title: Analysis of elements in a minimal amount of temporomandibular joint fluid on fluid-attenuated inversion recovery magnetic resonance images.
abstract: OBJECTIVE
  The aim of this study was to elucidate possible elements in minimal amounts of fluid (MF) in the temporomandibular joint by analyzing signal intensities in T2-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) images.
  
  
  METHODS
  Fifteen joints (15 patients) with MF were subjected to MR imaging to obtain T2-weighted and FLAIR images. Regions of interest were placed on MF, cerebrospinal fluid (CSF), and gray matter (GM), and their signal intensities were measured on both images. The signal intensity ratio (SIR) obtained by the signal intensity of GM between MF and CSF was compared in T2-weighted and FLAIR images.
  
  
  RESULTS
  The average SIR of MF was lower than that of CSF on T2-weighted images, whereas it was higher on FLAIR images. The average suppression ratio of the signal intensity was lower for MF (24.1%) than for CSF (71.4%).
  
  
  CONCLUSIONS
  MF may contain elements such as protein that are capable of inducing a shortened T1 relaxation time on MR images.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Tokyo Dental College, Chiba City, Chiba, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hanyuda
authors.forename: Mika
authors.initials: M
authors.lastname: Otonari-Yamamoto
authors.forename: Kenichi
authors.initials: K
authors.lastname: Imoto
authors.forename: Junichiro
authors.initials: J
authors.lastname: Sakamoto
authors.forename: Sayaka
authors.initials: S
authors.lastname: Kodama
authors.forename: Takashi
authors.initials: T
authors.lastname: Kamio
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Sano
mesh_terms: D000328:Adult; D002555:Cerebrospinal Fluid; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013582:Synovial Fluid; D013705:Temporomandibular Joint Disorders / Q000175:diagnosis*