Ahmet Kemal Firat

Medical Park Hospitals, İstanbul, Istanbul, Turkey

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Publications (39)66.24 Total impact

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    ABSTRACT: Cutaneous anthrax, caused by Bacillus anthracis contacting the skin, is the most common form of human anthrax. Recent studies implicate the presence of additional, possibly toxin-related subtle changes, even in patients without neurological or radiological findings. In this study, the presence of subtle changes in cutaneous anthrax was investigated at the metabolite level using magnetic resonance spectroscopy. Study subjects were consisted of 10 patients with cutaneous anthrax without co-morbid disease and/or neurological findings, and 13 healthy controls. There were no statistical differences in age and gender between two groups. The diagnosis of cutaneous anthrax was based on medical history, presence of a typical cutaneous lesion, large gram positive bacilli on gram staining and/or positive culture for B. anthracis from cutaneous samples. Brain magnetic resonance imaging examination consisted of conventional imaging and single-voxel magnetic resonance spectroscopy. Magnetic resonance spectroscopy was performed by using point-resolved spectroscopy sequence (TR: 2000ms, TE: 136ms, 128 averages). Voxels of 20mm×20mm×20mm were placed in normal-appearing parietal white matter to detect metabolite levels. Cerebral metabolite peaks were measured in normal appearing parietal white matter. N-acetyl aspartate/creatine and choline/creatine ratios were calculated using standard analytical procedures. Patients and controls were not statistically different regarding parietal white matter N-acetyl aspartate/creatine ratios (p=0.902), a finding that implicates the conservation of neuronal and axonal integrity and neuronal functions. However, choline/creatine ratios were significantly higher in patient groups (p=0.001), a finding implicating an increased membrane turnover. In conclusion, these two findings point to a possibly anthrax toxins-related subtle inflammatory reaction of the central nervous system at the cellular level.
    No preview · Article · Apr 2012 · Medical Hypotheses
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    ABSTRACT: Infections in solid-organ transplant recipients are the most important causes of morbidity and mortality. A primary goal in organ transplant is the prevention or effective treatment of infection, which is the most common life-threatening complication of long-term immunosuppressive therapy. A 21-year-old woman who underwent heart transplant 3 years previous owing to dilated cardiomyopathy was referred to our hospital with symptoms of high fever and cough. The patient's history revealed that she had received a trimethoprim-sulfamethoxazole double-strength tablet each day for prophylactic purposes. On chest radiograph, pneumonia was detected, and in broncho-alveolar lavage sample, Pneumocystis jiroveci cysts were found. After diagnosing P. jiroveci pneumonia, trimethoprim-sulfamethoxazole was initiated at 20 mg/kg/d including intravenous trimethoprim in divided dosages every 6 hours. On the sixth day of therapy, she died in intensive care unit. In solid-organ transplant recipients, although antipneumocystis prophylaxis is recommended within the first 6 to 12 months after transplant, lifelong prophylaxis is also used in several settings. In addition, the physician should keep in mind that P. jiroveci pneumonia may develop in solid organ recipients, despite trimethoprim-sulfamethoxazole prophylaxis.
    No preview · Article · Dec 2010
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    ABSTRACT: Although morphological and histopathological changes in uterine leiomyomas have been investigated in detail, the microstructural disruptions could not be studied in the living organism. Diffusion-weighted magnetic resonance imaging (DWI) is a novel tool to assess microstructural changes in vivo. The aim of this study was to investigate and characterize the diffusional property of leiomyomatous tissues with DWI. Sixteen females with a total of 21 leiomyomas were imaged with a 1.5-tesla clinical MR scanner. DWI images of leiomyomas, adjacent myometrial and myometrial tissues of healthy controls were obtained and quantified using apparent diffusion coefficient (ADC) maps. Mean ADC values of these groups were 1,201, 1,684, 1,661 mm(2)/s x 10(-6), respectively. ADC values in leiomyomas were significantly lower than those observed in the myometrium (p < 0.001). Cut-off values produced 91% sensitivity and 100% specificity. As ADC values implied the presence of cytotoxic edema in leiomyomas, the technique was found to be promising in observing temporal variations in leiomyomas and to monitor even the most subtle effects of therapeutic interventions.
    No preview · Article · May 2009 · Gynecologic and Obstetric Investigation
