Background: Diffusion-weighted imaging (DWI) is an imaging modality using multi-section single-shot spin echo planar imaging (EPI) sequence which is extremely sensitive for detection of water motion within intra, extra, and transcellular regions. This character is important to differentiate between brain tumors either low (benign) or highly (malignant) cellular tumors. Objective: To evaluate the role of DWI and apparent diffusion coefficient (ADC) in evaluation and differentiation between different brain posterior fossa tumors in children and adults.Patients and methods: The study included 34 patients with different brain posterior fossa tumors for evaluation by conventional MRI (using 1.5 T MRI PHILIPS Achieva 2.1 Best Netherland) and DWI. Results: Our study showed that mean ADC values were significantly different between the four groups of posterior fossa tumors in children: juvenile pilocytic astrocytoma (JPA), medulloblastoma, ependymoma, and brain stem glioma while mean ADC values were not significantly different between posterior fossa tumors in the adult group. Regions of interest were manually positioned, and all values were automatically calculated and expressed in 10 −3 mm 2 /s. Conclusion: DWI is an ideal additional imaging technique, which is a rapid, easy, non-invasive imaging modality, with no contrast injection needed. It has been widely applied in the differentiation between posterior fossa brain tumors and in the diagnosis of various intracranial diseases.

Aim of the study: To investigate the role of MR diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) in the assessment of altered major white matter fibers in preterm infants and children with PVL. Patients and methods: We used diffusion tensor imaging to evaluate the major white matter tract fibers in 15 children with periventricular leukomalacia in correlation with cognitive and motor disability. Mean age of the patients was 28.5 months (range: 9-84 months). 5 normal control children were recruited (mean age: 21.4, range: 11-60 months). MR imaging was obtained by using a 1.5-T, whole-body scanner. DTI was acquired after the routine sequences. Then, data post-processing and fiber-tracking method was applied. Results: This study demonstrated the existence of the WM tract injury in PVL patients using the DTI tractography approach in correlation with neurodevelopmental delay in patients with various degrees of cognitive and motor impairment. Compared with the normal control group, the following abnormalities were detected on qualitative analysis of the white matter tracts. Corticospinal tracts: Decreased volume and cross-sectional area on the affected side. Ascending sensorimotor tracts: Thinning of sensory fiber tracts and posterior thalamic radiations. Commissural and association tracts: Significant damage of the callosal fibers was reported in cases with partial agenesis of the corpus callosum. Conclusion: DTI proved to be a promising noninvasive method for assessing the severity of white matter tract injury in patients with PVL. This is owing to the capability of fiber-tracking techniques to provide more information for understanding the pathophysiologic features of sensorimotor and

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Background: Diffusion Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) map provide information on Magnetic Resonance Imaging (MRI) about the cellularity of the tumor and have an important role in the pre-operative differentiation of different tumor types. The aim of the current study is to differentiate between pediatric and adult posterior fossa brain tumours using DWI calculation of ADC value of these tumours and correlate our findings with the histopathological reported data. Methods: Our study included a total of 34 patients with posterior fossa brain tumours. Conventional MRI and MRI DWI were applied for each patient. The calculation of the ADC value was performed for the pediatric and adult posterior fossa brain tumours. Results: This study included 34 patients with posterior fossa brain tumours,19 males and 15 females while the cases were selected randomly from the neurosurgery department. Our study has been divided into pediatric group which included 11 patients and adult group with 23 patients. We found a significant difference in 1 (regions of interest) ROI ADC values between all types of pediatric posterior fossa brain tumours (p<0.001). Furthermore, there was a significant difference in 3 ROIs ADC values between all types of pediatric posterior fossa brain tumours (p<0.001). There were no significant differences in 1 ROIs ADC values as well as 3 ROIs ADC values between the adult posterior fossa brain tumors (p value> 0.05). Conclusion: ADC values are simple and readily available techniques for preoperative differentiation of the most common posterior fossa.

Objective: Fetal thymus size evaluation through measuring its ultrasonographic maximum transverse diameter, in relation to fetal biometry changes in pregnancies complicated with FGR.Methods: Our study included 66 singleton pregnancies with intact membranes, aged (18 to 40 y) between 28 and 36 weeks of gestation with FGR,Patients with fetal or maternal infections, chromosomal or fetal congenital anomalies, or IUFD and patients start labor were excluded. All patientsunderwentultrasound evaluation weekly during the third trimester after history taking; examination and lab investigation were performed, where measurements of themaximum transverse diameter of the fetal thymus and fetal biometry (BPD percentile,FL percentile, AC percentile,EFW percentile,and Single deepest vertical pocket) were obtained. The small thymus was defined as a thymus perimeter ≤ 5 th percentile according to a fetal thymus nomogram, then Patients were classified into 2 groupsaccording to whether they had a small transverse thymus diameter (< 5 th %) or normal transverse thymus diameter (> 5 th %).The co-relation between fetal thymus size, obstetric history and fetal biometry changes by ultrasonography were performed. Results:The sixty-six FGR pregnancies were classified to 55 patients with thymus diameter less than 5 th percentile and 11 patients with thymus diameter more than 5 th percentile. The co-relation between thymus diameter less and more than 5 th percentile and obstetric history showed that no statistically significant difference as regarding history of abortion, history of stillbirth, history of preterm labor and history of IUGR but there was statistically significant difference as regarding gestational age (GA) mean at enrollment (32.04 ± 2.7 vs. 36.5 ± 1.04) meaning IUGR fetuses with a thymus diameter <5 th % presented lower GA at enrollment. The correlation between thymus diameter and fetal biometry shows a highly significant positive correlation between thymus transverse diameter and FL, AC, EFW, and AF vertical pocket but non-significant correlation as regards BPD in all cases of both groups.The comparison between thymus diameters less and more than 5 th percentile in relation to fetal ultrasonic biometry showed that no statistically significant difference as regarding BPD mean percentile and FL mean percentile, on other hand, AC and EFW mean percentiles were statistically significantly higher among IUGR fetuses with normal thymus diameter (>5 th percentile) [3.2 ± 2.7 vs. 6.6 ± 2.2 & 3.06 ± 2.6 vs. 6.09 ± 2.5]. 90.91% of IUGR fetuses with normal thymus diameter (>5 th percentile) have adequate amniotic fluid as estimated by single deepest vertical pocket versus 34.55% of IUGR fetuses with thymus diameter <5 th percentile with a statistically significant difference. All IUGR fetuses with oligohydramnios (n=20) had small thymus < 5 th %. Conclusion:There is a highlypositive correlation between thymus transversediameter and AC, EFW, and AF vertical pocket inpregnancies complicated with FGR.