Role of spinal MRI in the follow-up of children treated for medulloblastoma

BACKGROUND. The purpose of the current study was to describe the usefulness of spinal magnetic resonance imaging (MRI) in children with medulloblastoma or primitive neuroectodermal tumor (PNET) of the posterior fossa. METHODS. Children consecutively diagnosed with medulloblastoma/PNET and followed in the Hospital for Sick Children/Toronto were identified. A homogenous cohort of children treated with craniospinal irradiation as part of their initial treatment was considered. Contrast-enhanced spinal MRIs done concomitantly with cranial MRIs (doublets) were reviewed. Recurrence was defined as any new abnormal lesion (in the brain or in the spine) in symptomatic or asymptomatic patients. Doublets after the first recurrence were excluded in the final analysis. The utility of a spinal MRI in the presence of a negative cranial MRI was assessed. RESULTS. In all, 73 patients (21 females and 52 males; median age, 6.6 years, median follow-up time, 4.3 years) had at least 1 evaluable doublet during the follow-up period. Since concomitant cranial and spinal MRI was introduced as the standard evaluation for medulloblastoma/PNET in 1991, 286 doublets were evaluable. Fourteen spinal MRIs and 25 cranial MRIs showed new nodular or leptomeningeal lesions. In 2 patients, repeat MRIs ruled out recurrence (false-positive). All confirmed spinal recurrences were associated with intracranial recurrence. Of 261 doublets with negative cranial MRI, no new lesion was identified on spinal MRI. CONCLUSIONS. An absence of progression on cranial MRI is highly predictive of absence of progression on spinal MRI. There is little evidence that surveillance spinal MRI (in children who underwent craniospinal radiation as part of their initial treatment) improves the detection of recurrences in children with medulloblastoma.