Incidental head and neck findings on 18F-fluoro-deoxy-glucose positron emission tomography computed tomography

Incidental uptake of fluorodeoxyglucose in the Waldeyer's ring and risk of oropharyngeal malignancy

PURPOSE

Fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly used to diagnose and stage malignancy. The aim of this article is to investigate the significance of incidental FDG uptake in the Waldeyer's ring and to assess its value in predicting clinically occult oropharyngeal malignancy.

METHODS

All FDG-PET/CT scans performed in Imperial College NHS Foundation Trust, UK between January 2012 and November 2018 were included. Patients with known or suspected oropharyngeal malignancy or lymphoma were excluded. Minimum follow-up was 12 months.

RESULTS

A total of 724 scans revealed oropharyngeal uptake of FDG. Of these, 102 were included in the study. Most patients (62.1%) were scanned as part of staging for other malignancies. Oropharyngeal FDG uptake was asymmetrical in 57.3% of the cases. Uptake was more common in the tonsils (56.3%), followed by the tongue base (31.1%) and both sites (12.6%). In 41.7% of reports, appearance was described as likely physiological; however, 52.4% of reports advised direct visualisation, clinical correlation or ENT opinion. Only 24.3% (25/102) of patients were referred and seen by ENT, 14.6% (15/102) of which had an interval PET scan and 8.7% (9/102) proceeded to tissue diagnosis. There was one oropharyngeal cancer identified and one unexpected metastasis from esophageal cancer.

CONCLUSION

Incidental uptake on PET/CT in the oropharynx is common. However, malignancy is rare (1.9%) and, when present, is associated with high SUVmax and asymmetrical uptake. Imaging results must be correlated clinically. These patients should be seen by an ENT specialist yet most may not require further investigations.

Incidental Findings on FDG PET/CT in Head and Neck Cancer

Objective

18F-fluoro-deoxy-glucose positron emission tomography/computed tomography (FDG PET/CT) imaging is common in head and neck cancer and often identifies incidental findings that necessitate additional patient evaluations. Our goal was to assess the frequency and nature of these incidental imaging findings on FDG-PET/CT.

Study Design

Retrospective cohort study.

Setting

Tertiary medical center.

Subjects and Methods

All patients with head and neck cancer who had undergone FDG-PET/CT imaging between January 2014 and June 2015 at our institution were evaluated for incidental findings.

Results

A total of 293 patients met criteria; more than one-third (n = 103) had at least 1 finding unrelated to their head and neck cancer, for a total of 134 incidental findings. Incidental findings within the head and neck (33.5% of all) excluding the thyroid were most common: 35% incidental findings were concerning for malignancy; of these, 25.5% were malignant with further workup. Recommendations were given by the head and neck radiologist on 72 (53.7%) findings: 74.5% of potentially malignant findings and 42.5% of benign findings had recommendations for follow-up. Significantly more patients with findings described as malignant were given recommendations for follow-up ( P = .0004).

Conclusion

Incidental findings on FDG-PET/CT are present in more than one-third of patients with head and neck cancer. More than one-third of incidental findings were concerning for malignancy. This study illustrates how the incidental findings discovered on FDG PET/CT frequently necessitate additional evaluations unrelated to the index head and neck cancer. The impact of these additional assessments on the cost and quality of health care warrants future evaluation.