Apparent Diffusion Coefficient Signal Intensity Ratio Predicts the Effect of Revascularization on Ischemic Cerebral Edema

• Published in: Cerebrovascular diseases (Basel, Switzerland) Vol. 45; no. 3-4; p. 93
• Main Authors: Bevers, Matthew B, Battey, Thomas W K, Ostwaldt, Ann-Christin, Jahan, Reza, Saver, Jeffrey L, Kimberly, W Taylor, Kidwell, Chelsea S
• Format: Journal Article
• Language: English
• Published: Switzerland 01.01.2018
• Subjects: Aged; Aged, 80 and over; Brain Edema - diagnostic imaging; Brain Edema - etiology; Brain Edema - prevention & control; Brain Ischemia - complications; Brain Ischemia - diagnostic imaging; Brain Ischemia - physiopathology; Brain Ischemia - therapy; Diffusion Magnetic Resonance Imaging; Disability Evaluation; Embolectomy - adverse effects; Female; Humans; Male; Middle Aged; North America; Predictive Value of Tests; Recovery of Function; Risk Factors; Stroke - complications; Stroke - diagnostic imaging; Stroke - physiopathology; Stroke - therapy; Time Factors; Treatment Outcome; North America; Diffusion-weighted imaging; Acute stroke imaging; Cerebral edema; Acute ischemic stroke; MRI of acute stroke
• DOI: 10.1159/000487406

Apparent diffusion coefficient (ADC) imaging is a biomarker of cytotoxic injury that predicts edema formation and outcome after ischemic stroke. It therefore has the potential to serve as a "tissue clock" to describe the extent of ischemic injury and potentially predict response to therapy. The goal of this study was to determine the relationship between baseline ADC signal intensity, revascularization, and edema formation. We examined the ADC signal intensity ratio (ADCr) of the stroke lesion (defined as the baseline DWI hyperintense region) compared to the contralateral normal hemisphere in 65 subjects from the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy trial. The associations between ADCr, neurologic outcome, and cerebral edema were examined. Finally, we explored the interaction between baseline ADCr and vessel recanalization at day 7 on post-stroke edema. We found that lower initial ADCr was associated with a worse outcome on the modified Rankin Scale (mRS) at 90 days (52.2% of those with ADCr <64% were mRS 5-6 vs. 19.1% with ADCr ≥64%, p = 0.006). Those subjects with reconstitution of flow distal to the initial vessel occlusion showed greater normalization of ADCr on follow-up scan (increase in ADCr of 16.4 ± 2.07 vs. 1.99 ± 4.33%, p = 0.0039). In those patients with low baseline ADCr, successful revascularization was associated with reduced edema (median swelling volume 164 mL [interquartile range (IQR) 53.3-190 mL] vs. 20.7 mL [IQR 3.20-55.1 mL], p = 0.024). This study reaffirms the association of ADCr with outcome after stroke, supports the idea that reperfusion may attenuate rather than enhance post-stroke edema, and indicates that the degree of edema with and without revascularization may be predicted by ADCr.