Role of FDG-PET/CT in Oncology: Insights and Applications

In oncology, accurate diagnosis and effective treatment planning rely heavily on advanced imaging technologies. One such essential tool is fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT). This hybrid imaging modality provides molecular-level insights often unattainable with conventional imaging techniques. The European Society for Hybrid, Molecular and Translational Imaging (ESHIMT) has offered practice recommendations to optimise its usage in staging, restaging, and treatment response assessment.

Staging and Restaging in Cancer Treatment

[¹⁸F]FDG-PET/CT has emerged as a crucial tool in the initial staging and restaging of cancer. It allows clinicians to evaluate the extent of disease by detecting both primary tumours and distant metastases. Its sensitivity in identifying metastatic lesions surpasses that of traditional CT and MRI, particularly in cancers like lung, lymphoma, and head and neck cancers. This makes it an invaluable asset in determining the appropriate treatment course—surgery, chemotherapy, or radiotherapy—by providing a comprehensive view of the tumour's spread. Moreover, in cases of restaging, where recurrence is suspected, [¹⁸F]FDG-PET/CT enables earlier detection and intervention, even before morphological changes become apparent on conventional imaging.

Treatment Monitoring and Response Assessment

Another significant application of [¹⁸F]FDG-PET/CT is in monitoring treatment response. By measuring the metabolic activity of cancer cells, the imaging can assess the effectiveness of therapies such as chemotherapy, radiotherapy, or immunotherapy. The PET Response Evaluation Criteria in Solid Tumours (PERCIST) incorporates data from [¹⁸F]FDG-PET/CT, offering a more nuanced analysis than traditional anatomical methods like RECIST, which focuses on tumour size. In cancers such as lymphoma, [¹⁸F]FDG-PET/CT has shown to be particularly beneficial in detecting early non-responders to therapy, allowing clinicians to adjust treatment strategies sooner and improving patient outcomes.

Challenges and Limitations

While [¹⁸F]FDG-PET/CT has revolutionised cancer imaging, it is not without limitations. One of the primary challenges is its non-specificity, as FDG uptake can occur in both malignant and benign conditions, such as inflammation or infection. This can lead to false positives, necessitating further histological confirmation. Additionally, its spatial resolution is lower than CT or MRI, particularly for small lesions under 5mm, which may be missed on PET. Another challenge is the high cost and limited availability, making it less feasible for routine use in early-stage cancers or follow-up scans. However, ongoing research and technological advancements, such as PET/MR systems, promise to address some of these shortcomings by improving image resolution and reducing radiation exposure.

The [¹⁸F]FDG-PET/CT hybrid imaging modality plays a pivotal role in the accurate diagnosis, staging, and treatment monitoring of various cancers. Combining the functional insights of PET with the anatomical detail of CT offers a comprehensive approach that has become indispensable in oncology. However, careful patient selection and clinical context are essential to maximise its benefits while acknowledging its limitations. With technological advancements, such as the development of new tracers and hybrid imaging technologies, [¹⁸F]FDG-PET/CT's role in personalised cancer care is set to expand even further.

Source: European Radiology

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