title: Relationship between contrast enhancement on fluid-attenuated inversion recovery MR sequences and signal intensity on T2-weighted MR images: visual evaluation of brain tumors.
abstract: OBJECTIVE
  To investigate the relationship between the degree of contrast enhancement in fluid-attenuated inversion recovery (FLAIR) sequences and tumor signal intensity on T2-weighted images.
  
  
  METHODS
  A total of 96 patients suspected of having brain tumors were examined by MR imaging, and whenever a brain tumor with an enhancing part larger than the slice thickness was demonstrated on postcontrast T1-weighted images, postcontrast FLAIR images were additionally acquired. The tumor signal intensity on the T2-weighted images was visually classified as follows: equal or lower compared with normal cerebral cortex (group 1), higher than normal cortex (group 2), and as high as cerebrospinal fluid (CSF) (group 3). When a lesion contained several parts with different signal intensities on T2-weighted images, we assessed each part separately. In each group, we visually compared pre- and postcontrast FLAIR images and assessed whether tumor contrast enhancement was present. When contrast enhancement was present on FLAIR sequence, the degree of contrast enhancement in T1-weighted and FLAIR sequences was visually compared.
  
  
  RESULTS
  Postcontrast T1-weighted images showed 46 enhancing lesions, including 48 parts, in 31 MR examinations. FLAIR images of the lesion-parts in group 1 (N=18) did not show significant contrast enhancement. In group 2 (N=12), all the parts were enhanced in FLAIR sequences, and three parts were enhanced more clearly in the FLAIR sequences than in the T1-weighted sequences. In group 3 (N=18), all the parts were enhanced equally or more clearly in the FLAIR sequences than in the T1-weighted sequences.
  
  
  CONCLUSIONS
  The signal intensity in FLAIR sequences is largely influenced by both T1 and T2 relaxation time; there is a close relationship between the signal intensity of brain tumors on T2-weighted images and the degree of contrast enhancement on FLAIR sequences. When tumors have higher signal intensity than normal cortex on T2-weighted images, additional postcontrast FLAIR imaging may improve their depiction.
authors.affiliation: Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan. tkubota@koto.kpu-m.ac.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Kubota
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Osamu
authors.initials: O
authors.lastname: Kizu
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hirota
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Ito
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ishihara
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Nishimura
mesh_terms: D000236:Adenoma / Q000175:diagnosis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001254:Astrocytoma / Q000175:diagnosis; D001932:Brain Neoplasms / Q000175:diagnosis*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA