Utility of 18F-fluoride PET/CT and 18F-FDG PET/CT in the detection of bony metastases in heightened-risk head and neck cancer patients

Role of 18F-NaF PET/CT in bone metastases

The use of 18F sodium fluoride (18F-NaF) in positron emission tomography (PET/CT) is increasing. This resurgence of an old tracer has been driven by several factors, including its superior diagnostic performance over standard 99mTc-based bone scintigraphy (BS), availability of PET/CT imaging systems, a shortened examination time and an increase in the number of regional commercial PET radiotracer distribution. In this special article, we aimed to highlight the current place of the 18F-NaF PET/CT in the imaging of bone metastases (BM) in a variety of malignancies. A special focus is given to the following ones: breast cancer (BC), prostate cancer (PCa). Also, other malignancies such as bladder cancer, lung cancer, thyroid cancer, multiple myeloma, head and neck cancer, hepatocellular carcinoma have been addressed. At last, we summarize the advantages and limits of the 18F-NaF PET/CT compared to other imaging modalities in these settings.

18F-Sodium Fluoride PET: History, Technical Feasibility, Mechanism of Action, Normal Biodistribution, and Diagnostic Performance in Bone Metastasis Detection Compared with Other Imaging Modalities

The skeleton is the third most common site for metastasis overall, after the lungs and liver. Accurate diagnosis of osseous metastasis is critical for initial staging, treatment planning, restaging, treatment monitoring, and survival prediction. Currently, ^99mTc-methylene diphosphonate whole-body scanning is the cornerstone of imaging to detect osseous metastasis. Although ¹⁸F-sodium fluoride (¹⁸F-NaF) was one of the oldest medical tracers for this purpose, it was replaced by other tracers because of their better physical properties, until recently. Continued development of PET scanners has opened a new era for ¹⁸F-NaF, and given its higher sensitivity, there have been increasing applications in imaging. In this review, we will discuss the history, technical aspects, radiobiology, and biodistribution of this tracer. Finally, we compare the accuracy of ¹⁸F-NaF PET with other conventional imaging methods for detection of osseous metastasis.

Comparisons between glucose analogue 2-deoxy-2-(18F)fluoro-D-glucose and 18F-sodium fluoride positron emission tomography/computed tomography in breast cancer patients with bone lesions

AIM: To compare 2-deoxy-2-(¹⁸F)fluoro-D-glucose(¹⁸F-FDG) and ¹⁸F-sodium (¹⁸F-NaF) positron emission tomography/computed tomography (PET/CT) accuracy in breast cancer patients with clinically/radiologically suspected or known bone metastases.

METHODS: A total of 45 consecutive patients with breast cancer and the presence or clinical/biochemical or radiological suspicion of bone metastatic disease underwent ¹⁸F-FDG and ¹⁸F-fluoride PET/CT. Imaging results were compared with histopathology when available, or clinical and radiological follow-up of at least 1 year. For each technique we calculated: Sensitivity (Se), specificity (Sp), overall accuracy, positive and negative predictive values, error rate, and Youden’s index. McNemar’s χ² test was used to test the difference in sensitivity and specificity between the two diagnostic methods. All analyses were computed on a patient basis, and then on a lesion basis, with consideration ofthe density of independent lesions on the co-registered CT (sclerotic, lytic, mixed, no-lesions) and the divergent site of disease (skull, spine, ribs, extremities, pelvis). The impact of adding ¹⁸F-NaF PET/CT to the work-up of patients was also measured in terms of change in their management due to ¹⁸F-NaF PET/CT findings.

