Resectability assessment of head and neck cancer – PET/MR versus PET/CT
Tetsuro Sekine1,2, Felipe Barbosa1, Gaspar Delso3, Irene A Burger1, Paul Stolzmann1, Edwin ter Voert1, Gerhard Huber1, Spyros Kollias1, Gustav Von Schulthess1, Patrick Veit-Haibach1, and Martin Huellner1

1University Hospital Zurich, Zurich, Switzerland, 2Nippon Medical School, Tokyo, Japan, 3GE Healthcare, Waukesha, WI, United States

Synopsis

Head and neck cancer is supposed to be one field where PET/MR might offer benefits over PET/CT. Our study revealed that there was an insignificant trend towards higher accuracy of PET/MR than PET/CT for the resectability assessment of head and neck cancer.

Purpose

Treatment strategies for head and neck cancer strongly depend on eventual tumor resectability. Besides factors defining T4b stage, such as invasion of the mediastinum, invasion of the prevertebral space and vascular encasement or invasion, tumor resectability also depends on several other factors. Head and neck cancer is supposed to be one field where PET/MR might offer benefits over PET/CT, particularly with regard to local tumor invasion. However, specific data about the imaging assessment of tumor resectability with PET/MR are currently lacking. The purpose of this prospective study was to compare the diagnostic accuracy of contrast-enhanced PET/MR with that of contrast-enhanced PET/CT in the assessment of tumor resectability in patients with head and neck cancer.

Methods

This prospective study was approved by the institutional review board and by national government authorities. Sequential contrast-enhanced PET/CT-MR was performed in 175 patients (133 males, median age 65 years, range 24 – 91 years) referred for the staging or re-staging of head and neck cancer. Tumors were assessed with PET/CT and PET/MR for the presence of resectability-defining factors: T4b status (mediastinal invasion, invasion of the prevertebral space, vascular encasement), and another eight findings that would imply obstacles for surgical removal (invasion of the laryngeal cartilage, invasion of the pre-epiglottic fat pad, perineural spread, orbital invasion, bone infiltration, skull base invasion, dural infiltration, invasion of the brachial plexus).

Results

One hundred seventy five patients referred for the initial staging (n = 31) or re-staging (n = 144) of head and neck cancer underwent PET/CT-MR imaging. One hundred seventeen patients were excluded subsequently due to absence of tumor on both clinical examination and imaging. According to the standard of reference, 30 (52%) of the remaining 58 patients were diagnosed as resectable (20 patients were confirmed by histopathological findings, the other 10 patients were confirmed by imaging and clinical findings). The remaining 28 patients (48%) were diagnosed as not resectable (10 patients were confirmed by intraoperative and histopathological findings, the other 18 patients were confirmed by imaging and clinical findings). In these 28 patients diagnosed as not resectable, 62 lesions with a potential impact on resectability were found, thereof 15 T4b-defining factors and 47 other factors. Overall, the sensitivity/specificity/accuracy of resectability-defining factors of PET/CT and PET/MR was 0.919/0.990/0.983 and 0.984/0.993/0.992 (p = 0.727), respectively, per lesion, and 0.964/0.867/0.914 and 0.964/0.900/0.931 (p = 0.687), respectively, per patient.

Conclusion

Contrast-enhanced PET/MR is as accurate as contrast-enhanced PET/CT in determining the potential resectability of head and neck cancer. Although no significant difference was found, there was a tendency towards more reliable results obtained with PET/MR.

Acknowledgements

This research project was supported by an institutional research grant from GE Healthcare. Patrick Veit-Haibach received IIS Grants from Bayer Healthcare and Siemens Healthcare, and speaker fees from GE Healthcare. Gustav von Schulthess is a grant recipient of GE Healthcare funding and receives speaker fees from GE Healthcare. The other authors declare no other conflicts of interest.

References

[1] Yousem DM, Gad K, Tufano RP. Resectability issues with head and neck cancer. AJNR Am J Neuroradiol. 2006;27(10):2024-36.

Figures

59y female with recurrent SCC of the floor of the mouth. Ce-CT (a), fs-T2WI (b), fused PET images (c and d). The severe artifacts from dental implants on CT limit the interpretation of tumor extension (arrows on a). In contrast, on T2WI, an almost continuously defined thin hyperintense line between the tumor and the prevertebral muscles is seen (thin arrows on b). The lesion was correctly diagnosed as resectable on PET/MR, being confirmed by clinical examination.

82y male after surgery and CRT of an adenocarcinoma of the hard palate. CT (a), T2WI (b), ce-T1WI (c) and fused PET (d and e). The slightly enhancing lesion around the right cavernous sinus is depicted on CT (arrows on a) and this is clearer on T2WI and ce-T1WI (arrows on b and c). It was diagnosed as perineural spread and carotid artery invasion. In this lesion, FDG uptake is observed but difficult to distinguish from brain FDG uptake(arrows on d and e). This might be a pitfall on PET.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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