Nuclear Medicine and Molecular Imaging
Core concepts
Understand radiopharmaceuticals and their mechanisms: FDG (glucose metabolism), bone scan (osteoblastic activity), and ventilation/perfusion (V/Q) for PE. Know PET/CT indications: staging, response assessment, and the significance of SUV. Learn thyroid imaging (uptake scan, post-ablation) and sentinel node mapping. Understand cardiac nuclear imaging (perfusion, viability) and renal functional imaging. Know the principles of radiation protection in nuclear medicine (ALARA, time/distance/shielding).
Traps
- FDG uptake is not cancer-specific-infection and inflammation also take up FDG.
- V/Q scan is useful when CTPA is contraindicated-know the interpretation (high/intermediate/low probability).
- SUV is not a diagnosis-use it in context.
- Bone scan is sensitive but not specific-correlate with radiographs.
- Do not forget patient preparation (fasting for FDG).
Worked example / rule of thumb
A patient with suspected PE and renal impairment: V/Q scan may be preferred over CTPA. Rule of thumb: FDG PET is for staging and response, not screening. For thyroid, uptake scan distinguishes hot from cold nodules-hot nodules are usually benign.
Key points
- FDG is not cancer-specific.
- V/Q scan when CTPA is contraindicated.
- SUV must be interpreted in context.
- Bone scan is sensitive but non-specific.
- ALARA in nuclear medicine.