Evaluation of the necessity of contrast in the follow-up MRI of schwannomas

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 (kappa = 0.902, P = 0.0001), whereas the agreement with the contrast-enhanced T1W sequence was good but not as good (kappa = 0.706, P = 0.001). CONCLUSION CISS, as a contrast-free sequence, may be an option in regular follow-up MRIs of vestibular schwannomas.