CT or MRI better for repeat seroma formation?

Seroma after initial abdominoplasty 2 yrs ago. Fluid removed over the course of 6 wks. Lipo 1 year later (PS wouldn't do both at same time). Developed fluid superficially, removed. Revision done this December explore bursa. PS didn't find anything. "Tacked" down skin to remove neg space. However, now 3 months 2nd surgery and again fluid has developed. Looking for add'l info as PS not very helpful. Recommend MRI or CT for best visualization and planning. US showed multiple large fluid pockets.