Additional value of integrated PET/CT over PET alone  in the initial staging and follow up of head and neck malignancy.
OBJECTIVE
Clinical application of FDG-PET in head and neck cancer includes identification of metastases, unknown primary head and neck malignancy, or second primary carcinoma, and also recurrent tumor after treatment. In this study, the additional value of PET/CT fusion images over PET images alone was evaluated in patients with initial staging and follow up of head and neck malignancy.


METHODS
Forty patients with suspected primary head and neck malignancy and 129 patients with suspected relapse after treatment of head and neck malignancy were included. FDG-PET/CT study was performed after the intravenous administration of FDG (5 MBq/kg). Target of evaluation was set at primary tumor, cervical lymph node, and whole body. PET images and PET with CT fusion images were compared. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Results of PET and PET/CT were compared with postoperative histopathological examination, and case by case comparison of PET and PET/CT results for each region was performed. The additional value of CT images over PET only images was assessed. Statistical differences in sensitivity and specificity were evaluated.


RESULTS
In the comparative evaluation of 507 targets by PET alone and PET/CT, 401 targets showed agreement of the results. Of the 106 discordant targets, 103 showed a positive result on PET alone and negative result on PET/CT. These results showed a significant difference (p< 0.01). Sensitivity of PET/CT was slightly higher than that of PET without statistical significance, while specificity of PET/CT was significantly higher than that of PET alone (Initial staging: 90.5% vs. 62.2%, p < 0.01; Follow up: 97.2% vs. 74.4%, p < 0.01). In Fisher's direct probability test, a significant difference was noted in the sensitivity (Initial staging: 91.3% vs. 87.0%, p < 0.01; Follow up: 93.9% vs. 91.4%, p <0.01).


CONCLUSIONS
Combined PET/CT showed improved diagnostic performance than PET alone by decreasing the number of false positive findings in patients with initial staging and follow up of head and neck malignancy.
Ishikita
Tomohiro
T
Department of Stomatology and Maxillofacial Surgery, Gunma University Graduate School of Medicine, Maebashi, Japan.
Oriuchi
Noboru
N
Higuchi
Tetsuya
T
Miyashita
Go
G
Arisaka
Yukiko
Y
Paudyal
Bishnuhari
B
Paudyal
Pramila
P
Hanaoka
Hirofumi
H
Miyakubo
Mitsuyuki
M
Nakasone
Yoshiki
Y
Negishi
Akihide
A
Yokoo
Satoshi
S
Endo
Keigo
K
D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18