Improving the classification of brain tumors in mice with perturbation enhanced (PE)-MRSI

Integr Biol (Camb). 2012 Feb;4(2):183-91. doi: 10.1039/c2ib00079b. Epub 2011 Dec 23.

Abstract

Classifiers based on statistical pattern recognition analysis of MRSI data are becoming important tools for the non-invasive diagnosis of human brain tumors. Here we investigate the potential interest of perturbation-enhanced MRSI (PE-MRSI), in this case acute hyperglycemia, for improving the discrimination between mouse brain MRS patterns of glioblastoma multiforme (GBM), oligodendroglioma (ODG), and non-tumor brain parenchyma (NT). Six GBM-bearing mice and three ODG-bearing mice were scanned at 7 Tesla by PRESS-MRSI with 12 and 136 ms echo-time, during euglycemia (Eug) and also during induced acute hyperglycemia (Hyp), generating altogether four datasets per animal (echo time + glycemic condition): 12Eug, 136Eug, 12Hyp, and 136Hyp. For classifier development all spectral vectors (spv) selected from the MRSI matrix were unit length normalized (UL2) and used either as a training set (76 GBM spv, four mice; 70 ODG spv, two mice; 54 NT spv) or as an independent testing set (61 GBM spv, two mice; 31 ODG, one mouse; 23 NT spv). All Fisher's LDA classifiers obtained were evaluated as far as their descriptive performance-correctly classified cases of the training set (bootstrapping)-and predictive accuracy-balanced error rate of independent testing set classification. MRSI-based classifiers at 12Hyp were consistently more efficient in separating GBM, ODG, and NT regions, with overall accuracies always >80% and up to 95-96%; remaining classifiers were within the 48-85% range. This was also confirmed by user-independent selection of training and testing sets, using leave-one-out (LOO). This highlights the potential interest of perturbation-enhanced MRSI protocols for improving the non-invasive characterization of preclinical brain tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose / metabolism
  • Brain Neoplasms / blood
  • Brain Neoplasms / classification*
  • Brain Neoplasms / pathology
  • Female
  • Glioblastoma / blood
  • Glioblastoma / classification*
  • Glioblastoma / pathology
  • Histocytochemistry
  • Hyperglycemia / metabolism
  • Magnetic Resonance Spectroscopy / methods*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Oligodendroglioma / blood
  • Oligodendroglioma / classification*
  • Oligodendroglioma / pathology
  • Pattern Recognition, Automated / methods

Substances

  • Blood Glucose