Chapter 7 124 regarding intensity and/or extension. Partial metabolic response (PMR) was defined as any other response. A blinded nuclear medicine specialist re-evaluated all PET/ CT images. To account for inter- reader variability, the PET/CT response categories from the re- evaluation were compared with those obtained from the report. If the report was written by the same dedicated specialist, a second dedicated nuclear medicine specialist re-evaluated these scans. Histopathological response analysis The histopathological response was assessed according to the Mandard tumour regression (TRG) score. Amajor histopathological response was defined as TRG 1 or 2, a partial response as TRG 3, and a poor histopathological response as TRG 4 or 5.14 Statistical analysis Continuous values were recorded in two categories according to the median. Categorical variables were analysed using the chi-squared test. Response prediction was deemed accurate when PET/CT showed a CMR, PMR or NR for a major, partial or poor histopathological response, respectively. The PET/CT response categories from the re-evaluation were compared with those obtained from the report using weighted kappa. Weighted kappa was also used to compare the PET/CT response categories to the magnetic resonance TRG categories, defined as complete response (TRG 1 or 2), partial response (TRG 3) and no response (TRG 4 or 5).15 Statistical analyses were performed using IBMSPSS® version 23 for Windows® (IBM, Armonk, New York, USA).