Early expansion of the intracranial CSF volume after palliative whole-brain radiotherapy: results of a longitudinal CT segmentation analysis.
OBJECTIVE
To assess cerebral atrophy after radiotherapy, we measured intracranial cerebrospinal fluid volume (ICSFV) over time after whole-brain radiotherapy (WBRT) and compared it with published normal-population data.


METHODS
We identified 9 patients receiving a single course of WBRT (30 Gy in 10 fractions over 2 weeks) for ipsilateral brain metastases with at least 3 years of computed tomography follow-up. Segmentation analysis was confined to the tumor-free hemi-cranium. The technique was semiautomated by use of thresholds based on scanned image intensity. The ICSFV percentage (ratio of ICSFV to brain volume) was used for modeling purposes. Published normal-population ICSFV percentages as a function of age were used as a control. A repeated-measures model with cross-sectional (between individuals) and longitudinal (within individuals) quadratic components was fitted to the collected data. The influence of clinical factors including the use of subependymal plate shielding was studied.


RESULTS
The median imaging follow-up was 6.25 years. There was an immediate increase (p < 0.0001) in ICSFV percentage, which decelerated over time. The clinical factors studied had no significant effect on the model.


CONCLUSIONS
WBRT immediately accelerates the rate of brain atrophy. This longitudinal study in patients with brain metastases provides a baseline against which the potential benefits of more localized radiotherapeutic techniques such as radiosurgery may be compared.
Sanghera
Paul
P
Odette Cancer Centre, Toronto, Ontario, Canada.
Gardner
Sandra L
SL
Scora
Daryl
D
Davey
Phillip
P
D000328:Adult; D000367:Age Factors; D000368:Aged; D001284:Atrophy / Q000000981:diagnostic imaging / Q000209:etiology; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology* / Q000528:radiation effects; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary; D002555:Cerebrospinal Fluid / Q000000981:diagnostic imaging / Q000502:physiology / Q000528:radiation effects*; D003072:Cognition Disorders / Q000517:prevention & control; D016371:Cranial Irradiation / Q000009:adverse effects* / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010166:Palliative Care / Q000379:methods; D011859:Radiography