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    ABSTRACT: Incontinentia pigmenti (IP) is a rare, X-linked dominant disorder that presents at or soon after birth with characteristic cutaneous signs. The eyes and central nervous system are the next most commonly affected systems. We aimed to describe the ophthalmological, neurological and radiodiagnostic findings of a patient with IP and bilateral retinal detachment. Clinical and laboratory findings of a four-month-old female baby who did not have light fixation and had neurological maturation retardation are presented. Characteristic skin lesions of IP were noted especially at the extremities, bilaterally. On neurological examination, motor and mental maturation were retarded and axial hypotonia was noted. Bilateral retinal detachment was the cause of absent eye fixation noted during ophthalmologic examination, and the detachments were also documented by ultrasonography and magnetic resonance imaging (MRI). Otologic examination was normal. Focal left frontal lobe atrophy, corpus callosum hypoplasia and prominence of right hemisphere were also noted on MRI. MR spectroscopy revealed negative lactate peak at the involved left frontal lobe. Bilateral retinal detachment is a probable finding in IP and patients with neurological symptoms should be investigated for associated sight-threatening ocular pathologies.
    Preview · Article · Jan 2009 · The Turkish journal of pediatrics
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    ABSTRACT: The aim of this study was to investigate possible metabolic alterations in cerebral tissues on magnetic resonance spectroscopy (MRS) in patients with impaired glucose tolerance (IGT) and with type 2 diabetes mellitus (T2-DM). Twenty-five patients with T2-DM, 13 patients with IGT, and 14 healthy volunteers were included. Single-voxel spectroscopy (TR: 2000 ms, TE: 31 ms) was performed in all subjects. Voxels were placed in the frontal cortex, thalamus, and parietal white matter. N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, and myo-inositol (MI)/Cr ratios were calculated. Frontal cortical Cho/Cr ratios were increased in patients with IGT compared to control subjects. Parietal white matter Cho/Cr ratios were significantly higher in patients with IGT when compared to patients with T2-DM. In the diabetic group, frontal cortical MI/Cr ratios were increased, and parietal white matter Cho/Cr ratios were decreased when compared to the control group. Frontal cortical NAA/Cr and Cho/Cr ratios and parietal white matter Cho/Cr ratios were decreased in diabetic patients with poor glycemic control (A1C>10%). A1C levels were inversely correlated with frontal cortical NAA/Cr and Cho/Cr ratios and with parietal white matter Cho/Cr ratios. T2-DM and IGT may cause subtle cerebral metabolic changes, and these changes may be shown with MRS. Increased Cho/Cr ratios may suggest dynamic change in membrane turnover in patients with IGT. Diabetic patients with poor glycemic control may be associated with neuronal dysfunction/damage in brain in accordance with A1C levels and, in some, extend with insulin resistance.
    No preview · Article · Jul 2008 · Journal of diabetes and its complications
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    ABSTRACT: We aimed to evaluate whether the subtle metabolic cerebral changes are present in normal-appearing white matter on conventional MRI, in patients with acute brucellosis, by using MR spectroscopy (MRS). Sixteen patients with acute brucellosis and 13 healthy control subjects were investigated with conventional MRI and single-voxel MRS. Voxels were placed in normal-appearing parietal white matter (NAPWM). N-Acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were calculated. There was no significant difference between the study subjects and the control group in NAA/Cr ratios obtained from NAPWM. However, the Cho/Cr ratios were significantly higher in patients with acute brucellosis compared to controls (p=0.01). MRS revealed metabolic changes in normal-appearing white matter of patients with brucellosis. Brucellosis may cause subtle cerebral alterations, which may only be discernible with MRS. Increased Cho/Cr ratio possibly represents an initial phase of inflammation and/or demyelination process of brucellosis.
    No preview · Article · Apr 2008 · European Journal of Radiology
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    B Alicioglu · H M Karakas · A K Firat
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    ABSTRACT: A case of 5 year old juvenile patient with dermatomyositis together with conventional and diffusion-weighted MRI images is reported. The reported case was atypical for the pattern of involvement of the accompanying oedema which was affecting distal parts of the extremities and anterior muscle groups. Electromyography was negative. The case confirmed by a pathologist demonstrates the use of diffusion weighted imaging in determining unequivocal oedema and its exact extent.
