. Simple average of forecasts could be biased due to common information among the forecasters. The algorithm uses meta-predictions to remove a potential bias in the collective forecast. Chapter 3 presents another solution to the same problem. Forecasters are incentivized such that the collective forecast becomes unbiased. Chapter 4 develops an incentive mechanism to elicit subjective information truthfully. The incentives are based on people’s meta-predictions. Truth-telling participants expect higher rewards. This motivation can improve the quality of the self-reported information. Chapter 5 focuses again on the “Wisdom of Crowds.” The chapter proposes a new algorithm to transform the average probability forecast. The transformed forecasts are much closer to the true probability of the uncertain event. Each chapter in this dissertation introduces a new incentive mechanism or an algorithm. Therefore, this dissertation makes methodological contributions to the literature on elicitation and aggregation of subjective information. Furthermore, each chapter presents experimental results to demonstrate

Published
2023

19. Guess what I think: Essays on the wisdom in meta-predictions

Author

Peker, Ahmet Cem, Baillon, Aurelien, Bleichrodt, Han, and Applied Economics

Abstract

People’s self-reported beliefs, judgments and experiences are highly subjective and can be unreliable. However, such information is also very valuable. Researchers would like to know the true motives of people to understand their behavior. Practitioners can use subjective data to make better decisions. Furthermore, subjective judgments are useful in forecasting. Previous work suggests that the “Wisdom of Crowds” is an effective solution for predicting uncertain quantities. This dissertation develops novel methods to elicit and aggregate subjective information effectively. All methods are based on the following idea: What people think about other people’s judgments (“meta-prediction”) is related to their own judgment on the matter. Chapter 2 proposes a new forecast aggregation algorithm that improves the “Wisdom of Crowds” on the likelihood of an event. Simple average of forecasts could be biased due to common information among the forecasters. The algorithm uses meta-predictions to remove a potential bias in the collective forecast. Chapter 3 presents another solution to the same problem. Forecasters are incentivized such that the collective forecast becomes unbiased. Chapter 4 develops an incentive mechanism to elicit subjective information truthfully. The incentives are based on people’s meta-predictions. Truth-telling participants expect higher rewards. This motivation can improve the quality of the self-reported information. Chapter 5 focuses again on the “Wisdom of Crowds.” The chapter proposes a new algorithm to transform the average probability forecast. The transformed forecasts are much closer to the true probability of the uncertain event. Each chapter in this dissertation introduces a new incentive mechanism or an algorithm. Therefore, this dissertation makes methodological contributions to the literature on elicitation and aggregation of subjective information. Furthermore, each chapter presents experimental results to demonstrate practical effectiveness. The findings suggest that the meta-predictions can be useful. It is also easy to collect meta-predictions in simple surveys. Thus, this dissertation motivates subsequent work that could use meta-predictions even more extensively.

Published
2023

22. High-frequency optical coherence tomography predictors of aneurysm occlusion following flow diverter treatment in a preclinical model.

Author

King, Robert M., Peker, Ahmet, Anagnostakou, Vania, Raskett, Christopher M., Arends, Jennifer M., Dixit, Harish G., Ughi, Giovanni J., Puri, Ajit S., Gounis, Matthew J., and Shazeeb, Mohammed Salman

Subjects
BIOLOGICAL models, IN vivo studies, ANIMAL experimentation, RABBITS, SURGICAL stents, OPTICAL coherence tomography, RESEARCH funding, ANGIOGRAPHY, INTRACRANIAL aneurysms, ALGORITHMS
Abstract

