Diagnostic value of ¹⁸F-NaF PET/CT and MRI in detecting skull-base bone invasion of nasopharyngeal carcinoma

Objective: To evaluate the value of ¹⁸F-NaF PET/CT and MRI in the diagnosis of skull-base bone invasion (SBBI) in patients with nasopharyngeal carcinoma(NPC). Methods: Sixty-three NPC patients (45 males, ¹⁸Females; age range 23-72 years) were enrolled in this prospective study. Parents underwent ¹⁸F-NaF PET/CT and MRI to confirm whether the skull base was invaded. The reference standard was based on the follow-up imaging in 6 months. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the two imaging modalities were calculated. χ² test was used to analyze their difference. The SBBI foci and their distribution detected by the two imaging modalities were compared. Results: Thirty-four NPC patients demonstrated SBBI in follow-up imaging. The diagnostic sensitivity, specificity,positive predictive value, negative predictive value, and accuracy of ¹⁸F-NaF PET/CT were 97.1%(33/34), 89.7%(26/29), 91.7%(33/36), 96.3%(26/27) and 93.7%(59/63), respectively. For MRI, the parameters were 91.2%(31/34), 86.2%(25/29), 88.6%(31/35), 89.3%(25/28) and 88.9%(56/63), respectively. The diagnostic efficiency of the two imaging modalities had no significant difference (χ² = 0.162-1.062, all P > 0.05). ¹⁸F-NaF PET/CT detected 133 lesions and MRI detected 97 lesions, and the clivus was the most common site of SBBI. Conclusions: ¹⁸F-NaF PET/CT and MRI have similar diagnostic efficiency in detecting SBBI. ¹⁸F-NaF PET/CT can detect more lesions than MRI do, and has potential advantage for detecting tiny bone lesions in skull base. (authors)