    Preview · Article · Feb 2008 · Prague medical report
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    ABSTRACT: The purpose of this study was to determine the pre- and postpubertal 1H magnetic resonance spectroscopic characteristics of the normal testis to establish baseline values for further clinical studies. The subjects consisted of male volunteers, of whom 19 were prepubertal with ages between 7 and 13 years and 24 were postpubertal with ages between 19 and 39 years. Their testes were evaluated at 1.5 T with magnetic resonance spectroscopy; in addition, testis volumes were measured. Major metabolite peaks were identified and their ratios were calculated. Metabolite differences of testis between pre- and postpubertal age were analyzed. Major constituents of spectra were 3.21 ppm choline and 0.9-1.3 ppm lipid peaks. At the echo time (TE) spectrum of 31 ms, choline/lipid ratios ranged from 0.35 to 8.30 (mean=1.87) in postpubertal males and from 0.06 to 5.45 (mean=0.88) in prepubertal males (P<.013). At the TE spectrum of 136 ms, choline/lipid ratios ranged from 0.66 to 15.42 (mean=4.09) in postpubertal males and from 0.05 to 4.91 (mean=0.9) in prepubertal males (P<.016). Choline/lipid ratio was higher in the postpubertal period. The existence of higher choline peak in that age group should be due to the initiation of spermatogenesis. The decrease in the lipid peak may represent the effect of testosterone on testicular tissue or may be due to histochemical changes initiated by puberty. The significant decrease in choline/lipid ratio noted after puberty could represent the presence of spermatogenesis. This hypothesis should be evaluated by further studies on postpubertal subjects with impaired spermatogenesis.
    Full-text · Article · Feb 2008 · Magnetic Resonance Imaging
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    ABSTRACT: Tendon disorders are rare events associated with fluoroquinolone congestion. Skin reactions are more frequent than tendon disorders. We reported this case as the combination of ciprofloxacin-induced urticaria and tenosynovitis has been unreported in young women. A 28-year-old woman without underlying disease developed urticarias and tendinopathy 4 days after the initiation of ciprofloxacin treatment for urinary infection. MRI of the left foot revealed increased synovial fluid surrounding the tendon of the flexor hallucis longus muscle representing tenosynovitis. Ciprofloxacin was ceased due to the possibility of ciprofloxacin-induced tendinopathy and urticaria. Complete resolution of her symptoms and findings occurred 3 days after discontinuation of ciprofloxacin without any additional treatment. Early discontinuation of fluoroquinolone therapy when tendinopathy is suspected is the basis of therapy. So, it should be kept in mind that fluoroquinolone-induced tendinopathy may occur in an otherwise healthy young patient with no risk factors and in a site other than the Achilles tendon.
    No preview · Article · Feb 2008 · Chemotherapy
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    ABSTRACT: In hyperarginenemia, there is a defect in argininase enzyme, which is a catalyzer of urea cycle. Though the pathogenesis of neuronal damage in hyperargininemia is not clear, high serum and cerebrospinal fluid arginine levels can be directly related with neuronal damage. In this study, our aim was to assess brain magnetic resonance images and magnetic resonance spectroscopy (MRS) patterns of two siblings with hyperarginenemia. We acquired single voxel MRS from the white matter to show the myelination pattern and to figure out any abnormal peak of metabolite stored due to enzymatic defect. We observed mild cerebral and cerebellar atrophy and infarct at bilateral posterior putamen and insular cortex localization on conventional images and elevated choline/creatine ratios and abnormal peak at 3.8 ppm, most likely representing arginine deposition. To the best of our knowledge, this is the first article revealing the brain MRS pattern of hyperargininemia. We reported the clinical and imaging findings of patients and discuss the correlation.
    No preview · Article · Feb 2008 · Journal of neuroimaging: official journal of the American Society of Neuroimaging
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    ABSTRACT: Hydrocephalus is an important etiological factor in neurological decline. With the advent of fetal ultrasound, fetal hydrocephalus is now more frequently detected than in the past. Ultrasonography (USG) provides information on general morphology, but microstructural changes that may play a prognostic role are beyond the resolution of that technique. These changes may theoretically be revealed by diffusion-weighted magnetic resonance imaging (DW-MRI). In this study, our preliminary findings of DW-MRI on the hydrocephalic fetuses are presented.
    No preview · Article · Dec 2007 · Magnetic Resonance Imaging

