Interpretation of suspect head and neck fixations seen on PET/CT in lung cancer

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.

Parotid incidentalomas: a systematic review

OBJECTIVE

Parotid incidentalomas on fluorodeoxyglucose positron emission tomography/computed tomography imaging are rare. A systematic review was performed to assess their aetiology and association with scanning indication, and to develop an evidence-based algorithm for their management.

METHODS

A literature search was performed on 25 August 2020 using the keywords 'incidentaloma', 'incidental finding', 'parotid', 'parotid gland', 'salivary gland' and 'head and neck'. Articles were reviewed by two authors before their inclusion.

RESULTS

Forty articles were included, totalling 558 incidentalomas. The mean incidence was 0.74 per cent. Lung cancer was the most common imaging indication. The most common aetiologies were cystadenolymphoma, pleomorphic salivary adenoma and metastases. Only cystadenolymphoma (p = 0.015) and pleomorphic salivary adenoma (p = 0.011) were significantly associated with a primary malignancy (lung). The most common further investigations were aspiration cytology, ultrasound imaging and core biopsy, usually prior to parotidectomy.

CONCLUSION

If appropriate, parotid incidentalomas should be followed up with flexible endoscopy, skin examinations, and head and neck examinations. Ultrasound-guided core biopsy provides higher accuracy, avoiding repeat sampling and excision biopsy.

Incidental findings on CT angiography of the head and neck in stroke patients. Evaluation of frequency and detection rate

OBJECTIVE

A comprehensive CT algorithm in suspected ischemic stroke consists of a native CT scan, CT perfusion imaging of the brain and a CT angiography from the aortic arch to the vertex. Besides core findings of the brain and targeted vessels, various other findings may be identified. We analyzed a large patient sample and estimated the frequency of incidental findings (IFs) and whether these findings were correctly mentioned in the radiological reports.

PATIENTS AND METHODS

In the time period between 01/16 and 02/19 the radiological database of one hospital containing 1625 patients admitted for stroke suspicion were retrospectively evaluated. In total 1175 patients with ischemic stroke CTs were included. IFs were classified according to Lumbreras et al. for their clinical relevance. The primary radiological report was used to classify, whether the finding was reported initially or not.

RESULTS

Overall, 1988 IFs were identified in 1175 patients (mean 1.7 findings per patient). The most frequent finding were thyroid incidentalomas with n = 461 (23.2 % of all findings), followed by signs of mucosal swelling and/or opacification of the nasal sinus (n = 391, 19.7 %). Regarding clinical relevance, 181 findings were of major relevance (9.1 % of all findings), 902 were of moderate relevance (45.4 %) and 905 were of minor relevance (45.5 %). Overall, 772 findings (38.8 %) were not reported and 1216 (61.2 %) were sufficiently reported by the radiologist.

CONCLUSION

The present study corroborates that incidental findings are frequent in patients undergoing ischemic stroke CT, which are about half of moderate and major relevance. About 40 % of these findings were not mentioned in the primary radiology report, including findings of high clinical relevance. The radiologist should be aware of these findings.

Incidence and Economic Impact of Incidental Findings on 18F-FDG PET/CT Imaging

PURPOSE

The study sought to determine the incidence of incidental findings on whole-body positron emission tomography with computed tomography (PET/CT) imaging and the average costs of investigations to follow-up or further characterize incidental findings.

METHODS

Imaging reports of 215 patients who underwent whole-body PET/CT imaging were retrospectively reviewed. Our provincial picture archiving and communication system was queried and patient charts were reviewed to identify all investigations performed to follow-up incidental findings within 1 year of the initial PET/CT study. Costs of follow-up imaging studies (professional and technical components) and other diagnostic tests and procedures were determined in Canadian dollars (CAD) and U.S. dollars (USD) using the 2015 Ontario Health Insurance Plan Schedule of Benefits and Fees and 2016 U.S. Medicare Physician Fee Schedule, respectively.

