Lymph node visualisation: an unusual artefact in the 99mTc-pyrophosphate bone scan

Area of Science:

• Nuclear medicine
• Radiopharmacology

Background:

• Extraskeletal uptake in bone scintigraphy is an infrequent observation.
• This finding is usually associated with tracer extravasation at the injection site.

Purpose of the Study:

• To investigate the phenomenon of extraskeletal tracer uptake in bone scans.
• To understand the underlying mechanism of this uncommon finding.

Main Methods:

• Review of bone scan cases exhibiting extraskeletal uptake.
• Analysis of tracer behavior following extravasation at the injection site.

Main Results:

• Extraskeletal uptake, presumed to be in lymph nodes, was observed.
• This phenomenon occurred exclusively with extravasation of the tracer at the injection site.
• Colloid formation was identified as the likely cause of the observed uptake.

Conclusions:

• Extraskeletal tracer uptake in lymph nodes during bone scans is a rare event.
• Tracer extravasation and subsequent colloid formation are implicated in this finding.