Table 2.
DWI Location | DWI Change in Time | T2 FLAIR | Other Features | |
---|---|---|---|---|
Epilepsy | - Commonly involves (1) cortex, (2) subcortical region, (3) hippocampus, (4) claustrum, (5) splenium (6) pulvinar - Nonvascular distribution |
Hyperintensity can occur within hours and resolve within days to weeks depending on severity and etiologies | Hyperintensities may appear if structural lesions exist or irreversible cell death occurs | Absent vascular occlusion |
Ischemic stroke | Distributed within vascular territories | Hyperintensities can occur within minutes and reach a peak after days before gradually reducing | Hyperintensities persist in the ischemia sites for years | DWI reversal may occur after early reperfusion with t-PA or endovascular therapy |
limbic encephalitis | May involve uncus, amygdala, hippocampus | Nonspecific patterns (requires further research) | Autoimmune: bilateral mesial temporal lobe Infectious: unilateral temporal lobe, insular involvement, absence of basal ganglion. |
Two patterns raise concerns regarding seizure: (A) gyriform hippocampal restriction and (B) diffuse hippocampal diffusion restriction that spares the most medial temporal lobe structures |
Transient global amnesia | - Dot-like hyperintense lesions 1–2 mm in diameter - Commonly in the lateral aspect of the hippocampus (CA-1 region) |
Hyperintensity appears with a delay of 24–48 h after onset | Hyperintensities highly detected 2–4 days after onset | |
CJD | - Mainly affects striatum and cortex - Gyriform hyperintensity correlates to location of periodic sharp-wave complex on EEG |
Hyperintensity appears 0.5–7 (mean: 1.6) months after symptoms onset, is progressive and persistent over months, then disappears in the end phase | Isointensity to mild hyperintensity (DWI > T2 FLAIR) |
Pulvinar sign (symmetrical hyperintensity in the posterior thalamic nuclei on DWI or T2WI) or hockey stick sign (affecting the dorsomedial thalamic nuclei) specific in vCJD, sometimes in sCJD |
PRES | Similar to T2WI | Hypointense to isointense | - Hyperintensities appear in the parieto-occipital, posterior frontal cortex, white matter - Less commonly in the brainstem, basal ganglia, and cerebellum |
DWI and ADC hyperintensity indicate vasogenic edema |
DWI, Diffusion-Weighted Imaging; T2 FLAIR, T2-weighted-Fluid-Attenuated Inversion Recovery; CJD, Creutzfeldt–Jakob disease; EEG, Electroencephalography; vCJD, variant Creutzfeldt–Jakob Disease; sCJD, sporadic Creutzfeldt–Jakob Disease; PRES, Posterior reversible encephalopathy syndrome; ADC, Apparent diffusion coefficient.