Diffusion Lesion Reversal After Thrombolysis

Abstract

In acute ischemic stroke, the diffusion-weighted imaging (DWI) lesion is commonly considered a surrogate marker of irreversible core, and this underpins all MR methods currently in use to screen candidates for reperfusion therapy, notably according to the perfusion (PWI)-DWI mismatch model. 1 Accurate assessment of DWI lesion volume is also crucial to establish cutoffs above which thrombolysis may not be beneficial and may even be harmful. However, the reliability of the DWI hyperintense lesion as a depiction of the infarct core is challenged by reports of occasionally sustained, albeit often partial, DWI lesion reversal after reperfusion. [2][3][4][5][6][7][8] Permanent DWI lesion reversal is well established in the animal literature using temporary artery occlusion models. 9 In human stroke, DWI lesion reversal was initially reported immediately after intra-arterial therapy. 6 A systematic review suggested that the rate of permanent DWI reversal was substantial and highlighted the potential unreliability of DWI hyperintensities for infarct core imaging. 10 Although DWI lesion reversal after reperfusion is a well-accepted phenomenon, studies have been discrepant regarding its exact extent. 3,8,11,12 Moreover, the clinical implication, if any, of DWI lesion reversal is unclear. In the prospective multicenter Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) study of patients treated by intravenous tissue-type plasminogen activator (tPA) 3 to 6 hours after stroke onset, DWI lesion reversal was associated with early reperfusion and a favorable clinical outcome. 8 However, in a further analysis of DEFUSE, pooled with the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) data, the amount of DWI reversal was reported as small and hence Background and Purpose-In acute stroke, diffusion-weighted imaging (DWI) lesions are commonly considered markers of irreversible ischemia yet can occasionally reverse. However, the extent and clinical correlates of DWI reversal in thrombolyzed patients remain unclear. We assessed the extent of reversible acute DWI lesions (RADs) and their relationships with clinical outcome in patients thrombolyzed ≤4.5 hours from onset. Methods-Data were retrospectively analyzed. RAD was defined as an acute DWI lesion not part of a 24-hour DWI lesion as determined voxelwise. Associations with an early neurological improvement (early neurological improvement=ΔNational Institutes of Health Stroke Scale ≥8 or National Institutes of Health Stroke Scale ≤2 at 24 hours) or an excellent outcome (modified Rankin Scale ≤1) were assessed in multivariate analyses. Results-One hundred seventy-six patients were included. The median (interquartile range) time to treatment from onset was 150 minutes . Eighty-nine patients (50%) exhibited visually-detectable RAD irrespective of its extent. Over the whole population, the median percentage and volume of RAD were 11% (4-36) and 2.4 mL (0.5-8). Subtracting RAD from initial DWI altered perfusion-weighted imaging-DWI classifica...

Reperfusion Within 6 Hours Outperforms Recanalization in Predicting Penumbra Salvage, Lesion Growth, Final Infarct, and Clinical Outcome

“…During the entire cohort, median and percentage DWI lesion reversal volume were 5.4 mL (2.7-11.8) and 43% (22-72), respectively. Reperfused patients had a higher percentage of DWI lesion reversal than those without reperfusion: 68% (33-89) versus 24% (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31), respectively (P=0.002). No significant difference in volume of DWI lesion reversal was found between patients with or without reperfusion (P=0.14).…”

Baseline collateral status and infarct topography in post-ischaemic perilesional hyperperfusion: An arterial spin labelling study

“…Baseline collateral status is now recognised to be important in the evaluation and treatment of cerebral ischaemia. 32,33 The presence and a higher grade of collateral supply through leptomeningeal sources correlate with the presence of smaller final infarct volume, 37 improved recanalisation rates, and favourable functional outcomes in patients undergoing endovascular revascularisation therapy. 27,[38][39][40] Therapeutically effective recanalization in a setting of poor baseline collaterals may result in increased rates of HT, 38,41 thereby leading to worsening of neurological status by restricting effective reperfusion.…”

“…The early neurological change was categorised as early neurological improvement (ENI) or early neurological deterioration (END). ENI was defined as a gain of NIHSS !8 within the first 24 h or NIHSS < 2 at 24 h. 32,33 END was defined as !4-point deterioration on 24 h NIHSS. 34 Final infarct volume (DWI lesion) at 24 h was calculated.…”

The role of imaging in acute ischemic stroke

“…8). However, users should be cautious of the spontaneous resolution of some DWI hyperintense lesions 119 ( Fig. 9), and the inclusion of benign oligemia within the PWI abnormalities that are not at risk for infarction.…”

“…104 The extent of mismatched tissue varies depending on the perfusion parameter selected and the threshold selected to represent the PWI abnormality. 60,70,71,104,119,170 In a post hoc analysis of the DEFUSE trial, 4 defining penumbra by using Tmax of 4-6 seconds provided the most accurate estimate of the penumbra. 162 Other studies recommended using Tmax > 6 seconds.…”