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Dive into the research topics where Umut Ozyer is active.

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Featured researches published by Umut Ozyer.


European Journal of Radiology | 2009

CT-guided cutting needle lung biopsy using modified coaxial technique: Factors effecting risk of complications

Erkan Yildirim; Ismail Kirbas; Ali Harman; Umut Ozyer; H. Gurkan Tore; Cuneyt Aytekin; Fatih Boyvat

PURPOSE We present our 7-year experience with coaxial computed tomography (CT)-guided cutting needle lung biopsy and evaluate the factors affecting risk of complications. MATERIAL AND METHOD Between June 2000 and March 2007, we performed 225 CT-guided coaxial lung biopsies in 213 consecutive patients (161 men, 52 women). Lesion size, lesion depth, lesion location, needle-pleural angle, presence of pleural effusion, patients position, and complications secondary to biopsy procedure (pneumothorax and bleeding) were noted. Pneumothorax was graded as mild, moderate, and severe. Bleeding complications were graded as mild, moderate, and severe. RESULTS Two hundred twenty-five biopsy procedures were performed in 213 patients. The mean diameter of the lung lesion was 41.3+/-20.1mm. The mean distance from the peripheral margin of the lesion to the pleura was 17.3+/-19.2mm. After 225 procedures, there were 42 mild (18.6%), 13 moderate (5.7%), and 4 severe (1.7%) pneumothoraxes. Small hemoptysis occurred in 27 patients (12%), and mild parenchymal hemorrhage occurred in 2 patients (0.8%). The overall complication rate was 39.1%. Although, a statistically significant correlation was found between female sex, presence of emphysema, lesion depth, and pneumothorax, none of these factors had a predictive value for pneumothorax. Although, statistically significant correlations were found between female sex, lesion size, and bleeding, only lesion size had a predictive value for bleeding. CONCLUSION The most frequent and important complications of this procedure are pneumothorax and bleeding. But any factor is the predictor of pneumothorax and lesion depth is a poor predictor of bleeding complication.


CardioVascular and Interventional Radiology | 2007

Percutaneous Therapy of Ureteral Obstructions and Leak After Renal Transplantation: Long-Term Results

Cuneyt Aytekin; Fatih Boyvat; Ali Harman; Umut Ozyer; T. Colak; Mehmet Haberal

The purpose of this study was to evaluate the long-term outcome of percutaneous therapy of ureteral complications after renal transplantation. Between January 2000 and June 2006 we percutaneously treated 26 renal transplant patients with ureteral obstruction (n=19) and leak (n=7). Obstructions were classified as early (<2 months after transplantation) or late (>2 months). Patients with leak were treated with nephro-ureteral catheter placement and subsequent double-J stenting. Balloon dilatation, stent placement, and basket extraction were used to treat ureteral obstructions. Patients were followed with ultrasonography. No major procedure-related complication occurred. The mean follow-up time was 34.3 months (range: 6 to 74 months). Initial clinical success was achieved in all 19 patients with obstruction and 6 of 7 patients with leak. Four of 9 early obstructions and 4 of 10 late obstructions recurred during the follow-up. All recurrences were initially managed again with percutaneous methods, including cutting balloon technique and metallic stent placement. Although there was no recurrence in patients with successfully treated leak, stricture was seen at the previous leak site in two patients. These strictures were also successfully managed percutaneously. We conclude that in the treatment of ureteral obstruction and leak following renal transplantation, percutaneous therapy is an effective alternative to surgery. However, further interventions are usually needed to maintain long-term patency.


American Journal of Roentgenology | 2009

Long-Term Results of Angioplasty and Stent Placement for Treatment of Central Venous Obstruction in 126 Hemodialysis Patients: A 10-Year Single-Center Experience

Umut Ozyer; Ali Harman; Erkan Yildirim; Cuneyt Aytekin; Feza Karakayali; Fatih Boyvat

