Is a brain mri result of "moderate volume loss of the bilateral frontal lobes" coupled with recent memory loss, significant drop of executive function, difficulty retracing, brief/mild episodes of confusion/ams sufficient to diagnose mci or dementia?

This isolated finding, on the MRI could be useful in correlating your symptoms, but, on its own is not definitive. Not feasible to be precise, but you might have signs of a frontal-temporal dementia, but certainly other disorders could fit. Do discuss these issues with your neurologist, or psychiatrist, and go forwards. A PET scan may be the most accurate way of pursuing your diagnosis.

The MRI findings are suggestive, but various cognitive tests and good history,quizzing family members & neurologic examination, beyond simple screening ones, are needed & used to diagnose frontal temporodementia & rule out depression, medication effects,toxicity,sleep apnea. The MRI was also important to exclude brain tumors or other intracranial pathology.