LAUSR

In Response: We thank Drs Yu, Zheng, and You for their interest in our recent article, and we appreciate their valuable comments on hematoma irregularity. Hematoma shape irregularities has been shown to be associated with higher 30-day mortality and major disability at 90 days. In previous studies, an irregularly shaped hematoma has been shown to be associated with hematoma growth. However, the judgment of hematoma irregularity is subjective and may vary substantially from one study to another. In a study of 241 patients with intracerebral hemorrhage, Shimoda et al defined satellite sign as a small (maximal diameter <10 mm) hemorrhage close to but completely isolated from the main hematoma. The authors reported that presence of satellite sign was associated with worse functional outcome. More recently, Yu et al have demonstrated that satellite sign is an independent predictor for hematoma expansion in patients with spontaneous intracerebral hemorrhage. Yu et al have done an excellent study that may shed light on our understanding of potential mechanism of the satellite sign. In our study, we have proposed a new imaging marker called island sign to describe patients with extreme hematoma irregularities. We defined island sign as (1) ≥3 scattered small hematomas all separate from the main hematoma or (2) ≥4 small hematomas some or all of which may connect with the main hematoma. We agree with Yu and colleagues that both satellite sign and island sign can be related to shape irregularity. Empirically, we found that satellite sign–positive patients with only one small hemorrhage close to but completely isolated from the main hematoma are less likely to expand and may have good functional outcome. Moreover, we found that patients with ≥4 small hematomas that all connect with the main hematoma are also at high risk of hematoma expansion. These patients are considered to have negative satellite sign according to the definition proposed by Shimoda et al. In summary, satellite sign is an imaging marker of hematoma irregularity, and island sign represents extremely irregularly shaped hematomas. Because island sign had more stringent criteria, it is likely to be a more specific imaging predictor of hematoma expansion. As Yu and colleagues point out, we look forward to upcoming results of large-scale studies investigating the diagnostic accuracy of island sign and satellite sign in predicting hematoma expansion and outcome in patients with intracerebral hemorrhage.