I would go to Google images and study similar results to yours. Infarct of the brain generally means a stroke has happened, I believe. Ask for a copy of your MRI disk, and study it because they think we're too stupid to deserve an explanation. I snuck and made a copy of mine on the way to delivering it to my doctor. I have the right to know, and so do you. I would suggest doing brain training games for your memory online. There are sites you can go to for free. Dual n Back training has helped my memory substantially, I think. Atrophy means shrinkage and death of brain cells, but I believe you can always rebuild injuries to the brain. Stop smoking if you smoke, okay? Please? I see your name on here from time-to-time, and think it would be a bummer to lose a nice member of the Medhelp community, such as yourself.
Gliosis is a proliferation of star-shaped glial cells, or astrocytes, responding to injury which results in scarring Gliosis. That, along with neuron loss, is a main feature of many diseases of the central nervous system, including M. S., Alzheimer's, and stroke.
I don't know what white matter gliosis is. But right posterior frontal infarct means you have damage to the back of your right frontal lobe, and moderate atrophy with increased ventricles means your brain is overall smaller and as a result the ventricles are larger than normal.