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

Abstract

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). 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. 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). 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.