T+RB-PTS shows better recovery of CBF after tPA-lytic treatment than RB-PTS. (A) Comparison of CBF responses to 10 mg/kg tPA treatment at 30 minutes after photoactivation by LSCI in the proximal MCA-directed RB (n = 4) vs T+RB (n = 3) PTS (asterisk indicates the photoactivation site; white arrow indicates the direction of MCA blood flow). Shown are the typical CBF-tracing and LSCI images of blood flow in the proximal MCA-supplying territory (1), the distal MCA territory (2), and the contralateral hemisphere (3; area size: 1.6 mm × 1.6 mm for each). Note the stepwise CBF elevation in the distal, but not the proximal, MCA territory, in the T+RB-PTS model after tPA infusion. In contrast, the tPA treatment failed to produce CBF recovery in the RB-PTS model. (B) Comparison of CBF recovery at 5 and 24 hours after tPA infusion at 30 minutes postphotoactivation in the RB-PTS and T+RB-PTS model (the area size for LSCI measurement: 3 mm × 4.8 mm). The tPA treatment failed to improve CBF recovery compared with the infusion of vehicle at 5 or 24 hours postphotoactivation (n = 4). In contrast, the same tPA treatment produced ∼14% more CBF recovery at 5 hours (P = .13) and ∼25% more at 24 hours in the T+RB-PTS model (P = .03; n = 6).