Different criteria for defining “spot sign” in intracerebral hemorrhage show different abilities to predict hematoma expansion and clinical outcomes: a systematic review and meta-analysis

The “spot sign” is a well-known radiological marker used for predicting hematoma expansion and clinical outcomes in patients with intracerebral hemorrhage (ICH). We performed a meta-analysis to assess the predictive accuracy of spot sign, depending on the criteria used to identify them. We conducted a systematic review of clinical studies that clearly stated their definition of spot sign and that were indexed in the Cochrane Library, MEDLINE, EMBASE, and the China National Knowledge Infrastructure databases. We collected data on computed tomography (CT) parameters, spot sign diagnostic criteria, hematoma expansion, and clinical outcomes. Based on the eligibility criteria, we included 17 studies in this systematic review. CT imaging modality, type, time from symptom onset to CT, time from contrast infusion to scan, slice thickness, tube current, and tube electric discharge showed variation across studies. Three different definitions of the spot sign were applied: (1) a hyperdense spot within the hematoma; (2) one or more focal areas/regions of contrast pooling of any size and morphology that occurred within a hemorrhage, were discontinuous from the normal or abnormal vasculature adjacent to the hemorrhage, and showed an attenuation rate ≥ 120 UH; or (3) serpiginous or spot-like contrast density on CTA images that occurred within the hematoma margin, showed twice the density of the hematoma background, and did not contact vessels outside the hematoma. Three definitions for the spot sign were identified, all of which were associated with hematoma expansion, mortality, and unfavorable functional outcome. Subgroup analyses based on these definitions showed that spot sign identified using the second definition were more likely to be associated with hematoma expansion (OR 18.31, 95% CI 9.11–36.8) and unfavorable functional outcomes (OR 8.78, 95% CI 3.24–23.79), while those identified using the third definition were associated with increased risk of mortality (OR 6.88, 95% CI 1.43–33.13). Clinical studies identify spot sign using different CT protocols and criteria. These differences affect the ability of spot sign to predict hematoma expansion and clinical outcomes in ICH patients.