It is also more sensitive for small white matter lesions in traumatic or diffuse axonal injury (DAI). Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2-weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all TBI patients with both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all TBI patients with both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. If the clinical focus has transitioned from short-term management to long-term prognostication in the acute phase, then an early MRI may be of greater value, particularly in patients who have mild TBI with normal CTs (approximately 15% will have persistent neurocognitive sequelae at 1 year). A prospective Level 1 trauma multicenter study has found that approximately 27% of patients who have mild TBI with normal CTs show abnormalities on early MRI (eg, small cortical contusions or hemorrhagic axonal injury) and that these findings may be clinically relevant in improving prediction of 3-month outcomes [38]. There is ongoing research in the utility of blood-based biomarkers (eg, GFAP) to determine which patients who have mild TBI and negative CT were more likely to benefit from MRI [39].
Head Trauma PCAs. It is also more sensitive for small white matter lesions in traumatic or diffuse axonal injury (DAI). Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2-weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all TBI patients with both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all TBI patients with both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. If the clinical focus has transitioned from short-term management to long-term prognostication in the acute phase, then an early MRI may be of greater value, particularly in patients who have mild TBI with normal CTs (approximately 15% will have persistent neurocognitive sequelae at 1 year). A prospective Level 1 trauma multicenter study has found that approximately 27% of patients who have mild TBI with normal CTs show abnormalities on early MRI (eg, small cortical contusions or hemorrhagic axonal injury) and that these findings may be clinically relevant in improving prediction of 3-month outcomes [38]. There is ongoing research in the utility of blood-based biomarkers (eg, GFAP) to determine which patients who have mild TBI and negative CT were more likely to benefit from MRI [39].