Purpose or Case Report: Head CT is often performed in the emergency setting to evaluate for new neurologic symptoms. CT is limited in evaluation of acute stroke, brainstem and posterior fossa lesions, demyelinating disease, and diffuse axonal injury. Unremarkable head CT may be falsely reassuring and can delay treatment. Limited sequence MR (LSMR) is a new approach for evaluating a patient with neurologic symptoms. In order for LSMR to be feasible, it must be accurate, efficient, and cost-effective.
Methods & Materials: Our study retrospectively reviewed 88 patients evaluated with CT and MR. We hypothesized that an LSMR consisting of axial FLAIR, diffusion weighted images, and a sagittal sequence could identify all potentially catastrophic, urgent findings and triage the patient to the appropriate level of care. An R4 resident reviewed the SSMRs, blinded to everything but the indication for the initial exam and patient age. LSMR findings were documented, as was recommendation for any further imaging. Reports for the CT and MR were compared to LSMR findings to evaluate for concordance. Incidental type findings like small pineal cysts, very small arachnoid cysts, and mild paranasal sinus disease were not considered when evaluating for discordance.
Results: LSMR found more critical findings than CT in 8/88 patients, including acute infarcts (n=2), white matter T2/FLAIR hyperintensities (n=2), cortical maldevelopments (n=3), and posterior fossa malformations (n=1). The full MRI performed better than SSMR, as would be expected. Findings seen on full MRI not as apparent on LSMR included mesial temporal sclerosis and cortical dysplasias (n=4), inferior frontal contusions (n=1), and better characterization of posterior fossa malformation (n=1). CT missed no critical findings, and was more sensitive than LSMR in 2 cases, one with a temporal bone fracture (extensive intracranial hemorrhage seen on CT and LSMR), and one with some gyral calcifications (AVM / acute hemorrhage seen on CT and LSMR).
Conclusions: Our study indicates that LSMR is a feasible alternative to CT for the rapid evaluation of the pediatric patient with new neurologic symptoms. LSMR can be done rapidly, obviating the need for sedation. There is no ionizing radiation. Cost for limited MR is comparable to head CT. LSMR was more sensitive than CT, and provided valuable information regarding patient triage. We are looking forward to implementing this protocol with our emergency providers.