Detection and restaging of residual and/or recurrent nasopharyngeal carcinoma after chemotherapy and radiation therapy: comparison of MR imaging and FDG PET/CT.

Purpose: To compare the accuracy of magnetic resonance (MR) imaging and combined fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT), alone and in combination, in detection and restaging treated nasopharyngeal carcinoma (NPC).
Materials and Methods: This retrospective study was performed after institutional review board approval and informed consent were obtained. Sixty-three consecutive patients treated for NPC underwent follow-up with both MR imaging and FDG PET/CT. Findings were evaluated according to the TNM classification. Final diagnosis was confirmed at biopsy or imaging follow-up for at least 6 months. Proportions and their 95% confidence intervals were computed; for comparison of data obtained separately from MR imaging and FDG PET/CT and those obtained from their combined use, the McNemar test was used. P < .05 was considered to indicate a statistically significant difference.
Results: There was a trend toward greater overall accuracy of MR over PET/CT in detecting residual and/or recurrent NPC at the primary site; 92.1% (58 of 63 patients) for MR versus 85.7% (54 of 63) for FDG PET/CT (P = .16). Overall accuracy for tumor restaging was 74.6% (47 of 63) for MR and 73.0% (46 of 63) for FDG PET/CT (either modality used alone), but the overall combined accuracy was 92.1% (58 of 63) (all P values < .01).
Conclusion: MR imaging demonstrated a trend toward higher accuracy than did FDG PET/CT in detecting residual and/or recurrent NPC at the primary tumor site. The combined use of MR and FDG PET/CT was more accurate for tumor restaging than when either modality was used independently.
((c) RSNA, 2008.)