  • No preview · Article · Sep 2007 · Pediatrics International
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    ABSTRACT: The differential diagnosis of mass lesions of the pontocerebellar angle is not always possible by conventional magnetic resonance imaging (MRI). In this study, we investigated the role of dynamic contrast-enhanced MRI in the differential diagnosis of acoustic neurinoma, meningioma, and paraganglioma. Twelve patients (8 females, 4 males; mean age 47.5 years; range 8 to 71 years) whose diagnoses were acoustic neurinoma (n=3), paraganglioma (n=5), and meningioma (n=4) were evaluated by simultaneous conventional and dynamic contrast-enhanced MRI. Prior to postcontrast T1-weighted images, dynamic MRI was obtained. On these images, maximum contrast enhancement (Cmax) and time to peak enhancement (Tmax) were calculated at 15 different time points. Time-signal intensity curve patterns of the lesions were compared. According to the four main time-signal intensity curve patterns described in the literature, acoustic neurinomas, meningiomas, and paragangliomas exhibited type C, type A-B, and type A curve patterns, respectively. Our results suggest that dynamic contrast MRI may have an additional but limited role in the differential diagnosis of extra-axial intracranial tumors such as those of the pontocerebellar angle.
    No preview · Article · Feb 2007 · Kulak burun bogaz ihtisas dergisi: KBB = Journal of ear, nose, and throat
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    ABSTRACT: Postradiotherapy necrosis in the larynx is a rare but serious complication. It must be differentiated from tumor recurrence with radiological and histopathological studies. Herein, we presented two patients with stage II and stage IV larynx carcinoma who developed chondroradionecrosis following radiotherapy. The first patient did not accept surgical treatment and was treated with curative radiotherapy at a dose of 70 Gy. The other one received adjuvant radiotherapy at a dose of 46 Gy following total laryngectomy and bilateral functional neck dissection. The two patients were evaluated with computed tomography and magnetic resonance imaging, respectively. Pathologic examination of multiple biopsies taken from both cases showed coagulation necrosis without malignancy. The first patient had grade IV radionecrosis according to the Chandler classification and underwent total laryngectomy because of non-functional larynx. Histopathologically, there were no malignant cells, but widespread fibrosis and coagulation necrosis. The other patient was treated with conservative treatment and local debridement.
    No preview · Article · Feb 2007 · Kulak burun bogaz ihtisas dergisi: KBB = Journal of ear, nose, and throat
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    Y Firat · A K Firat · H M Karakaş · C Onal
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    ABSTRACT: Sinonasal ossifying fibroma is a rare, slow-growing, benign bony tumour, frequently involving the maxilla and mandible in the head and neck region. Although it is known to be the second most frequent fibro-osseous tumour of paranasal sinus, to the best of our knowledge, ossifying fibroma of frontal sinus causing brain abscess has not been presented yet in the relevant literature. We present the clinical, pathological and radiological findings of ossifying fibroma of the frontal sinus associated with brain abscess.
    Full-text · Article · Dec 2006 · Dentomaxillofacial Radiology
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    ABSTRACT: A female aged 12 months with developmental delay and left-sided reverse ocular bobbing (rapid deviation of the eye upward and a slow return to the horizontal position) was observed. At birth, an upper left gingival mass, pathologically diagnosed as a benign granular cell tumour, was removed. On computed tomography (CT), left middle cerebral pedincular and midpontine lesions were seen. Magnetic resonance imaging revealed additional white matter hamartomas, corticosubcortical tubers, and subependymal nodules. The patient was re-examined at 36 months. Her general developmental quotient was equivalent to 23 months of age. Third cranial nerve functions and auditory brainstem response were normal. Her abnormal eye movements were still present. Reverse bobbing is usually observed in patients who are unconscious and who have significant pontine pathology and disruption of the reticular formation. This case is the first tuberous sclerosis-related ocular bobbing case to our knowledge and is interesting as the causative lesion was relatively mild, and ocular horizontal movements were preserved.
    Full-text · Article · Nov 2006 · Developmental Medicine & Child Neurology
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    Ahmet Kemal Firat · Hakki Muammer Karakas · Cengiz Yakinci
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    ABSTRACT: Magnetic resonance spectroscopy (MRS) of a 12-year-old female patient with glutaric aciduria type II was compared with data obtained from four healthy age- and sex-matched volunteers. In the clinically active phase, conventional magnetic resonance imaging showed mild ventricular dilatation. Frontal lobe choline/creatine (Cho/Cr) ratio (1.98) was higher than the ratios reported for the comparison participants (1.64 [SD 0.21]). The N-acetylaspartate/creatine (NAA/Cr) ratio (1.95) was lower than normal limits (2.66 [SD 0.23]). After successful riboflavin treatment and dietary restriction for proteins, the NAA/Cr ratio was within the normal range (2.44) and Cho/Cr ratio was below the normal range (1.15), suggesting riboflavin-responsive multiple acyl-coA dehydrogenase deficiency. An elevated Cho/Cr ratio and decreased NAA/Cr ratio is consistent with a demyelinating process in the active phase of glutaric aciduria type II. MRS helps to monitor the progress of the disease and the efficacy of treatment by revealing changes in NAA/Cr and Cho/Cr ratios.
    Preview · Article · Nov 2006 · Developmental Medicine & Child Neurology

