title: TE = 32 ms vs TE = 100 ms echo-time (1)H-magnetic resonance spectroscopy in prostate cancer: Tumor metabolite depiction and absolute concentrations in tumors and adjacent tissues.
abstract: OBJECTIVE
  To compare the depiction of metabolite signals in short and long echo time (TE) prostate cancer spectra at 3T, and to quantify their concentrations in tumors of different stage and grade, and tissues adjacent to tumor.
  
  
  METHODS
  First, single-voxel magnetic resonance imaging (MRI) spectra were acquired from voxels consisting entirely of tumor, as defined on T2-weighted and diffusion-weighted (DW)-MRI and from a biopsy-positive octant, at TEs of 32 msec and 100 msec in 26 prostate cancer patients. Then, in a separate cohort of 26 patients, single-voxel TE = 32 msec MR spectroscopy (MRS) was performed over a partial-tumor region and a matching, contralateral normal-appearing region, defined similarly. Metabolite depiction was compared between TEs using Cramér-Rao lower bounds (CRLB), and absolute metabolite concentrations were calculated from TE = 32 msec spectra referenced to unsuppressed water spectra.
  
  
  RESULTS
  Citrate and spermine resonances in tumor were better depicted (had significantly lower CRLB) at TE = 32 msec, while the choline resonance was better depicted at TE = 100 msec. Citrate and spermine concentrations were significantly lower in patients of more advanced stage, significantly lower in Gleason grade 3+4 than 3+3 tumors, and significantly lower than expected from the tumor fraction in partial-tumor voxels (by 14 mM and 4 mM, respectively, P < 0.05).
  
  
  CONCLUSIONS
  Citrate and spermine resonances are better depicted at short TE than long TE in tumors. Reduction in these concentrations is related to increasing tumor stage and grade in vivo, while reductions in the normal-appearing tissues immediately adjacent to tumor likely reflect tumor field effects.
authors.affiliation: CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: Meer
authors.initials: M
authors.lastname: Basharat
authors.affiliation: CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Payne
authors.affiliation: CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: Veronica A
authors.initials: VA
authors.lastname: Morgan
authors.affiliation: Academic Urology Unit, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Parker
authors.affiliation: Academic Urology Unit, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: David
authors.initials: D
authors.lastname: Dearnaley
authors.affiliation: CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
authors.forename: Nandita M
authors.initials: NM
authors.lastname: deSouza
mesh_terms: D000368:Aged; D000465:Algorithms; D014408:Biomarkers, Tumor / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013096:Spermine / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D014408:Biomarkers, Tumor; D019343:Citric Acid; D013096:Spermine
keywords: citrate; magnetic resonance spectroscopy; prostate cancer; spermine