Diffusion imaging in different brain lesions

Diffusion images in different brain lesions.

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.

Infarction starts with In while infection also starts with In, so both give hyper intense in diffusion and hypo intense in ADC map. 


The reverse occurs in tumors where diffusion gives hypo intense while ADC map gives hyper intense.


So ADC map gives hypo intensity in infection while gives hyper intensity in tumors.