A Fuat Yapar

Baskent University, Engüri, Ankara, Turkey

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Publications (53)121.2 Total impact

  • Nese Torun · Mehmet Reyhan · Ali Fuat Yapar · Muge Karatas
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    ABSTRACT: We report a 68-year-old woman with papillary thyroid carcinoma metastasizing to choroid. The choroid metastasis was diagnosed with SPECT-CT and then was treated with high-dose radioactive iodine therapy. Copyright
    No preview · Article · Jan 2016 · Clinical Nuclear Medicine
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    ABSTRACT: Breast metastases from an extramammary primary tumor are very rare, particularly in men. In this study, we present a case of a 74-year-old man with isolated breast metastasis from lung adenocarcinoma as an incidental finding on PET/CT and diagnosed concomitantly with the primary tumor. Detection of isolated incidental metastatic lesions in the breast on PET/CT imaging has a significant clinical impact on patients with known malignant disease due to change of disease stage, management, and also treatment method.
    No preview · Article · Nov 2015 · Clinical nuclear medicine
  • Gül Nihal Nursal · Mehmet Reyhan · Ali Fuat Yapar
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    ABSTRACT: Static renal scintigraphy with Tc-DMSA is commonly used for the evaluation of renal morphology and function. Extrarenal uptake of Tc-DMSA is a rare finding described previously on sites such as bone metastasis, hemangioma, and splenic amyloidosis. We report a case with Tc-DMSA activity in the lungs.
    No preview · Article · Jun 2015 · Clinical nuclear medicine
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    Full-text · Article · Jun 2015
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    S. Erhamamci · M. Reyhan · G.N. Nursal · N. Torun · A.F. Yapar
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    ABSTRACT: Objective: Clinical data are presented on patients with tumor thrombosis (TT) incidentally detected on FDG PET/CT imaging, as well as determining its prevalence and metabolic characteristics. Materials and methods: Out of 12,500 consecutive PET/CT examinations of patients with malignancy, the PET/CT images of 15 patients with TT as an incidental finding were retrospectively investigated. A visual and semiquantitative analyses was performed on the PET/CT scans. An evaluation was made of the pattern of FDG uptake in the involved vessel as linear or focal via visual analyses. For the semiquantitative analyses, the metabolic activity was measured using SUVmax by drawing the region of interest at the site of the thrombosis and tumor (if any). Results: The prevalence of occult TT was 0.12%. A total of 15 patients had various malignancies including renal (1 patient), liver (4), pancreas (2), stomach (1), colon (1), non-Hodgkin lymphoma (1), leiomyosarcoma (1), endometrial (1), ovarian (1), malign melanoma (1) and parotid (1). Nineteen vessels with TT were identified in 15 patients; three patients had more than one vessel. Various vessels were affected; the most common was the inferior vena cava (n=7) followed by the portal (n=5), renal (n=3), splenic (n=1), jugular (n=1), common iliac (n=1) and ovarian vein (n=1). The FDG uptake pattern was linear in 12 and focal in 3 patients. The mean SUVmax values in the TT and primary tumors were 8.40±4.56 and 13.77±6.80, respectively. Conclusion: Occult TT from various malignancies and locations was found incidentally in 0.12% of patients. Interesting cases with malign melanoma and parotid carcinoma and with TT in ovarian vein were first described by FDG PET/CT. Based on the linear FDG uptake pattern and high SUVmax value, PET/CT may accurately detect occult TT, help with the assessment of treatment response, contribute to correct tumor staging, and provide additional information on the survival rates of oncology patients.
    Full-text · Article · May 2015 · Revista Española de Medicina Nuclear e Imagen Molecular