Background High-frequency optical coherence tomography (HF-OCT) is an intravascular imaging method that allows for volumetric imaging of flow diverters in vivo. Objective To examine the hypothesis that a threshold for both volume and area of communicating malapposition can be predictive of early aneurysm occlusion. Methods Fifty-two rabbits underwent elastase aneurysm formation, followed by treatment with a flow diverter. At the time of implant, HF-OCT was acquired to study the rate and degree of communicating malapposition. Treated aneurysms were allowed to heal for either 90 or 180 days and euthanized following catheter angiography. Healing was dichotomized into aneurysm remnant or neck remnant/complete occlusion. Communicating malapposition was measured by HF-OCT using a semi-automatic algorithm able to detect any points where the flow diverter was more than 50 µm from the vessel wall. This was then summed across image slices to either a volume or area. Finally, a subsampled population was used to train a statistical classifier for the larger dataset. Results No difference in occlusion rate was found between device type or follow-up time (p=0.28 and p=0.67, respectively). Both volume and area of malapposition were significantly lower in aneurysms with a good outcome (p<0.001, both). From the statistical model, a volume of less than 0.56 mm3 or a normalized area less than 0.69 as quantified by HF-OCT was predictive of occlusion (p<0.001, each). Conclusions HF-OCT allows for measurements of both volume and area of malapposition and, from these measurements, an accurate prediction for early aneurysm occlusion can be made. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Retroperitoneal extensive free air bubbles due to decompression illness

Author

ALTAY, CANAN, SEÇİL, MUSTAFA, Akin, IŞIL, ÖZGÜL, HAKAN ABDULLAH, and Peker, Ahmet

Abstract

Decompression illness (DCI) is a rare condition caused by air bubbles that arise because of a rapid decrease in ambient pressure. These air bubbles exert both physical and chemical effects associated with a range of findings from asymptomatic clinical presentation to death. In the literature, changes in consciousness, severe musculoskeletal and abdominal pain, respiratory distress, and skin changes have been described.The diagnosis of DCI is difficult, but anamnesis and physical examination are helpful. Radiologic evaluation is useful for determining possible complications in patients with severe disease and excluding other acute pathologies. In computed tomography (CT) images of patients diagnosed with DCI, air bubbles in the portal venous system, iliac and mesenteric veins, the vena cava inferior (VCI), and the cerebral and spinal arteries have been described before. Herein, we present the clinical and CT findings of two cases of DCI with extensive intra-abdominal free bubbles evident on abdominal CT.

Published
2021

36. A comparison between the efficacy of eccentric exercise and extracorporeal shock wave therapy on tendon thickness, vascularity, and elasticity in Achilles tendinopathy: A randomized controlled trial.

Author

Benli, Merve Demir, Tatari, Hasan, Balcı, Ali, Peker, Ahmet, Şimşek, Kürşat, Yüksel, Oğuz, Kırık, Ayşe Birsu Topcugil, and Tarhan, Mehmet Ali

Abstract

Objectives: This study aims to compare the efficacy of the eccentric exercise (EE) and extracorporeal shock wave therapy (ESWT) on chronic midportion Achilles tendinopathy and evaluate the efficacy of these treatment modalities on tendon thickness, vascularity, and elasticity. Patients and methods: In this randomized controlled trial, a total of 63 patients (40 females, 23 males; mean age: 37.3±12.2; range, 18 to 55 years) with chronic midportion Achilles tendinopathy were enrolled between April 2017 and December 2019. The patients were allocated randomly to two groups: the first group was treated with EE every day for three months with the Alfredson protocol, and the second group received four sessions of ESWT at weekly intervals. The study was terminated at the end of three months. Visual Analog Scales (VAS), Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaires, and ultrasonography measurements were assessed before and after treatment. Patient pain was evaluated at the two-year follow-up. Results: At the three-month follow up, VAS scores decreased, and VISA-A scores increased in both groups (p<0.001). At the two-year-follow-up, VAS scores significantly decreased in the EE group (p<0.001), but the difference was statistically insignificant in the ESWT group (p=0.095). Tendon thickness and stiffness increased in the EE group (p=0.003 and p=0.03, respectively) while the difference was statistically insignificant in the ESWT group after treatment (p=0.173 and p=0.702, respectively). Conclusion: Eccentric exercise and ESWT are efficient in the short term, whereas EE is efficient on tendon pain in the long term. While EE increases tendon thickness and stiffness, ESWT has no effect on these measures. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Dijital ınkjet yazıcılarla sofra eşyası ürünlerinin dekorlanması ve örnek uygulamalar