RESULTS: The two imaging methods of ¹⁸F-FDG and ¹⁸F-fluoride PET/CT were significantly different at the patient-based analysis: Accuracy was 86.7% and 84.4%, respectively (McNemar’s χ² = 6.23, df = 1, P = 0.01). Overall, 244 bone lesions were detected in our analysis. The overall accuracy of the two methods was significantly different at lesion-based analysis (McNemar’s χ² = 93.4, df = 1, P < 0.0001). In the lesion density-based and site-based analysis, ¹⁸F-FDG PET/CT provided more accurate results in the detection of CT-negative metastasis (P < 0.002) and vertebral localizations (P < 0.002); ¹⁸F-NaF PET/CT was more accurate in detecting sclerotic (P < 0.005) and rib lesions (P < 0.04). ¹⁸F-NaF PET/CT led to a change of management in 3 of the 45 patients (6.6%) by revealing findings that were not detected at ¹⁸F-FDG PET/CT.

CONCLUSION: ¹⁸F-FDG PET/CT is a reliable imaging tool in the detection of bone metastasis in most cases, with a diagnostic accuracy that is slightly, but significantly, superior to that of ¹⁸F-NaF PET/CT in the general population of breast cancer patients. However, the extremely high sensitivity of ¹⁸F-fluoride PET/CT can exploit its diagnostic potential in specific clinical settings (i.e., small CT-evident sclerotic lesions, high clinical suspicious of relapse, and negative ¹⁸F-FDG PET and conventional imaging).

Performance of 18F-fluoride PET or PET/CT for the detection of bone metastases: a meta-analysis

PURPOSE

This study aimed to evaluate the diagnostic accuracy of F-fluoride PET or PET/CT compared with Tc-MDP bone scintigraphy and F-FDG PET/CT in the detection of bone metastases.

PATIENTS AND METHODS

An electronic search was conducted using PubMed/MEDLINE and EMBASE. The methodological quality of the included studies was assessed with Quality Assessment of Diagnostic Accuracy Studies 2. All analyses were performed on Stata version 12.0 and Meta-DiSc version 1.4.

RESULTS

Twenty articles containing 1170 patients were identified. On a patient basis, the pooled sensitivity, specificity, and the area under the summary receiver operating characteristic curve of F-fluoride PET or PET/CT were 92% (95% confidence interval [CI], 89%-95%), 93% (95% CI, 91%-95%), and 0.985, respectively. On a lesion basis, the pooled sensitivity, specificity, and area under the summary receiver operating characteristic curve of F-fluoride PET or PET/CT were 87% (95% CI, 85%-88%), 95% (95% CI, 94%-96%), and 0.979, respectively. When compared with Tc-MDP bone scintigraphy, F-fluoride PET or PET/CT showed both higher sensitivity (96% vs. 88%, P = 0.002) and specificity (91% vs. 80%, P = 0.001). When compared with F-FDG PET/CT, F-fluoride PET/CT showed higher sensitivity (94% vs. 73%, P = 0.003), whereas no significant difference was observed in specificity (88% vs. 98%, P = 0.06).

CONCLUSIONS

F-fluoride PET or PET/CT has an excellent diagnostic capacity for the detection of bone metastases and shows advantages when compared with Tc-MDP bone scintigraphy and F-FDG PET/CT.

Multimodal imaging of bone metastases: From preclinical to clinical applications

Metastases to the skeletal system are commonly observed in cancer patients, highly affecting the patients' quality of life. Imaging plays a major role in detection, follow-up, and molecular characterisation of metastatic disease. Thus, imaging techniques have been optimised and combined in a multimodal and multiparametric manner for assessment of complementary aspects in osseous metastases. This review summarises both application of the most relevant imaging techniques for bone metastasis in preclinical models and the clinical setting.

(18)F-NaF PET/CT: EANM procedure guidelines for bone imaging

The aim of this guideline is to provide minimum standards for the performance and interpretation of (18)F-NaF PET/CT scans. Standard acquisition and interpretation of nuclear imaging modalities will help to provide consistent data acquisition and numeric values between different platforms and institutes and to promote the use of PET/CT modality as an established diagnostic modality in routine clinical practice. This will also improve the value of scientific work and its contribution to evidence-based medicine.

