CT infarct density modifies the effect of infarct volume on outcomes and is independently associated with better outcomes, suggesting that 24-hour CT infarct volume and density may provide complementary information on the infarct burden.
Key Findings
Results
Standardized infarct density significantly modified the effect of infarct volume on 90-day modified Rankin Scale score and mortality.
P-interaction = 0.001 for the interaction between standardized infarct density and infarct volume on modified Rankin Scale score
P-interaction = 0.014 for the interaction between standardized infarct density and infarct volume on mortality
Effect modification was assessed using interaction terms in adjusted regression analyses
Data derived from the AcT (Alteplase Versus Tenecteplase in Acute Ischemic Stroke Within 4.5 Hours) trial
Results
Higher standardized infarct density (indicating less severe infarct degree) was independently associated with better 90-day modified Rankin Scale scores.
Adjusted common odds ratio (acOR) of 0.87 (95% CI, 0.80–0.96) per 1 standardized-Hounsfield Unit increase in standardized infarct density
This association remained significant after adjustment in regression analyses
Standardized infarct density was calculated as mean Hounsfield Unit divided by SD to capture within-lesion heterogeneity
Median standardized infarct density in the cohort was 4.8 standardized-Hounsfield Units (IQR, 4.0–5.8)
Results
Infarct volume alone was not independently associated with 90-day functional outcome after accounting for infarct density.
Adjusted common odds ratio for infarct volume was 0.96 (95% CI, 0.90–1.01) per 5-mL increase, which was not statistically significant
Median infarct volume in the included cohort was 7.5 mL (IQR, 1.6–28.0)
This finding contrasts with the historical view that final infarct volume is the most critical radiological outcome in ischemic stroke
Methods
Of 1577 AcT trial patients, 839 (53.2%) met inclusion criteria of having a detected 24-hour CT infarct and no parenchymal hematoma.
Median age of included patients was 75 years (IQR, 64–84)
414 (49.3%) of included patients were female
Patients without a detected 24-hour CT infarct or with parenchymal hematoma were excluded
The parent trial enrolled patients with acute ischemic stroke treated within 4.5 hours
Methods
The 24-hour CT standardized infarct density metric was developed to capture within-lesion heterogeneity of infarcted tissue.
Standardized infarct density was defined as mean Hounsfield Unit divided by SD for every patient's infarct lesion
This metric was designed to reflect the degree or severity of infarction, with higher values indicating less severe infarct
The measure was intended to address discrepancies between final infarct volume and functional outcomes that occur frequently in clinical practice
Conclusions
The study concludes that 24-hour CT infarct volume and density may provide complementary information on infarct burden in acute ischemic stroke.
Infarct density independently predicted outcomes while infarct volume did not reach statistical significance
The complementary nature of the two measures is highlighted as a key clinical implication
Findings suggest that density-based assessment could supplement volumetric measures in radiological evaluation of stroke
What This Means
This research suggests that the darkness (density) of a stroke lesion on a CT scan taken 24 hours after stroke onset carries important information about how well a patient will recover — information that is not fully captured by simply measuring the size of the stroke. Researchers analyzed data from 839 patients enrolled in a large clinical trial comparing two clot-busting drugs. They found that stroke lesions with more uniform, higher-density (brighter) appearance on CT — indicating less severe tissue damage — were associated with better functional outcomes at 90 days, while the volume of the stroke alone was not a statistically significant predictor of outcome once density was taken into account.
The key insight is that two strokes of the same size can have very different outcomes depending on the severity of tissue damage within the lesion, which is reflected by CT density. A larger but less severely damaged infarct may lead to better recovery than a smaller but more completely destroyed area of brain tissue. The researchers developed a standardized measure of infarct density (mean Hounsfield Units divided by its variability within the lesion) to capture this within-lesion heterogeneity.
This research suggests that radiologists and neurologists evaluating stroke patients should consider not just how large a stroke appears on CT, but also how dense or heterogeneous the damaged tissue looks. Incorporating CT infarct density alongside volume into clinical assessments and research trials could improve predictions of patient recovery and potentially help guide treatment decisions after stroke.
Pensato U, Zhang J, Barakhanov K, Tanaka K, Bala F, Kaveeta C, et al.. (2026). Association of 24-Hour Computed Tomography Infarct Density on Functional Outcomes in Stroke: Secondary Analysis From the AcT Trial.. Journal of the American Heart Association. https://doi.org/10.1161/JAHA.125.046038