title: Short-term temperature effect on the HRMAS spectra of human brain tumor biopsies and their pattern recognition analysis.
abstract: OBJECTIVE
  To investigate the effect of temperature (0 versus 37 degrees C) in the high-resolution magic angle spinning spectroscopy (HRMAS) pattern of human brain tumor biopsies and its influence in recognition-based tumor type prediction. This proof-of-principle study addressed the bilateral discrimination between meningioma (MM) and glioblastoma multiforme (GBM) cases.
  
  
  METHODS
  Forty-three tumor biopsy samples were collected (20 MM and 23 GBM), kept frozen and later analyzed at 0 degrees C and 37 degrees C by HRMAS. Post-HRMAS histopathology was used to validate the tumor type. Time-course experiments (100 min) at both temperatures were carried out to monitor HRMAS pattern changes. Principal component analysis and linear discriminant analysis were used for classifier development with a training set of 20 biopsies.
  
  
  RESULTS
  Temperature-dependent, spectral pattern changes mostly affected mobile lipids and choline-containing compounds resonances and were essentially reversible. Incubation of 3 MM and 3 GBM at 37 degrees C during 100 minutes produced irreversible pattern changes below 13% in a few resonances. Classification performance of an independent test set of 7 biopsies was 100% for the pulse-and-acquire, CPMG at echo times (TE) of 30 ms and 144 ms and Hahn Echo at TE 30 ms at 0 degrees C and 37 degrees C. The performance for Hahn Echo spectra at 136 ms was 83.3% at 0 degrees C and 100% at 37 degrees C.
  
  
  CONCLUSIONS
  The spectral pattern of mobile lipids changes reversibly with temperature. HRMAS demonstrated potential for automated brain tumor biopsy classification. No advantage was obtained when acquiring spectra at 37 degrees C with respect to 0 degrees C in most of the conditions used for the discrimination addressed.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Campus Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Valverde-Saubí
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Candiota
authors.forename: Maria Antònia
authors.initials: MA
authors.lastname: Molins
authors.forename: Miguel
authors.initials: M
authors.lastname: Feliz
authors.forename: Oscar
authors.initials: O
authors.lastname: Godino
authors.forename: Myriam
authors.initials: M
authors.lastname: Dávila
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Acebes
authors.forename: Carles
authors.initials: C
authors.lastname: Arús
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D001932:Brain Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D016002:Discriminant Analysis; D006801:Humans; D016014:Linear Models; D009682:Magnetic Resonance Spectroscopy; D025341:Principal Component Analysis; D013696:Temperature; D013997:Time Factors
chemical_list: D014408:Biomarkers, Tumor