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    ABSTRACT: Elastofibroma dorsi (ED) is a rare pseudotumor of the soft tissues that can also show 18F-fluorodeoxyglucose ((18)F-FDG) uptake on positron emission tomography combined with computed tomography (PET/CT) imaging. The aim of this retrospectively study was to describe the metabolic characteristics of ED incidentally detected by (18)F-FDG PET/CT imaging. Between November 2009 and August 2013 at our institution, 10,350 consecutive PET/CT examinations were retrospectively investigated. In 176 of these patients, ED was recorded as an incidental finding. Fifty-five of 176 patients also had follow-up scans after chemoradiotherapy. A total of 231 scans with ED in 176 patients were identified. To determine the metabolic activity of ED, the maximum standardized uptake value (SUVmax) was calculated semiquantitatively. For measurement size of ED, the longest axis of transaxial CT images was used. Seven of the 176 patients underwent surgery due to suspected metastases and/or invasion of primary malignancy and/or symptoms or incidental during surgery. The prevalence of ED in our series was 1.7 %. The lesions were located in the subscapular region in all patients, except in one case with a lesion in the infrascapular region. A total of 419 ED lesions in 231 scan of 176 patients were evaluated. Mean ± SD SUVmax and long axis values for these 419 lesions were 2.31 ± 0.61 (range 1.0-4.30) and 56.78 ± 17.01 mm (range 19-112 mm), respectively. Of these 176 patients, 141 (80.1 %) had bilateral lesions and 35 (19.9 %) had unilateral lesions. There were statistically significant differences in the SUVmax and long axis values between the right and left side in the bilateral lesions (p = 0.001). No significant differences in the SUVmax and long axis values of the lesion were found between pre- and posttreatment in the patients with follow-up scans. Elastofibroma dorsi located in the scapular region is usually bilateral, asymmetric and with mild or moderate metabolic activity on PET/CT imaging. In addition, the metabolic activity and size of ED remained stable after chemoradiotherapy. Awareness of these metabolic characteristics of ED is important for preventing misinterpretation during (18)F-FDG PET/CT studies.
    Full-text · Article · Feb 2015 · Annals of Nuclear Medicine
  • Gül Nihal Nursal · Ali Fuat Yapar
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    ABSTRACT: We report a case of a 37-year-old woman with severe headache that is provoked by postural changes who was referred to the nuclear medicine department for radionuclide cisternography to demonstrate suspected cerebrospinal fluid leakage. There was an increased uptake laterally on the left paraspinal region of upper thoracal spine and posteriorly on the upper cervical region. Fused SPECT/CT images located the exact leakage site as at the first costovertebral junction level on the left side laterally and on the posterior region of the first and second cervical spine. The treatment with epidural blood patch was successful.
    No preview · Article · Jul 2014 · Clinical Nuclear Medicine
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    ABSTRACT: Simultaneous occurence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) in a single patient is an unusual event. The incidence, cell origin, histopathology features and prognosis of these two carcinomas are considered completely different. The aim of this retrospective study was to describe clinical, pathologic characteristics and the prevalence of diagnosing such patients in our clinic. Between October 2003 and December 2013, 1.420 consecutive patients diagnosed by histology as having differentiated thyroid carcinoma (DTC) and treated with radioactive iodide (RAI) were retrospectively investigated. Of these, 4 patients were diagnosed by histology as having simultaneous MTC and PTC. The clinical and pathology characteristics of these patients are described. The prevalence of simultaneous MTC and PTC of these 4 patients in our clinic was 0.28% of all patients with DTC. The age of the 4 patients ranged from 44 to 63 years and were three females and one male. These patients are currently alive without disease from either of the two types of cancer. In two of these patients, MTC was located in the left and PTC in the right thyroid lobe. One patient had MTC in the right lobe and PTC in both lobes. The remaining patient had both cancers in the left lobe as a mixed tumor. We are able to present the pathology of only 2 of these 4 patients. In these 2 patients MTC was located in the left and PTC in the right thyroid lobe, one of them was female and the other was male, aged 44 and 49, respectively. In conclusion, our results suggested that simultaneous occurrence of MTC and PTC had a prevalence in our clinic of 0.28% among 1420 consecutive patients with DTC or 0.14%, if only the 2 patients in whom we are able to present their pathology slides are considered. Our cases suggest that these two tumors are usually independent and coincidental events in every patient.
