Kazim Gumus

Susceptibility-Based Differentiation of Intracranial Calcification and Hemorrhage in Pediatric Patients.

Differential diagnosis of intracranial hemorrhage versus calcification on conventional magnetic resonance images (MRIs) is often challenging. Although computed tomography (CT) confirms calcification, phase information obtained during susceptibility-weighted imaging can be useful in distinguishing between 2 pathologies. Fourteen patients previously diagnosed to have hemorrhage or calcification with imaging were included in the study retrospectively. Phase shift values of hemorrhage and calcification were compared by using Student t test. The pathologies identified were tuberous sclerosis, Sturge-Weber syndrome, craniopharyngioma, congenital cytomegalovirus, subependymal hemorrhages, and hemorrhagic microembolic infarction. Calcifications appeared hypointense whereas hemorrhages were hyperintense on phase maps (left-handed magnetic resonance system). Statistical comparison of phase shift values yielded significant difference between hemorrhage versus calcification (P < .01). Phase maps were found to offer valuable data to differentiate 2 pathologies when used complementary to conventional magnetic resonance images. Considering the relatively higher risks of radiation exposure in children, susceptibility-weighted imaging with phase maps may help to waive radiation exposure from CT.

Diagnosis of intracranial calcification and hemorrhage in pediatric patients: Comparison of quantitative susceptibility mapping and phase images of susceptibility-weighted imaging

PURPOSE To prospectively compare the diagnostic capabilities of quantitative susceptibility mapping (QSM) with those of phase images of susceptibility-weighted imaging (SWI) in the detection and differentiation of intracranial calcification and hemorrhage in pediatric patients. METHOD Sixteen pediatric patients (9 girls, 7 boys) with a mean age of 9.4±6.3 (SD) years (range, 6 days-15 years) were included. Fifty-nine calcifications and 31 hemorrhages were detected. Sensitivities and specificities of the two magnetic resonance (MR) imaging techniques were calculated and compared using McNemar test. RESULTS QSM had a sensitivity of 84.7% and specificity of 100% for the detection of calcification. SWI phase images had a sensitivity of 49.1% and specificity of 100%. For the detection of hemorrhage, QSM had a sensitivity of 90.3% and a specificity of 98.3% whereas SWI phase images yielded a sensitivity of 64.5% and specificity of 96.6%. Overall, QSM displayed significantly better sensitivity than SWI phase images in identification of calcification and hemorrhage (P<0.05). CONCLUSION QSM is more reliable than SWI phase images in the identification of intracranial calcification and hemorrhage in pediatric patients using MR imaging.

Brain diffusion tensor imaging in children with tuberous sclerosis

PURPOSE To evaluate diffusion characteristics of tubers and white matter lesions in children with tuberous sclerosis (TS) using diffusion tensor imaging (DTI). MATERIALS AND METHODS Eighteen children (11 male, 7 female; mean age 9.3years, age range 1-16years) with a definite diagnosis of TS were recruited in this study. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) values in 89 tubers and 37 white matter lesions were measured and compared with those of contralateral normal regions. RESULTS ADC, AD, and RD values were significantly higher and FA values were lower in lesions, than the ones measured in contralateral normal regions for tubers (P<0.001). Similarly RD values were significantly higher and FA values were lower in white matter lesions (P<0.05). ADC and AD measures were detected to increase in white matter lesions, however no statistically significant difference was observed. The increase in the mean values of RD was significantly greater than the increase in the AD values for tubers and white matter lesions (P<0.05). CONCLUSION DTI can provide valuable information about the cytoarchitectural changes in TS lesions beyond morphologic MRI findings alone.

