Intensity of gadolinium enhancement on MRI is useful in differentiation of intracochlear inflammation from tumor.

OBJECTIVE: Magnetic resonance imaging is the gold standard in retrocochlear imaging; however, its role in management of inner ear diseases remains poorly defined. In this study, we investigate the utility of MRI in defining the nature of intracochlear pathology.

STUDY DESIGN: A retrospective review of 11 patients with inner ear abnormalities on MRI between 2010 and 2013. Patients' diagnosis included cholesteatoma, labyrinthitis, meningitis, and intralabyrinthine schwannoma.

SETTING: Tertiary care hospital.

MAIN OUTCOME MEASURES: T1, T2, and postcontrast signal intensities were measured within the lesion and normalized in reference to the contralateral normal cochlea. The following ratios were calculated: T1 postgadolinium lesion/contralateral cochlea, T2 lesion/contralateral cochlea and T1 lesion/contralateral cochlea. Statistical analysis was conducted using the unpaired Student's t test using IBM SPSS Statistics version 20.0.0.

RESULTS: The relative intensity ratios were useful in defining the nature of inner ear lesion. Normalized T1 postgadolinium lesion intensities were significantly higher in the tumor group (3.98 ± 0.880 versus 1.71 ± 0.370, p < 0.0002). Normalized T1 precontrast signal intensities were higher in tumors (1.33 ± 0.200 versus 0.842 ± 0.426, p < 0.0626), and T2 values were lower in tumors (0.838 ± 0.491 versus 1.10 ± 0.305, p < 0.317); however, these did not reach significance.

CONCLUSION: Intensity of gadolinium enhancement on MRI is useful in differentiation of inflammation from tumors; normalized T1 postgadolinium intensity ratio greater than 3 is strongly suggestive of intralabyrinthine tumor.