Normal CT, Infarcting Brain: How MRI DWI Changes Acute Stroke Care

Описание: Normal CT, Infarcting Brain: How MRI DWI Change Acute Stroke Care#Neuromedicine#Neurology#neurology,
#neurology #neuromedicine #brainhealth Diffusion-weighted magnetic resonance imaging (DWI) has become a cornerstone in the evaluation of acute ischemic stroke, owing to its ability to detect cerebral ischemia within minutes of symptom onset, often when non-contrast CT is still normal. DWI reflects the microscopic Brownian motion of water molecules, and in acute ischemia, failure of cellular energy metabolism leads to cytotoxic edema, resulting in restricted diffusion that appears as hyperintensity on DWI with corresponding hypointensity on ADC maps.
Unlike conventional MRI sequences, DWI provides early identification of infarct core, allowing differentiation between irreversible tissue injury and potentially salvageable brain tissue when interpreted alongside other sequences. The presence of DWI–FLAIR mismatch is particularly useful in identifying hyperacute stroke and estimating lesion age in patients with unknown time of onset. Importantly, DWI findings must always be interpreted in conjunction with ADC maps to distinguish true restricted diffusion from T2 shine-through and to avoid common diagnostic pitfalls.
Beyond ischemic stroke, restricted diffusion can also be seen in conditions such as abscess, seizures, encephalitis, highly cellular tumors, and prion disease, emphasizing the need for careful correlation with clinical features, lesion distribution, and temporal evolution. Understanding the temporal changes of DWI and ADC—including ADC pseudonormalization in the subacute phase and increased ADC in chronic infarction—is essential for accurate stroke dating and management decisions.
Overall, MRI with diffusion-weighted imaging does not merely confirm the diagnosis of stroke; it defines tissue fate, guides reperfusion therapy, and directly influences clinical outcomes, making it an indispensable tool in modern stroke care.