Retrospective study of late radiation-induced damages after focal radiotherapy for childhood brain tumors.

PURPOSE: To study a robust and reproducible procedure to investigate a relation between focal brain radiotherapy (RT) low doses, neurocognitive impairment and late White Matter and Gray Matter alterations, as shown by Diffusion Tensor Imaging (DTI), in children. METHODS AND MATERIALS: Forty-five patients (23 males and 22 females, median age at RT 6.2 years, median age at evaluations 11.1 years) who had received focal RT for brain tumors were recruited for DTI exams and neurocognitive tests. Patients' brains were parceled in 116 regions of interest (ROIs) using an available segmented atlas. After the development of an ad hoc, home-made, multimodal and highly deformable registration framework, we collected mean RT doses and DTI metrics values for each ROI. The pattern of association between cognitive scores or domains and dose or DTI values was assessed in each ROI through both considering and excluding ROIs with mean doses higher than 75% of the prescription. Subsequently, a preliminary threshold value of dose discriminating patients with and without neurocognitive impairment was selected for the most relevant associations. RESULTS: The workflow allowed us to identify 10 ROIs where RT dose and DTI metrics were significantly associated with cognitive tests results (p<0.05). In 5/10 ROIs, RT dose and cognitive tests were associated with p<0.01 and preliminary RT threshold dose values, implying a possible cognitive or neuropsychological damage, were calculated. The analysis of domains showed that the most involved one was the "school-related activities". CONCLUSION: This analysis, despite being conducted on a retrospective cohort of children, shows that the identification of critical brain structures and respective radiation dose thresholds is achievable by combining, with appropriate methodological tools, the large amount of data arising from different sources. This supported the design of a prospective study to gain stronger evidence.

Prenatal Irradiation-Induced Hippocampal Abnormalities in Rats Evaluated Using Manganese-Enhanced MRI.

The aim of this study was to characterize hippocampal abnormalities in rats after prenatal x-ray irradiation using manganese-enhanced MRI (MEMRI). All radiation-exposed rat brains showed a reduced volume with prominent dilatation of lateral ventricles. Moreover, MEMRI-enhanced areas within the hippocampus were reduced in volumes by approximately 25% of controls, although the entire volume of hippocampus was decreased by approximately 50% of controls. MEMRI signals were enhanced strongly in the hilus and granular layer of the dentate gyrus (DG) and the pyramidal layer and infrapyramidal region of the CA3 region, and moderately along the CA1/2 pyramidal cell layer in the control rats. In radiation-exposed rats, MEMRI signals in the CA1/2 regions disappeared due to disrupting their laminar organization, although strong MEMRI signals were sustained in the DG and CA3 regions. Histopathological examinations in radiation-exposed rats revealed disorganizations of the DG granule cell layer and the CA3 pyramidal cell layer with reducing the cell density. The CA1/2 pyramidal cell layer was disrupted by invading ectopic cell mass. Neural cell adhesion molecule (NCAM)-positive fiber bundles were sustained in radiation-exposed rats, although they distributed aberrantly in the suprapyramidal CA3 region with a slight reduction of NCAM staining. Furthermore, glial components consisted largely by astrocytes and minor by microglia were densely distributed in the DG rather than in other hippocampal regions, and their density radiation-exposed rats. In conclusion, MEMRI signal enhancements could delineate different neuronal and/or glial components among hippocampal regions. We characterized microstructures of the deformed hippocampus as well as its macrostructures in a prenatally radiation-exposed rat model using in vivo MEMRI. The present findings provide advantageous information for detecting nondestructively hippocampal deformations in neurodevelopmental disorders.

Prevalence and Characterization of Thyroid Hemiagenesis in Japan: The Fukushima Health Management Survey.

BACKGROUND: Thyroid hemiagenesis is a rare congenital variant characterized by the lack of development of one thyroid lobe with no clinical manifestations. METHODS: This study was performed to determine the prevalence and characteristics of thyroid hemiagenesis in a normal Japanese population. This cross-sectional study was performed from October 9, 2011, to April 30, 2015. In total, 299,908 children and young adults in the Fukushima Health Management Survey were examined to determine the presence of thyroid agenesis or hemiagenesis. Thyroid width, thickness, and length were measured in 292,452 of these subjects. RESULTS: Thyroid agenesis was diagnosed in 13 subjects, and hemiagenesis was detected in 67 subjects (0.02%; 22.3/100,000 individuals). Although there was no significant sex-related difference (p = 0.067), the female:male ratio was 1.67:1.00. Females were significantly dominant in right hemiagenesis, while there was no difference in left hemiagenesis between males and females. The thyroid volumes at the 2.5th and 97.5th percentiles for age and body surface area were determined for each sex. Multivariate regression analysis showed that a large hemithyroid volume was independently associated with the presence of contralateral hemiagenesis (p < 0.001). CONCLUSION: The prevalence of thyroid hemiagenesis in the present study is in agreement with that reported in other countries. The prevalence of right hemiagenesis was higher in females, and the larger contralateral lobe in patients with rather than without hemiagenesis may have been caused by a compensatory feedback mechanism to prevent hypothyroidism. In addition, the prevalence of hemiagenesis, especially right hemiagenesis, may be affected by sex-related factors similar to those in patients with an ectopic thyroid gland.

Dynamic contrast-enhanced MRI detects acute radiotherapy-induced alterations in mandibular microvasculature: prospective assessment of imaging biomarkers of normal tissue injury.

