• Anouk van der Hoorn, Jiun-Lin Yan, Timothy J Larkin, Natalie R Boonzaier, Tomasz Matys, and Stephen J Price.
• University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: a.van.der.hoorn@umcg.nl.
• World Neurosurg. 2016 Aug 1; 92: 159-165.

BackgroundAlthough targeted by radiotherapy, recurrence in glioblastoma occurs mainly periresectionally owing to tumor infiltration. An increase in the apparent diffusion coefficient (ADC) has been shown in the large high-T2 area on magnetic resonance imaging posttreatment; however, until now ADC has not been investigated directly in the more relevant periresectional area.MethodsHistogram analysis was used to assess periresectional ADC values in patients with glioblastoma postradiotherapy versus preradiotherapy. Periresectional ADC values starting at 0-5 mm in 5-mm increments up to 20-25 mm were extracted and compared using 2-way repeated-measurements analysis of variance.ResultsMean ADC values directly adjacent to the resection area (0-5 mm) were significantly higher postradiotherapy compared with preradiotherapy (P = .017). ADC values in the 0- to 5-mm region were also higher than those in 5- to 10-, 10- to 15-, and 15- to 20-mm regions (P < .05). Regional standard deviations in ADC values were higher postradiotherapy compared with preradiotherapy for the 0- to 5-mm region up to the 15- to 20-mm region, inclusive (P < .05); however, Cox regression analysis showed no survival benefits from the increased ADC in the 0- to 5-mm region postradiotherapy.ConclusionsIncreased ADC values, representing a decrease in infiltrative tumor load, were demonstrated in a limited direct periresectional area. This finding adds to previous studies evaluating ADC response in the larger high-T2 area in relation to survival.Copyright © 2016 Elsevier Inc. All rights reserved.

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