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Öğe Basal ganglia involvement in the late stage of vacuolating megalencephalic leukoencephalopathy(2005) Karakas H.M.; Firat A.K.; Yakinci C.; Kahraman B.Vacuolating megalencephalic leukoencephalopathy is a recently defined entity characterized by swelling of white matter, subcortical cysts in fronto-temporal regions and slow progression of neurological symptoms that contrasts with the severity of radiological findings. We present a late follow-up of a case with vacuolating megalencephalic leukoencephalopathy. There was an improvement of the brain swelling and associated sulcal enlargement. Of notice was basal ganglia involvement which has not been described previously.Öğe Chondroradionecrosis in two patients with laryngeal carcinoma(2007) Firat Y.; Kizilay A.; Firat A.K.; Serin M.; Erkal H.S.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.Öğe Clinical outcomes of neonatal hypoxic ischemic encephalopathy evaluated with diffusion-weighted magnetic resonance imaging(2006) Da? Y.; Firat A.K.; Karakaş H.M.; Alkan A.; Yakinci C.; Erdem G.Purpose: Detection of early phase neurological deficit in babies with hypoxic-ischemic encephalopathy (HIE) is the most important step to determine the appropriate preventive treatment methods. Diffusion-weighted imaging (DWI) is the most sensitive radiological modality to detect ischemic changes in the brain, in their earliest phase. Herein, we present the results of our study about the role of DWI in the diagnosis and determining the prognosis of HIE in neonates. Materials and methods: The study included 36 cases (4 preterm, 32 term babies) who were diagnosed with HIE within 24 hours of birth and classified according to modified Samat staging. They were examined for the presence of neurological sequelae at 3 and 6 months of age with electroencephalography (EEG), visual evoked potential (VEP), brainstem auditory evoked potential (BAEP), and Denver II developmental screening tests. All 36 patients underwent conventional magnetic resonance (MR) imaging and DWI within the first 24 hours of birth; survivors underwent repetitive imaging exams at the end of the first week and then after a month. Results: Seventeen stage I cases (47%), 12 stage II cases (33%), and 7 stage III cases (20%) were detected. DWI obtained within the first 24 hours showed high sensitivity (100%) in detecting the permanent neurological sequelae but with very low specificity (20%). The negative predictive value of DWI in this period was 100%; however, in DWI obtained at the end of the first month, not only its sensitivity was preserved, but its specificity reached 80%. The negative predictive value of DWI in this period was preserved and the positive predictive value improved. The importance of DWI in detecting sequelae at the end of the first month was also demonstrated by McNemar (p = 0.250) and Kappa (Kappa = 0.719) tests. There was no difference between conventional MR imaging and DWI in detecting sequelae at the end of first month. Conclusion: DWI is superior to other imaging modalities in detecting ischemia; not only because of its high sensitivity in the early phase, but also because of its high sensitivity and specificity in the late phase. Moreover, with its high negative predictive value, DWI can be used for excluding the possibility of sequelae development in the early phase of HIE cases for medico-legal purposes. © Turkish Society of Radiology 2006.Öğe Diffusion weighted MR findings of brain involvement in tuberous sclerosis(2006) Firat A.K.; Karakaş H.M.; Erdem G.; Yakinci C.; Biçak U.Purpose: Diffusion Weighted Imaging (DWI) is effective in identifying microstructural cerebral parenchymal changes. We studied the diffusion characteristics of hamartomas and normal white matter in cases with tuberous sclerosis (TS). Materials and methods: Diffusion weighted images of 6 TS cases (ages between 3-15 years, mean 9.0 years, SD 4.4 years) that presented to our center for magnetic resonance (MR) imaging have been retrospectively evaluated. In addition to 56 non-calcified hamartomas of TS patients, apparent diffusion coefficient (ADC) values measured from frontal, parietal normal white matter, and basal ganglions of TS patients were compared with values obtained from 9 normal subjects (ages 1-13 years, mean 8.9 years, SD 3.4 years). Hamartomas were divided into 3 subgroups based on their locations, and the ADC values measured in these groups were compared. Results: ADC values of all hamartomas were between 838 and 2230, with a mean value of 1408 mm2/sec × 10-3 (SD: 273.2); ADC values of the white matter of normal subjects were between 695 and 857, with a mean value of 776.1 mm2/sec × 10-3 (SD: 44.23) (p < 0.0001). ADC values of subependymal nodules, white matter hamartomas, and subcortical tubers were 838-2230 (mean: 1440.5 mm2/sec × 10-3; SD: 526.46), 1046-1622 (mean: 1328.6 mm2/sec × 10-3; SD: 189.4), and 981-1973 (mean: 1417.4 mm2/sec × 10-3; SD: 219.5), respectively (p = 0.666). Conclusion: Diffusion characteristics of white matter hamartomas resulting from TS clearly differ from those of normal white matter, but no significant difference was observed in ADC values of these lesions based on their locations. Moreover, the ADC measurements of normal white matter in these cases did not differ from those of the control group, indicating that the disease does not cause a common explicit damage in white matter and central gray matter, other than hamartomas, which can be detected by DWI. DWI may only be used in the differential diagnosis of hamartomas from secondary lesions with T1 and T2W signal intensities similar to those of hamartomas and with different diffusion characteristics. © Turkish Society of Radiology 2006.Öğe Dynamic contrast-enhanced magnetic resonance imaging findings of mass lesions of the pontocerebellar angle(2007) Firat A.K.; Karakaş H.M.; Kahraman B.; Firat Y.; Altinok T.; Kizilay A.OBJECTIVES: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.Öğe Encephalopathy due to hypernatremic dehydration: Computerized tomography and magnetic resonance imaging findings: Case report(Turkiye Klinikleri, 2006) Firat A.K.; Karakaş H.M.; Yakinci C.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. Copyright © 2006 by Türkiye Klinikleri.Öğe Giant sinus of valsalva aneurysm(AVES İbrahim KARA, 2006) Karakaş H.M.; Kahraman B.; Sa?ir A.; Firat A.K.[No abstract available]Öğe Incidental diagnosis of intestinal malrotation on computerized tomography: A case report(Turkiye Klinikleri, 2006) Firat A.K.; Karakaş H.M.; Karaca S.; Si?irci A.Malrotation is an anomaly of rotation and fixation of midgut. It usually presents in infancy. Diagnosis of malrotation is challenging in patients who are asymptomatic during the first year because the symptoms develop during the chronic period and they are nonspecific. Some cases may be diagnosed incidentally in adulthood. We presented the CT and upper GIS series findings of a 10-year old male patient with midgut malrotation who was incidentally diagnosed by the evaluation of CT examination. Copyright © 2006 by Türkiye Klinikleri.Öğe Spontaneous bilateral intrasphenoidal lateral encephaloceles: CT and MRI findings(Medquest Communications LLC, 2004) Firat A.K.; Firat Y.Lateral intrasphenoidal encephaloceles are rare anomalies. We describe a unique case in which spontaneous bilateral intrasphenoidal lateral encephaloceles were discovered in a 53-year-old man during a work-up for cerebrospinal fluid leak. We discuss our clinical findings and the results of preoperative computed tomography and magnetic resonance imaging.Öğe Spontaneous intracranial hypotension with pituitary adenoma(Springer Milan, 2006) Firat A.K.; Karakas H.M.; Firat Z.Y.; Kahraman B.; Erdem G.Spontaneous intracranial hypotension (SIH) is an unusual syndrome that is characterised by positional headache, neck rigidity, nausea and vomiting. The characteristic magnetic resonance imaging (MRI) findings are diffuse smooth pachymeningeal thickening and enhancement, downward displacement of posterior fossa structures and pituitary gland enlargement. An unusual case of SIH with pituitary macro-adenoma and subsequent subdural haemorrhage is presented, and its clinical picture, MRI findings and possible pathophysiological mechanism are discussed. © Springer-Verlag Italia 2006.Öğe Transient renal medullary hyperechogenicity in newborns with acute renal failure and dehydration: Ultrasonography follow-up(2006) Çelik T.; Firat A.K.; Kahraman A.S.; Erdem G.; Karakaş H.M.; Yakinci C.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.