Magnetic Susceptibility Changes in the Basal Ganglia and Brain Stem of Patients with Wilson’s Disease: Evaluation with Quantitative Susceptibility Mapping

Objectives: Wilson’s disease (WD) is characterized with the accumulation of copper in the liver and brain. The objective of this study is to quantitatively measure the susceptibility changes of basal ganglia and brain stem of pediatric patients with neurological WD using quantitative susceptibility mapping (QSM) in comparison to healthy controls. Methods: Eleven patients with neurological WD (mean age 15 ± 3.3 years, range 10–22 years) and 14 age-matched controls were prospectively recruited. Both groups were scanned on a 1.5 Tesla clinical scanner. In addition to T1- and T2-weighted MR images, a 3D multi-echo spoiled gradient echo (GRE) sequence was acquired and QSM images were derived offline. The quantitative measurement of susceptibility of corpus striatum, thalamus of each hemisphere, midbrain, and pons were assessed with the region of interest analysis on the QSM images. The susceptibility values for the patient and control groups were compared using two-sample t-test. Results: One patient with WD had T1 shortening in the bilateral globus pallidus. Another one had hyperintensity in the bilateral putamen, caudate nuclei, and substantia nigra on T2-weighted images. The rest of the patients with WD and all subjects of the control group had no signal abnormalities on conventional MR images. The susceptibility measures of right side of globus pallidus, putamen, thalamus, midbrain, and entire pons were significantly different in patients compared to controls (P < 0.05). Conclusion: QSM method exhibits increased susceptibility differences of basal ganglia and brain stem in patients with WD that have neurologic impairment even if no signal alteration is detected on T1- and T2-weighted MR images.

Neural Correlates of Default Mode Network Connectivity in Children with Attention Deficit and Hyperactivity Disorder

The Purpose: The objective of this study is to explore neural correlates of Default Mode Network (DMN) regions in children with attention deficit and hyperactivity disorder (ADHD) using resting-state functional magnetic resonance imaging (rs-fMRI). Methods: The study included ten children with ADHD (aged between 9 and 16) and ten age-matched controls. Four DMN regions (medial prefrontal cortex (MPFC), the posterior cingulate cortex (PCC), left and right inferior parietal lobes (IPL) and the corresponding Broadmann areas in each one were used as seeds and their functional connectivity with the whole brain was explored and compared between ADHD and control groups using t-test (p<0.05). Results: We observed that when DMN regions were selected as seeds, the connected regions were different between two groups and were mostly in the right hemisphere in ADHD patients contrary to the left hemisphere in the control group. Conclusion: In conclusion, neural correlates of DMN regions differ in ADHD patients compared to healthy controls. Our findings suggest that in ADHD patients, DMN regions show more connectivity with the right hemisphere of the brain whereas the left hemisphere is more functionally connected with DMN in health controls. Further research is required to explore this atypical DMN connectivity in ADHD using larger cohort.

Macrocerebellum: Volumetric and Diffusion Tensor Imaging Analysis.

Macrocerebellum is a rare entity characterized by an enlarged cerebellum. We describe a case of a 48-month-old child with macrocerebellum. We performed serial volumetric analysis [total brain volume (TBV) and cerebellar volume] over a period of 4 years. We analyzed the white matter microstructure in the cerebellum using diffusion tensor imaging (DTI). In our patient, we found higher fractional anisotropy (FA) and lower mean diffusivity (MD) in the cerebellar white matter compared to age-matched controls. Our results may represent accelerated myelination secondary to the abnormal cerebellar development.

Diffusion tensor and volumetric magnetic resonance imaging findings in the brains of professional musicians

