Can left cca narrow by 75% in four months?please tell

Can left cca narrow by 75% in four months?please tell

I got my uncle’s left cca normal in feb but in june dsa it is showing that left cca lumen is 75% narrowed and dissected upto 4cm.
Is there any test by which i can confirm that when does the artery occluded or test which can show whether the blood is still liquid or clot has formed?