OBJECTIVE The objective of our study was to report and compare long-term results of percutaneous transluminal angioplasty and stenting of central venous obstruction in hemodialysis patients. MATERIALS AND METHODS Hemodialysis patients who underwent successful endovascular treatment of central venous obstruction were retrospectively evaluated. Stenotic lesions greater than 50% or inducing extremity swelling were subject to treatment. The primary treatment was angioplasty, and stent placement was accomplished in angioplasty-resistant obstructions. Angioplasty was the primary treatment of recurrence after stent placement. Additional stenting was reserved for angioplasty-resistant recurrences. RESULTS One hundred forty-seven veins in 126 patients (63 males, 63 females) between 15 and 82 years old primarily underwent 101 angioplasties and 46 stent placements. The mean follow-up was 22.1 +/- 16.3 (SD) months. The average number of interventions per vein in the stent group (2.7 +/- 2.4 interventions) was significantly higher than that in the angioplasty group (1.5 +/- 1.0 interventions). Primary patency was significantly higher in the angioplasty group (mean, 24.5 +/- 1.7 months) than that in the stent group (mean, 13.4 +/- 2.0 months). Assisted primary patency of the angioplasty group (mean, 31.4 +/- 2.0 months) and that of the stent group (mean, 31.0 +/- 4.7 months) were equivalent. The overall mean primary patency was 21.1 +/- 1.4 months, and the overall mean assisted primary patency was 31.7 +/- 2.5 months. There were no significant differences in patency rates with regard to patient sex, the type of stent used, the vein or veins treated, or the type of lesions. CONCLUSION Endovascular treatment of central venous obstruction is a safe and effective procedure in hemodialysis patients. Stenting has a significantly lower primary patency rate than angioplasty but adds to the longevity of vein patency in angioplasty-resistant lesions; therefore, stent placement should be considered in angioplasty-resistant lesions.


American Journal of Roentgenology | 2008

Percutaneous Sonographic Guidance for TIPS in Budd-Chiari Syndrome : Direct Simultaneous Puncture of the Portal Vein and Inferior Vena Cava

Fatih Boyvat; Ali Harman; Umut Ozyer; Cuneyt Aytekin; Z. Arat

OBJECTIVE Budd-Chiari syndrome (BCS) is a clinical condition characterized by hepatic venous outflow obstruction. A transjugular intrahepatic portosystemic shunt (TIPS) is an effective means of decompressing the portal system in patients unresponsive to traditional medical therapy. TIPS may be difficult in patients with BCS owing to the presence of hepatic venous occlusive disease. We present our experience using direct percutaneous simultaneous puncture of the portal vein and the inferior vena cava to place a TIPS in patients with BCS. MATERIALS AND METHODS Between September 2003 and October 2006, percutaneous sonographically guided TIPS was performed on 11 patients (five women and a girl, four men and a boy; age range, 6-43 years). Indications for the TIPS procedure were intractable ascites in nine patients and intractable ascites and variceal bleeding in two patients. RESULTS Technical success was achieved in all patients. The mean portosystemic pressure gradient was reduced from 23.5 to 9.8 mm Hg. The cumulative rate of primary patency was 60% at 1 year. Nine revisions were performed in five patients. In nine of the 11 patients, ascites resolved completely, and in two patients, it was relieved. CONCLUSION Excellent technical and clinical success can be achieved with percutaneous sonographically guided direct simultaneous puncture of the portal vein and inferior vena cava in patients with BCS.


European Radiology | 2007

Management of infracentimetric thyroid nodules with respect to ultrasonographic features

Reha Butros; Fatih Boyvat; Umut Ozyer; Banu Bilezikçi; Z. Arat; Cuneyt Aytekin; Nilgun Guvener; Beyhan Demirhan

An assumed indolent course of thyroid microcarcinomas and concerns about the cost-effectiveness of treatment raise management issues. As various studies have reported controversial results, management remains unclear. The purpose of this study was to examine the use of ultrasonography (US) in detecting malignancies in a series of 589 infracentimetric nodules. Results of fine-needle aspiration biopsies (FNAB) revealed 503 nodules with adequate cytology. Of these, 473 (94%) were benign, 13 (2.6%) were suspicious for malignancy, 13 (2.6%) were malignant, and 4 (0.8%) were follicular neoplasms. Hypoechogenicity and accompanying lymphadenopathy were the independently significant features in detecting malignancies. Certain combinations of US features increase the significance and predictive value for malignant cytology particularly in the presence of lymphadenopathy. When the postoperative histological results of ten patients with a final diagnosis of papillary carcinoma were evaluated for extent of disease, seven (70%) had one or more of the findings of multifocality, metastatic lymph nodes, or extracapsular involvement, thus proving their clinical significance. Our results indicate that thyroid microcarcinomas should be taken seriously if there are possible signs of malignancy on US. With respect to the high benign nature of the micronodules (94%), the number of interventional procedures should be lowered by making assessments based on a combination of US features including lymphadenopathy.


