PET/CT Imaging for Cancer Staging: Recommended Body Parts
For cancer staging, a whole-body PET/CT scan from skull base to mid-thigh is recommended as the standard approach, with specific additional imaging based on cancer type and clinical suspicion. 1
Standard PET/CT Protocol for Cancer Staging
- Whole-body PET/CT from skull base to mid-thigh is the standard protocol for most cancer staging, providing comprehensive evaluation of primary tumor, regional lymph nodes, and distant metastases 1
- FDG (fluorodeoxyglucose) is the most widely used radiopharmaceutical for PET/CT imaging, indicated for assessment of abnormal glucose metabolism to assist in evaluation of malignancy 2
- PET/CT fusion provides superior diagnostic accuracy by combining metabolic information from PET with precise anatomical localization from CT 1
Cancer-Specific Considerations
Lung Cancer
- For lung cancer, PET/CT should include thorax, upper abdomen (liver/adrenal glands), and bone structures to evaluate for common metastatic sites 1
- PET/CT has 83% sensitivity and 92% specificity for mediastinal nodal metastases in lung cancer 1
- PET/CT should ideally be performed within 60 days of planned resection and within 30 days before radiation therapy for optimal nodal staging accuracy 1
Colorectal Cancer
- For colorectal cancer, PET/CT from skull base to mid-thigh with additional focus on liver and lungs is recommended as these are common metastatic sites 1
- PET/CT has been shown to detect more lung metastases than chest radiography in colorectal cancer patients 1
Mesothelioma
- For mesothelioma, PET/CT should include thorough evaluation of the pleura, mediastinum, and assessment for transdiaphragmatic invasion 1
- PET/CT has shown 100% sensitivity and specificity for stage II and III mesothelioma in some studies 1
Additional Imaging Considerations
- MRI brain with contrast is recommended in addition to PET/CT for patients with clinical stage II, III, or IV non-small cell lung cancer, even without neurologic symptoms 1
- MRI brain is more sensitive than CT for detecting small brain metastases, as PET has limited sensitivity for brain lesions due to high physiologic glucose uptake 1
- If abnormalities suggesting metastatic disease in the abdomen are observed on initial PET/CT, a dedicated abdominal CT scan with IV and oral contrast should be performed 1
Technical Considerations and Pitfalls
- PET/CT has limitations in detecting small lesions (<1 cm) and lesions with low metabolic activity 3
- False positives can occur with inflammatory conditions, infections, and post-treatment changes 3
- False negatives can occur with small lesions, mucinous tumors, and hyperglycemia 4
- CT contrast enhancement is recommended when delineation of tumor from vascular structures is needed, particularly with substantial mediastinal involvement 1
Special Situations
- For thyroid nodules, ultrasound is more sensitive than CT, but PET/CT may detect incidental thyroid nodules with high metabolic activity that warrant further evaluation 5
- For patients with suspected distant metastases based on clinical evaluation, whole-body PET/CT is strongly recommended over regional imaging 1
- For patients with extensive mediastinal infiltration, CT assessment may be sufficient without invasive confirmation 1
PET/CT technology has revolutionized cancer staging by providing metabolic and anatomic information in a single examination, allowing for more accurate staging and treatment planning compared to conventional imaging methods 6.