Volume Quantification of Endolymph after Intravenous Administration of a Single Dose of Gadolinium Contrast Agent: Comparison of 18- versus 8-minute Imaging Protocols

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Purpose: We measured the volume of the endolymphatic space by extending a previously proposed less observer-dependent method of area quantification and compared volume measurements obtained using long (18 min, Image A) and short (8 min, Image B) scan times.
Methods: We performed MR imaging of 40 ears in 20 patients with clinically suspected endolymphatic hydrops 4 hours after intravenous administration of single-dose gadolinium-based contrast material (IV-SD-GBCM). Two observers separately measured the ratio of the volume of the endolymph to that of total lymph in the cochlea and vestibule by extending the area ratio measurement method previously reported (Image A and B). The correlation between the values by Image A and B was calculated.
Results: We observed a strong linear correlation between Images A and B in the cochlear images; the Pearson’s correlation coefficient (r) was 0.928 for Observer A and 0.926 for Observer B (P < 0.001, for all). A strong linear correlation was also observed in the vestibular images; the Pearson’s correlation coefficient (r) was 0.962 for Observer A and 0.968 for Observer B (P < 0.001, for all).
Conclusion: Measurement of endolymphatic volume after IV-SD-GBCM may be feasible using an MR imaging protocol with a reduced scan time of 8 min. This method might facilitate greater use of endolymphatic hydrops imaging in clinical applications.