F-18 FDG PET brain imaging in symptomatic arthroprosthetic cobaltism

Area of Science:

• Neuroscience
• Toxicology
• Biomaterials Science

Background:

• Cobalt-chromium (Co-Cr) alloys are used in arthroprosthetics.
• Systemic cobalt toxicity can manifest with neurological symptoms.
• Previous studies focused on local effects and small case series of neurological findings.

Purpose of the Study:

• To assess cobalt-induced brain hypometabolism using quantitative F-18 FDG PET.
• To identify patterns of brain involvement and susceptible regions.
• To evaluate the reversibility of hypometabolism after prosthetic revision.

Main Methods:

• Screened 247 patients with Co-Cr arthroprosthetics for cobalt levels.
• Selected symptomatic patients with elevated blood (>0.4 mcg/L) or urine cobalt (>1 mcg/L).
• Performed quantitative F-18 FDG PET brain imaging and analyzed metabolism using FDA-approved software.

Main Results:

• 123 patients exceeded cobalt thresholds; 69 underwent PET imaging.
• Significant regional hypometabolism was observed in scanned patients.
• Hypometabolism patterns included temporal, frontal, and Broca's areas; 8/15 revised patients showed improved metabolism.

Conclusions:

• Elevated cobalt levels from arthroprosthetics cause a distinct pattern of brain hypometabolism.
• Neurological toxicity may occur at lower cobalt levels than currently accepted.
• Quantitative PET imaging can assist in managing cobalt toxicity and guiding treatment decisions.