Abstract Body: Introduction: Early prediction of final infarct volume is a vital component of clinical recovery. Ischemic infarct volume is an independent predictor of stroke prognosis with larger volumes nonlinearly correlating to worse outcomes. Virtual non contrast imaging (VNC) is a dual-energy computed tomography head (CTH) utilized in differentiating post-thrombectomy contrast staining from hemorrhage due to reperfusion injury. Studies show VNC improves visualization of early infarcts and can be a reliable predictor of final infarct volume. This study investigates difference between initial VNC infarct and final CTH infarct volumes as well as association with modified Rankin Scale (mRS).
Methods: This is a retrospective, observational, single-center study of 14 patients who underwent mechanical thrombectomy for acute ischemic stroke between January 2023 and August 2024. Inclusion and exclusion criteria and exclusion flowchart are listed in Figure 1 and 2, respectively. Demographics, National Institute of Health Stroke Scale (NIHSS) and mRS data were extracted from the electronic medical record. Infarct volumes on initial VNC and final CTH were measured using the ABC/2 or ABC/3 formula for ellipsoid or irregular infarcts, respectively. Statistical analysis was conducted with a paired t-test (p-value <0.05) to compare matched volume differences.
Results: Patient sample was 50% male and 50% female. Age ranged from 45 to 94 years old with a mean of 71. Mean and median initial NIHSS was 19 with a range 4 to 29. Mean discharge NIHSS was 21. VNC underestimated final infarct volume by a mean difference of 4.68 milliliters in a full sample analysis. This mean difference was statistically significant (p-value 0.038) indicating VNC volume may not reliably predict the final infarct volume in the full sample. However, analysis without outliers yielded a statistically insignificant difference (p-value 0.3102) indicating VNC volume may be a reliable predictor in smaller infarcts. Figure 3 depicts increasing infarct volumes on VNC or final CTH trended towards worse mRS indicating VNC may have a role in prognostication.
Conclusion: VNC may be a predictor of final infarct volume in patients with small infarct sizes with minimum cerebral edema. Limitations of this study include small sample size and cerebral edema as a confounder in large infarct volume measurements. Further studies correlating VNC infarct with final MRI infarct volume and functional outcome are needed.