Zafer Koc
Başkent University
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Featured researches published by Zafer Koc.
American Journal of Roentgenology | 2007
Zafer Koc; Levent Oguzkurt; Serife Ulusan
OBJECTIVE The aims of this study were to present the prevalence, imaging and clinical findings, and possible causes of portal venous system aneurysms. MATERIALS AND METHODS From 1998 to 2006, a total of 38 portal venous system aneurysms identified in 25 patients were retrospectively reviewed. The data of seven patients diagnosed using color Doppler sonography or CT before March 2004 were not consecutive, but the data recorded thereafter comprised the analysis of 4,186 consecutive patients who underwent routine abdominal MDCT. The patients were 14 men and 11 women (mean age -/+ SD, 53 -/+ 17 years). RESULTS The prevalence of portal venous system aneurysm among 4,186 consecutive patients was 0.43%. There were no differences with respect to patient age, patient sex, and intrahepatic or extrahepatic location of aneurysm between those with and those without portal venous system aneurysm. Seven of the 25 patients with portal venous system aneurysm were symptomatic because of portal vein thrombosis, and six of them had recurrence. These patients had significantly larger aneurysms than those without symptoms. Four of those seven symptomatic patients evaluated for thrombophilia had an underlying defect. Other associated findings were splenomegaly (n = 16), portal hypertension (n = 8), cirrhosis (n = 3), psoriasis (n = 2), portal vein variation (n = 1), chronic pancreatitis (n = 1), and cutis laxa (n =1). CONCLUSION Portal venous system aneurysms were rare in our study group but occurred more frequently than previously thought. All thrombosed aneurysms, most with a recurrence, were symptomatic and larger in patients with symptoms of portal venous system aneurysm than in those without symptoms. There were no differences among patients with portal venous system aneurysm and those without portal venous system aneurysm with respect to patient age and patient sex. Among those with aneurysms, there was no difference between subjects with intrahepatic versus extrahepatic aneurysms. A thrombophilic defect probably played a role in development of thrombosis in the portal venous system aneurysm.
Journal of Vascular and Interventional Radiology | 2008
Levent Oguzkurt; Ugur Ozkan; Serife Ulusan; Zafer Koc; Fahri Tercan
PURPOSE To retrospectively evaluate compression of the left common iliac vein as demonstrated at computed tomography (CT) in patients with iliofemoral deep vein thrombosis due to iliac vein compression syndrome (IVCS) and compare compression ratios with those of asymptomatic subjects. MATERIALS AND METHODS Between March 2003 and June 2007, compression of the left common iliac vein by the right common iliac artery, as demonstrated with CT, in 34 patients (25 women and nine men; mean age, 51 years; age range, 21-79 years) with IVCS was retrospectively evaluated. Compression ratios were compared with those of 34 age- and sex-matched asymptomatic subjects. A t test was used to compare the compression ratios. RESULTS The percentages of compression of the left common iliac vein were 45%-100% (mean, 74% +/- 17) for patients with IVCS and 0%-68% (mean, 28% +/- 20) for control subjects (P < .05). Of the 34 patients with IVCS, 11 (32%) had less than 70% compression and 23 (68%) had at least 70% compression. CONCLUSIONS There was considerable overlap between the degree of compression in patients with IVCS and control subjects. Compression of the left common iliac vein was significantly more prominent in patients with lower extremity deep vein thrombosis due to IVCS when compared with control subjects. Compression in excess of 70% as demonstrated at CT can be helpful for identifying possible underlying IVCS in patients with a left lower extremity deep vein thrombosis.
