[Optimization of delivering minimum Gd-DTPA at the posterior upper point on tympanic medial wall and hT2W-3D-FLAIR sequence for detecting endolymphatic hydrops].

To optimize delivery of gadolinium-diethylenetriamine pentaacetic acid(Gd-DTPA) at the posterior upper point on tympanic medial wall and heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery (hT2W-3D-FLAIR) sequence, and to implement the technique of detecting endolymphatic hydrops using gadolinium-enhancement MRI. Thirteen patients with periphery vertigo, who visited Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Changhai Hospital during June and December of 2017, were enrolled in the study.0.10-0.20 ml of Gd-DTPA in various dilutions (10, 20, and 40-fold) were delivered at the posterior upper point on tympanic medial wall using a soft-tipped tympanic suction and drug-spraying needle through an artificially perforated tympanic membrane. Inner ear MRI was performed at 8, 24 h after Gd-DTPA administration using a 3T MR machine in combination with a 20-channel Tim 4G head/neck coil and the sequence of hT2W-3D-FLAIR to detect the gadolinium-enhancement signal within the inner ear and possible endolymphatic hydrops. The scanning time was either 8 min 35 s or 15 min 11 s. Efficient inner ear uptake of Gd-DTPA was detected and induced high signal to noise ratio of MRI in patients receiving targeted delivery of 0.15-0.20 ml of 10-fold diluted contrast agent at the posterior upper point on tympanic medial wall. At 8 h after delivery, significant uptake was detected in the scala tympani and vestibuli of hook region and basal turn of the cochlea, and perilymhatic compartment of the vestibule. At 24 h after delivery, the distribution of Gd-DTPA became homogenous in each turn of the cochlea and perilymphatic compartment of the vestibule. However, obvious individual variance existed in the inner ear uptake when 0.10 ml of 40-fold diluted Gd-DTPA was delivered. Efficient inner ear uptake and high quality images that generated in patients receiving 0.10, 0.15, and 0.20 ml of 20-fold Gd-DTPA demonstrated endolymphatic hydrops with minor individual variance. There was insignificant difference in the enhancement signal of inner ear between 0.15 and 0.10 ml groups when Gd-DTPA was diluted at 20-fold except for the signal of semicircular canal of 0.15 ml group (190.00±53.95 165.50±42.13, =2.61, <0.05). There was insignificant difference in the image quality between 8 min 35 s and 15 min 11 s canning time. Various degrees of endolymphatic hydrops were detected in 7 cochleae and 11 vestibule, and both simultaneous cochlear and vestibular endolymphatic hydrops were detected in 4 ears. Cochlear endolymphatic hydrops was detected in all the 3 patients with definite Meniere's disease, and 2 of them had combined cochlear and vestibular endolymphatic hydrops. Endolymphatic hydrops was not detected in patients with possible Meniere's disease nor with symptoms of superior semicircular canal dehiscence. Targeted delivery of 0.10 ml with 20-fold diluted Gd-DTPA (total dosage of 5 μmol) at the posterior upper point on tympanic medial wall in combination with 8 min 35 s scanning time hT2W-3D-FLAIR sequence for inner ear MRI in a 3T MR machine is a clinically practical method to detect endolymphatic hydrops, and reduce the requirement for MRI hardware.