title: Signal alteration of the cochlear perilymph on 3 different sequences after intratympanic Gd-DTPA administration at 3 tesla: comparison of 3D-FLAIR, 3D-T1-weighted imaging, and 3D-CISS.
abstract: OBJECTIVE
  Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging after intratympanic gadolinium injection is useful for pathophysiologic and morphologic analysis of the inner ear. However, statistical analysis of differences in inner ear signal intensity among 3D-FLAIR and other sequences has not been reported. We evaluated the signal intensity of cochlear fluid on each of 3D-FLAIR, 3D-T(1)-weighted imaging (T(1)WI), and 3D-constructive interference in the steady state (CISS) to clarify the differences in contrast effect among these 3 sequences using intratympanic gadolinium injection.
  
  
  METHODS
  Twenty-one patients underwent 3D-FLAIR, 3D-T(1)WI, and 3D-CISS imaging at 3 tesla 24 hours after intratympanic injection of gadolinium. We determined regions of interest of the cochleae (C) and medulla oblongata (M) on each image, evaluated the signal intensity ratio between C and M (CM ratio), and determined the ratio of cochlear signal intensity of the injected side to that of the non-injected side (contrast value).
  
  
  RESULTS
  The CM ratio of the injected side (3.00+/-1.31, range, 0.53 to 4.88, on 3D-FLAIR; 0.83+/-0.30, range, 0.36 to 1.58 on 3D-T(1)WI) was significantly higher than that of the non-injected side (0.52+/-0.14, range, 0.30 to 0.76 on 3D-FLAIR; 0.49+/-0.11, range, 0.30 to 0.71 on 3D-T(1)WI) on 3D-FLAIR and 3D-T(1)WI (P<0.001), although no significant difference was observed on 3D-CISS (10.03+/-2.19, range, 5.19 to 14.98, on the injected side; 9.52+/-1.63 range, 7.48 to 13.48, on the non-injected side) (P=0.11). The mean contrast value on 3D-FLAIR (5.93+/-2.57, range, 1.22 to 11.05) was significantly higher than that on 3D-T(1)WI (1.73+/-0.60, range, 0.98 to 3.09) (P<0.001).
  
  
  CONCLUSIONS
  The 3D-FLAIR sequence is the most sensitive for observing alteration in inner ear fluid signal after intratympanic gadolinium injection. Our results warrant use of 3D-FLAIR as a sensitive imaging technique to clarify the pathological and morphological mechanisms of disorders of the inner ear.
authors.affiliation: Department of Radiology, Nagoya University Graduate School of Medicine, Shouwa-ku, Nagoya, Japan. yamazaki@med.nagoya-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kawai
authors.forename: Takashi
authors.initials: T
authors.lastname: Nihashi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakashima
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003051:Cochlea / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology; D008875:Middle Aged; D010498:Perilymph; D014432:Tympanic Membrane; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA