Diagnostic Value of Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging for Multilocular Ameloblastoma

Contrast-enhanced (CE)-MR image is useful to distinguish cystic and solid portions on multilocular lesion, however, the CE-MR examination is contraindicated in patients with kidney disease. Fluid-attenuated inversion recovery (FLAIR) image is one of methods which signal of fluid is suppressed. This study investigated qualitatively and quantitatively whether FLAIR images were useful for detecting and differentiating cystic and solid portions of multilocular ameloblastomas. We retrospectively reviewed 11 cases of multilocular ameloblastoma. FLAIR and short Ti inversion recovery (STIR) sequences were performed in all cases. CE-MR images in 10 cases, and T1-weighted images (T1WI) in 7 cases. FLAIR, STIR, CE-MR, and T1WI images were visually evaluated (qualitative analysis). Signal-to-noise ratio (SNR) of cystic and solid portions were measured and compared among the images of all sequences (quantitative analysis). FLAIR imaging could detect cystic portions with very low SI in all cases because cystic fluid was well suppressed on the images, and the solid portion showed intermediate SI. On some STIR images, the solid portion was masked by the markedly high SI of the cystic fluid. CE-T1WI and CE-FLAIR images showed no enhancement of the cystic portion but enhancement of the solid portion. On FLAIR image, SNR of solid was higher than cystic portion (p < 0.05). Cystic and solid portions of a lesion could be detected and distinguished on FLAIR imaging. FLAIR images are thus useful for diagnosing multilocular ameloblastoma when CE-MR cannot be performed.