Rapid Apparent Diffusion Coefficient Evolution After Early Revascularization

Abstract

Background and Purpose- In this era of endovascular therapy (EVT) with early, complete recanalization and reperfusion, we have observed an even more rapid apparent diffusion coefficient (ADC) normalization within the acute ischemic lesion compared with the natural history or IV-tPA-treated patient. In this study, we aimed to evaluate the effect of revascularization on ADC evolution within the core lesion in the first 24 hours in acute ischemic stroke patients. Methods- This retrospective study included anterior circulation acute ischemic stroke patients treated with EVT with or without intravenous tPA (IVT) from 2015 to 2017 compared with a consecutive cohort of IVT-only patients treated before 2015. Diffusion-weighted imaging and ADC maps were used to quantify baseline core lesions. Median ADC value change and core reversal were determined at 24 hours. Diffusion-weighted imaging lesion growth was measured at 24 hours and 5 days. Good clinical outcome was defined as modified Rankin Scale score of 0 to 2 at 90 days. Results- Twenty-five patients (50%) received IVT while the other 25 patients received EVT (50%) with or without IVT. Between these patient groups, there were no differences in age, sex, baseline National Institutes of Health Stroke Scale, interhospital transfer, or IVT rates. Thirty-two patients (64%) revascularized with 69% receiving EVT. There was a significant increase in median ADC value of the core lesion at 24 hours in patients who revascularized compared with further ADC reduction in nonrevascularization patients. Revascularization patients had a significantly higher rate of good clinical outcome at 90 days, 63% versus 9% (P=0.003). Core reversal at 24 hours was significantly higher in revascularization patients, 69% versus 22% (P=0.002). Conclusions- ADC evolution in acute ischemic stroke patients with early, complete revascularization, now more commonly seen with EVT, is strikingly different from our historical understanding. The early ADC normalization we have observed in this setting may include a component of secondary injury and serve as a potential imaging biomarker for the development of future adjunctive therapies. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT00009243.

Keywords: biomarkers; embolectomy; ischemia; magnetic resonance imaging; reperfusion; stroke.

Figure 1.

Plot of baseline ADC value (μm²/s) versus 24-hour ADC value (μm²/s) - ADC at 24 hours is dependent on revascularization status.

Figure 2.

Top panel: EVT patient, 54-year-old male presenting 2 hours from onset, baseline NIHSS 23, baseline DWI volume 26mL and ADC positive, treated with IV tPA within 60 minutes from triage at outside hospital, transferred and received EVT within 90 minutes of triage at hub hospital. TICI score of 3, complete reperfusion at 24hr, renormalization of 24hr ADC, ENI with 24hr NIHSS 8, and 24hr and 5-day DWI volumes 30mL and 34mL with 5-day ADC. Middle panel: IVT patient, 45-year-old female presenting 2 hours from onset, baseline NIHSS 17, baseline DWI volume 46mL and ADC positive, treated with standard IV tPA 70 minutes from triage at the hub hospital, complete reperfusion at 24hr and renormalization of 24hr ADC, ENI with 24hr NIHSS 8, and 24hr and 5-day DWI volumes 28mL and 44mL with 5-day ADC. Bottom panel: IVT patient, 59-year-old female presenting 39 minutes from onset, baseline NIHSS 22, baseline DWI volume 143mL and ADC positive, treated with IV tPA 69 minutes from triage at the hub hospital, no reperfusion or renormalization of 24hr ADC, no ENI with 24hr NIHSS 22, and 24hr and 5-day DWI volumes 135mL and 111mL with 5-day ADC.

Figure 3.

Thirty-year old woman with right M1 middle cerebral artery occlusion, treated with IV tPA at 90 minutes from symptom onset and endovascular therapy with TICI score of 3; reperfusion achieved at 3 hours from symptom onset. Baseline NIHSS 7, 24-hour NIHSS 0, 90-day mRS 0. The 24-hour MRI was obtained at 21.7 hours relative to the baseline MRI. The 30-day FLAIR MRI was obtained at 37 days relative to the baseline MRI.