    Full-text · Article · Jul 2014 · Hellenic journal of nuclear medicine
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    Cem Onal · Mehmet Reyhan · Ozan C Guler · Ali Fuat Yapar
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    ABSTRACT: We sought to evaluate failure patterns and prognostic factors predictive of recurrences and survival in cervical cancer patients who are treated with definitive chemoradiotherapy (ChRT), who have a subsequent complete metabolic response (CMR) with (18) F-fluorodeoxyglucose positron-emission tomography (FDG-PET) after treatment. The records of 152 cervical cancer patients who were treated with definitive chemoradiotherapy were evaluated. All patients underwent pre-treatment positron emission tomography (PET-CT), and post-treatment PET-CT was performed within a median of 3.9 months (range, 3.0-9.8 months) after the completion of ChRT. The prognoses of partial response/progressive disease (PR/PD) cases (30 patients, 18 %) and CMR cases (122 patients, %82) were evaluated. Univariate and multivariate analysis effecting the treatment outcome was performed in CMR cases. The median follow-ups for all patients and surviving patients were 28.7 (range, 3.3-78.7 months) and 33.2 months (range, 6.23-78.7 months), respectively. Four-year overall survival (OS) rate was significantly better in patients with CMR compared to patients with PR/PD (66.9 % vs. 12.4 %, p < 0.001, respectively). Patients with PR/PD had higher maximum standardized uptake value (SUVmax) of primary cervical tumor (26.4 ± 10.1 vs. 15.9 ± 6.3; p < 0.001) and larger tumor (6.4 cm ± 2.3 cm vs. 5.0 cm ± 1.4 cm; p < 0.001) compared to patients with CMR. Of the 122 patients with post-treatment CMRs, 25 (21 %) developed local, locoregional, or distant failure. In univariate analysis, tumor size ≥ 5 cm, 'International Federation of Obstetricians and Gynecologists' (FIGO) stage ≥ IIB, and pelvic and/or para-aortic lymph node metastasis were predictive of both overall survival (OS) and disease-free survival (DFS), while histology was predictive of only OS. In multivariate analysis, tumor size, stage and lymph node metastasis were predictive of OS and DFS. Although CMR is associated with better outcomes, relapses remain problematic, especially in patients with bulky tumors (≥ 5 cm), extensive stage (≥ IIB) or pelvic and/or para-aortic lymph node metastasis. These findings could support the need for more aggressive treatment or adjuvant chemotherapy regimens.
    Full-text · Article · Feb 2014 · European Journal of Nuclear Medicine
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    Erkan Topkan · Cem Parlak · Ali Fuat Yapar
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    ABSTRACT: The impact of [(18)F]fluorodeoxyglucose-positron emission tomography (PET)/computed tomography (CT) restaging on management decisions and outcomes in patients with locally advanced pancreatic carcinoma (LAPC) scheduled for concurrent chemoradiotherapy (CRT) is examined. Seventy-one consecutive patients with conventionally staged LAPC were restaged with PET/CT before CRT, and were categorized into non-metastatic (M0) and metastatic (M1) groups. M0 patients received 50.4 Gy CRT with 5-fluorouracil followed by maintenance gemcitabine, whereas M1 patients received chemotherapy immediately or after palliative radiotherapy. In 19 patients (26.8%), PET/CT restaging showed distant metastases not detected by conventional staging. PET/CT restaging of M0 patients showed additional regional lymph nodes in 3 patients and tumors larger than CT-defined borders in 4. PET/CT therefore altered or revised initial management decisions in 26 (36.6%) patients. At median follow-up times of 11.3, 14.5, and 6.2 months for the entire cohort and the M0 and M1 cohorts, respectively, median overall survival was 16.1, 11.4, and 6.2 months, respectively; median locoregional progression-free survival was 9.9, 7.8, and 3.4 months, respectively; and median progression-free survival was 7.4, 5.1, and 2.5 months, respectively (P < 0.05 each). These findings suggest that PET/CT-based restaging may help select patients suitable for CRT, sparing those with metastases from futile radical protocols, and increasing the accuracy of estimated survival.
    Full-text · Article · Oct 2013 · Cancer Imaging
  • Yapar A.F · Topkan E

