Changes Mimicking New Leptomeningeal Disease After Intensity-Modulated Radiotherapy for Medulloblastoma

Abstract

Purpose-Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease.Methods and Materials-We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006.Results-After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluidattenuated inversion-recovery signal changes in the brainstem or cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died.Conclusion-Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease.

Imaging Changes in Very Young Children with Brain Tumors Treated with Proton Therapy and Chemotherapy

“…4-7 However, median and mean ages at diagnosis and treatment of the patients in our series, 1.8 and 2.4 years respectively, were much younger than the median ages of 7.1 years and 8.1 years at presentation in two of those series 6,7 and mean age of 5.4 years in one of those studies. 5 Median and mean times to lesion development in our series of children post-PT is shorter than the time to appearance of photon radiation therapy -related lesions, which have been reported to arise a median of 6 to 10 months after the start or completion of radiation therapy.…”

“…5 Median and mean times to lesion development in our series of children post-PT is shorter than the time to appearance of photon radiation therapy -related lesions, which have been reported to arise a median of 6 to 10 months after the start or completion of radiation therapy. 4-7 The lesions in our series also tended to regress sooner (1.5 months to 3.5 months) than time interval of 2 to 26 months described for patients treated with photons. 4-7 The differences in time course may be related to the use of PT, the induction or maintenance chemotherapy regimen, the age of the patients included in our series 8,9 or other factors coincident with the performance of the protocol including surgical sequelae.…”

“…4-7 The lesions in our series also tended to regress sooner (1.5 months to 3.5 months) than time interval of 2 to 26 months described for patients treated with photons. 4-7 The differences in time course may be related to the use of PT, the induction or maintenance chemotherapy regimen, the age of the patients included in our series 8,9 or other factors coincident with the performance of the protocol including surgical sequelae. 10-12 …”

Imaging Changes in Pediatric Intracranial Ependymoma Patients Treated With Proton Beam Radiation Therapy Compared to Intensity Modulated Radiation Therapy

“…Several studies have identified treatmentrelated transient brain lesions and recommended imaging features, location, and temporal course that clearly separates them from recurrence or necrosis (7)(8)(9).…”

The role of radiotherapy in adult medulloblastoma: long-term single-institution experience and a review of the literature

“…The role of new techniques, for example IMRT (Intensity Modulated Radiation Therapy), tomotherapy, protontherapy, and carbon ion radiation in the reduction of doses to OARs during the irradiation of brain malignancies is under investigation [63][64][65], as well as the role of new imaging techniques [66]. Results also seem promising for medulloblastoma patients, although they should be prospectively evaluated and some reports are not completely satisfactory [63][64][65][67][68][69][70][71][72], indicating that particular attention should be given to the volumes of treatment and to the toxic effects of concomitant chemotherapy [73,74]. Despite the small number of analysed patients, our results seem to show that radiation therapy results in a good outcome without a significant negative late impact on neuropsychological abilities.…”