jpeg are not good for scientific study as jpeg is a lossy image compression. In particular, jpeg files blur sharp lines.
TIFF is not a bad image format, but it was originally a binary file standard for scanned files and lacked many many of the features it has now. The first published specification (still binary I gather) was in 1986.
Meanwhile staring in 1983 work had begun on what was to become DICOM standard, with the first published version in 1985 with a specific focus on medical imaging (e.g., CT and MRI). DICOM "is a standard for handling, storing, printing, and transmitting information in medical imaging". DICOM is a complete set of specifications for handling medical images with multiple modalities, multiple trials, multiple patients, associated databases, and so on. There is a lot more to DICOM than just storing "images". For example a DICOM file has to store instrument settings, patient identifier, multiple slices, conversion factors for determining physical X/Y/Z coordinates, and so on. Just about anything you might want to do with digital medical images falls under DICOM, not just producing pictures.
You can do a lot of useful image work with TIFF files. If you are using scientific medical imaging instruments you are probably going to be dealing with DICOM.
But whatever you do, avoid using JPEG for serious science work.
