Browsing by Author "Algin, O."

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Open Access
Assessment of the corticospinal fiber integrity in mirror movement disorder
(Churchill Livingstone, 2018) Solmaz, B.; Özyurt, M. G.; Ata, D. B.; Akçimen, F.; Shabsog, M.; Türker, K. S.; Dalçik, H.; Algin, O.; Başak, A. N.; Özgür, M.; Çavdar, S.
Mirror movements are unintended movements occurring on one side of the body that mirror the contralateral voluntary ones. It has been proposed that mirror movements occur due to abnormal decussation of the corticospinal pathways. Using detailed multidisciplinary approach, we aimed to enlighten the detailed mechanism underlying the mirror movements in a case subject who is diagnosed with mirror movements of the hands and we compared the findings with the unaffected control subjects. To evaluate the characteristics of mirror movements, we used several techniques including whole exome sequencing, computed tomography, diffusion tensor imaging and transcranial magnetic stimulation. Computed tomography showed the absence of a spinous process of C5, fusion of the body of C5-C6 vertebrae, hypoplastic dens and platybasia of the posterior cranial fossa. A syrinx cavity was present between levels C3-C4 of the spinal cord. Diffusion tensor imaging of the corticospinal fibers showed disorganization and minimal decussations at the lower medulla oblongata. Transcranial magnetic stimulation showed that motor commands were distributed to the motor neuron pools on the left and right sides of the spinal cord via fast-conducting corticospinal tract fibers. Moreover, a heterozygous missense variation in the deleted in colorectal carcinoma gene has been observed. Developmental absence of the axonal guidance molecules or their receptors may result in abnormalities in the leading of the corticospinal fibers. Clinical evaluations and basic neuroscience techniques, in this case, provide information for this rare disease and contribute to our understanding of the normal physiology of bimanual coordination.
Open Access
Clustering fMRI data with a robust unsupervised learning algorithm for neuroscience data mining
(Elsevier, 2018) Aljobouri, H. K.; Jaber, H. A.; Koçak, O. M.; Algin, O.; Çankaya, I.
Background: Clustering approaches used in functional magnetic resonance imaging (fMRI) research use brain activity to divide the brain into various parcels with some degree of homogeneous characteristics, but choosing the appropriate clustering algorithms remains a problem. New method: A novel application of the robust unsupervised learning approach is proposed in the current study. Robust growing neural gas (RGNG) algorithm was fed into fMRI data and compared with growing neural gas (GNG) algorithm, which has not been used for this purpose or any other medical application. Learning algorithms proposed in the current study are fed with real and free auditory fMRI datasets. Results: The fMRI result obtained by running RGNG was within the expected outcome and is similar to those found with the hypothesis method in detecting active areas within the expected auditory cortices. Comparison with existing method(s): The fMRI application of the presented RGNG approach is clearly superior to other approaches in terms of its insensitivity to different initializations and the presence of outliers, as well as its ability to determine the actual number of clusters successfully, as indicated by its performance measured by minimum description length (MDL) and receiver operating characteristic (ROC) analysis. Conclusions: The RGNG can detect the active zones in the brain, analyze brain function, and determine the optimal number of underlying clusters in fMRI datasets. This algorithm can define the positions of the center of an output cluster corresponding to the minimal MDL value.
Open Access
Detection of cholesteatoma: high-resolution DWI using RS-EPI and parallel imaging at 3 tesla
(Elsevier Masson SAS, 2017) Algin, O.; Aydın, H.; Ozmen E.; Ocakoglu, G.; Bercin, S.; Porter, D. A.; Kutluhan, A.
The purpose of this study is to evaluate the impact of RS-EPI-DWI in the detection of cholesteatoma and to compare with single-shot echo-planar DWI (SS-EPI-DWI). Diffusion-weighted and apparent diffusion-coefficient (ADC) images were obtained using RS-EPI and SS-EPI techniques in 30 patients. Presence of cholesteatoma (3 point scale), amount of artefacts (4 point scale), visibility (4 point scale), and ADC values of the lesions were assessed. The results of both techniques were compared with each other and gold-standard (GS) test results. Lesion visibility and presence of artefact scores of RS-EPI-DWI group were significantly different from those of the SS-EPI group. RS-EPI-DWI images had fewer artefacts and higher visibility scores. The sensitivity, specificity, negative/positive-predictive, and overall-agreement values of RS-EPI-DWI technique were 100%, 78%, 100%, 74%, and 87%; respectively. These values for SS-EPI-DWI technique were 91%, 60%, 88%, 67%, and 75%; respectively. Also, these values were higher on axial plane than coronal plane images for ADC measurements. Based on gold-standard test findings, agreement values were good (κ = 0.74) for RS-EPI-DWI and moderate for SS-EP-DWI (κ = 0.50) techniques (P < 0.001 for both). The RS-EPI-DWI technique allows a higher spatial-resolution and this technique is less susceptible to artefacts when compared with SS-EPI technique. © 2017 Elsevier Masson SAS
Open Access
Evaluation of hydrocephalus patients with 3D-SPACE technique using variant FA mode at 3T
(Springer, 2018) Algin, O.
The major advantages of three-dimensional sampling perfection with application optimized contrasts using different flip-angle evolution (3D-SPACE) technique are its high resistance to artifacts that occurs as a result of radiofrequency or static field, the ability of providing images with sub-millimeter voxel size which allows obtaining reformatted images in any plane due to isotropic three-dimensional data with lower specific absorption rate values. That is crucial during examination of cerebrospinal-fluid containing complex structures, and the acquisition time, which is approximately 5 min for scanning of entire cranium. Recent data revealed that T2-weighted (T2W) 3D-SPACE with variant flip-angle mode (VFAM) imaging allows fast and accurate evaluation of the hydrocephalus patients during both pre- and post-operative period for monitoring the treatment. For a better assessment of these patients; radiologists and neurosurgeons should be aware of the details and implications regarding to the 3D-SPACE technique, and they should follow the updates in this field. There could be a misconception about the difference between T2W-VFAM and routine heavily T2W 3D-SPACE images. T2W 3D-SPACE with VFAM imaging is only a subtype of 3D-SPACE technique. In this review, we described the details of T2W 3D-SPACE with VFAM imaging and comprehensively reviewed its recent applications.
Open Access
Reduction of the radiofrequency heating of metallic devices using a dual‐drive birdcage coil
(Wiley, 2013) Eryaman, Yiğitcan; Türk, Esra Abacı; Oto, C.; Algin, O.; Atalar, Ergin
In this work, it is demonstrated that a dual-drive birdcage coil can be used to reduce the radiofrequency heating of metallic devices during magnetic resonance imaging. By controlling the excitation currents of the two channels of a birdcage coil, the radiofrequency current that is induced near the lead tip could be set to zero. To monitor the current, the image artifacts near the lead tips were measured. The electric field distribution was controlled using a dual-drive birdcage coil. With this method, the lead currents and the lead tip temperatures were reduced substantially [<0.3°C for an applied 4.4 W/kg SAR compared to >4.9°C using quadrature excitation], as demonstrated by phantom and animal experiments. The homogeneity of the flip angle distribution was preserved, as shown by volunteer experiments. The normalized root-mean-square error of the flip angle distribution was less than 10% for all excitations. The average specific absorption rate increased as a trade-off for using different excitation patterns. Copyright © 2012 Wiley Periodicals, Inc.