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Published on: August 14, 2019
Prognostic value of diffusion-weighted MRI for post-cardiac arrest coma
Karen G Hirsch1, Nancy Fischbein2, Michael Mlynash2
1From the Departments of Neurology (K.G.H., M. Mlynash, S.K., I.E., C.V., A.F.C., G.A.) and Radiology (N.F., M. Moseley), Stanford University, CA; Department of Radiology (R.B.), University of Melbourne, Parkville, VIC, Australia; and Department of Medicine (J.T.), University of California, Los Angeles. khirsch@stanford.edu.
Objective:
To validate quantitative diffusion-weighted imaging (DWI) MRI thresholds that correlate with poor outcome in comatose cardiac arrest survivors, we conducted a clinician-blinded study and prospectively obtained MRIs from comatose patients after cardiac arrest.
Methods:
Consecutive comatose post-cardiac arrest adult patients were prospectively enrolled. MRIs obtained within 7 days after arrest were evaluated. The clinical team was blinded to the DWI MRI results and followed a prescribed prognostication algorithm. Apparent diffusion coefficient (ADC) values and thresholds differentiating good and poor outcome were analyzed. Poor outcome was defined as a Glasgow Outcome Scale score of ≤2 at 6 months after arrest.
Results:
Ninety-seven patients were included, and 75 patients (77%) had MRIs. In 51 patients with MRI completed by postarrest day 7, the prespecified threshold of >10% of brain tissue with an ADC <650 ×10-6 mm2/s was highly predictive for poor outcome with a sensitivity of 0.63 (95% confidence interval [CI] 0.42-0.80), a specificity of 0.96 (95% CI 0.77-0.998), and a positive predictive value (PPV) of 0.94 (95% CI 0.71-0.997). The mean whole-brain ADC was higher among patients with good outcomes. Receiver operating characteristic curve analysis showed that ADC <650 ×10-6 mm2/s had an area under the curve of 0.79 (95% CI 0.65-0.93, p < 0.001). Quantitative DWI MRI data improved prognostication of both good and poor outcomes.
Conclusions:
This prospective, clinician-blinded study validates previous research showing that an ADC <650 ×10-6 mm2/s in >10% of brain tissue in an MRI obtained by postarrest day 7 is highly specific for poor outcome in comatose patients after cardiac arrest.
Insights
Quantitative diffusion-weighted imaging (DWI) MRI can predict poor outcomes in cardiac arrest survivors. An apparent diffusion coefficient (ADC) threshold of <650 ×10-6 mm2/s in over 10% of brain tissue is highly specific for poor prognosis.
Area of Science:
- Neuroimaging
- Neurology
- Cardiology
Background:
- Comatose cardiac arrest survivors require accurate prognostication for clinical decision-making.
- Quantitative diffusion-weighted imaging (DWI) MRI offers potential for objective outcome prediction.
Purpose of the Study:
- To validate specific quantitative DWI MRI thresholds for predicting poor outcomes in comatose cardiac arrest survivors.
- To assess the accuracy of apparent diffusion coefficient (ADC) values in prognostication.
Main Methods:
- Prospective, clinician-blinded study enrolling comatose adult cardiac arrest survivors.
- MRIs were obtained within 7 days post-arrest and analyzed for ADC values.
- Poor outcome defined as Glasgow Outcome Scale ≤2 at 6 months; prognostication algorithm used.
Main Results:
- In 51 patients with MRI by postarrest day 7, >10% brain tissue with ADC <650 ×10-6 mm2/s predicted poor outcome with 96% specificity and 94% PPV.
- Mean whole-brain ADC was higher in patients with good outcomes.
- Quantitative DWI MRI improved prognostication accuracy for both good and poor outcomes.
Conclusions:
- The study validates that DWI MRI with ADC <650 ×10-6 mm2/s in >10% brain tissue by postarrest day 7 is highly specific for poor outcome.
- Quantitative DWI MRI is a valuable tool for prognostication in comatose cardiac arrest survivors.
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