Indian Journal of Radiology and Imaging | 2009

Imaging of a retained laparotomy towel that migrated into the colon lumen

Umut Ozyer; Fatih Boyvat

Retention of surgical instruments, most commonly small laparotomy sponges, is a known complication of surgery. Such retained instruments may remain silent or may cause a variety of complications. We report a case in which a retained laparotomy towel migrated into the colon. This is an infrequently reported complication. We were able to document the passage of the towel through the colon on plain radiographs. The USG and MRI findings are also described.


Acta Radiologica | 2009

Correction of displaced peritoneal dialysis catheters with an angular stiff rod

Umut Ozyer; Ali Harman; Cuneyt Aytekin; Fatih Boyvat; N. Ozdemir

Background: Fluoroscopically guided guidewire manipulations are readily available and inexpensive methods of correcting malfunctioning peritoneal dialysis catheters, with reported success rates ranging from 25% to 67%. Purpose: To improve the success rates of guidewire manipulations with a modified technique. Material and Methods: Using a stiff rod and a stiff wire under fluoroscopy guidance, catheters that had migrated were drawn back into the rectovesical pouch. An angular rod was used to lever the catheter downward, and the guidewire was used to push the catheter down. Results: No complications developed, and immediate success was achieved in 13 of 14 interventions. With this technique, catheter patency in chronic ambulatory peritoneal dialysis (CAPD) patients (11/12) was higher than that of previously reported methods. Durable success was maintained in nine of 12 patients after a single intervention. All re-manipulations (2/2) were successful. Conclusion: Although used in only 14 interventions in 12 patients, the outcome was promising. This method is a safe and favorable alternative to other guidewire manipulations, based on absence of complications and high success.


Fetal Diagnosis and Therapy | 2005

Fetal MRI of a Severe Dandy-Walker Malformation with an Enlarged Posterior Fossa Cyst Causing Severe Hydrocephalus

Mehmet Teksam; Umut Ozyer; Alexander M. McKinney; Ismail Kirbas; Banu Cakir

We present a case of severe Dandy-Walker malformation with enlarged posterior fossa cyst extruding through the incisura of the tentorium and causing severe hydrocephalus. A posterior fossa malformation was suspected by ultrasonography and was further evaluated by fetal magnetic resonance imaging (MRI). Fetal MRI demonstrated that there were no associated anomalies and the decision was made to continue with labor instead of terminating the pregnancy. The precise diagnosis and absence of associated anomalies revealed by MRI aided in parent counseling and obstetrical management.


Journal of Vascular Access | 2015

Ultrasound-guided brachiocephalic vein catheterization in infants weighing less than five kilograms

Cuneyt Aytekin; Umut Ozyer; Ali Harman; Fatih Boyvat

Purpose To describe our experience with the use of ultrasound-guided supraclavicular brachiocephalic vein approach for central vein catheterization in infants weighing less than 5 kg. Methods A retrospective review was performed for infants who underwent ultrasound-guided central vein catheterization from January 2012 to November 2014. Infants weighing less than 5 kg with supraclavicular brachiocephalic vein access were included in the study. Indications for central venous access, venous access side, catheter type and complications were evaluated. Results Thirty-four catheterizations in 34 infants weighing from 1.5 to 4.9 kg (median 3.48 kg) were included in the study (aged 11 days to 7 months and 10 days, weight range 1.5 to 4.9 kg). Technical success rate was 97% (33 of 34 infants). No technical or clinical major complications were observed. Conclusions Ultrasound-guided supraclavicular brachiocephalic vein access is a favorable alternative for central venous catheterization in low-weight infants with regard to high technical success rate and absence of major complications.


CardioVascular and Interventional Radiology | 2010

Emergency Renal Ablation for Life-Threatening Hemorrhage from Multiple Capsular Branches During Renal Artery Stenting

Cuneyt Aytekin; Utku Mahir Yıldırım; Umut Ozyer; Ali Harman; Fatih Boyvat

A 55-year-old woman underwent bilateral renal artery stent placement with good angiographic result. After the procedure, the patient complained of left flank pain secondary to subcapsular hematoma. Retrospective evaluation of images taken during stent implantation favored the diagnosis of guidewire perforation. Three hours after the procedure, contrast-enhanced computed tomography and subsequent renal angiography showed multifocal extravasations. We performed emergent renal ablation for the treatment of massive bleeding. To our knowledge, this is the first use of transcatheter renal ablation technique for this purpose.

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