Partial rescue of the perfusion deficit area by thrombolysis

Abstract

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 Ͻ 0.0006). The acute TTP volumes were smaller than the acute MTT volumes, but as large as the T2 lesions on day 8. The MTT/T2 lesion volume reduction was significant (P Ͻ 0.03) in patients who received the GPIIb/IIIa receptor antagonist tirofiban (N ϭ 13) in addition to the low-dose rtPA. This corresponded to a greater neurological improvement compared to patients who received rtPA alone (P Ͻ 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 Ϯ 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.

Computed tomography and magnetic resonance perfusion imaging in ischemic stroke: Definitions and thresholds

“…The same patients were definitely used in 3 pairs of studies from which we counted the patients only once: Murphy and colleagues (2006)45 and Murphy and colleagues (2008)52; Koenig and colleagues49 and Klotz and Konig54; Sobesky and colleagues28 and Heiss and colleagues 27. We were unable to establish the overlap in patients, if any, that contributed to the analyses in 3 further groups of MR studies (first group,32, 44, 74 second group,36, 39, 41 and third group38, 40). Assuming that these studies shared all their patients, then the maximum number of patients contributing threshold data from the 21 MR studies would be 397, not 551.…”

“…Of these, 220 papers were rejected based on the full text, leaving 69 potentially relevant papers (49 MR and 20 CT). Data on definitions were obtained from all 69 papers; 21 MR25–44 and 10 CT45–54 papers, published by 19 different research groups worldwide, provided threshold data.…”

“…Four MR30, 32, 42, 44 and 5 CT studies45–47, 50, 52 presented data according to recanalization, but not for both recanalized and nonrecanalized patients (details upon request). Perfusion thresholds were validated using perfusion values obtained from PET imaging performed contemporaneously with MR imaging in 3 of 21 studies26–28 and with an MR or CT imaging outcome, eg, infarct extent on follow‐up imaging, in 18 of 21 MR25, 29–44, 74 and all 10 CT studies, but only about one‐half gave the timing of follow‐up imaging45–47, 49, 51, 52 (Supporting Table 1), which ranged from less than 7 days,29, 34, 36, 39, 74 to 90 days 35. Statistical analyses included voxel‐based ROC curve analysis in 11 studies (none corrected for multiple intercorrelated voxels) and various correlation analyses (univariate and multivariate) in the rest (4 did not provide details).…”

Treatment of Acute Ischaemic Stroke

“…A perfusion-diffusion mismatch pattern is present in some 70% of patients with anterior circulation stroke scanned within 6 h of onset, 237 is strongly associated with proximal MCA occlusion, 237 and resolves on reperfusion. 238,239 A recent study reported low favorable clinical responses and high mortality rates in a small group of patients (N = 8) with matched perfusion and diffusion abnormalities who underwent attempted intraarterial thrombolysis, especially those with large infarcts. 240 The penumbra on perfusion imaging has been de fi ned as regions where DWI is normal and TTP >4 s, 241 although, for practical purposes, any region that is abnormal on perfusion imaging but normal on DWI may represent salvageable tissue.…”

MRI of ischemic stroke in canines: Applications for monitoring intraarterial thrombolysis

“…The "tissueat-risk" or ischemic penumbra is often radiologically described as the tissue experiencing abnormal perfusion but lying outside the diffusion lesion (11)(12)(13)(14)(15)(16)(17)(18). In this work we will follow the convention that "infarcted" will be used to describe tissue with restricted diffusion and reduced perfusion while "ischemic" will describe tissue with reduced perfusion only.…”