FRCR MCQ ----Diffusion imaging

Q.All are true regarding diffusion imaging in stroke except

a. DWI changes have been observed at less than 1 hour after the onset of ischemia

b. the ADC map shows hyperintensity beyond 10 days of stroke

c.Infarcts with greater percentages of low ADC values  have higher rates of hemorrhagic transformation

d. Enhancement and restricted diffusion often coexist in arterial infarction.

e. DWI of lesion volumes  enlarge over time after the acute stroke.

ANS---d

Enhancement and restricted diffusion are not generally found 

coexisting in arterial infarction.

ADC values is seen low within hours after the stroke and continue

 to decline for the next few days. They remain reduced through the

 first 4 to 5 days after stroke and then undergo pseudonormalization

 between 4 and 10 days . After this the ADC subsequently has been

 found to rise in the lesion (i.e., the ADC map shows 

hyperintensity) beyond 10 days.

DWI has been shown to improve lesion localization and detect the age of the infarction more accurately, DWI has also been shown more accurately to detect and size ischemic lesions.