Assessing the Utility of 18F-Fluorodeoxyglucose Positron Emission Tomography in the Differential Diagnosis Between Spinal Schwannomas and Meningiomas

Abstract

Objective The advantage of 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) for the differential diagnosis of schwannoma and meningioma remains unclear. The purpose of this study was to compare the maximum standardized uptake value (SUVmax) with computed tomography (CT) and magnetic resonance imaging (MRI) findings and assess its utility in the differential diagnosis of schwannomas and meningiomas. Methods This study included 42 patients who underwent surgery and had pathological diagnoses of schwannomas (S group) or meningiomas (M group). Multivariate logistic regression analyses were conducted using meningioma prevalence as the dependent variable, and confounders were selected from those with p-values <0.05, including calcification, dural tail sign, tumor volume, and SUVmax at each spinal level as independent variables. Results The SUVmax of the spinal canal type at the level of the cervical vertebrae was significantly higher in the M group (4.6 ± 0.8) than in the S group (2.7 ± 1.4; P = 0.017). Multivariate logistic regression analysis showed that the dural tail sign was significantly associated with differential diagnosis between the S and M groups (odds ratio [OR], 0.851; 95% confidence interval [CI], 0.704-1.031, p<0.001). Conclusions The dural tail sign on MRI, but not the SUVmax of FDG-PET, was the most useful for the differential diagnosis between schwannomas and meningiomas.

Keywords: 18f-fluorodeoxyglucose-positron emission tomography; dural tail sign; meningioma; schwannoma; suvmax.

Figure 1. Flow diagram of the study.

Among the 89 patients who underwent FDG-PET/CT for spinal cord tumors at our institution between October 2009 and February 2020, 42 patients who underwent surgery and were pathologically diagnosed with schwannomas (S group) or meningiomas (M group) were included in this study. There were 28 and 14 cases in the S and M groups, respectively. The S group included 9 men and 19 women, and the M group included 2 men and 12 women. FDG-PET: 18F-fluorodeoxyglucose-positron emission tomography; CT: computed tomography.

Figure 2. Representative CT and MRI findings of schwannomas and meningiomas.

(A–D) Schwannoma (spinal canal type). (E–H) Meningioma (spinal canal type). (A, B, E, F) CT images. (C, D, G, H) Contrast-enhanced MRI findings. CT: computed tomography; MRI: magnetic resonance imaging.

Figure 3. Representative PET/CT images of schwannomas and meningiomas.

(A, B) Schwannoma (spinal canal type). (C, D) Schwannoma (dumbbell type). (E, F) Meningioma (spinal canal type). PET: positron emission tomography; CT: computed tomography.

Figure 4. Tumor location and measurement of tumor volume.

(A–D) Meningioma (spinal canal type). (A) T2-weighted MR images sagittal plane. (B) T2-weighted MR images axial plane. (C) Contrast-enhanced MR imaging axial plane. (D) The region of the tumor was isolated and a three-dimensional model was created. MR, magnetic resonance.

Figure 5. Relationship between SUVmax and tumor volume in the S and M groups.

(A) Schwannoma. ○：Dumbbell type, ●：Spinal canal type. (B) Meningioma. ●：Spinal canal type. Significant differences (p < 0.05) were calculated using the *Spearman’s rank correlation coefficient. The black circle indicates the spinal canal type. The white circle indicates the dumbbell type. SUVmax: maximum standardized uptake value.