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Postoperative Surveillance Magnetic Resonance Imaging for Cerebellar Astrocytoma

Published online by Cambridge University Press:  02 December 2014

Michael Vassilyadi*
Division of Neurosurgery, The Ottawa Hospital Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Mohammed F. Shamji
Division of Neurosurgery, The Ottawa Hospital
Zachary Tataryn
Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Daniel Keene
Division of Neurology, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Enrique Ventureyra
Division of Neurosurgery, The Ottawa Hospital Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
The Children’s Hospital of Eastern Ontario, Division of Neurosurgery, 401 Smyth Road, Ottawa, Ontario, K1H 8L1, Canada.
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Patients with low grade astrocytomas generally have good prognosis when total resection can be achieved, but surveillance neuroimaging is commonly performed to detect recurrence or progression. This study evaluated the utility and yield of such strategy for pilocytic and non-pilocytic cerebellar astrocytomas.


A 20-year retrospective review was performed of patients undergoing resection of cerebellar astrocytoma at a single institution. A negative MRI string (NMS) ratio was computed as the fraction of total follow-up period over which surveillance neuroimaging was negative for recurrence or progression. Chi-squared analysis differentiated NMS ratio by resection extent and lesion histopathology.


Twenty-eight patients with pilocytic (n=15) and non-pilocytic (n=13) astrocytoma underwent 34 craniotomies, with total resection in 19 cases. Surveillance MRIs (n=167) among total resection patients were uniformly negative for recurrent disease at average seven years follow-up (NMS ratio = 1.0). The 43 surveillance MRIs among subtotal resection patients revealed disease progression in two patients within six months of operation (NMS ratio = 0.78, p<0.05). No differences in NMS ratio were observed between pilocytic and non-pilocytic astrocytoma subtypes.


This study illustrates pediatric patients with low-grade cerebellar astrocytomas undergoing total resection may not benefit from routine surveillance neuroimaging, primarily because of low recurrence likelihood. Patients with subtotal resection may benefit from surveillance of residual disease, with further work aimed at exploring the schedule of such follow-up.

Copyright © The Canadian Journal of Neurological 2009


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