  • No preview · Article · Oct 2006 · Anadolu kardiyoloji dergisi: AKD = the Anatolian journal of cardiology
  • A.K. Firat · H.M. Karakaş · C. Yakinci
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    ABSTRACT: Magnetic resonance imaging (MRI) provides unique information about various pathological changes of the brain. We present CT and MRI findings of an infant with hypernatremic dehydration. CT imaging was performed at admission and MRI was obtained 4 weeks later. CT revealed hypodensity in the bilateral border zone of centrum semiovale and in the parasagital region of the left parietal lobe. These CT and MRI findings are compatible with vasogenic edema deteriorating to venous infarction. We present the early stage CT and late stage conventional MRI findings and discuss the effectiveness and priority of imaging techniques in this disease.
    No preview · Article · Oct 2006 · Turkiye Klinikleri Journal of Medical Sciences
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    ABSTRACT: Our purpose was to assess the time interval between the visualization of renal medullary hyperechogenicity and its resolution in neonates with acute renal failure. Seven newborns with renal medullary hyperechogenicity and acute renal insufficiency noted on ultrasonography (US) were included in the study group. Their ages were ranged between three and six days. All of the patients underwent US at the first presentation and in the follow-up. In all of the patients diffuse medullary hyperechogenicity was noted in the bilateral kidney. Biochemistry examinations revealed abnormal BUN and creatine level in all neonates and additional hypernatremia in four of them. The medullary hyperechogenicity totally disappeared between the 10th and 30 th days of the neonatal period. Renal functions had normalized before the resolution of medullary hyperechogenicity between the 7th and 10th days. Transient medullary hyperechogenicity may be delayed due to presence of abnormal renal functions. For this reason, while deciding to examine these patients for metabolic disease. persistent renal medullary hyperechogenicity after 10 days in the neonatal period should be evaluated in accordance with biochemistry findings.
    No preview · Article · Oct 2006 · Cocuk Sagligi ve Hastaliklari Dergisi

Publication Stats

262 Citations
66.24 Total Impact Points

Institutions

  • 2012
    • Medical Park Hospitals
      İstanbul, Istanbul, Turkey
  • 2004-2009
    • Inonu University
      • Department of Radiology
      Malatia, Malatya, Turkey
  • 2008
    • Trakya University
      • Department of Radiology
      Adrianoupolis, Edirne, Turkey
  • 2006
    • Ankara Numune Training and Research Hospital
      Engüri, Ankara, Turkey
  • 2003-2006
    • Hacettepe University
      • Department of Radiology
      Engüri, Ankara, Turkey
  • 2005
    • University of Texas Southwestern Medical Center
      • Department of Radiology
      Dallas, Texas, United States