Imaging Case 24:
Head & Neck cancer - Squamous Cell Carcinoma of the palate and alveolus
Surgeons treating oral squamous cell carcinoma aim for a minimum marginal clearance of 5 mm. The complex three-dimensional anatomy of the oral cavity makes achieving these clear resection margins particularly challenging. When margins are close or involved, patients often require re-excision. However, histopathology analysis of margins takes at least fourteen days, making additional resection impractical once final results are available. As a result, adjuvant radiotherapy is commonly required, increasing morbidity—sometimes with lifelong consequences. Moreover, involved margins significantly raise the risk of treatment failure, particularly when a bone margin is affected, as adjuvant therapy is less effective in bone than in soft tissue.
This case highlights the potential of intraoperative specimen PET-CT imaging to address these challenges by providing real-time visualization of the tumor within the resected specimen. By enabling immediate, informed decision-making during surgery, this technique may improve resection completeness and reduce the need for additional treatment.
The case is presented with the support of Mr. Gary Walton, consultant head and neck surgeon, Dr. Oludolapo Adesanya, consultant radiologist, and colleagues of University Hospitals Coventry & Warwickshire, Coventry, United Kingdom, as part of the ‘eXcision’ trial (IRAS ID: 342171, REC reference 24/YH/0137). The ‘eXcision’ trial is a single center prospective pilot study investigating the diagnostic performance of high-resolution specimen PET-CT in prostate cancer and head and neck cancer resection.
Patient History
A 50-year-old patient was diagnosed with squamous cell carcinoma of the left palate and alveolus. Preoperative imaging, i.e., MRI and CT, showed bone invasion, indicating a T4N0M0 staging. The patient was scheduled for resection of the tumor, i.e., a left maxillectomy neck dissection with a free flap reconstruction.
Figure 1. Transverse, coronal and sagittal slices of the PET-CT specimen images of the resected tumor specimen. A MIP view of the CT-only image to highlight anatomical context is shown as well. Specimen orientation is as indicated. Abbreviations: med, medial; lat, lateral; sup, superior; inf, inferior; ant, anterior; pos, posterior. A window of 0-80% was used for representing radiotracer uptake.
Specimen PET-CT images
Figure 2. Specimen PET-CT image of the resected tumor specimen, for different planes with 18F-FDG uptake close to the maxillary air sinus and buccal sulcus region, respectively. Orientation of the specimen is indicated on the figure.
Table 1. A summary of the histopathological findings of the resected specimens.
Histopathological Evaluation
After PET-CT imaging, the surgical specimen was sent to the pathology department for routine histopathological evaluation. This evaluation was available after more than fourteen days. Table 1 shows the results of histopathology.
The close margins confirmed by histopathology corresponded to the air-filled maxillary sinus and buccal sulcus area, the same regions where radiotracer uptake was visualized close to the border of the specimen on the specimen PET-CT images. Important to note is that these close margins are adjacent to either an air-filled cavity (maxillary sinus) or represent the free edge of the specimen (buccal sulcus) and are therefore not an indication for adjuvant therapy. Therefore, histopathology confirmed complete resection of tumor and confirmed the findings from the intraoperative imaging.
Histopathological evaluation also confirmed bone invasion, as suspected on the specimen PET-CT images.
Discussion and conclusion
There is an excellent correlation between the specimen PET-CT images and the histopathology report, particularly in identifying areas with radiotracer uptake at the border and bone invasion. Regions of radiotracer uptake near the specimen’s border align with the anatomical sites of closest margins observed on histopathology—specifically, the maxillary sinus and buccal sulcus. These close margins are either adjacent to an air-filled cavity (maxillary sinus) or represent the free edge of the specimen (buccal sulcus) and therefore do not indicate a need for adjuvant therapy.
Pathology typically takes at least fourteen days, with even longer delays if bone invasion requires confirmation. Therefore, this case highlights the potential value of specimen PET-CT imaging for head and neck cancer, as it could provide crucial real-time information during surgery. By aiding surgeons in assessing resection completeness, this approach may help reduce the need for adjuvant therapy in selected patients. Additionally, this case also highlights the ability of intraoperative PET-CT to visualize radiotracer uptake in bone tissue. This could help enable surgeons to ensure that bone resection margins are adequate at the time of surgery.
References
Debacker JM et al. High-Resolution 18F-FDG PET/CT for Assessing Three-Dimensional Intraoperative Margins Status in Malignancies of the Head and Neck, a Proof-of-Concept. J Clin Med 2021; 10:3737.