Intracranial Thrombus Morphology and Composition Undergoes Time-Dependent Changes in Acute Ischemic Stroke: A CT Densitometry Study

The aim of our study was to assess whether cerebral artery clots undergo time-dependent morphological and compositional changes in acute ischemic stroke. We performed a retrospective chart review of patients admitted within 5 h from symptom onset to three European stroke centers and evaluated non-contrast-enhanced CT (NECT) for hyperdense artery signs (HAS) in 2565 scans. The occlusion site, density of HAS expressed in Hounsfield units (HU), area of HAS, and relative density (rHU) (HU clot/HU non-affected artery) were studied and related to time from symptom onset, clinical severity, stroke etiology, and laboratory parameters. A HAS was present in the middle cerebral artery (MCA) in 185 (7.2%) and further explored. The mean time from symptom onset to CT was 100 min (range 17–300). We found a time-dependent loss of density in the occluded M1 segment within the first 5 h (N = 118, 95% CI [−15, −2], p = 0.01). Further, the thrombus area in the M2 segment decreased with time (cubic trend N = 67, 95% CI [−63, −8], p = 0.02). Overall, and especially in the M2 segment, a lower clot area was associated with higher fibrinogen (−21.7%, 95% CI [−34.8, −5.8], p = 0.009). In conclusion, our results disclosed time-dependent changes of intracranial thrombi with regard to occlusion site, density and area.