Yazar "Karakaş H.M." seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Age-related changes in the incidence of pineal gland calcification in Turkey: A prospective multicenter CT study(2008) Turgut A.T.; Karakaş H.M.; Özsunar Y.; Altin L.; Çeken K.; Alicio?lu B.; Sönmez I.The goal of this cross-sectional observational study was to determine the incidence of pineal gland calcification (PGC), to investigate the interaction of PGC and aging, and to compare the incidence of PGC among the populations living in Turkey. In a prospective study the rate of PGC on CT scans of 1376 individuals in six referral centers from different regions of Turkey was investigated, with emphasis on effects of climatological parameters and aging on PGC. It was found that the incidence of PGC increased rapidly after first decade and the increase remains gradual thereafter, higher in males than in females for all age groups. There was a significant difference for incidence and degree of PGC between different clinics and between both sexes (p < 0.001). In addition, there was a significant difference for the degree of PGC between the clinics in low altitude group and those in high altitude group (p < 0.001 for each). Logistic regression analysis revealed that age, sex, altitude and intensity of sunlight exposure significantly affected the risk of PGC (odds ratios (OR) 1.335, 95% confidence intervals (CI) 1.261-1.414, p < 0.001; OR 1.900, 95% CI 1.486-2.428, p < 0.001; OR 0.715, 95% CI 0.517-0.990, p < 0.05; OR 0.997, 95% CI 0.994-0.999, p < 0.01, respectively). Furthermore, by multiple linear regression analysis, high altitude and increased intensity of sunlight exposure were found to affect the degree of PGC (? = 0.003, p < 0.001). It is concluded that there is a close relationship between PGC and the aforementioned parameters, supporting a link between the development of PGC and these. This study provides some reference data for new clinical studies on the putative role of pineal gland in future. © 2008 Elsevier Ireland Ltd. All rights reserved.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 Learning of serial digits leads to frontal activation in functional MR imaging(2006) Karakaş H.M.; Karakaş S.Purpose: Clinical studies have shown that performance on the serial digit learning test (SDLT) is dependent upon the mesial temporal lobes, which are responsible for learning and its consolidation. However, an effective SDLT performance is also dependent upon sequencing, temporal ordering, and the utilization of mnemonic strategies. All of these processes are among the functions of the frontal lobes, in spite of this, the relationship between SDLT performance and the frontal lobes has not been demonstrated with previously used mapping techniques. The aim of this study was to investigate the areas of the brain that are activated by SDLT performance. Materials and methods: Ten healthy, eight handed volunteers (mean age, 20.1 years; SD: 3.3) who had 12 years of education were studied with a 1.0 T MR imaging scanner. BOLD (blood oxygen level dependent) contrast and a modified SDLT were used. Activated loci were automatically mapped using a proportional grid. Results: In learning, the most consistent activation was observed in B-a-7 of the right (80%) and the left hemispheres (50%). In recall, the most consistent activation was observed in B-a-7 of the eight hemisphere (60%). Activations were observed in 2.5±0.97 Talairach volumes in learning, whereas they encompassed 1.7±0.95 volumes in recall. The difference between both phases (learning and recall) regarding total activated volume was significant (p<0.05). Conclusion: The prefrontal activation during SDLT performance was not related to learning or to recall, but to a function that is common to both of these cognitive processes. A candidate for this common factor may be the executive functions, which also include serial position processing and temporal ordering. © Turkish Society of Radiology 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.Öğe The value of qualitative and semiquantitative ultrasonographic findings in the differential diagnosis of lymphomatous superficial lymph node enlargements(2004) Ökten Ö.Ö.; Tunçbilek N.; Karakaş H.M.The value of the gray-scale (GSUSG), color Doppler (CDUSG), and power Doppler (PDUSG) ultrasonography in the differential diagnosis of lymphomatous superficial lymph node enlargements were evaluated. The study group consisted of 33 males and 16 females (5-74 yrs old, mean age 36.1 yrs) in whom physical examination had revealed superficial lymph node enlargements. All patients were investigated with Doppler USG (Sonoline Elegra Advanced, Siemens, Germany) using 7.5 Mhz linear transducer. Longitudinal/ transverse dimensions (L/T) and hilar echogenecity of lymph nodes were evaluated with GSUSG. During the CDUSG and PDUSG examination, we classified the nodes into 3 patterns: type I, "hilar normal"; type II, "hilar activated"; and type III, "peripheral". Pulsatility (PI) and resistivity (RI) indexes were calculated using CDUSG. Above parameters were analyzed to determine their differential diagnostic values using ANOVA based discriminant analysis, Student's-T test and ROC curve analysis. When clinical data and histopathological findings were combined, 27 subjects were diagnosed as lymphoma, and 22 cases were classified as lymphadenitis. Multiple comparison analysis of qualitative GSUSG and PDUSG features consisting of hilar echogenecity, L/T value and vascular type patterns was able to differentiate lymphomatous lymph nodes and lymphadenitis with 86.8% accuracy (p<0.001). On the contrary, semiquantitative features (RI, PI) were not able to classify lymph nodes (p>0.05). Semiquantitative RDUS parameters are not valuable in the differential diagnosis of lymphomatous superficial lymph node pathologies. Qualitative GSUSG and PDUSG features, on the other hand, may be used as an alternative work-up to cytological studies in patients in whom diagnostic surgical procedures cannot be performed.
