Fig 2. Graphic illustration of the calculation of BBBP by using the Patlak model. A, The Patlak plots are constructed from the arterial and parenchymal time-enhacement curves (the recorded values used to create the illustrated Patlak plot are reported in Table 3). The first-pass component of the Patlak plots is clearly not linear, especially within the tissue at risk (shown in green in B), whereas the delayed phase respects the linear steady-state assumption of the Patlak model. B, BBBP maps at the level of the basal ganglia are shown. They are extracted from the Patlak plots and calculated pixel by pixel. The first-pass BBBP map is noisier than the delayed-phase BBBP map because the quality of the linear fit is less and results in BBBP values that are overestimated compared with the delayed-phase BBBP values. This is true again especially within the tissue at risk (shown in green). The PCT infarct core (shown in red) and at-risk brain tissue (shown in green) are automatically calculated by the software by using the MTT and CBV thresholds reported in the literature as the most accurate (PCT salvageable brain tissue: MTT > 145% of the contralateral side values plus CBV 2.0 mL x 100 g^–1; PCT infarct core: MTT > 145% of the contralateral side values plus CBV < 2.0 mL x 100 g^–1).²⁰