Is an Intravenous Injection of Gadolinium Really Necessary for Intralabyrinthine Schwannomas MR Examination?

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Abstract

Objectives:

Our aim was to confirm the usefulness of T2-weighted (T2W) gradient-echo sequence for detection and topographic diagnosis of intralabyrinthine schwannomas (ILS) compared with T1W contrast-enhanced sequence as gold standard, to evaluate the necessity of intravenous gadolinium injection for ILS follow-up imaging.

Methods:

Thirty patients with ILS were retrospectively enrolled and compared to a control group of 30 patients with no inner ear pathology. All patients underwent a T2W gradient-echo steady-state free precession (SSFP) acquisition at 3T, which was visually analyzed by two radiologists and compared to contrast-enhanced T1W sequence. A quantitative analysis was also performed, with the measurement of the tumor and inner ear signal on T2W images and the measurement of the tumor length in cochlear schwannomas.

Results:

T2W FIESTA-C sequence correctly diagnosed ILS with a sensitivity (Se) of 95% and a specificity (Sp) of 100%, with matching results for their topographic evaluation (Se 92%, Sp 98%) compared with the gold-standard. The difference between the two sequences was only 2.5%, with excellent interobserver agreement. The tumor signal on T2W images was significantly lower than the normal bright signal of the normal inner ear fluids (mean signal ratio = 0.42 vs 0.98).

Conclusion:

The positive and topographic diagnostic accuracy of T2W FIESTA-C sequence was excellent compared with the T1W contrast-enhanced sequence, even though the latter remains easier and faster to analyze for an untrained radiologist. The performances of T2W gradient-echo sequence at 3T make it a reasonable alternative strategy for following ILS after they are diagnosed.

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