Differentiation of cerebellopontine angle (CPA) schwannoma from meningioma is often a difficult process to identify.
To identify imaging features for distinguishing CPA schwannoma from meningioma and to investigate the usefulness of susceptibility-weighted imaging (SWI) in differentiating them.
Between March 2010 and January 2015, this study pathologically confirmed 11 meningiomas and 20 schwannomas involving CPA with preoperative SWI were retrospectively reviewed. Generally, the following MRI features were evaluated: 1) maximal diameter on axial image, 2) angle between tumor border and adjacent petrous bone, 3) presence of intratumoral dark signal intensity on SWI, 4) tumor consistency, 5) blood-fluid level, 6) involvement of internal auditory canal (IAC), 7) dural tail, and 8) involvement of adjacent intracranial space. On CT, 1) presence of dilatation of IAC, 2) intratumoral calcification, and 3) adjacent hyperostosis were evaluated. All features were compared using Chi-squared tests and Fisher's exact tests. The univariate and multivariate logistic regression analysis were performed to identify imaging features that differentiate both tumors.
The results noted that schwannomas more frequently demonstrated dark spots on SWI (P = 0.025), cystic consistency (P = 0.034), and globular angle (P = 0.008); schwannomas showed more dilatation of internal auditory meatus and lack of calcification (P = 0.008 and P = 0.02, respectively). However, it was shown that dural tail was more common in meningiomas (P < 0.007). In general, dark spots on SWI and dural tail remained significant in multivariate analysis (P = 0.037 and P = 0.012, respectively). In this case, the combination of two features showed a sensitivity and specificity of 80% and 100% respectively, with an area under the receiver operating characteristic curve of 0.9.
In conclusion, dark spots on SWI were found to be helpful in differentiating CPA schwannoma from meningioma. It is noted that combining dural tail with dark spots on SWI yielded strong diagnostic value in differentiating both tumors.
Representative images of meningioma (upper row) in a 35-year-old woman and schwannoma (bottom row) in a 66-year-old male. From left to right, each column represents T2-weighted (a, d), contrast-enhanced T1-weighted (b, e) and SWI (c, f) of tumor located in left cerebellopontine angle. Schwannoma shows punctate dark signal intensities on SWI (f) while meningioma shows none (c) (arrows). SWI = susceptibility-weighted image.
A receiver operator characteristic curve based on two significant imaging features from multivariate logistic regression-dark spots on SWI and dural tail sign. At the optimal threshold point (open circle), the AUC was 0.9 with a sensitivity and a specificity of 80% and 100%, respectively. AUC = area under the receiver operator characteristic curve.
Baseline Cha racteristics of Patients and Tumors (n = 31)
Characteristics | Meningioma (n = 11) | Schwannoma (n = 20) | P-value |
---|---|---|---|
Sex, n (%) | 0.724 | ||
Female Male Age, mean ± SD Tumor location, n (%) | 7 (63.6%) 4 (36.4%) 61.5 ± 12.3 | 10 (50.0%) 10 (50.0%) 51.7 ± 18.5 | 0.125 0.248 |
Left | 4 (36.4%) | 13 (65.0%) | |
Right | 7 (63.6%) | 7 (35.0%) |
SD = standard deviation
Comparison of Imaging Features of Tumors
MRI features, n (%) | Meningioma (n = 11) | Schwannoma (n = 20) | P-value |
---|---|---|---|
Maximal tumor diameter (cm), mean ± SD | 4.2 ± 1.4 | 3.8 ± 1.3 | 0.373 |
Dark spot on SWI |
0.025 | ||
none | 6 (54.5%) | 2 (10.0%) | |
< 50% | 4 (36.4%) | 14 (70.0%) | |
≥ 50% | 1 (9.1%) | 4 (20.0%) | |
Tumor consistency | 0.034 | ||
Solid | 9 (81.8%) | 7 (35.0%) | |
Solid and cystic | 2 (18.2%) | 13 (65.0%) | |
Blood-fluid level | 0.474 |
||
Absent | 11 (100.0%) | 17 (85.0%) | |
Present | 0 (0.0%) | 3 (15.0%) | |
IAC component | 0.056 | ||
Absent | 8 (72.7%) | 6 (30.0%) | |
Present | 3 (27.3%) | 14 (70.0%) | |
Dural tail sign | 0.007 | ||
Absent | 5 (45.5%) | 19 (95.0%) | |
Present | 6 (54.5%) | 1 (5.0%) | |
Angle |
0.008 | ||
Broad | 9 (81.8%) | 5 (25.0%) | |
Globular | 2 (18.2%) | 15 (75.0%) | |
CT imaging features, n (%) | |||
Meatus dilatation | 0.008 |
||
Absent | 11 (100.0%) | 9 (45.0%) | |
Present | 0 (0.0%) | 11 (55.0%) | |
Calcification | 0.02 |
||
Absent | 7 (63.6%) | 20 (100.0%) | |
Present | 4 (36.4%) | 0 (0.0%) | |
Hyperostosis | 0.749 |
||
Absent | 11 (100.0%) | 18 (90.0%) | |
Present | 0 (0.0%) | 2 (10.0%) |
Fisher's exact test; other categorical comparisons by Pearson's Chi-squared tests
Proportion of dark spot on susceptibility-weighted imaging out of total tumor area
Angle between tumor and adjacent petrous bone IAC = internal auditory canal; SWI = susceptibility-weighted imaging
Univariate and Multivariate Logistic Regression Analysis Using Clinical and Imaging Characteristics
Variables | Univariate analysis | Multivariate analysis |
||
---|---|---|---|---|
OR (95% CI) | P-value | OR (95% CI) | P-value | |
Age | 0.96 [0.91, 1.0] | 0.13 | ||
Sex, male | 1.75 [0.4, 8.52] | 0.467 | ||
Maximal tumor diameter | 0.76 [0.42, 1.36] | 0.362 | ||
Dark spot on SWI (none vs. present) | 2.73 [1.27, 6.98] | 0.017 | 3.25 [1.19, 12] | 0.037 |
Tumor consistency | 8.36 [1.61, 65.9] | 0.02 | ||
Blood-fluid level | 0.994 | |||
IAC component | 6.22 [1.31, 37.0] | 0.029 | 2.94 [0.32, 30.5] | 0.331 |
Dural tail sign | 0.04 [0, 0.33] | 0.009 | 0.03 [0, 0.33] | 0.012 |
Angle |
13.5 [2.5, 111.6] | 0.005 | ||
Meatus dilatation | 0.995 | |||
Calcification | 0.995 | |||
Hyperostosis | 0.995 |
Variables with P < 0.02 were further analyzed in multivariate analysis
Angle formed between tumor margin and adjacent petrous bone CI = confidence interval; OR = odds ratio