    No preview · Chapter · Sep 2013
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    ABSTRACT: Introduction: The aim of this study was to compare computed tomography (CT)- and positron emission tomography (PET)/CT-based gross tumor volume (GTV) delineation and its subsequent expansion to the planning target volume (PTV), and to analyze the resultant doses of 3-dimensional conformal radiotherapy (3D-CRT) to critical organs. Methods: 15 patients with unresectable extrahepatic cholangiocarcinoma (EHCC) were enrolled into this study. PTVCT-based plans were initially made, and then PTVPET-CT-based plans were created using the same beam angles and isocenter. The dosimetric parameters analyzed included GTVCT, PTVCT, GTVPET-CT and PTVPET-CT. Prescribed and delivered radiation doses to target volumes and delineated organs at risk were also compared. Results: Mean GTV and PTV were significantly reduced in the PET/CT-based plan compared to the CT-based plan; the mean reductions of GTV and PTV were 28.7% and 15.2%, respectively. The mean value for GTVPET/GTVCT mismatch was 49.5 ± 28.9%, and that for GTVCT/GTVPET was 95.9 ± 19.5%. The mean value for PTVPET-CT/PTVCT mismatch was 21.9 ± 7.0% and that for PTVCT/PTVPET-CT was 39.1 ± 9.2%. Liver doses were significantly reduced (17.1%) in the PET/CT-based plan compared to the CT-based plan; the doses received by at least 30% and 50% of the liver were 30.0%, and 27.3%, respectively. Conclusion: The potential benefit of PET/CT is the reduction in geographic misses and regional treatment failures associated with CT-based planning.
    Full-text · Article · Sep 2013 · Onkologie
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    ABSTRACT: Metastatic insulinomas may sometimes present with recurrent life-threatening hypoglycemia episodes. Such patients usually fail to respond to various therapeutic agents which causes constant dextrose infusion requirement. Herein, we present a resistant case of inoperable malignant insulinoma who was treated with many therapeutic agents and interventions including somatostatin analogues, Yttrium-90 radioembolization, everolimus, radiotherapy, and chemoembolization. Close blood sugar monitorization during these therapies showed the most favourable response with everolimus. Everolimus treatment resulted in rapid improvement of hypoglycemia episodes, letting us discontinue dextrose infusion and discharge the patient. However, experience with everolimus in such patients is still limited, and more precise data can be obtained with the increasing use of this agent for neuroendocrine tumours.
    Full-text · Article · May 2013 · Case Reports in Endocrinology
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    ABSTRACT: Purpose: We investigated the usability of standardized uptake values (SUV) obtained from both two- and three-dimensional (2D and 3D) positron-emission tomography and computed tomography (PET-CT) imaging, and compared the images obtained from these techniques in terms of image quality, lesion detectability, and the presence of artifacts. Materials and methods: Image data from 100 patients, who had undergone two PET imagings obtained in 2D and 3D mode after a low dose CT, were evaluated prospectively. Subjective analysis of 2D and 3D images was performed by two readers evaluating the following criteria: overall image quality, detectability of each identified lesion, and the presence of artifacts. The lesions recognized by the readers were also analyzed quantitatively by measuring SUV values. Results: There was a significant difference between the SUVs obtained in 2D and 3D modes. Regardless if the first scan was performed in 2D or 3D mode, the values obtained from 3D imaging were significantly lower than those obtained from 2D imaging (mean SUV(max) was 10.48±7.57 for 2D, and 9.66±6.93 for 3D, P < 0.001). Visual analysis did not reveal significant differences regarding lesion detectability between two modes. Conclusion: In oncological PET-CT applications, SUV values are significantly lower in 3D compared with 2D mode. Thus when serial scanning is needed to evaluate response to therapy in the same patient, the imaging modality should be taken into account and performed with the same method to avoid misinterpretation. Additionally, 3D PET-CT imaging can be used instead of 2D PET-CT due to its shorter scanning time without loss of lesion detectability.
    No preview · Article · Dec 2012 · Diagnostic and interventional radiology (Ankara, Turkey)
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    ABSTRACT: Background: Assessment of carbohydrate antigen (CA) 19-9 levels is used for diagnosis and follow-up of pancreaticobiliary cancers, and high levels of this biomarker are suggestive of a malignancy. CA 19-9 may also be elevated in patients with conditions other than tumors, such as cholestasis, biliary obstruction, and cholecystitis. Case report: A 50-year-old male patient presented with jaundice and elevated CA 19-9 levels (161,902 IU/ml). Repeated biopsies of the common bile duct revealed no malignancies. Radiological findings indicated a mass protruding through the common bile duct. Positron emission tomography demonstrated increased (18)F-fluoro2-deoxy-D-glucose uptake in the liver and a mass resembling metastasis was detected. A Whipple procedure was performed and demonstrated no tumor. Postoperatively, CA 19-9 levels decreased to within normal limits (27 IU/ml). Conclusion: These results indicate that CA 19-9 levels should not be the sole criterion for a diagnosis of malignancy. Although other analytical tools may aid diagnosis, surgical exploration may be required in some instances to avoid misdiagnosis and determine whether radiological results are falsely positive.
    No preview · Article · Dec 2012 · Onkologie
  • A.F. Yapar

