Visualization of the Eustachian Tube Cartilage on Delayed Contrast-enhanced 3D-MR Imaging: A Preliminary Comparison...

To evaluate whether delayed contrast-enhanced 3D MRI using a non-ionic gadolinium-based contrast agent enables reliable visualization of the Eustachian tube cartilage (ETC) and to compare the signal intensity characteristics between ionic and non-ionic contrast agents.

Thirty-five participants underwent 3T fat-suppressed 3D-Motion-Sensitized Driven-Equilibrium (MSDE) T1-weighted MRI 4 hr after receiving either gadobutrol (non-ionic, n = 18) or gadoterate meglumine (ionic, n = 17). The visualization of the ETC was qualitatively evaluated using a 5-point Likert scale by 2 neuroradiologists. Signal intensity ratios relative to the medulla were measured for the ETC, nasal turbinate mucosa, and lateral pterygoid muscles. Semi-automated 3D segmentation of the ETC was performed in representative cases.

The inter-observer agreement for the qualitative scores was substantial (κ = 0.786-0.808). Qualitative ETC visual scores were significantly higher in the gadobutrol group than in the gadoterate meglumine group (median, 5.0 vs. 4.0; P < 0.001). The ETC-to-medulla signal intensity ratios were significantly higher with gadobutrol bilaterally (right: 1.52 ± 0.20 vs. 1.21 ± 0.19, P < 0.0001; left: 1.54 ± 0.26 vs. 1.24 ± 0.22, P = 0.00088). No significant differences were observed in control soft tissues. Furthermore, semi-automated 3D segmentation of the ETC was successfully achieved in representative cases using high-resolution MR datasets with a non-ionic contrast agent.

Delayed contrast-enhanced 3D-MRI with a non-ionic contrast agent allows clear, high-contrast visualization and 3D reconstruction of the ETC, outperforming the ionic agents.