Diagnostic value of F-18 FDG PET/CT for local and distant disease relapse surveillance in surgically treated RCC patients: Can it aid in establishing consensus follow up strategy?

BACKGROUND: Aim of the study was to evaluate the diagnostic performance of FDG PET-CT for the detection of local and distant disease relapse in surgically treated patients with renal cell carcinoma (RCC). MATERIAL AND METHODS: This retrospective study includes 96 patients underwent FDG PET-CT scanning in the post-surgical follow up within the first 6–12 months referred to nuclear medicine department, to perform PET/CT study. Each patient underwent FDG PET-CT with low dose CT, followed immediately by full dose Ce-CT. Sites of the relapse were categorized into local and distant recurrence. Distant recurrence sites were divided into lymph nodes, lung, bone, and other soft tissue sites. The final diagnosis of disease status was made on subsequent follow up by conventional imaging (CT/MRI), FDG PET-CT, or histopathology whenever possible. RESULTS: Local and/or distant disease relapse was confirmed in 69 (71.9%) patients and the rest 28.1% were free. Regarding local recurrence FDG PET-CT showed specificity of 100% compared to 98.6% with Ce-CT (p > 0.05) and higher sensitivity noted with Ce-CT (100%) compared to 96% with FDG PET-CT. For global distant sites of metastases Ce-CT revealed high sensitivity and NPV of 93.3% & 96.9% respectively yet lower specificity (93.96%) and PPV (87.5%) was seen with Ce-CT compared to 99.6% and 99.1% with FDG PET-CT respectively. The higher Ce-CT sensitivity was attributed to its ability to detected 100% of cases of lung metastases compared to 80.6% with FDG PET-CT (P-value < 0.05). CONCLUSION: FDG PET-CT appears to be a very efficient tool in post-surgical surveillance of patients with RCC with notable ability to probe even uncommon sites of distant recurrence

Value of diffusion MRI versus [18F]FDG PET/CT in detection of cervical nodal metastases in differentiated thyroid cancer patients

Background: In differentiated thyroid cancer (DTC) patients, cervical nodal metastasis is a negative prognostic factor. Preoperative imaging plays an important role in treatment planning for nodal metastasis and recurrence. The aim of the study is to compare the diagnostic performance of the diffusion-weighted magnetic resonance imaging (DW-MRI) and the F-18 flurodeoxyglucose positron emission computed tomography ([18F]FDG PET/CT) in detection of cervical nodal deposits in DTC patients. Materal and methods: The study was conducted on 30 patients, each performed both modalities just before the surgery. The gold standard was the pathological specimens with post-operative clinico-radiological follow-up, to assess the diagnostic performance of each modality. Results: Based on pathological and post-operative clinico-radiological follow up data. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were 84%, 80%, 50%, 95% and 83% for PET/CT compared to 84%, 60%, 42.8%, 91.3% and 80% for DW-MRI. On comparing the diagnostic performance of combined DW-MRI and PET/CT to each modality alone, the sensitivity and NPV were improved to 96% and 80% respectively. Conclusions: [18F]FDG PET/CT study is a valuable diagnostic modality for the assessment of cervical nodal deposits in DTC patients, surpassing DW-MRI. Combined PET/CT and DW-MRI techniques seemed to have synergistic performance, mainly in terms of sensitivity and NPV, for detection of nodal metastases

Diagnostic & prognostic impact of 18F-NaF PET/CT versus 99mTc-MDP bone scan in detection of bone metastases: Initial and follow up assessment

Purpose: To assess the role of 18F-NaF PET/CT in the detection of metastatic bone disease compared to 99mTc-MDP bone scan (+/-SPECT/CT). Methods: 64 adult patients with locally advanced primary tumor were enrolled in this study. All patients underwent pretherapy 18F-NaF PET/CT and 99mTc-MDP bone scan. Results: Among the 64 patients 18F-NaF PET/CT revealed positive bone metastases in 26 patients, only 19 of them have positive results in 99mTc-MDP bone scan, while the remaining 7 patients were falsely negative in 99mTc-MDP bone scan. On the other hand 18F-NaF PET/CT diagnosed 38 patients free of osseous metastases, 5 patients of them were falsely diagnosed having osseous metastases by 99mTc-MDP bone scan. None of patient has positive bone metastases by 99mTc-MDP & negative 18F-NaF PET/CT for bone metastases in our study group. The overall results revealed significant higher sensitivity for 18F-NaF PET/CT (100%) compared to 99mTc-MDP bone scan (73.08%) (P<0.05) as well as higher specificity for 18F-NaF PET/CT (100%) compared to 99mTc-MDP bone scan (86.8%) (P<0.05). Conclusion: 18F-NaF PET/CT is a high-quality skeletal imaging with convenient diagnostic performance in either lytic or sclerotic bone lesions surpassing that of Tc99m MDP, with lower equivocal interpretations