Author

Peker, Ahmet Osman, Türkel, Efe, and Seramik ve Cam Tasarımı Ana Sanat Dalı

Subjects
Fine Arts, Güzel Sanatlar
Abstract

Bu tez dört ana bölümden oluşmaktadır. İlk bölümde porselen endüstrisinde kullanılan dekor teknikleri ve baskı çeşitleri anlatılmıştır. Dekal baskı, silikon baskı(Tampo), inkjet (püskürtme) hakkında fotoğraflarla beraber genel bilgi verilmiştir.İkinci bölümde ise dijital inkjet baskı yöntemi ile dekorlamada kullanılan makine, inkjet boya türleri, dijital inkjet yazıcısının çalışma prensibi, püskürtme kafalarının bakımı ve temizlenmesi fotoğraflarla ve grafiklerle anlatılmıştır.Üçüncü bölümde tasarımcılar için önem arz eden dijital baskıda renk yöntemi, ICC profil oluşturma, desen oluşturma yöntemleri bilgisayar ekran görüntüleri ve fotoğraflar kullanılarak anlatılmıştır.Dördüncü bölümde dijital inkjet baskı ile ''Hayat Çizgisi'' adlı çalışma endüstriyel tabakların yüzeylerine örnek uygulama yapılmıştır.Sonuç bölümünde ise porselen endüstrisinde kullanılan dijital baskı teknolojisinin üreticiye, tasarımcıya, ürüne ve alıcıya etkisi sorgulanmış, gelişimi devam eden bu teknolojinin ileriki zamanlarda sofra eşyası endüstrisinde ulaşacağı düzey ön görülmüştür.Anahtar Sözcükler: Porselen, Sofra Eşyası, Baskı Teknikleri, Inkjet, Dijital, Desen, Renk This thesis consists of four main chapters. In the first part, general information about all the pattern technologies, decal printing, silicon printing, inkjet (pulverisation) used in the porcelain industry are given with photographs.In the second part, the machine used in decorating with digital inkjet printing method, types of inkjet paints, working principle of digital inkjet printer, maintenance and cleaning of spray heads are explained with photos and graphics.In the third part, the color method in digital printing, Icc profiling, pattern creation methods which have importance for designers are explained by using computer screenshots and photographs.In the fourth chapter, called as 'Lifeline' design is applied as an example to the surfaces of industrial plates with digital inkjet printing.In the conclusion section, the effect of digital printing technology used in the porcelain industry on the manufacturer, designer, product and buyer was questioned, and the level that this developing technology will reach in the tableware industry is predicted in the future.Keywords: Porcelain, Tableware, Printing Techniques, Inkjet, Digital, Pattern, Color 113

Published
2020

45. Orbita Manyetik Rezonans Görüntüleme ile elde olunan vitreus ölçümlerinin glokom tanısındaki rolü

Author

Barış, Mustafa, Peker, Ahmet, Akbulut, Betül, Ayhan, Ziya, Barış, Mine, Karabay, Nuri, and Ege Üniversitesi

