The role of diffusion weighted magnetic resonance imaging in assessment of normal myelination in infantile brain

Background: Myelination is a dynamic process starting during fetal life and proceeds predominantly after birth in a well-defined, predetermined manner. MR techniques such as diffusion-weighted images and the measurement of the apparent diffusion coefficient (ADC) have been applied to the study of normal brain development. Aim of the work: To demonstrate the role of Diffusion Weighted Imaging and ADC maps in assessing normal progression of the infantile brain myelination. Patients and methods: The present work included 30 infants with normal MRI study of the brain, normal psychomotor development and normal neurological examination. Conventional MRI, DWI and ADC maps were done for all the infants, the average ADC values were calculated in selected areas in white matter. Results: The age of studied children ranged from 1 month to 3 years, 13 males (43.3%) and 17 females (56.7%). In each of the selected areas of the white matter of the brain, examined ADC showed the highest values at birth and there was a significant decrease with age (p < 0.05). Conclusion: ADC values decrease with progressive increase of age. Using ADC values is useful in assessment of normal myelination development in the infantile brain and matches the results of conventional MRI

Role of brain magnetic resonance spectroscopy in the evaluation of suspected mitochondrial diseases in children: Experience in 30 pediatric cases

Introduction: Mitochondrial diseases are a group of inherited disorders caused by derangement of mitochondrial respiration. MR spectroscopy (MRS) has been shown to detect abnormal accumulation of lactate in brain parenchyma and CSF in patients with mitochondrial disorders, but the frequency of detection is largely unknown. Aim of the work: To evaluate the role of brain MR spectroscopy in the assessment of suspected mitochondrial diseases in the pediatric age group. Patients and methods: Thirty children with suspected mitochondrial diseases were examined by MRS. Examination was done using multisection technique and multiple echo times mainly short (35 ms) and intermediate (144 ms). Mitochondrial disease criteria scoring system was used to confirm the suspected diagnosis. Results: All patients showed elevated lactate peak with the CSF being the most sensitive (100%). Among the 30 patients, 26 (86.7%) had elevated levels of blood lactate/pyruvate ratio. Conventional MRI showed highly suggestive features in 15 patients while non specific findings were detected in 11 patients and 4 showed normal appearing brain. Conclusions: MRS provides a noninvasive tool for the diagnosis of mitochondrial diseases, especially in children with non specific findings on MRI, normal appearing MRI or a normal blood lactate/pyruvate ratio