Objective:

To evaluate the value of single-photon emission computed tomography (SPECT)/CT and magnetic resonance imaging (MRI) in the diagnosis of skull-base bone invasion (SBBI) in the patients with nasopharyngeal carcinoma (NPC).

Methods:

Eighty-three first-visit NPC patients (57 ma

les

26 females; age range 16-72 years) were enrolled in this retrospective study. The patients underwent SPECT/CT and MRI to confirm whether the skull base was invaded.

99m

Tc-MDP SPECT and MRI were performed in one week. The region of interest (ROI) was drawn on the area of the suspected skull base and the upper cervical vertebral body on the slices. A lesion-to-spine ratio (L/S) was calculated. L/S＞1 indicated malignant. The sensitivity

specificity

positive predictive value

negative predictive value and accuracy of the two imaging modalities were calculated.

Results:

Sixty-four NPC patients were found SBBI in follow-up imaging. The diagnostic sensitivity

specificity

missed diagnosis rate and misdiagnosis rate of MRI were 100%

94.74%

0

5.26%

respectively. The correspondence parameters of SPECT/CT were 93.75%

84.21%

6.25%

15.79%

respectively. There was no significant difference in the diagnostic efficiency between the two imaging modalities (

2

=1.37

P

=0.242).

Conclusion:

SPECT/CT and MRI have similar diagnostic efficiency in detecting SBBI. MRI can detect more lesions than SPECT/CT

but SPECT/CT has potential advantages in detecting tiny bone lesions in the skull.