Palpable Supratrochlear Nodes

I was dx'd at age 47 in 2000 with Stage 2 IDC of the right breast.  Had Lumpectomy, AC/Taxol chemo, radiation and tamoxifen.  Did well until late 2005 when I was dx'd with a new primary breast cancer in the left breast.  This time it was a Stage 3c, 5.1cm ILC with 23/23 nodes positive.  Had bilateral mastectomy, Xeloda/Taxotere chemo, 3 field radiation and am currently taking daily Aromasin plus IV Zometa every 3 months.  Developed Stage 2 lymphedema of the left arm less than 3 months after surgery.

Dec 5th, 2007 was my 2 year anniversary of the bilateral mastectomy and so far my 3 month checkups and 6 month CT body scans have been normal.  I am due for my next CT body scan in Jan 2008.  Just had a 3 month checkup yesterday and brought to my surgeons attention some palpable lymphnodes at the right antecubital area.  Largest one about 4-6mm in size, firm, nodular, not painful.  My surgeon felt a PET scan might be preferable to CT.  My medical onc then examined same area and felt unlikely to be cancer since nodes are only palpable on extension of the elbow and no palpable nodes felt behind the elbow.  Medical onc feels a PET scan has a high false positive rate will not give any more useful information than a CT scan will. I am having my scheduled CT scan in 4 weeks.

Is there any criteria for determining when a PET vs CT is better for specific diagnoses?  I am also concerned that my right arm is currently not affected by lymphedema but is certainly at risk for LE due to my surgical history. If a CT scan shows there is abnormal activity at the supratrochlear nodes, would standard treatment include a nodal biopsy?  

[Cleveland Clinic]

Dear LMALM53, Different tests provide different pieces of information.  A PET scan gives information as to whether there is an area where cells are more active.  CAT is an X-ray technique that gives doctors information in two-dimensional slices, or cross-sections.   The determination of what test to perform would need to take into context what information is being sought.  Neither test would be able to provide a definitive diagnosis but might offer information that is more or less suspicious of spread of cancer.   As these lymphnodes are palpable perhaps a biopsy would easily answer the question.  These decisions would need to be put into context of the entire clinical picture.