New developments in neuroimaging, such as functional magnetic resonance imaging (MRI) and positron emission tomography, have revolutionized our understanding of abnormal brain function in many disease states, including schizophrenia, Parkinson's disease, and post-traumatic stress disorder. To study further whether critical illness-associated CD is associated with occult brain injury in humans, it would be useful to have an imaging test that can detect subtle evidence of brain injury. Unfortunately, traditional CT scans and MRI do not appear to be sensitive enough to pick up the microscopic cellular changes that may underlie CD [42] . Two small studies assessed brain CT findings in critically ill patients with sepsis [79, 80] . Neither study demonstrated any CT abnormalities, although brain pathology in nonsurvivors was consistent with the previously cited findings of Sharshar and colleagues [49] [50] [51] [52] . A recent study of ARDS survivors (n = 15) [81] found that many of these individuals exhibited signs of significant brain atrophy and ventricular enlargement on head CTs obtained during their acute illness, but there were no significant correlations between these abnormalities and subsequent neurocognitive scores.