Separate visualization of endolymphatic space, perilymphatic space and bone by a single pulse sequence; 3D-inversion recovery imaging utilizing real reconstruction after intratympanic Gd-DTPA administration at 3 Tesla

Abstract

Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the perilymphatic space. Three-dimensional FLAIR can differentiate endolymphatic space from perilymphatic space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of perilymphatic space (positive value), endolymphatic space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing perilymphatic space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic space, perilymphatic space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

Ratio of Vestibular Endolymph in Patients with Isolated Lateral Semicircular Canal Dysplasia

“…The area of endolymph (ELA) was defined as the area of low signal in the vestibule in hT 2 W-3D-FLAIR 14 or HYDROPS2 13 images for patients who received GBCM by IV administration and in hT 2 W-3D-FLAIR or 3D-real IR images 15 for those who received contrast by the IT method. When measuring the ELA, we used hT 2 W-3D-FLAIR images if perilymph surrounded the ELA and HYDROPS2 or 3D-real IR images if the ELA was large and not completely surrounded by the perilymph.…”

Visualization of Endolymphatic Hydrops after Intratympanic Injection of Gd-DTPA: Comparison of 2D and 3D Real Inversion Recovery Imaging

“…Voxel size was 0.4 mm×0.4 mm×0.8 mm.``Real'' reconstruction allows positive and negative signal intensity values. 5 Parameters of 2D real IR were: sequence type, conventional 2D TSE with constant ‰ip angle of 1809for the TSE train; TR, 6000 ms; TE, 267 ms; TI, 1650 ms; slice-selective inversion pulse, echo train length, 60; echo spacing, 12.2 ms; FOV, 160 mm; matrix 320×320 without ZIP; 10 slices; slice thickness, 2 mm with 0.2-mm gap; bandwidth, 250 Hz/pixel; and reconstruction mode``real.'' We used GRAPPA with acceleration factor of 2 and 6 excitations, and scan time was 5.7 min (10 slices were covered by 3 times of 1.9 min scan covering 3-4 slices).…”

“…Voxel size was 0.5 mm×0.5 mm×2 mm.``Real'' reconstruction allows positive and negative signal intensity values. 5 We performed 3D CISS imaging to obtain reference images of the labyrinthine ‰uid-space anatomy using parameters: 0.4-mm isotropic voxels with ZIP in the slice encoding direction; TR, 6.4 ms; TE, 3.2 ms; and ‰ip angle, 509 . Scan time was 3.5 min.…”

“…4 A 3D inversion-recovery sequence with real reconstruction (3D real IR) at 3T then allowed the separate visualization of endolymph, perilymph, and bone using a single pulse sequence. 5 Labyrinthine structure is very complex. Because of the complexity of the labyrinthine structure, 3D real IR and 32-channel head coil at 3T have been used for 3D visualization of endo-/perilymph space.…”

“…6 The previously reported 3D real IR method using 3D turbo spin echo (3D TSE) requires 15 minutes' scan time. 5,6 Wider use of the method will require shorter scan time. Software limitations of diŠerent manufacturers' scanners sometimes make it di‹-cult to duplicate the 3D real IR protocol.…”