Subjects
0-Belirlenecek
Abstract

Amaç: Glokom, optik sinirin progresif dejenerasyonu ve retinal ganglion hücrelerinin kaybı ile karakterize bir grup hastalıktır. Glokomda humör aköz ve vitreus içerisinde protein özelliğinde birçok biyobelirtecin artışı tanımlanmaktadır. Ancak “proteomik” olarak adlandırılan bu proteinlerin biyokimyasal analizi oldukça güçtür. Diğer yandan manyetik rezonans görüntüleme (MRG) tetkikinde, protein içerik, sinyal değişikliğine neden olmaktadır. Çalışmamızın amacı; vitreus içerisinde bulunan protein özelliğindeki moleküllerin MR sinyal değişikliğine neden olabileceği hipotezinden yola çıkarak glokom tanısının orbita MR ile konulmasının etkinliğini araştırmaktır. Gereç ve Yöntem: Hastanemizin Göz Hastalıkları AD. Glokom birimine Nisan - Kasım 2018 ve Ağustos - Ekim 2019 tarihleri arasında başvuran hastalardan glokom tanısı olan ve orbita MR incelemesi bulunanlar retrospektif olarak saptanarak çalışmamıza dahil edilmiştir. Çocuk hastalar, göz travması ya da hasarı bulunan hastalar dışlanmıştır. Kontrol grubu olarak glokom hastalığı bulunmayan, diğer sebeplerle orbita MR tetkiki elde olunan ve orbita MR incelemesi normal olan hastalar seçilmiştir. Hasta ve kontrol grubunun orbita MR tetkiklerinde T1 ve T2 ağırlıklı aksiyel kesitlerde, bilateral bulbus okuli vitreus düzeyine “region of interest” (ROI) yerleştirilerek intensite değerleri ölçülmüştür. Aynı ROI, incelemeye dahil olan beyin omurilik sıvısı (BOS) alanına da yerleştirilerek ölçüm yapılmıştır. Vitreus ve BOS ölçümleri birbirine oranlanarak normalizasyonu sağlanmıştır. İstatistiksel farklılık Mann Whitney U testi uygulanarak araştırılmıştır. Bulgular: Hasta grubunda 16 hastanın 31 gözü, kontrol grubunda ise 16 olgunun 32 gözü değerlendirilmiştir. İki grubun, T1 ağırlıklı görüntülerden gerçekleştirilen ölçümleri arasında istatistiksel olarak anlamlı fark saptanmıştır (p=0,045). Bununla birlikte T2 ağırlıklı görüntülerde ölçümler arasında anlamlı fark saptanmamıştır (p=0,729). Sonuç: Bu çalışma sonucunda glokom hastalarında izlenen vitreal proteinoz değişikliklerin radyolojik olarak da saptanabileceği gösterilmiştir., Objective: Glaucoma is a disease which causes progressive degeneration of optic nerve and cellular damage in retinal ganglion. in glocoma, increase of some protein nature biomarkers (proteomics) in vitreous were defined. Chemical analysis of proteomics is very difficult. on the other hand, it is known that protein content causes intensity changes in magnetic resonance imaging (MRI). Aim of this study, is to evaluate the role of orbital MRI measurements on detecting the presence of proteomics in vitreous. Materials and Methods: Glaucoma patients with orbital MRI investigations in our ophthalmology clinic from April to November 2018 and from August to October 2019 were collected retrospectively. Patients under 18 years of age or with eye trauma clinic or history were excluded. Patients with normal orbital MRI which had been performed due to reasons other than glaucoma were selected for the control group. Vitreous measurements were performed by placing “region of interest” (ROI) on T1 and T2 weighted axial images. Cerebrospinal fluid (CSF) measurements were also performed by using same ROI on the same sequence. Vitreous measurements were divided by CSF measurements for normalization. Mann Whitney U test were performed to evaluate the statistically significant difference. Results: in glaucoma group 31 eyes of 16 patients and in control group 32 eyes of 16 patients were evaluated. Measurements performed on T1 weighted images showed statistically significant difference between two groups (p=0.045). on the other hand, no statistically significant difference was found between the groups with T2 weighted image measurements (p=0.729). Conclusion: Our study showed that it is possible to detect vitreous changes with orbital MRI measurements.

Published
2020

46. May Serum Creatine Kınase (CK) Level Be a Malnutrition Parameter In Patients Wıth End-Stage Kidney Failure?

Author

Peker, Ahmet, Akar, Harun, and Tanrısev, Mehmet

Subjects
Biyoelektriksel empedans, Kreatin kinaz, End-stage renal disease, Sarcopenia, Bioelectrical impedance, Malnutrition, Son dönem böbrek hastalığı, Creatine kinase, Sarkopeni, Malnütrisyon
Abstract

