[Iatrogenic lung microembolism detected by 18FDG PET/CT]

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Positron emission tomography/computed tomography (PET/CT) is crucial for staging and monitoring cancer treatment.
• 18F-FDG PET/CT is widely used in oncology for assessing metabolic activity.
• Accurate interpretation of PET/CT findings is essential for patient management.

Observation:

• Two oncology patients, one with Hodgkin's disease and another with melanoma, underwent 18F-FDG PET/CT scans.
• Both patients exhibited hypermetabolic foci in the lung parenchyma on 18F-FDG PET imaging.
• These hypermetabolic findings lacked corresponding morphologic abnormalities on the CT component of the PET/CT scan.

Findings:

• The observed hypermetabolic foci in the lungs were initially concerning for metastatic disease or inflammation.
• However, the absence of CT abnormalities suggested an alternative explanation.
• Combined interpretation indicated lung microembolisms, likely originating from the radiotracer injection site.

Implications:

• This case highlights a potential imaging artifact or benign finding in 18F-FDG PET/CT scans.
• Clinicians should consider the possibility of injection-site related microembolisms when encountering unexpected lung hypermetabolism.
• Differentiating these findings from true lung pathology is critical to avoid misdiagnosis and unnecessary interventions in cancer patients.