Purpose: The purpose of our study was to determine whether gadolinium is necessary in follow-up MRIs for evaluating vestibular schwannomas.
Materials and methods: A retrospective analysis of 49 magnetic resonance imaging (MRI) examinations of 20 vestibular schwannoma patients was performed. Patients received between 1 and 4 follow-up scans, and the mean follow-up period was 15.3 months. Two radiologists independently reviewed the initial and follow-up MRI examinations. Tumor measurements obtained using the constructive interference in steady state (CISS) and contrast-enhanced T1-weighted (T1W) sequences were compared. Both radiologists used both of the sequences to analyze any differences in the tumor sizes measured in consecutive MRI scans.
Results: The linear anteroposterior and transverse tumor diameter measurements obtained by the two observers using both sequences were strongly correlated (r = 0.962-0.987, P < 0.001). The observers agreed to a very high degree when detecting changes in the tumor size using the CISS sequence (κ = 0.902, P = 0.0001), whereas the agreement with the contrast-enhanced T1W sequence was good but not as good (κ = 0.706, P = 0.001).
Conclusion: CISS, as a contrast-free sequence, may be an option in regular follow-up MRIs of vestibular schwannomas.