Sensitivity and Specificity of PET CT Scans
PET/CT demonstrates high sensitivity (88-95%) and variable specificity (35-100%) for detecting malignant disease, with superior diagnostic performance compared to conventional imaging modalities. 1
General PET/CT Performance Characteristics
- PET/CT combines metabolic information from PET with anatomical detail from CT, providing more accurate diagnosis and staging than either modality alone 2
- For detection of pleural malignancy, PET/CT shows sensitivity of 88-95% and specificity of 35-100% 1
- In mesothelioma staging, PET/CT demonstrates 100% sensitivity and 100% specificity for both stage II and stage III disease, outperforming both CT and MRI 1
Disease-Specific Performance
Liver Lesions and Metastases
- In patients with primary malignancy, FDG-PET/CT differentiates between malignant and benign liver lesions with 75% accuracy 1
- For hepatic metastases detection, PET/CT shows superior sensitivity (97%) and specificity (75%) compared to contrast-enhanced CT alone (88% and 17%, respectively) 1
- In patients with indeterminate lesions found by CT or MRI, FDG-PET/CT has high sensitivity (96%) but limited specificity (33%) 1
Breast Cancer
- For detecting distant metastases in breast cancer, PET/CT demonstrates sensitivity of 100%, specificity of 96%, positive predictive value of 80%, negative predictive value of 100%, and accuracy of 97% 1
- PET/CT shows higher sensitivity and specificity (97% and 91%) for detecting distant metastases compared to conventional imaging (86% and 67%) 1
- For bone metastases in breast cancer, PET/CT detects significantly more lesions than bone scan (mean 14.1 vs 7.8 lesions) 1
Lung Cancer
- In non-small cell lung cancer, PET/CT shows superior performance for locoregional lymph node assessment with sensitivity of 86%, specificity of 85%, accuracy of 85%, positive predictive value of 64%, and negative predictive value of 95% 3
- These values are significantly better than contrast-enhanced CT alone (69%, 71%, 70%, 43%, and 88%, respectively) 3
Other Malignancies
- For lymphoma staging, combined PET/CT can achieve 100% sensitivity and 95% specificity for splenic involvement 4
- In neuroendocrine tumors, Ga-68-DOTATATE PET/CT shows sensitivity of 80-100% and specificity of 82-100%, outperforming FDG-PET/CT 1
- For post-chemotherapy seminoma residuals, PET demonstrates 80% sensitivity and 100% specificity for detecting viable tumor, significantly better than CT specificity 5
Limitations and Caveats
- False positives on PET/CT are common in tuberculosis pleuritis, inflammatory disorders, and previous talc pleurodesis 1
- PET/CT has limited sensitivity for detecting small lung nodules due to partial volume effect and respiratory motion 1
- PET/CT has lower sensitivity for certain tumor types, such as infiltrating lobular carcinoma of the breast 1
- The diagnostic performance varies by cancer type, stage, and specific clinical context 1
Clinical Applications
- PET/CT is particularly valuable for staging and restaging of various malignancies including colorectal, lung, breast, head and neck cancers, and lymphomas 2
- For patients with suspected metastatic disease, PET/CT can modify staging in 14-28% of patients with late-stage disease 1
- PET/CT is recommended as an optional additional test before preoperative systemic therapy in breast cancer when tumor size is >2 cm or there are positive lymph nodes 1
- Integrated PET/CT has the highest accuracy for staging malignant pleural mesothelioma, with better sensitivity across T, N, and M criteria compared to CT and MRI 1