Amaç: Bu çalışmanın amacı; Son Dönem Böbrek Yetmezliği (SDBY) nedeniyle hemodiyaliz (HD) ve periton diyalizi (PD) tedavisi alan hastalarda serum CK düzeyleri ile malnutrisyon parametreleri arasındaki ilişkiyi incelemektir.Gereç ve Yöntem: Prospektif olarak yürütülen bu çalışmada, Türkiye’ nin Ege bölgesinde hizmet veren bir hastanede SDBY nedeniyle HD tedavisi alan 60 hasta ve PD tedavisi alan 30 hasta değerlendirildi. Hastaların serum CK düzeyi ile Mini Nutrisyonel Değerlendirme Testi (MND)’ nden aldıkları puanlar, albumin ve C-Reaktif Protein (CRP) gibi biokimyasal parametreler, arteriyel kan gazı değerleri, KT/V oranı, Biyoelektriksel İmpedans Analiz (BİA) yöntemiyle bakılan total vücut suyu, kas kütlesi, vücut kitle indeksi (VKİ) yağsız vücut kütlesi ve VYO (vücut yağ oranı) gibi değişkenler arasındaki ilişki incelendi.Bulgular: HD ve PD hastalarında CK düzeyleri ile yaş, diyaliz süresi ve Ca değerleri arasında ilişki saptanmadı (p>0,05). HD ve PD hastalarının CK düzeyleri ve MND puanları ile BİA parametrelerinden yağsız vücut kütlesi, vücut kas kütlesi ve VKİ değerleri arasında pozitif yönde, TVS değerleri arasında negatif ilişki saptandı (p 0.05). A positive correlation was found between CK levels and MNA scores and triceps skinfold thickness, lean body mass, body muscle mass and BMI values of PD and HD patients, and a significant negative correlation between total body water values (p

Published
2020
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48. İhracat kredi sigortası, ihracat artışı ve iktisadi büyüme etkisi:Türkiye örneği

Author

Çetiner, Emine Müge, Eke, Selda, and Peker, Ahmet Erdal

Subjects
Açık hesap ihracat, Exports, Open Account Exports, Economic Growth, İhracat Kredi Sigortası, İhract, Kredi Sigortası, İktisadi Büyüme, Credit Insurance, Export Credit Insurance
Abstract

İhracat kredi sigortası, ihracatçıların uluslararası ticarette karşılaştıkları ticari ve politik riskleri güvence altına almak amacıyla kullandıkları bir risk yönetim aracıdır. Bu çalışmanın amacı, ülkemizde kısa vadeli ihracat kredi sigortası, ihracat ve GSYİH arasındaki ilişkiyi deneysel veriler kullanarak ölçmektir. Çözümlemede, nicel araştırma metodlarından ex-post facto yöntemi tercih edilmiştir. Araştırmada, basit regresyon çözümlemesi ile çalışmada ele alınan varsayımlar test edilmiştir. Export credit insurance is a risk management tool for exporters who want to secure themselves against commercial and political risks in international trade. The purpose of this study is to analyze the relationship between short term export credit insurance, total exports and GDP in our country by using empirical data. Ex post facto method was used as being one of the quantitative research methods. Simple regression analysis was employed to test the hypothesis under the investigation.

Published
2019

49. İHRACAT KREDİ SİGORTASI, İHRACAT ARTIŞI VE İKTİSADİ BÜYÜMEYE ETKİSİ: TÜRKİYE ÖRNEĞİ

Author

ÇETİNER, Müge, EKE, Selda, and PEKER, Ahmet Erdal

Subjects
Açık hesap ihracat,kredi sigortası,ihracat kredi sigortası,ihracat,iktisadi büyüme, Social, Sosyal, Open account exports,credit insurance,export credit insurance,exports,economic growth
Abstract

Export creditinsurance is a risk management tool for exporters who want to secure themselvesagainst commercial and political risks in international trade. The purpose ofthis study is to analyze the relationship between short term export creditinsurance, total exports and GDP in our country by using empirical data. Expost facto method was used as being one of the quantitative research methods.Simple regression analysis was employed to test the hypothesis under theinvestigation., İhracat kredisigortası, ihracatçıların uluslararası ticarette karşılaştıkları ticari vepolitik riskleri güvence altına almak amacıyla kullandıkları bir risk yönetimaracıdır. Bu çalışmanın amacı, ülkemizdekısa vadeli ihracat kredi sigortası, ihracat ve GSYİH arasındaki ilişkiyideneysel veriler kullanarak ölçmektir. Çözümlemede, nicel araştırmametodlarından ex-post facto yöntemi tercih edilmiştir. Araştırmada, basitregresyon çözümlemesi ile çalışmada ele alınan varsayımlar test edilmiştir.

Published
2019

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