Abstract Body: BACKGROUND: Identifying patients likely to have significant hematoma expansion (HE) has been a challenge in clinical trials of intracerebral hemorrhage (ICH). Non-contrast CT (NCCT) markers of HE have been described. Time from symptom onset to CT affects the predictive value of these markers, with limited data in the ultra-early time period (<3h from onset). We aimed to describe the frequency of NCCT markers in the ultra-early period of ICH, and their association with HE.

METHODS: We performed a pooled analysis of individual patient data from the STOP-AUST and STOP-MSU randomized controlled trials, which tested the effect of tranexamic acid on hematoma growth. We included ICH patients scanned within 2 hours of symptom onset. The presence of NCCT density and shape markers was assessed by two authors. HE was defined as an increase in hematoma volume of >33% or >6ml from baseline. Regression analyses were adjusted for treatment group and baseline hematoma volume.

RESULTS: There were 246 patients included in this analysis (median age 67 years, 38.8% female, median time from onset to imaging 75 min [IQR 59-88 min], 50.4% tranexamic acid), of whom 105 (42.7%) had HE on 24-hour imaging. Inter-rater agreement was excellent for all NCCT markers (kappa score >0.8). Most patients (85.7%) had ≥1 marker of HE. The most frequent marker was the swirl sign (74.3%) and the least frequent was the blend sign (7.3%) (Table 1). HE occurred more often in patients with any marker at baseline (45.5% vs 25.6%, p=0.03). The blend sign (15.2% vs 1.4%, p<0.01), island sign (38.1% vs 24.8%, p=0.01) and satellite sign (44.8% vs 34.8%, p=0.04) were more common in patients with HE than those without.

The presence of any marker was not independently associated with HE (aOR1.63 [95%CI 0.70-3.80], p=0.26). The blend sign was the only sign independently associated with HE (aOR 11.58 [95%CI 2.57-52.19], p=0.01). On diagnostic performance for HE, specificity was highest for the blend sign (0.99, 95% CI 0.95-1.00), with limited sensitivity of 0.15 (95%CI 0.09-0.24) (Table 1). The area under the receiver operator curve showed similar values for all markers suggesting low discriminative ability (Delong test p=0.81).

CONCLUSIONS: NCCT markers are commonly present in the ultra-early period of ICH and associated with subsequent hematoma growth. Despite association with HE, the discriminative utility in the early timeframe appears insufficient, and the search for an optimal target should continue.