[Positron emission tomography in head and neck squamous cell carcinomas]

Value of PET/CT 3D visualization of head and neck squamous cell carcinoma extended to mandible

PURPOSE

To study an original 3D visualization of head and neck squamous cell carcinoma extending to the mandible by using [18F]-NaF PET/CT and [18F]-FDG PET/CT imaging along with a new innovative FDG and NaF image analysis using dedicated software. The main interest of the 3D evaluation is to have a better visualization of bone extension in such cancers and that could also avoid unsatisfying surgical treatment later on.

PATIENTS AND METHODS

A prospective study was carried out from November 2016 to September 2017. Twenty patients with head and neck squamous cell carcinoma extending to the mandible (stage 4 in the UICC classification) underwent [18F]-NaF and [18F]-FDG PET/CT. We compared the delineation of 3D quantification obtained with [18F]-NaF and [18F]-FDG PET/CT. In order to carry out this comparison, a method of visualisation and quantification of PET images was developed. This new approach was based on a process of quantification of radioactive activity within the mandibular bone that objectively defined the significant limits of this activity on PET images and on a 3D visualization. Furthermore, the spatial limits obtained by analysis of the PET/CT 3D images were compared to those obtained by histopathological examination of mandibular resection which confirmed intraosseous extension to the mandible.

RESULTS

The [18F]-NaF PET/CT imaging confirmed the mandibular extension in 85% of cases and was not shown in [18F]-FDG PET/CT imaging. The [18F]-NaF PET/CT was significantly more accurate than [18F]-FDG PET/CT in 3D assessment of intraosseous extension of head and neck squamous cell carcinoma. This new 3D information shows the importance in the imaging approach of cancers. All cases of mandibular extension suspected on [18F]-NaF PET/CT imaging were confirmed based on histopathological results as a reference.

CONCLUSIONS

The [18F]-NaF PET/CT 3D visualization should be included in the pre-treatment workups of head and neck cancers. With the use of a dedicated software which enables objective delineation of radioactive activity within the bone, it gives a very encouraging results. The [18F]-FDG PET/CT appears insufficient to confirm mandibular extension. This new 3D simulation management is expected to avoid under treatment of patients with intraosseous mandibular extension of head and neck cancers. However, there is also a need for a further study that will compare the interest of PET/CT and PET/MRI in this indication.

Prospective comparison of 18F-NaF PET/CT versus 18F-FDG PET/CT imaging in mandibular extension of head and neck squamous cell carcinoma with dedicated analysis software and validation with surgical specimen. A preliminary study

BACKGROUND

The aim of this study is to propose a new method to quantify radioactivity with PET/CT imaging in mandibular extension in head and neck squamous cell carcinoma (HNSCC), using innovative software, and to compare results with microscopic surgical specimens.

PATIENTS AND METHODS

This prospective study enrolled 15 patients who underwent ¹⁸F-NaF and ¹⁸F-FDG PET/CT. We compared the delineations of bone invasions obtained with ¹⁸F-NaF PET/CT and ¹⁸F-FDG PET/CT with the results of histopathological analysis of mandibular resections (from right and left bone borders). A method for visualization and quantification of PET images was developed.

RESULTS

For all patients, a significant difference (p = 0.032 for right limits and p = 0.011 for left limits) was observed between ¹⁸F-FDG PET/CT imaging and histopathology results, and no significant difference (p = 0.88 for right limits and p = 0.55 for left limits) was observed between ¹⁸F-NaF PET/CT imaging and histopathology results. The right limits were less than 10 mm in 93% of patients, and the left limits were less than 10 mm in 86% of patients.

CONCLUSIONS

The dedicated software enabled the objective delineation of radioactivity within the bone. We can confirm that ¹⁸F-NaF is a precise and specific bone marker for the assessment of intraosseous mandibular extensions of head and neck cancers.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

[Role of PET-CT with 18-FDG in the management of UADT squamous-cell carcinomas: a retrospective study of 43 cases]

INTRODUCTION

The aim of our retrospective study was to evaluate the role of PET-CT in the management of upper-aerodigestive tract (UADT) squamous-cell carcinomas.

MATERIAL AND METHODS

Our study included 43 patients with UADT squamous-cell carcinomas having undergone PET-CT for: initial staging (n=20), diagnosis of recurrent disease (n=16), and response to treatment (n=7).

RESULTS

PET-CT diagnosed distant metastases missed by conventional imaging in four patients (20%) in initial staging, four patients (25%) in diagnosis of recurrent disease, and two patients (29%) in response to treatment. Overall, PET-CT induced a shift in the management of 10 patients (28%).

DISCUSSION

Our study and other publications suggest that PET-CT should be used in: initial staging in Stage III and IV; detection of recurrent disease; and evaluation of treatment response.