title: Assessment of internal auditory canal tumors: a comparison of contrast-enhanced T1-weighted and steady-state T2-weighted gradient-echo MR imaging.
abstract: OBJECTIVE
  Although contrast-enhanced T1-weighted MR imaging is the standard of reference for diagnosing tumor in the cerebellopontine angle, high-resolution T2-weighted imaging may show more details of the seventh and eighth cranial nerve branches, resulting in more accurate tumor volume measurements. The purpose of this study was to compare two MR sequences for their ability to delineate internal auditory canal tumors.
  
  
  METHODS
  Twenty-seven ears in 21 patients with 16 confirmed schwannomas were studied with the 3D T2-weighted prototype segment-interleaved motion-compensated acquisition in steady state (SIMCAST) and the T1-weighted contrast-enhanced spoiled gradient-echo (SPGR) techniques. Twenty-eight axial sections were acquired using parameters of 17/3.3 (TR/TE), a 40 degrees flip angle, a 20 x 15-cm or 22 x 16-cm field of view (FOV), a 512 x 256 matrix, and a 0.4- or 1.2-mm section thickness for the SIMCAST technique, and 30/4.2, a 30 degrees flip angle, a 20 x 20-cm FOV, a 512 x 288 matrix, and a 1.5-mm section thickness for the SPGR technique. Tumor appearance and depiction of surrounding anatomy, including the cranial nerves, were evaluated. Tumor volumes were measured by manual tracing.
  
  
  RESULTS
  Both sequences clearly identified tumors that ranged in size from 0.06 to 3.0 cm3. Measurements on both sequences agreed, on average, within 14%. The information from both sequences was complementary. SIMCAST usually delineated the CSF spaces better, whereas SPGR more clearly showed the tumor/brain boundary.
  
  
  CONCLUSIONS
  SIMCAST and SPGR are suitable for tumor detection and volume measurements. SPGR has somewhat better contrast, but SIMCAST excels at depicting the surrounding anatomy and tumor involvement of the seventh and eighth cranial nerves.
authors.affiliation: Department of Radiology, The Ohio State University, Columbus 43210, USA.
authors.forename: P
authors.initials: P
authors.lastname: Schmalbrock
authors.forename: D W
authors.initials: DW
authors.lastname: Chakeres
authors.forename: J W
authors.initials: JW
authors.lastname: Monroe
authors.forename: A
authors.initials: A
authors.lastname: Saraswat
authors.forename: B A
authors.initials: BA
authors.lastname: Miles
authors.forename: D B
authors.initials: DB
authors.lastname: Welling
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003287:Contrast Media; D007758:Ear, Inner / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media