To analyze imaging features on high resolution CT (HRCT) and MRI of facial nerve venous malformation (FNVM).

A total of 23 patients with pathologically confirmed FNVM were retrospectively included from January 2016 to December 2020 in the Shanghai Ninth People′s Hospital, Shanghai Jiao Tong University School of Medicine. All patients underwent preoperative temporal bone HRCT, non-contrast MRI, diffusion weighted imaging (DWI) and dynamic contrast enhanced MRI (DCE-MRI). The location, morphology, and signal intensity of the lesions, as well as the enhancement pattern on DCE-MRI were reviewed. The time-intensity curve (TIC) was analyzed and the apparent diffusion coefficient (ADC) was measured.

The locations of FNVM lesions were geniculate ganglion (n=19), mastoid segment (n=1) and internal auditory canal (n=3). Among 19 cases in geniculate ganglion, HRCT showed honeycomb-like bone change (n=13) or expansive bone destruction with sharp border (n=6). The case located in mastoid segment also presented as honeycomb-like changes. The other 3 cases in internal auditory canal presented with patchy hyperdensity bone change (n=2) or resorptive bone destruction (n=1). All 23 lesions demonstrated as irregular nodules with obviously heterogeneous enhancement on MRI. The lesions showed isointensity (n=14), hypointensity (n=8) or hyperintensity (n=1) on T₁WI, and hyperintensity (n=15) or isointensity (n=8) on fat-suppression T₂WI. The ADC values of the lesions were (1.18±0.20)×10^-3 mm²/s. A characteristic "point-to-plane" progressive enhancement pattern displayed on DCE-MRI, with type Ⅰ TIC (persistent pattern) presented.

The imaging characteristics of FNVM are honeycomb-like bone changes on HRCT and"point-to-plane"progressive enhancement pattern on DCE-MRI.

Facial nerve; Tomography, X-ray computed; Magnetic resonance imaging; Venous malformation