Diagnostic and interventional radiology | 2008
Zafer Koc; Serife Ulusan; Naime Tokmak
PURPOSE The aim of this study was to present the imaging characteristics of patients with hepatobiliary fascioliasis and describe a new imaging finding. MATERIALS AND METHODS Imaging and clinical findings of five patients diagnosed with hepatobiliary fascioliasis were retrospectively evaluated. All patients were examined by abdominal ultrasonography (US) and computed tomography (CT); two were additionally evaluated by abdominal magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP). Diagnosis was confirmed by serology and parasitology tests in all patients. RESULTS Presenting complaints were abdominal pain in four patients, with fever in one of the four. All patients also had eosinophilia and abnormal liver function tests. In all patients, US examinations showed multiple hypoechoic nodules or parenchyma heterogeneity. CT examinations showed linear or branching, and nodular hypodense lesions in the liver. As a new imaging finding, hyperdense materials were identified in the dilated bile duct in one patient. MRI showed T1 hypo and T2 hyperintense areas of liver parenchyma in two patients, with peripheral enhancement in one of them. Filling defects and dilation of the intra-extrahepatic bile ducts were identified by US and MRCP in two patients. In these two patients Fasciola flukes were removed by ERCP. Medical treatment (triclabendazole) was successful in all patients. CONCLUSION Hepatobiliary fascioliasis is a rare disease which may have typical imaging findings in the liver and bile ducts as seen in our patients. Imaging characteristics with clinical findings may have a diagnostic clue especially in endemic areas.
International Journal of Neuroscience | 2008
Filiz Koç; Deni˙z Yerdelen; Zafer Koc
The neurofibromatoses are genetic disorders of the nervous system that primarily affect the development and growth of neural (nerve) cell tissues. The neurofibromatoses are classified as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). NF1 is the more common type of the neurofibromatoses. The gene responsible for NF1 is located on the chromosome region 17q11.2 and for familial moyamoya disease on chromosome 17q25. This article reports on a 20-year-old female with neurofibromatosis-1 who developed moyamoya syndrome. More extensive reports and further investigations of such families having this combination will certainly provide a better understanding of this link in the near future.
Journal of Magnetic Resonance Imaging | 2014
Zafer Koc; Gurcan Erbay
To explore the optimal b value in diffusion‐weighted imaging (DWI) for differentiation of benign and malignant abdominal lesions.
Acta Radiologica | 2012
Gurcan Erbay; Zafer Koc; Elif Karadeli; Baris Kuzgunbay; M Resit Goren; Nebil Bal
Background Limited data are available regarding the use of diffusion-weighted (DW) magnetic resonance imaging (MRI) with multiple b values for characterization of renal lesions. Purpose To demonstrate and compare the diagnostic performance of DW-MRI with multiple b values for renal lesion characterization. Material and Methods Sixty-three lesions (36 malignant, 27 benign) in 60 consecutive patients (48 men, 12 women; age 60 ± 12.5 years) with solid/cystic renal lesion diagnosed after MRI were included prospectively. Single-shot echo-planar DW abdominal MRI (1.5T) was obtained using seven b values with eight apparent diffusion coefficient (ADC) maps. Contrast-to-noise ratios (CNRs), signal intensities, lesion ADCs, and lesion/normal parenchyma ADC ratios were analyzed. Receiver-operating characteristic analysis was performed. Results The mean signal intensities of malignant lesions (at b0, 50, and 200s/mm2) were significantly lower than those of benign lesions (P < 0.05). The mean ADC values at all b value combinations of malignant lesions were significantly lower than those of benign lesions (P < 0.000), excluding the ADC value at b50 s/mm2. ADC with all b values could better distinguish between benign and malignant lesions. A 1.35 × 10−3 mm2/s threshold ADC value permitted this distinction with 85.2% sensitivity and 65.6% specificity. The lesion/normal parenchyma ADC ratio was more effective than the lesion ADC. Conclusion In addition to the ADC value, the signal intensity curve on DW images using multiple b values could be helpful for differentiation of malignant and benign renal lesions.
International Journal of Neuroscience | 2007
Zafer Koc; Filiz Koc; Deniz Yerdelen; Hakan Ozdogu
Rhino-orbital-cerebral mucormycosis is a rare but often fatal opportunistic necrotizing infection of the sinuses, orbit, and brain caused by saprophytic fungi. It usually develops in patients with diabetes or immune system deficiency. In this study, imaging features in 3 patients with rhino-orbital-cerebral mucormycosis who presented with various symptoms and different cerebral involvements are discussed. Headache, blurred vision, fever, painful ophthalmoplegia, and cranial nerve involvement were among the clinical findings. Computed tomography and magnetic resonance imaging are the best imaging methods for assessing the extent of this disease. Relatively typical but nonspecific characteristics are bone destruction, vascular invasion, and central hypointensity in the paranasal sinuses or an intracranial mass that is revealed by T2-weighted magnetic resonance imaging. Imaging findings include cavernous sinus involvement, cerebral infarct, and intracerebral hemorrhage. Because of the invasive and fulminant nature of rhino-orbital-cerebral mucormycosis, successful treatment seems to be based on early diagnosis and on the management of underlying immunologic problems.
