Partial rescue of the perfusion deficit area by thrombolysis

Purpose: To investigate the evolution of the perfusion deficit area following systemic thrombolysis with recombinant tissue plasminogen activator (rtPA) in a clinical study on acute cerebral ischemia. Materials and Methods: We performed volumetric measurements of the acute ischemic lesions in MR images of perfusion (TTP, MTT, and rCBV) and in diffusion-weighted (DW) images, as well as the manifest stroke lesions in T2-weighted MR images on day 8. We compared the data of 29 patients who were subjected to systemic thrombolysis with those of 18 patients who were not eligible for thrombolysis. Results: In the treated patients there were prominent MTT/ DWI and TTP/DWI mismatches (P < 0.0006). The acute TTP volumes were smaller than the acute MTT volumes, but as large as the 72 lesions on day 8. The MTT/T2 lesion volume reduction was significant (P < 0.03) in patients who received the GPIIb/IIIa receptor antagonist tirofiban (N = 13) in addition to the low-dose rtPA. This corresponded to a greater neurological improvement compared to patients who received rtPA alone (P < 0.05). In contrast, in the nontreated patients the initial MTT and TTP lesion volumes were of similar magnitude and predicted the T2 lesions on day 8. In the treated and nontreated patients the TTP lesion signified the viability threshold of acute ischemia, which corresponded to a rCBF of 25 +/- 11 mL/100 g/min. Conclusion: The perfusion deficit area comprises the ischemic core that is destined to undergo necrosis, and an ischemic rim that is salvageable by systemic thrombolysis.