title: Salivary gland tumors at in vivo proton MR spectroscopy.
abstract: OBJECTIVE
  To prospectively evaluate whether proton magnetic resonance (MR) spectroscopy can be used to characterize salivary gland tumors (SGTs).
  
  
  METHODS
  Ethics committee approval and informed consent were obtained. Hydrogen 1 ((1)H) MR spectroscopy was performed with echo times of 136 and 272 msec at 1.5 T in both SGTs and normal parotid glands. Spectra were analyzed in the time domain by using prior knowledge in the fitting procedure to obtain peak amplitudes of choline (Cho), creatine (Cr), and unsuppressed water. Mean Cho/Cr and Cho/water ratios for each subgroup of SGTs were obtained, and results were compared by using a nonparametric t test.
  
  
  RESULTS
  Successful spectra were acquired in 56 patients (35 men, 21 women; mean age, 56 years) with a total of nine malignant tumors and 47 benign SGTs (24 Warthin tumors, 22 pleomorphic adenomas, one oncocytoma). At an echo time of 136 msec, Cho/Cr ratios were obtained in 26 (47%) of 55 spectra, with a mean value (+/- standard deviation) of 1.73 +/- 0.47, 5.49 +/- 1.86, 3.46 +/- 0.84, and 2.45 for malignant tumors, Warthin tumors, pleomorphic adenomas, and oncocytoma, respectively. Differences were significant between Warthin tumors and pleomorphic adenomas (P = .028) and between benign SGTs and malignant tumors (P < .001). At an echo time of 272 msec, Cho/Cr ratios were obtained in 16 (30%) of 53 spectra, with a mean value of 2.27 +/- 0.69, 6.92 +/- 1.47, and 3.67 +/- 1.23 for malignant tumors, Warthin tumors, and pleomorphic adenomas, respectively. Differences were also significant between Warthin tumors and pleomorphic adenomas (P = .041) and benign SGTs and malignant tumors (P = .004). There was a significant difference in mean Cho/water ratio for Warthin tumors versus pleomorphic adenomas at echo times of 136 msec (P = .003) and 272 msec (P = .002) but not for benign SGTs versus malignant tumors.
  
  
  CONCLUSIONS
  (1)H MR spectroscopy may be used to characterize SGTs, but a larger study is required to validate these initial results.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Faculty of Medicine, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China. b834756@mailserv.cuhk.hk
authors.forename: Ann D
authors.initials: AD
authors.lastname: King
authors.forename: David K W
authors.initials: DK
authors.lastname: Yeung
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
authors.forename: Gary M K
authors.initials: GM
authors.lastname: Tse
authors.forename: H Y
authors.initials: HY
authors.lastname: Yuen
authors.forename: K T
authors.initials: KT
authors.lastname: Wong
authors.forename: Andrew C
authors.initials: AC
authors.lastname: van Hasselt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002794:Choline / Q000378:metabolism; D003287:Contrast Media; D003401:Creatine / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016015:Logistic Models; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012468:Salivary Gland Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D012815:Signal Processing, Computer-Assisted
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA; D003401:Creatine; D002794:Choline