title: Proton magnetic resonance spectroscopy as a potential tool for differentiating between abdominal fluid collections.
abstract: OBJECTIVE
  To determine the utility of proton magnetic resonance spectroscopy (MRS) in distinguishing abdominal fluid types.
  
  
  METHODS
  Abdominal fluid samples were obtained from patients undergoing therapeutic percutaneous drainage. In vitro spectroscopy was performed using a 1.5-T scanner and a head coil. Single voxel spectra were obtained using a point resolved spin-echo sequence with water suppression (TR/TE 2000 msec/35 msec). The peak pattern for each sample was examined and the signal-to-noise ratio (SNR) estimated (ratio of tallest peak to noise at <0 ppm).
  
  
  RESULTS
  Thirty-five samples were analyzed: purulent collection (eight), serosanguinous collection (eight), non-chylous ascites (six), chylous ascites (one), bile (seven), and bile with iodinated contrast media (five). The mean SNR of the dominant peak was: purulent collection, 12.7; serosanguinous collection, 3.2; non-chylous ascites, 2.4; chylous ascites, 8.8; bile, 1.4; and bile with contrast media, 60.8. Pus samples had a broad based peak pattern with continuous signal of >1.5 ppm width situated within the range 0.2-2.5 ppm, not found in other samples. Chylous ascites (one sample) had a distinctive peak at 1.2 ppm. Bile with contrast had three peaks at 3.5/3.6, 2.6, and 2.1 ppm. No other patterns were found to be discriminatory. Common non-specific patterns seen included a bifid peak at 1.1-1.3 ppm and a broad based peak situated between 3 and 4 ppm.
  
  
  CONCLUSIONS
  The H1 spectra of purulent fluid has a higher SNR than common non-purulent abdominal fluids and a distinct broad based peak pattern from 0.2-2.5 ppm. Proton spectroscopy may be a useful tool for distinguishing purulent from non-purulent intra-abdominal collections.
authors.affiliation: University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Canada. paulburn@talk21.com
authors.forename: Paul R
authors.initials: PR
authors.lastname: Burn
authors.forename: Masoom A
authors.initials: MA
authors.lastname: Haider
authors.forename: Turki
authors.initials: T
authors.lastname: Alfuhaid
authors.forename: M Peter
authors.initials: MP
authors.lastname: Brown
authors.forename: Timothy P L
authors.initials: TP
authors.lastname: Roberts
mesh_terms: D018784:Abdominal Abscess / Q000175:diagnosis; D001201:Ascites / Q000175:diagnosis* / Q000209:etiology; D001202:Ascitic Fluid / Q000737:chemistry; D003937:Diagnosis, Differential; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D010865:Pilot Projects; D011522:Protons
chemical_list: D011522:Protons