Application of positron emission tomography/computed tomography in radiation treatment planning for head and neck cancers

Figure 1 Positron emission tomography/computed tomography improves gross tumor and nodal volume delineation in a patient with oral tongue cancer. A: In the CT image, the tumor is difficult to separate from the soft tissues of the tongue; B: In the PET image, there is sharp demarcation of the primary tumor; C: The GTV is outlined in red based on CT scan; D: The GTV outlined in red based on ¹⁸FDG PET/CT is much smaller. ¹⁸FDG-PET/CT: 18-fluorodeoxygluocose positron emission tomography/computed tomography; GTV: Gross tumor and nodal volume.

Figure 2 Positron emission tomography/computed tomography discovers multiple primaries in a patient with a right lateral tongue cancer. A: PET/CT images revealed that in addition to an oral tongue tumor, this patient had a primary tumor of the soft palate (inferior white arrow) as well as the cervical esophagus (black arrow); B-D: The IMRT plan for this patient demonstrates all three tumors covered in the high dose CTV. PET/CT: Positron emission tomography/computed tomography; IMRT: Intensity modulated radiation therapy.

Figure 3 Positron emission tomography/computed tomography upstages a T1 nasopharyngeal cancer patient from N0 to N1. A-D: PET/CT images reveal that in addition to the T1 nasopharyngeal primary, there is increased FDG uptake in a level II node which was 1.0 cm in size (arrows). FNA of this node confirmed metastatic carcinoma. Thus, the patient was upstaged as T1N1 and treated with concurrent chemotherapy with IMRT; E-H: The IMRT plan for this patient treated the right level II node to a dose of 70 Gy. IMRT: Intensity modulated radiation therapy; PET/CT: Positron emission tomography/computed tomography; FDG: Fluorodeoxygluocose.

Figure 4 Positron emission tomography/computed tomography extends the high dose CTV contralaterally in a patient with a T2N2B base of tongue cancer. A: PET/CT reveals a contralateral level III node (white arrow), and thus, the patient was upstaged as T2N2C; B: An IMRT plan of this patient showing that this node was treated to 70 Gy and contralateral levels II and III were treated to 63 Gy. IMRT: Intensity modulated radiation therapy; PET/CT: Positron emission tomography/computed tomography.

Figure 5 Positron emission tomography/computed tomography detects a low neck lymph node involved by metastasis. Increased FDG uptake in the low neck reveals a metastatic lymph node which would otherwise be difficult to detect because of the presence of muscular and vascular structures in this region of the neck (A-D). FDG: Fluorodeoxygluocose.

Figure 6 Positron emission tomography/computed tomography allows for unilateral tonsil cancer treatment in a patient with a T2N0 left tonsil cancer. A, B: PET/CT shows no evidence of lymph node metastasis in the contralateral (right) neck; C, D: An IMRT plan of the radiation treatment plan showing effective contralateral sparing. IMRT: Intensity modulated radiation therapy; PET/CT: Positron emission tomography/computed tomography.

Figure 7 Positron emission tomography/computed tomography allows for detection for occult primary in a patient with multiple involved left neck nodes. A: PET/CT showing the initial presentation with multiple enlarged left neck nodes (white arrows); B: A conventional CT scan does not reveal a source of primary cancer; C: PET/CT demonstrated increased FDG uptake in the left base of tongue (white arrow) and a directed biopsy of this area revealed this as the primary site; D: IMRT treatment plan for this patient showing that the left base of tongue was included in the high-dose (70 Gy) volume while sparing uninvolved mucosal areas. IMRT: Intensity modulated radiation therapy; PET/CT: Positron emission tomography/computed tomography.

Figure 8 Positron emission tomography/computed tomography demonstrates tumor recurrence in a patient with a resected T4aN2b right buccal mucosa cancer prior to postoperative radiation. A-B: PET-CT obtained 50 d after surgery before postoperative radiation shows recurrent tumor (white arrow) in the infratemporal fossa; C-D: An IMRT treatment plan for this patient showing the recurrent tumor treated to a definitive radiation dose of 70 Gy rather a typical postoperative radiation dose of 60 Gy. IMRT: Intensity modulated radiation therapy; PET/CT: Positron emission tomography/computed tomography.