RESULTS

At least 1 incidental finding was reported in 161 reports (74.9%). The mean number of incidental findings ranged from 0.64 in patients <45 years of age to 2.2 in patients 75 years of age and older. Seventy-five recommendations for additional investigations were made for 64 (30%) patients undergoing PET/CT imaging, and 14 of those were carried out specifically to follow-up incidental findings. Averaged across all 215 patients, the total cost of investigations recommended to follow-up incidental findings was CAD$105.51 (USD$127.56) per PET/CT study if all recommendations were acted on, and CAD$22.77 (USD$29.14) based on investigations actually performed.

CONCLUSIONS

As the incidence of incidental findings increases with age and a larger proportion of elderly patients is expected as population demographics change, it will be increasingly important to consider incidental findings on PET/CT imaging with standardized approaches to follow-up.

Focal fluorine-18 fluorodeoxyglucose-avid parotid findings in patients with lung cancer: prevalence and characteristics

OBJECTIVE

Correct interpretation of incidental tumors is important to plan an appropriate treatment. We assessed the incidence and imaging characteristics of fluorine-18 fluorodeoxyglucose (F-FDG)-avid focal parotid findings (FPFs) in patients with lung cancer.

PATIENTS AND METHODS

FPFs in PET-computed tomography reports of cancer patients were searched. Those with known parotid malignancies, lymphoma, and diffuse F-FDG uptake in the entire parotid gland were not included in the analysis.

RESULTS

FPFs were detected in 38/3120 cancer patients (1.23%), observed as a soft tissue mass with a mean diameter 1.6±0.5 cm (range 0.8-2.7 cm) and a mean maximum standardized uptake value of 7.7±3.7 (range 2.5-17.8). FPFs were observed in 23/604 (3.8%) patients with lung cancer, compared with 6/1366 (0.4%) with breast cancer and 5/842 (0.6%) with gastrointestinal malignancies. We assessed FPFs appearances in 23 patients with lung cancer (18 men, mean age 72.8±9.2); 20 (87%) were current or past smokers. There was no correlation between the stage or histopathological type of the lung cancer and the prevalence of parotid lesions. In four patients with histopathology, no malignancy was detected. For an additional 11 patients with available imaging and clinical follow-up (mean follow-up 15.5±13.5 months, range 3-42 months), FPFs were consistent with benign lesions.

CONCLUSION

FPFs were more prevalent among patients with lung cancer than in patients with other malignancies. As F-FDG avidity was moderate to high, FPFs may mimic distant metastases. It is important to consider FPFs in the interpretation of a focal parotid lesion as misinterpretation may result in denial of appropriate therapy.

Prevalence and risk of malignancy of focal incidental uptake detected by fluorine-18-fluorodeoxyglucose positron emission tomography in the parotid gland: a meta-analysis

This study aimed at performing a meta-analysis on the prevalence and risk of malignancy of focal parotid incidental uptake (FPIU) detected by hybrid fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) or (18)F-FDG PET alone. A comprehensive literature search of studies published up to July 2014 was performed. Records reporting at least 5 FPIUs were selected. Pooled prevalence and malignancy risk of FPIU were calculated including 95 % confidence intervals (95 % CI). Twelve records were selected for our meta-analysis. Pooled prevalence of FPIU detected by (18)F-FDG PET or PET/CT was 0.6 % (95 % CI 0.4-0.7 %), collecting data of 220 patients with FPIU. Overall, 181 FPIUs underwent further evaluation and 165 FPIUs were pathologically proven. Pooled risk of malignancy was 9.6 % (95 % CI 5.4-14.8 %), 10.9 % (95 % CI 5.8-17.3 %) and 20.4 % (95 % CI 12.3-30 %), considering all FPIUs detected, only those which underwent further evaluation and only those pathologically proven, respectively. Selection bias in the included studies, the heterogeneity among studies and the publication bias are limitations of our meta-analysis. Overall FPIUs are observed in about 1 % of (18)F-FDG PET or PET/CT scans and they are benign in most of the cases. Nevertheless, further evaluation is needed whenever FPIUs are detected by (18)F-FDG-PET or PET/CT to exclude malignant lesions or with possible malignant degeneration. Prospective studies are needed to confirm the findings reported by our meta-analysis.