Added Value of MRI over CT of the Brain in Intensive Care Unit Patients

Background: Intensive care unit (ICU) patients with neurological impairments often require neuroimaging. However, the relative sensitivity of various imaging modalities of the brain has not yet been explored in this population. Methods: In this study, we compare the findings of CT and MRI scans in ICU patients to (1) identify the number and rate of clinically relevant lesion detected by MRI while missed by CT and vice versa and (2) determine specific lesion types for which CT versus MRI discrepancies exist. A review of medical records included CT and MRI reports of patients who underwent these procedures while they were patients in our ICUs between July 2004 and July 2009. MRI and CT were compared regarding their ability to detect clinically relevant abnormalities. Odds ratios with 95% confidence limits were calculated to compare diagnostic categories regarding the rate of discrepant MRI versus CT findings, followed by power analyses to estimate sample sizes necessary to allow for further testing in a larger trial. Results: MRI revealed clinically relevant additional abnormalities over CT in 129 of 136 patients (95%) that included the detection of additional finding for 15/27 hemorrhagic lesions (55.6%), 33/36 (92%) ischemic strokes, 19/27 (70%) traumatic lesions, 8/14 (57%) infections, 15/24 (62.5%) metabolic abnormalities, and all seven neoplasms. Odds ratio analysis revealed the added sensitivity of MRI to be greater for ischemic and neoplastic lesions than for trauma, metabolic-related abnormalities, infection, or hemorrhage. Conclusions: MRI is more sensitive than CT in identifying clinically meaningful lesions in at least a subset of ICU patients, regardless of pathology. Valeur ajoutée de l’IRM par rapport au CT du cerveau chez les patients hospitalisés à l’unité de soins intensifs. Contexte : Chez les patients présentant une atteinte neurologique, hospitalisés à l’unité de soins intensifs (USI), il est souvent nécessaire d’avoir recours à la neuroimagerie. Cependant, la sensibilité relative de différentes modalités d’imagerie du cerveau n’a encore jamais été explorée dans cette population de patients. Méthode : Dans cette étude, nous avons comparé les constatations aux scans CT et IRM chez des patients de l’USI afin d’identifier le nombre et le taux de lésions significatives au point de vue clinique détectées par l’IRM mais manquées par le CT et vice versa et de déterminer le type de lésions pour lesquelles il existe des divergences entre le CT et