Patterns of Diffusion-Weighted Imaging in Patients Presenting with Confusion: A Three-Case Series

To provide an example of the diagnostic value of diffusion-weighted imaging (DWI) in patients who present with confusion or altered mental status by showing specific anatomical patterns of restricted diffusion, which can be used to make a correct etiological diagnosis. Three cases represent the typical DWI patterns that are attributed to various causes of altered consciousness. Case 1 was of a 66-year-old man with rapidly progressive dementia with bilateral symmetric cortical restricted diffusion in a ribbon-shaped distribution, the pathological cortical ribbon sign of Creutzfeldt-Jakob disease. Case 2 involved a 77-year-old man with fever and severe neurological impairments, which on MRI showed bilateral symmetric restricted diffusion; bilateral thalami, bilateral basal ganglia and bilateral midbrain structures, which is typical of West Nile virus encephalitis. The case of 3 provided an 11-day-old infant with viral nonococcal meningitis with diffuse restricted diffusion in the corpus callosum as well as in bilateral periventricular white matter, typical of parechovirus infection. DWI is more sensitive to pathology than conventional T2-weighted and FLAIR sequences, and in all three cases, this sensitivity was shown to detect pathological changes much earlier than these other sequences. In every case, there was a typical pattern of anatomical distribution, either cortical, deep gray matter, or white matter predominant, which was associated with certain underlying etiologies. The limited diffusion appeared as hyperintensity on DWI and hypointensity on apparent diffusion coefficient (ADC) maps, which proves the actual cytotoxic edema and not the T2 shine-through artifact. Notably, these unique DWI patterns were associated with rapid diagnostic narrowing when used in combination with a clinical setting despite the need to assume a broad range of differential diagnosis. It is important to recognize certain patterns of anatomical distribution of limited diffusion of DWI so as to set up timely diagnoses in patients with confusion. This association can enable radiologists to differentiate among infectious, neurodegenerative, and metabolic etiologies based on the clinical presentation and the characteristic DWI findings as a way of providing the necessary management and early intervention in the potentially curable conditions.