What Does Noninvasive Mean?

What does "noninvasive" mean? I had an interesting conversation with an oncologist today about this. He asked me to look at a CT of a patient of his who had retroperitoneal nodes to see if we could biopsy them. The CT was about 4 weeks old. I asked him why it took so long for him to call for a biopsy because the reading on the CT had stated that the radiologist had mentioned the nodes to him and that they could be biopsed. He mentioned that they wanted to evaluate the patient "noninvasively." They had obtained a magnetic resonance (MR) scan, a positron emission tomography (PET) scan, an endoscopic retrograde cholangiopancreatography (ERCP), and an endoscopic ultrasound.

I almost fell off my chair. I said, "What is your definition of noninvasive?" Since when is an ERCP with conscious sedation noninvasive?" For that matter, how noninvasive is an MR? Have you ever had one? I have. I found it loud, uncomfortable, and claustrophobic. To me, that is pretty invasive. I am not saying that these imaging tests are completely worthless, but really, how noninvasive are they, and versus a biopsy?

This is not an unusual discussion between an interventional radiologist and a referring physician. Many people still feel sticking a needle in a patient is the last thing one should do. Heck, many radiologists think the same way. Should we biopsy the questionable adrenal lesion or get an MR with fat saturation?