Sodium 18F-fluoride PET/CT of bone, joint, and other disorders

The use of (18)F-sodium fluoride ((18)F-NaF) with PET/CT is increasing. This resurgence of an old tracer has been fueled by several factors including superior diagnostic performance over standard (99m)Tc-based bone scintigraphy, growth in the availability of PET/CT imaging systems, increase in the number of regional commercial distribution centers for PET radiotracers, the recent concerns about potential recurring shortages with (99m)Tc-based radiotracers, and the recent decision by the Centers for Medicare and Medicaid Services to reimburse for (18)F-NaF PET/CT for evaluation of patients with known or suspected bone metastases through the National Oncologic PET Registry. The major goal of this article is to review the current evidence on the diagnostic utility of (18)F-NaF in the imaging assessment of the bone and joint in a variety of clinical conditions.

Molecular imaging in oncology: (18)F-sodium fluoride PET imaging of osseous metastatic disease

OBJECTIVE

This literature review details the history, pharmacokinetics, and utility of (18)F-sodium fluoride (Na(18)F) PET/CT in detecting osseous metastases compared with the current standard of care, technetium-99m methylene diphosphonate ((99m)Tc-MDP) bone scintigraphy. Additional discussion highlights solutions to impediments for broader implementation of this modality and insight into the complementary roles of (18)F-FDG PET/CT and Na(18)F PET/CT in oncology imaging, including preliminary data for combined Na(18)F and FDG PET/CT.

CONCLUSION

Na(18)F PET/CT is the most comprehensive imaging modality for the evaluation of osseous metastatic disease. Although further data acquisition is necessary to expand cost-benefit analyses of this imaging agent, emerging data reinforce its diagnostic advantage, suggest methods to mitigate impediments to broader utilization of Na(18)F PET/CT, and introduce a potentially viable technique for single-session combined Na(18)F and FDG PET/CT staging of soft-tissue and osseous disease.

Monitoring the response of bone metastases to treatment with Magnetic Resonance Imaging and nuclear medicine techniques: a review and position statement by the European Organisation for Research and Treatment of Cancer imaging group

Assessment of the response to treatment of metastases is crucial in daily oncological practice and clinical trials. For soft tissue metastases, this is done using computed tomography (CT), Magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET) using validated response evaluation criteria. Bone metastases, which frequently represent the only site of metastases, are an exception in response assessment systems, because of the nature of the fixed bony defects, their complexity, which ranges from sclerotic to osteolytic and because of the lack of sensitivity, specificity and spatial resolution of the previously available bone imaging methods, mainly bone scintigraphy. Techniques such as MRI and PET are able to detect the early infiltration of the bone marrow by cancer, and to quantify this infiltration using morphologic images, quantitative parameters and functional approaches. This paper highlights the most recent developments of MRI and PET, showing how they enable early detection of bone lesions and monitoring of their response. It reviews current knowledge, puts the different techniques into perspective, in terms of indications, strengths, weaknesses and complementarity, and finally proposes recommendations for the choice of the most adequate imaging technique.

Local ablative treatments of oligometastases from head and neck carcinomas

BACKGROUND

Median survival for recurrent/metastatic (unknown poly/oligometastatic status) head and neck cancer patients (HNSCC) is ten months with best systemic treatment. Metastatic ablation shows promising results in selected patients with several tumor types. We aimed to assess the role of surgery and stereotactic ablative body radiotherapy (SABR) with respect to survival in HNSCC.

MATERIALS AND METHODS

Published data on metastatic HNSCC treated ablatively were analyzed.

RESULTS

Five-year survival rates after pulmonary/liver metastasectomy exceed 20% in selected patients. Two-year survival after lung SABRT of metastasectomy yields 35%. Interesting data on survival and tolerance are reported in other metastatic sites.

CONCLUSION

Surgery yields the best level of evidence. However, non-invasive SABR is efficient and well-tolerated in lung/liver, bone and other metastatic locations. Systemic treatment may be given sequentially with ablative treatments, or omitted in well-identified situations. Proper patient selection for local ablative treatment and optimal therapeutic sequence should be assessed in randomized trials.