Differences between CT and MR imaging in acute closed head injuries

The authors sought to compare the early MRI and CT findings in patients suffering closed head injury and to investigate the impact of imaging discrepancies on treatment management. A group of 62 patients with closed head injury and discrepancy between the apparently normal or with minor findings CT scan, and their neurological statuses were prospectively studied with MRI. Both CT and MRI were performed within the first 6 days after injury. According to the Glasgow Coma Scale (GCS), 46 patients suffered severe head injury (GCS≤8) and 16 patients moderate head injury (GCS 9–12). Four MRI sequences in various planes were applied using a 1T MR scanner. CT findings were present in 19 out of 62 patients and MRI findings in 61. Extra-axial lesions were found in 52 patients with MRI and in 16 with CT. Subarachnoid hemorrhage (SAH) was observed in 40 patients with MRI and in 12 with CT. Intraventricular hemorrhage was observed in 15 patients with MRI and in 6 with CT. Intraaxial lesions were demonstrated in 54 patients with MRI and in 17 patients with CT. MRI demonstrated diffuse axonal injuries (DAI) type I in 27 patients, type II in 32 and type III in 9 as opposed to 2, 1 and 0 patients with CT respectively. Subcortical gray matter injuries were shown in 12 patients with MRI and 4 with CT. Primary brainstem injuries were shown in 6 patients with MRI and 1 with CT. The FLAIR sequence alone, revealed 89% of the findings demonstrated by all 4 MRI sequences. No statistically significant difference on GCS versus the hemorrhagic and non-hemorrhagic nature of the lesions was found (p>0.05). In conclusion, in closed head injury patients with minor or absent CT findings and severe or moderate injury, MRI findings are almost always present and include particularly DAI lesions and SAH. These differences in favor of MRI do not alter the treatment management.