Staging of untreated nasopharyngeal carcinoma with PET/CT: comparison with conventional imaging work-up.
OBJECTIVE
We prospectively compared PET/CT and conventional imaging for initial staging of nasopharyngeal carcinoma (NPC).


METHODS
A total of 111 patients with histologically proven NPC were investigated with PET/CT and conventional imaging (head-and-neck MRI, chest X-ray, abdominal ultrasound, and bone scan) before treatment. The respective findings were reviewed independently and then compared with each other.


RESULTS
With regard to T staging, PET/CT showed a discrepancy with head-and-neck MRI in 36 (32.4%) of the study subjects. With regard to N staging, PET/CT showed a discrepancy with head-and-neck MRI in 15 (13.5%) patients. Among the discordant cases, MRI was superior in demonstrating tumor involvement in the parapharyngeal space, skull base, intracranial area, sphenoid sinus, and retropharyngeal nodes while PET/CT was superior in demonstrating neck nodal metastasis. PET/CT disclosed 13 of 16 patients with distant malignancy compared with four patients disclosed by conventional imaging work-up. The false-positive rate of PET/CT was 18.8%. PET/CT correctly modified M staging in eight patients (7.2%) and disclosed a second primary lung malignancy in one patient (0.9%).


CONCLUSIONS
In NPC patients, MRI appears to be superior to PET/CT for the assessment of locoregional invasion and retropharyngeal nodal metastasis. PET/CT is more accurate than MRI for determining cervical nodal metastasis and should be the better reference for the neck status. PET/CT has an acceptable diagnostic yield and a low false-positive rate for the detection of distant malignancy and can replace conventional work-up to this aim. PET/CT and head-and-neck MRI are suggested for the initial staging of NPC patients.
Ng
Shu-Hang
SH
Molecular Imaging Center and Department of Diagnostic Radiology, Chang Gung Memorial Hospital, Chang Gung University, Kueishan, Taiwan. Shng6@ms25.hinet.net
Chan
Sheng-Chieh
SC
Yen
Tzu-Chen
TC
Chang
Joseph Tung-Chieh
JT
Liao
Chun-Ta
CT
Ko
Sheung-Fat
SF
Liu
Feng-Yuan
FY
Chin
Shu-Chyn
SC
Fan
Kang-Hsing
KH
Hsu
Cheng-Lung
CL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography