This study aimed to compare the ability of serial cranial ultrasounds (CUS) and early MRI scans in detecting preterm brain injuries. The study found that CUS allowed for more scans due to better feasibility in the NICU, and was better at detecting grade I-II intraventricular hemorrhages and perforator strokes. MRI was superior for identifying smaller cerebellar hemorrhages and provided more quantitative data. Overall, the combination of serial CUS and MRI provided the highest sensitivity for detecting common preterm brain injuries, though MRI could not be performed in the sickest infants.