Professional musicians represent an ideal model to study the training-induced brain plasticity. The current study aimed to investigate the brain volume and diffusion characteristics of musicians using structural magnetic resonance and diffusion tensor imaging (DTI). The combined use of volumetric and diffusion methods in studying musician brain has not been done in literature. Our study group consisted of seven male musicians playing an instrument and seven age- and gender-matched non-musicians. We evaluated the volumes of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) and calculated total intracranial volume (TIV) and measured the fractional anisotropy (FA) of pre-selected WM bundles: corpus callosum (CC), corticospinal tract (CST), superior longitudinal fasciculus (SLF), forceps major (ForMaj), forceps minor (ForMin), and arcuate fasciculus (AF). The mean WM/TIV volume in musicians was higher compared to non-musicians. The mean FA was lower in CC, SLF, ForMaj, ForMin, and right AF but higher in right CST in the musicians. The mean value of the total number of fibers was larger in the CST, SLF, left AF, and ForMaj in the musicians. The observed differences were not statistically significant between the groups (p>0.05). However, increased GM volume was found in the musicians compared to the non-musicians in the right and left cerebellum and supramarginal and angular gyrus, left superior and inferior parietal lobule and as well as left middle temporal gyrus. Our findings suggest differing brain structure in musicians and the confirmation of the results on a larger population.

Brain susceptibility changes in neurologically asymptomatic pediatric patients with Wilson’s disease: evaluation with quantitative susceptibility mapping:

Background Wilson’s disease (WD) is a copper metabolism disorder that causes hepatolenticular degeneration. It is important to diagnose WD before central nervous system involvement. Purpose To demonstrate the early susceptibility changes associated with the copper accumulation in the brain of neurologically asymptomatic pediatric patients with WD using quantitative susceptibility mapping (QSM). Material and Methods Twelve patients with neurologically asymptomatic WD (mean age = 13.7 ± 3.3 years) and 14 age-matched controls were prospectively examined using a 1.5-T clinical scanner. Routine magnetic resonance (MR) sequences and a three-dimensional multi-echo spoiled gradient echo (GRE) sequence were used and QSM maps were reproduced. The quantitative susceptibility of corpus striatum, thalamus, substantia nigra, and pons were analyzed with the region of interest analysis on QSM maps. The susceptibility values of two groups were statistically compared using a two-sample t-test. Results Conventional MR images of the patients and control group were similar. However increased magnetic susceptibility in the thalamus, pons and left posterior putamen were observed in the patients compared to the control group (p < 0.05). Conclusion We observed statistically increased susceptibility values in the brains of neurologically asymptomatic patients with WD although the conventional MR images were normal. This might be compatible with early brain impairment, before neurological symptoms occur.

A rare incidence of metal artifact on MRI

We present a rare example of metal artifacts observed in magnetic resonance imaging (MRI). A 32-year-old male patient was referred to our radiology department for brain MRI. T1-weighted spin echo, T2-weighted turbo spin echo, diffusion-weighted, and fluid attenuated inversion recovery (FLAIR) images were acquired on a 1.5 Tesla scanner (Magnetom Aera, Siemens Erlangen, Germany). Unusual circular shapes resembling water bubbles were observed at the vertex on the conventional MR images ( Figure 1 ). The patient was contacted if he had anything on his head, such as hair gel, etc. during MR imaging. It was found out that the patient was a metal worker who cuts metals and shapes things out of them and there were residual metal dusts on his scalp despite he had a shower before coming to the hospital.

The Role of Diffusion-Weighted Imaging in the Evaluation of the Whole Brain in Isolated Unilateral Polymicrogyria

The aim is to evaluate normal-appearing brain regions in isolated unilateral polymicrogyria patients and compare them with controls by using diffusion-weighted imaging and apparent diffusion coefficient. The diffusion-weighted images (b = 0-1000 s/mm2) of 10 pediatric patients (7 boys, 3 girls; mean age = 5.8 ± 4.3 years) with isolated unilateral polymicrogyria and age-sex matched 10 control patients were assessed retrospectively. There was a significant increase in apparent diffusion coefficient values of white matter underlying polymicrogyria, uninvolved white matter, deep gray matter (thalami, lentiform nuclei, caudate nuclei) and corpus callosum in polymicrogyria patients compared to control group (P < .01). The whole brain might be affected in isolated unilateral polymicrogyria patients. The abnormal deep gray matter in polymicrogyria patients would indicate a new point of view for pediatric neurologists about the probability of additional future neurological disorders.