There is a wealth of information available online regarding whole body imaging. Journal articles contain the most reliable information, though these articles can be very technical. Generally only the abstracts of articles are available to the public, with a subscription required for the full text. There has been research conducted on almost everything imaginable, including 3T vs 1.5T MRI.
3T MRI scanning can have serious heating effects on the body. Did you know that for the same scan, a 3T scanner will heat the body four times (4x) more than with a 1.5T scanner? For a small body area this is somewhat easily controlled. When looking at the abdominal organs, or the whole body, this heating becomes a serious concern, and one you should not take lightly. Anyone who has trouble dissipating heat (children, elderly, unwell) needs to be aware of the risks involved in 3T scanning.
Further, studies have shown image quality to be inferior to 1.5T scanning when imaging the abdomen, pelvis and spine. The reasons for this are varied. Reasons include the limited scans available to reduce the heating effects mentioned above as well as an inherent inability of 3T scanners to image larger volumes. (Dielectric effect)
Click here for a brief journal review comparing 3T to 1.5T whole body MRI.