Quantitative imaging assessment of radiation therapy (RT) for diffuse low-grade gliomas (DLGG) by measuring the velocity of diametric expansion (VDE) over time has never been studied. We assessed the VDE changes following RT and determined whether this parameter can serve as a prognostic factor. We reviewed a consecutive series of 33 adults with supratentorial DLGG treated with first-line RT with available imaging follow-up (median follow-up, 103 months). Before RT, all patients presented with a spontaneous tumor volume increase (positive VDE, mean 5.9 mm/year). After RT, all patients demonstrated a tumor volume decrease (negative VDE, mean, -16.7 mm/year) during a mean 49-month duration. In univariate analysis, initial tumor volume (>100 cm(3)), lack of IDH1 expression, p53 expression, high proliferation index, and fast post-RT tumor volume decrease (VDE at -10 mm/year or faster, fast responders) were associated with a significantly shorter overall survival (OS). The median OS was significantly longer (120.8 months) for slow responders (post-RT VDE slower than -10.0 mm/year) than for fast responders (47.9 months). In multivariate analysis, fast responders, larger initial tumor volume, lack of IDH1 expression, and p53 expression were independent poor prognostic factors for OS. A high proliferation index was significantly more frequent in the fast responder subgroup than in the slow responder subgroup. We conclude that the pattern of post-RT VDE changes is an independent prognostic factor for DLGG and offers a quantitative parameter to predict long-term outcomes. We propose to monitor individually the post-RT VDE changes using MRI follow-up, with particular attention to fast responders.

OBJECTIVE There are no guidelines for the management of postoperative lateral sinus thrombosis following posterior fossa surgery. Introducing treatment-dose anticoagulant therapy during the immediate postoperative period increases the risk of intracranial bleeding. This study assessed the incidence of and risk factors associated with postoperative lateral sinus thrombosis and the complications related to thrombosis and/or anticoagulation. METHODS This study was a retrospective monocentric analysis of adult patients who underwent surgical removal of a posterior fossa space-occupying lesion with available postoperative imaging. Postoperative lateral sinus thrombosis was defined as a T2 hypointensity within the venous sinus and/or a filling defect on postcontrast MRI or CT scan. RESULTS Among 180 patients, 12 (6.7%; 95% CI 3.0-10.4) were found to have lateral sinus thrombosis on postoperative imaging, none of whom were symptomatic. Unadjusted risk factors for postoperative lateral sinus thrombosis were a history of deep venous thrombosis (p = 0.016), oral contraceptive pill (p = 0.004), midline surgical approach (p = 0.035), and surgical exposure of the sinus (p < 0.001). Seven of the patients (58.3%) with a postoperative lateral sinus thrombosis received immediate treatment-dose anticoagulant therapy. Lateral sinus recanalization occurred radiologically at a mean time of 272 ± 23 days in 85.7% of patients (6 of 7) undergoing treatment-dose anticoagulant therapy and in 20% of patients (1 of 5) not receiving treatment-dose anticoagulant therapy. Postoperative complications occurred in 56.2% of patients (9 of 16) who received treatment-dose curative anticoagulant therapy and in 27% of patients (45 of 164) who did not. CONCLUSIONS Incidental radiological lateral sinus thrombosis following posterior fossa surgery has an incidence of 6.7%. To further define the benefit-to-risk ratio of a treatment-dose anticoagulant therapy, a prospective trial should be considered.