Nuclear Medicine and Molecular Imaging
Core concepts
Understand the principles of radiotracers and their indications: FDG-PET for oncology (staging, response), bone scan for metastases and osteomyelitis, V/Q scan for pulmonary embolism, and thyroid imaging. Know the appearance of normal physiologic uptake and the common pitfalls. Master the interpretation of FDG-PET: SUV, pitfalls (infection, inflammation, brown fat), and the role of combined PET/CT. Recognize the patterns of bone scan: superscan, three-phase bone scan for osteomyelitis, and the distinction from cellulitis. Understand the use of radionuclide therapy and dosimetry basics.
Traps
Do not interpret FDG uptake as malignancy without considering inflammation and infection. Brown fat uptake can mimic tumor. A superscan indicates diffuse metastatic disease, not normal. V/Q scan interpretation requires the PIOPED criteria and clinical context.
Rule of thumb
FDG accumulates in metabolically active tissue, including tumor, infection, and inflammation; correlate with CT and clinical context.
Worked example
A patient with fever and a prosthetic joint: a three-phase bone scan showing increased flow and uptake suggests infection, whereas a labeled leukocyte scan can improve specificity.