John W. Keyes

BACKGROUND: A single institution study was undertaken to evaluate the role of positron emission tomography (PET) scans with fluorodeoxyglucose (FDG) prior to radiation and following radiation. METHODS: Forty-five patients with head and neck cancers were evaluated with FDG-PET scans as well as either CT or MRI prior to treatment with definitive radiation (RT). These same scans were obtained following completion of RT at 1 month (36 patients), 4 months (28 patients), 12 months (19 patients), and 24 months (15 patients). Standard uptake values (SUV) normalized for blood glucose and lean body mass were calculated on the initial and 1-month post-treatment PET scans. RESULTS: Fifteen patients are alive without evidence of disease at 24 to 52 months following RT. Initial SUVs were calculated on the primary tumor site and ranged from 2.5 to 28.5. These values did not have any correlation with local control when examined for the entire group, primary site, or T stage. One-month post-RT SUV ranged from 1.8 to 6.24. Of the 36 1-month post-RT PET scans, six were interpreted as positive for residual disease and were confirmed by biopsy. Four of the five scans, which were interpreted as equivocal, were positive on biopsy. Seven of the 25 scans, which were interpreted as negative for tumor, were positive on biopsy. Four-month scans were more accurate for disease with disease noted in 0 of 18 negative scans, 6 of 7 positive scans, and 2 of 3 equivocal scans. CONCLUSIONS: PET is useful for initial imaging of head and neck cancers. SUV does not appear to be useful for predicting outcome following treatment with RT. One-month post-RT scans were inaccurate for predicting the presence of cancer. Four-month post-RT scans were a better predictor for the presence of cancer.

BACKGROUND: Positron emission tomography (PET) with labeled fluorodeoxyglucose (FDG) demonstrates increased tracer uptake in many neoplasms. This study was undertaken to define the patterns of FDG uptake in head and neck neoplasms before and after high dose irradiation. METHODS: Twenty-five patients were evaluated prospectively with PET and standard clinical and radiographic techniques before and after irradiation. RESULTS: Twenty-seven primary sites were confirmed pathologically in 23 patients and included the nasopharynx (four lesions), oropharynx (14 lesions), larynx (five lesions), oral cavity (two lesions), and paranasal sinuses (two lesions). Two patients had unknown primary sites. Twenty-four of 27 primary sites correlated with areas of increased tracer uptake on PET scans. Five patients had increased uptake in cervical lymph nodes that were uninvolved by radiographic or clinical criteria. Positron emission tomography seemed to be able to differentiate tumor activity from fluid-filled sinuses in two patients with paranasal sinus tumors. In two patients with unknown primary sites, increased uptake in the base of tongue after PET suggested occult primary sites. Positron emission tomography scans obtained 1 month after high dose irradiation (RT) indicated decreased levels of FDG uptake in all patients' tumors. However, these scans did not accurately reflect the status of disease in these patients. Scans obtained 4 months after RT were believed to assess more accurately the presence of malignancy. CONCLUSIONS: Positron emission tomography is a new modality that may be useful in defining tumor activity in clinically negative areas. Appropriately timed posttreatment PET may be useful in predicting outcome after definitive RT and in distinguishing viable tumors from normal tissue changes after RT in patients with head and neck carcinomas.

A prospective study was conducted to compare the accuracy of clinical examination, computed tomography (CT), and positron emission tomography (PET) in identifying head and neck squamous cell carcinoma metastatic to cervical lymph nodes. The findings in the necks of 49 patients evaluated by clinical examination and CT were compared to the findings in the same necks by PET, a newly available metabolic imaging modality. Pathology specimens were available for 45 of the necks. The findings of PET and CT correlated in 84% of cases. In the cases that did not correlate, CT proved correct in four of five cases. PET (82%) and CT (84%) were comparable and were both better than clinical examination (71%) in correctly identifying the presence or absence of metastatic disease.

Iodobenzamide (IBZM) is a D-2 dopamine receptor antagonist. In this paper the results of Phase I clinical studies of iodine-123-(123I)IBZM in humans are reported. Preliminary imaging studies, both planar and single-photon emission tomography (SPECT), of no-carrier added [123I]IBZM in humans show specific localization in the basal ganglia of the brain. At 2 hr after an i.v. injection, the brain uptake was 3.72% of the dose, and at 20 hr later the uptake diminished to 0.7%. Radiation dosimetry calculation indicated that the radiation dose to the brain was minimum, 0.039 rad/mCi, while the large intestine wall received the highest dose, 0.28 mrad/mCi. The radiation dosimetry and pharmacology data suggest that this agent is safe for human use.

BACKGROUND: The objective of this study was to review and describe the usage of fluorine-labeled deoxyglucose (FDG) and positron emission tomography (PET) in the diagnosis and management of head and neck cancer. METHODS: Several prospective series,-including 159 newly diagnosed and previously untreated and 23 previously irradiated head and neck squamous cell carcinoma patients initially seen at the Wake Forest University Medical Center and evaluated by clinical examination, conventional computed tomography/ magnetic resonance imaging (CT/MRI) scans, PET scans, and histopathologic studies,-were reviewed and the findings summarized for comparison of the correct differentiation of primary and metastatic cancers and for postirradiation tumor clearance in a subsegment of those cases. RESULTS: Positron emission tomography scanning using a fluorine-labeled deoxyglucose (FDG) radiotracer proved as reliable as conventional scanning for primary and metastatic tumor identification. Compared with clinical examination, PET was better for identification of nodal metastatic tumors but poorer for small primary tumors. For previously irradiated patients treated at least 4 months before the test, PET scanning was clearly superior to clinical examination and conventional imaging in differentiating tumor recurrence from soft-tissue irradiation effects. CONCLUSIONS: Fluorine-labeled deoxyglucose-PET scanning is comparable to conventional imaging of head and neck cancers in detecting primary and metastatic carcinoma. Lack of anatomic detail remains its major drawback. Currently, its greatest role is in the evaluation of the postradiotherapy patient.