Objective  To evaluate the clinical value of whole body magnetic resonance imaging (WB - MRI) in detecting distant metastases of initial nasopharyngeal carcinoma (NPC).

  Methods  Examinations of WB-MRI, bone scan, chest X-ray, and liver ultrasound were conducted on 291 consecutive NPC patients within one week before relative treatments. Two experienced radiologists interpreted the WB-MRI. Additional conventional MR or CT was performed on areas with abnormal lesions. Feasibility of metastatic lesions was pathologically confirmed, and all patients were clinically followed up with imaging modalities for at least 12 months. The number of bone, lung, and hepatic metastases detected by WB-MRI were separately compared with those detected by bone scan, chest X-ray, and liver ultrasound. All results were recorded and statistically analyzed by McNemar's test on SPSS (Version 15.0).

  Results  A total of 24 positive patients with bone metastases and 95 lesions of bone metastases were diagnosed by both WB-MRI and bone scan. Among these, 71 lesions were detected through WB-MRI and 36 lesions through bone scan. The difference between the results was significant, with WB-MRI higher than bone scan (P=0.004). Apart from those with bone metastases, six patients with lung metastases were diagnosed by WB-MRI and three patients by chest X-ray. No significant difference was observed (P>0.25). WB-MRI also diagnosed six hepatic metastases patients, whereas liver ultrasound detected only four. Similarly, there was no significant difference between them (P>0.5). Furthermore, 24 patients were diagnosed with hepatic hemangioma through liver ultrasound, and 12 patients were diagnosed by WB-MRI, showing a significant difference between them (P < 0.01). By contrast, 34 patients with hepatic cysts were diagnosed by WB-MRI, and 16 patients were detected by liver ultrasound, showing a significant difference between them (P < 0.005).

  Conclusion  WB-MRI is valuable in detecting distant metastases within the whole body, and it can serve as the first-line imaging technique for the M staging of untreated NPC patients.