Normal tissue toxicity is an important consideration in the continued development of more effective external beam radiotherapy (EBRT) regimens for head and neck tumors. The ability to detect EBRT-induced changes in mandibular bone vascularity represents a crucial step in decreasing potential toxicity. To date, no imaging modality has been shown to detect changes in bone vascularity in real time during treatment. Based on our institutional experience with multi-parametric MRI, we hypothesized that DCE-MRI can provide in-treatment information regarding EBRT-induced changes in mandibular vascularity. Thirty-two patients undergoing EBRT treatment for head and neck cancer were prospectively imaged prior to, mid-course, and following treatment. DCE-MRI scans were co-registered to dosimetric maps to correlate EBRT dose and change in mandibular bone vascularity as measured by Ktrans and Ve. DCE-MRI was able to detect dose-dependent changes in both Ktrans and Ve in a subset of patients. One patient who developed ORN during the study period demonstrated decreases in Ktrans and Ve following treatment completion. We demonstrate, in a prospective imaging trial, that DCE-MRI can detect dose-dependent alterations in mandibular bone vascularity during chemoradiotherapy, providing biomarkers that are physiological correlates of acute of acute mandibular vascular injury and recovery temporal kinetics.

Social behavioral testing and brain magnetic resonance imaging in chicks exposed to mobile phone radiation during development.

BACKGROUND: The potential adverse effect of mobile phone radiation is currently an area of great concern in the field of public health. In the present study, we aimed to investigate the effect of mobile phone radiation (900 MHz radiofrequency) during hatching on postnatal social behaviors in chicks, as well as the effect on brain size and structural maturity estimated using 3.0 T magnetic resonance imaging. At day 4 of incubation, 76 normally developing chick embryos were divided into the control group (n = 39) and the radiation group (n = 37). Eggs in the radiation group were exposed to mobile phone radiation for 10 h each day from day 4 to 19 of incubation. Behavioral tests were performed 4 days after hatching. T2-weighted MR imaging and diffusion tensor imaging (DTI) were subsequently performed. The size of different brain subdivisions (telencephalon, optic lobe, brain stem, and cerebellum) and corresponding DTI parameters were measured. The Chi-square test and the student's t test were used for statistical analysis. P < 0.05 was considered statistically significant. RESULTS: Compared with controls, chicks in the radiation group showed significantly slower aggregation responses (14.87 ± 10.06 vs. 7.48 ± 4.31 s, respectively; P < 0.05), lower belongingness (23.71 ± 8.72 vs. 11.45 ± 6.53 s, respectively; P < 0.05), and weaker vocalization (53.23 ± 8.60 vs. 60.01 ± 10.45 dB/30 s, respectively; P < 0.05). No significant differences were found between the radiation and control group for brain size and structural maturity, except for cerebellum size, which was significantly smaller in the radiation group (28.40 ± 1.95 vs. 29.95 ± 1.41 cm(2), P < 0.05). The hatching and heteroplasia rates were also calculated and no significant difference was found between the two groups. CONCLUSIONS: Mobile phone radiation exposure during chick embryogenesis impaired social behaviors after hatching and possibly induced cerebellar retardation. This indicates potential adverse effects of mobile phone radiation on brain development.

[Autonomic homeostasis of children born to parents irradiated in the result of the Chernobyl catastrophe with isolated abnormal chords of the left ventricle].

156 children of the main group (were born to parents irradiated in the result of Chernobyl disaster), in which according to Doppler echocardiography isolated abnormal chords of the left ventricle (AHLV) identified, 44 children of control group and 50 children of referent group were involved in the study Analysis of indicators of operational regulation of heart rate in children of primary group indicate the existence of autonomic dysregulation, which has the maximum expression in children with a threshold number of isolated abnormal chords. Evidence of autonomic dysregulation in children born to parents irradiated in the result of the Chernobyl disaster with isolated AHLV requires primary and secondary prevention to reduce the frequency of unfavourable clinical course.

[Bioelectrical activity of the myocardium in children born to parents irradiated during the Chernobyl disaster with isolated abnormal chords of the left ventricle].

A total 156 children of the main group (children born to parents irradiated during the Chernobyl disaster), who according to echocardiography revealed a different number of isolated abnormal chords of the left ventricle, 20 healthy children, 24 children of nosological control group and 50 children of referent group have been observed. It was found that isolated AHLV in children born to irradiated parents, was associated with changes in standard ECG, reflecting the presence of arrhythmias or predictors of their development. No significant differences in subgroups of children with different number of isolated AHLV have been established. Children with isolated AHLV born to parents irradiated during the Chernobyl accident, as all patients with minor structural anomalies of the heart, should be refered to a risk group in connection with the possibility of the development, in the first place, ventricular extrasystoles, paroxysmal ventricular tachycardia. Early diagnosis of isolated AHLV will allow to assess the outlook for further course of the disease and develop a plan of treatment and preventive measures.

Moyamoya syndrome after radiation therapy for optic pathway glioma: case report.

We present a 4-year-old girl with neurofibromatosis-1 who developed moyamoya syndrome characterized by bilateral stenosis or occlusion of the distal internal carotid arteries and their branches, leading to the development of an abnormal vascular network. In light of a literature review, the postradiation vasculopathy of the moyamoya type and its relationship with neurofibromatosis-1 are discussed.