If you haven't had a sputum collected by you, RT or your doctor, I'd be very surprised that your doc plans the antibiotics. Perhaps he's planning a bronchoscopy to get it and just plans to discuss that with you after your CT.
My CT's also looked like I had MAC with trees-in-bud, ground glass and mucus plugs. The local radiologist and pulmonologist thought I had it. The Mayo radiologists and pulmonologists thought I had it. I couldn't get a sputum even with RT trying. Therefore, they did the bronchoscopy to get the necessary sputum culture. After 6 weeks, it was NEGATIVE. 😀. No antibiotics. FWIW, the Penn Med radiologist read the later CT's as probable MAC because the CT hasn't cleared. My pulmonologist said I'll have just continue to show those changes.