The Clinical Value Of The Application Of ¹⁸F-FDG PET/CT In Head And Neck Cancers

Objectives:To evaluate the value of combined 18F-fluorodeoxyglucose(FDG) PET/CT in the detection of the occult primary in patients with biopsy-proven cervical lymph node metastases and persistent, recurrent or metastatic carcinoma after treatment.Materials and Methods:Between December 2008 and December 2010,64 consecutive patients underwent FDG-PET/CT were enrolled in this retrospective study.20 subjects with cervical metastases from an unknown primary, and 44 patients with suspected persistence, recurrence or metastases after treatment of head and neck malignancy were included. Performances of PET/CT and CT(or MRI) were compared using biopsy and/or clinical follow-up of at least 6 months as gold-standard. Sensitivity, specificity, accuracy, positive predictive value(PPV), and negative predictive value(NPV) were calculated. Results of PET/CT were compared with the overall sensitivity and specificity of FDG-PET/CT in detecting unknown primary and persistent or recurrent tumor respectively. Results:PET/CT increased the detection of a primary site from 35% to 60%(7 vs 12 subjuects). This difference was clinically significant. There were 2 false-positive and 1 false-negative for PET/CT scan. The sensitivity, specificity, accuracy, PPV, and NPV of PET/CT in detecting the occult primary were 91%,78%,85%,83%,87%, respectively, prior to CT(or MRI) alone, but the difference has no statistical significance; while the pooled sensitivity and specificity were 0.88(95% CI:0.84-0.91)and 0.85(95% CI:0.81-0.88), prior to CT(or MRI) alone, and p=0.002 in sensitivity. There were 28 patients suspected persistence, recurrence or metastases in 44 subjects. Locoregional persistence, recurrence and metastases cases were recognized in 13,9 and 9 patients respectively according to pathological or clinical follow-up(mean 11.23±6.78 months). There were 3 patients who had both recurrence and metastases. In search of persistent tumor site,13 patients had true positive PET/CT findings,1 false-positive and 1 false-negative. In search of recurrent lesion,9 patients had true positive PET/CT findings,1 false-negative and 0 false-positive. For detecting metastases,6 true positive, 3 false positive and 1 false-negative. The sensitivity, specificity, accuracy, PPV, and NPV of PET/CT in detecting persistence, recurrence and metastases were 92%,83%,89%,89%,88%, respectively, prior to CT(or MRI) alone, but the difference has no statistical significance; while the pooled sensitivity and specificity were 0.89 (95% CI:0.86-0.90) and 0.94 (95% CI:0.93-0.95), prior to CT(or MRI) alone, p=0.12 in sensitivity and p=0.02 in specificity.Conclusions:Combined PET/CT is actually superior to CT(or MRI) for the detection of potential head and neck primary tumor and persistent, recurrent or metastatic carcinoma after treatment, and the differences have remarkably statistical significance. PET/CT might be performed as part of the routine evaluation of patients with suspected recurrence prior to salvage treatment. False-positive rate might be reduced once taking dual-phase scan of PET/CT.