I've found the following to work well for me - generally, the letter "i" and then the first three letters of the main word and its ending letter. As in:

ihepc = intrahepatic
icory = intracoronary
iabdl = intra-abdominal
ioray = intraorally
ioral = intraoral
icavy = intracavitary
iutee = intrauterine
ivasr = intravascular
icral = intracranial
icerl = intracerebral

And along those lines.

How about you? Got a system that works great for these?