European Radiology | 2007
Zafer Koc; Serife Ulusan; Levent Oguzkurt
The aim of this study was to determine whether left renal vein (LRV) variation is associated with pelvic varices and left ovarian vein (LOV) reflux. Routine abdominal multidetector-row computed tomography scans of 324 women without symptoms of pelvic congestion syndrome were analyzed. Presence and type of LRV variants (circumaortic [CLRV] or retroaortic [RLRV]) were recorded. Diameters of the LRV, ovarian veins (OVs), and parauterine veins were measured and a specific LRV diameter ratio was calculated for each patient. Presence and severity of pelvic varices and LOV reflux were noted. Pelvic varices were detected in 59 (18%) of the total of 324 women, in 7 (37%) of the 19 women with RLRVs, in 7 (29%) of the 24 women with CLRVs, and in 45 (16%) of the 281 women with normal LRVs. The frequency of pelvic varices in the women with LRV variation was significantly higher than that in the group with normal LRV anatomy (33 vs. 16%; p=0.009). The frequency of pelvic varices in the women with RLRVs was also significantly higher than that in the group with normal LRV anatomy (p=0.02). LRV diameter ratio was correlated with presence of pelvic varices and presence of LOV reflux (p=0.0001 for both). This study revealed an association between pelvic varices and LRV variations in a population of predominantly multiparous women.
Onkologie | 2012
Cem Onal; Huseyin Abali; Zafer Koc; Sibel Kara
Background: Radiation recall pneumonitis (RRP) occurs in a previously irradiated field and is triggered by certain cytotoxic drugs, principally chemotherapeutic agents such as erlotinib. Erlotinib is a reversible epidermal growth factor receptor tyrosine kinase inhibitor (TKI) and is an effective second-line treatment for patients with advanced-stage non-squamous-cell lung cancer. Previously, only 2 cases of radiation recall after erlotinib treatment have been reported. Here, we report a case of RRP caused by treatment with erlotinib 4 months after palliative definitive hypofractionated radiation therapy (RT). Patient and Methods: A 58-year-old male patient with non-small cell lung cancer (adenocarcinoma) was treated with polychemotherapy, palliative RT (30 Gy in 10 fractions), and erlotinib thereafter. Results: Dosimetric analysis obtained from a 3-dimensional conformal RT planning system revealed that the volume of lung receiving at least 20 Gy (V20) was 21.2% and the mean lung dose was 12.7 Gy. These data indicate that systemic administration of a TKI, even after palliative RT, may lead to unexpected toxicity when the radiation field encompasses visceral organs. Conclusion: We conclude that the use of a TKI after RT may trigger radiation pneumonitis. Although evidence is limited, we advise clinicians to be cautious of RRP after erlotinib treatment.
Renal Failure | 2010
Hasan Micozkadioglu; Zafer Koc; Ruya Ozelsancak; Ismail Yildiz
Tuberous sclerosis complex (TSC) is an inherited multisystem disorder; it may involve kidney, brain, skin, lungs, and liver. We report a 37-year-old female TSC patient presenting with skin lesions (angiofibromas, molluscum pendulum). Radiologic examination revealed additional brain and renal lesions consisting of tumors, cysts, and angiomyolipomas. Treatment with rapamycin disclosed improvement in skin lesions. The number and volume of angiofibromas and molluscum pendulum reduced progressively in 6 months. During the ninth month of treatment, magnetic resonance imaging was repeated for renal and brain lesions. Imaging results showed reduction in tumor and angiomyolipoma volumes. Oral rapamycin therapy can improve renal, brain, and skin lesions in TSC disease. Therefore, it may be an alternative therapy for TSC patients.