Reversal of CT hypodensity after acute ischemic stroke

Stroke is the third leading cause of death and is a major contributor to morbidity and mortality in the United States [1]. This substantial figure makes the diagnosis of stroke in the acute setting incredibly important. While advances in imaging and intervention have boosted the identification and survival rate from stroke, the diagnosis of stroke remains a clinical one. Even though the importance of imaging in the acute stroke setting and beyond cannot be overstated, there are important limitations to its usefulness. Specifically, as an ischemic brain injury heals, it can transition from a radiologically hypodense region to a radiologically isodense region. This transition has previously been thought to occur roughly 2- to 3 weeks after an infarction using computed tomography (CT), and has been termed the "fogging effect." First identified in 1979 [2], this effect can mask a late diagnosis of stroke, as well as muddle the ability to quantify the boundaries of an infarct's territory weeks later. Thus, better understanding of the timing and qualities of this "fogging effect" is of paramount importance in the clinical course of stroke management.