Post-Operative Inflammatory Changes
Post-surgical inflammatory changes can present a diagnostic challenge for the PET/CT radiologist.
Very commonly, surgery results in ill-defined inflammatory soft tissue density in the operative bed, which can be difficult to distinguish from residual or recurrent malignancy. Further complicating matters, this post-operative inflammatory soft tissue is often intensely FDG-avid.
During the first weeks following surgery, distinguishing this ill-defined hypermetabolic inflammatory soft tissue from residual or recurrent malignancy can be exceedingly difficult. Frequently, only a follow up exam will permit this distinction:
“Post-operative changes of the right level II neck are now present. Ill-defined soft tissue fullness is noted in the operative bed, mild to moderately FDG-avid (SUV 2.9). While residual/recurrent active malignancy cannot be excluded, this typically represents post-operative inflammatory changes. Follow up is offered, if clinically warranted.”
Increased Suspicion for Malignancy:
- Soft tissue is intensely avid > 2 months after surgery (> 3-months after radiation). Exception: inguinal herniorrhaphy (discussed here).
- Hypermetabolic activity is limited to only a very focal portion of the soft tissue density in the operative bed.
- Any increase in size and/or metabolic activity of the soft tissue on a follow-up exam.
- Evidence of co-existing active malignancy exists (e.g. adjacent hypermetabolic nodes).
