In acute infarction:
Both CT and conventional MRI are unable to detect early infarction within first 6 hours of the attack .
With diffusion sequence,it has a sensitivity 94% and specificity 100% in detection of acute infarction within the first 6 hours of the attack(as hyper-intense lesion).
Differentiation between recent and old infarction.
Diffusion sequence can differentiate easly between recent and old infarction as follow:
-In diffusion sequence ,from 5 to 10 days the infarction become iso to hypo-intense while the recent one is of hyper-intense signal,while ADC map becomes from iso to hyper-intense signal.
So within this period of time(5 to 10 days following infarction) we will find the old infarction iso to hypo-intense by diffusion sequense while the recent one will be hyper-intense.
In case of brain infection:
-In diffusion showed hyper-intense while in ADC map,the abscess showed very low ADC value of 0.3
- In tumors , diffusion sequence showed hypo-intense while ADC value showed hyper-intensity signal.
-ADC map in infection showed hypo-intensity signal while in tumors showed hyper-intensity signal.
We can conclude the following:
-In demyelination, the flair sequence is more sensitive,it can detect small lesions.
-In hemorrhage,both diffusion and ADC map give hypo-intense signals with hyper-intense signals of cyto-toxic edema.
-Inflammation:
Diffusion------>hyper-intense
ADC map------>hypo-intense
-In tumors:
Diffusion------->hypo-intense
ADC map------->hyper-intense signals.
