Immediate post-operative MRI suggestive of the site and timing of glioblastoma recurrence after gross total resection: a retrospective longitudinal preliminary study.

Objectives: To retrospectively identify morphological and physiological post-operative magnetic resonance imaging (MRI) characteristics predictive of glioblastoma recurrences after gross total resection (gross-TR).

Methods: Resection margins of 24 glioblastoma were analysed immediately post-operatively (MRI ≤ 2 h) and early post-operatively (24 h ≤ MRI ≤ 48 h), and subdivided into areas with and without subtle contrast enhancement previously considered non-specific. On follow-up MRI, tumour regrowth areas were subdivided according to recurrence extent (focally/extended) and delay (≤6 and ≥12 months). Co-registration of pre-operative, immediately post-operative and early post-operative MRI with the first follow-up MRI demonstrating recurrence authorised their morphological (contrast enhancements) and physiological (rCBV) characterisation.

Results: Morphologically, on immediately post-operative MRI, micro-nodular and frayed enhancements correlate significantly with early recurrences (≤6 months). After gross-TR the absence of these enhancements is associated with a significant increase in progression-free survival (61 vs 15 weeks respectively) and overall survival (125 vs 51 weeks respectively). Physiologically, areas with a future focal recurrence have a trend toward higher rCBV than other areas.

Conclusion: Immediately post-operative topography of micro-nodular and frayed enhancements is suggestive of recurrence location and delay. Absence of such enhancements is associated with a fourfold increase in progression-free survival and a 2.5-fold increase in overall survival.

Key Points: • Immediately post-operative MRI reveals contrast enhancement after glioblastoma gross total resection. • Immediately post-operative micro-nodular and frayed enhancement correlate with early recurrence. • Absence of micro-nodular/frayed enhancement is associated with 61 weeks' progression-free survival. • Absence of micro-nodular/frayed enhancement is associated with 125 weeks' overall survival.