    No preview · Article · Nov 2012
  • Ali Fuat Yapar · Mehmet Reyhan
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    ABSTRACT: A 38-year-old man presented with declining appetite and progressive abdominal distention. Abdominal ultrasonography revealed omental and bowel wall thickening. Histopathologic examination showed a high-grade lymphoblastic Burkitt-like B-cell lymphoma. 18F fluorodeoxyglucose positron emission tomography/computed tomography images showed diffusely increased metabolic activity in the thickened omentum, intestines, mesentery, and peritoneum (omental caking). Diffuse peritoneal and omental seeding are well-known forms of dissemination of metastatic carcinoma. However, omental and peritoneal lymphomatosis are rare manifestations of high-grade lymphomas. This uncommon case demonstrates usefulness of F-18 fluorodeoxyglucose positron emission tomography/computed tomography in omental and peritoneal involvement in lymphoma.
    No preview · Article · Jul 2012 · Clinical nuclear medicine
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    Erkan Topkan · Cem Parlak · Ayşe Kotek · Ali Fuat Yapar · Berrin Pehlivan
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    ABSTRACT: We aimed to study the predictive value of combined 18F-fluoro-deoxy-D-glucose positron emission tomography and computerized tomography (FDG-PET-CT), on outcomes in locally advanced pancreatic carcinoma (LAPC) patients treated with concurrent chemoradiotherapy (C-CRT). Thirty-two unresectable LAPC patients received 50.4 Gy (1.8 Gy/fr) of RT and concurrent 5-FU followed by 4 to 6 cycles of gemcitabine consolidation. Response was evaluated by FDG-PET-CT at post-C-CRT 12-week. Patients were stratified into two groups according to the median difference between pre- and post-treatment maximum standard uptake values (SUVmax) as an indicator of response for comparative analysis. At a median follow-up of 16.1 months, 16 (50.0%) patients experienced local/regional failures, 6 of which were detected on the first follow-up FDG-PET-CT. There were no marginal or isolated regional failures. Median pre- and post-treatment SUVmax and median difference were 14.5, 3.9, and -63.7%, respectively. Median overall survival (OS), progression-free survival (PFS), and local-regional progression-free survival (LRPFS) were 14.5, 7.3, and 10.3 months, respectively. Median OS, PFS, and LRPFS for those with greater (N = 16) versus lesser (N = 16) SUVmax change were 17.0 versus 9.8 (p = 0.001), 8.4 versus 3.8 (p = 0.005), and 12.3 versus 6.9 months (p = 0.02), respectively. On multivariate analysis, SUVmax difference was predictive of OS, PFS, and LRPFS, independent of existing covariates. Significantly higher OS, PFS, and LRPFS in patients with greater SUVmax difference suggest that FDG-PET-CT-based metabolic response assessment is an independent predictor of clinical outcomes in LAPC patients treated with definitive C-CRT.
    Full-text · Article · Nov 2011 · BMC Gastroenterology
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    ABSTRACT: A 51-year-old woman had splenomegaly and enlarged multiple splenic hilar lymph nodes. The patient was referred to our department for F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) evaluation to determine the metabolic activity of lymph nodes and define a biopsy site. PET/CT images showed diffuse increased FDG uptake in an enlarged spleen and hypermetabolic splenic hilar lymph nodes. The metabolic activity in bone marrow also seemed diffusely increased. After splenectomy, histopathologic analysis showed the growth of Leishmania amastigotes in splenic tissue, and bone marrow biopsy did not reveal any significant pathology but only mild hypercellularity.
    No preview · Article · Nov 2011 · Clinical nuclear medicine
  • A. Fuat Yapar · Mehmet Reyhan

    No preview · Article · Apr 2011

Publication Stats

330 Citations
121.20 Total Impact Points

Institutions

  • 2004-2015
    • Baskent University
      • Department of Nuclear Medicine
      Engüri, Ankara, Turkey
    • Adana Medline Hospital
      Adhanah, Adana, Turkey
  • 2009
    • Saitama Medical University
      Saitama, Saitama, Japan
  • 2005
    • Baskent Üniversitesi Adana Uygulama ve Arastirma Merkezi
      Adhanah, Adana, Turkey
  • 2001
    • Cukurova University
      • Department of Nuclear Medicine
      Adhanah, Adana, Turkey
  • 2000
    • Baskent Üniversitesi Ankara Hastanesi
      Adhanah, Adana, Turkey