[National meetings for complex cases in pediatric radiation oncology: Back on six years experience]. / Réunions nationales de cas complexes en radiothérapie pédiatrique : retour sur six années d'expérience.

INTRODUCTION: Pediatric cancers are rare, representing almost 2,500 new cases each year in France meaning 1% of all cancers. Since 2012, a twice-monthly national web-based conference was held in France. Any patient with a pediatric type cancer requiring radiotherapy can be discussed. It aims at answering the physician with specific radiation therapy questions on rare and complex indications, at promoting the use of referential and the inclusion into clinical protocols. RESULTS: From 2012 to 2018, 1,078 cases were discussed for 940 patients in 142 meetings. Mean age was 10 years old (4 months to 45 years). The mean number of attendants was 6 (2 to 32). We review in this paper the main clinical features discussed in the web-conference and the decision of the web-conference. In 85% cases, the first treatment proposed was mostly accepted, but in 15%, other proposals were done (modifications of target volumes, doses or indications). CONCLUSIONS: Between 2012 and 2018, more than 1,000 pediatric irradiation cases were discussed in our web-based conference leading to 15% of change in radiation protocol. The rarity and the complexity of these situations need those meetings. They provide a place to improve the global knowledge and the quality of the treatments provided.

Impaired fMRI activation in patients with primary brain tumors.

To characterize peritumoral BOLD contrast disorders, 25 patients referred for resection of primary frontal or parietal neoplasms (low-grade glioma (LGG) (n=8); high-grade glioma (HGG) (n=7); meningioma (n=10)) without macroscopic tumoral infiltration of the primary sensorimotor cortex (SM1) were examined preoperatively using BOLD fMRI during simple motor tasks. Overall cerebral BOLD signal was estimated using vasoreactivity to carbogen inhalation. Using bolus of gadolinium, cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were estimated. In a 1cm(3) region-of-interest centered on maximal T-value in SM1 contralateral to movements, interhemispheric asymmetry was evaluated using interhemispheric ratios for BOLD and perfusion parameters. During motor tasks contralateral to the tumor, ipsitumoral sensorimotor activations were decreased in HGG and meningiomas, correlated to the distance between the tumor and SM1. Whereas CBV was decreased in ipsitumoral SM1 for HGG, it remained normal in meningiomas. Changes in basal perfusion could not explain motor activation impairment in SM1. Decreased interhemispheric ratio of the BOLD response to carbogen was the best predictor to model the asymmetry of motor activation (R=0.51). Moreover, 94.9+/-4.9% of all motor activations overlapped significant BOLD response to carbogen inhalation.

Perfusion-sensitive MRI of pilocytic astrocytomas: initial results.

PURPOSE: To present the imaging and perfusion data obtained in nine patients with pilocytic astrocytomas (PA) and to discuss the original functional issues of this technique. METHOD: Nine patients with pathologically proven PA underwent conventional and perfusion MR imaging. Various areas of relative cerebral blood volume (rCBV) within the tumors were obtained. The maximum rCBV ratios were identified and considered as representative of the tumor. The results were compared with the pathological findings. RESULTS: In all patients, rCBV was <1.5 (mean 1) and the signal intensity curve overshot the baseline. CONCLUSION: PA tend to have low rCBV values and a first-pass curve that crosses the baseline. These characteristics may be explained by the histological profile of the tumoral vascularity and are of relevance in the identification of these rare tumors.