protocol for malignant teratoma

My sister-in-law has been diagnosed with adenocarcinoma arising from a malignant teratoma. It presented on her lung and was removed, but the cells were colonic in nature. A new tumor has been discovered through biopsy that is attached to a vertebra; they will treat with radiation followed by chemo. However, they have told her that PET shows cancer in two more vertebra, but that the MRI shows none! Additionally, they have told here that there is no protocol for this type of cancer, and so have planned a generic andenocarcinoma protocol. We are so confused! Can you possibly shed some light on the discrepancy between MRI and PET results? Your help is so much appreciated! This is a very scary time - she's only 48 years old!

[Kamal S Saini, MD, MRCP (UK), DM]

Hi,
There is often a discrepancy between an anatomic based imaging like MRI and a functional (metabolic) based imaging like PET.
What the reports indicate is that there is some suspicious metabolic activity in additional vertebra (perhaps cancer has spread there), but MRI is not showing these lesions because the bones have not been physically damaged / distorted by these cancer cells yet.
This must be a very difficult time for you and your family.
Please be strong.
All the best, and God Bless!