Jm. Roda et al., Nonhistological diagnosis of human cerebral tumors by H-1 magnetic resonance spectroscopy and amino acid analysis, CLIN CANC R, 6(10), 2000, pp. 3983-3993
We describe a multivariate analysis procedure to classify human cerebral tu
mors nonhistologically in vitro, combining the use of H-1 magnetic resonanc
e spectroscopy (MRS) with automatic amino acid analysis of biopsy extracts.
Eighty-one biopsies were obtained surgically and classified histologically
in eight classes: high-grade astrocytomas (class 1, n = 19), low-grade ast
rocytomas (class 2, n 10), normal brain (class 3, n = 9), medulloblastomas
(class 4, n = 4), meningiomas (class 5, it = 18), metastases (class 6, n =
8), neurinomas (class 7, n = 9), and oligodendrogliomas (class 8, n = 4). P
erchloric acid extracts were prepared from every biopsy and analyzed by hig
h resolution 1H MRS and automatic amino acid analysis by ionic exchange chr
omatography. Intensities of 27 resonances and ratios of resonances were mea
sured in the H-1 MRS spectra, and 17 amino acid concentrations were determi
ned in the chromatograms. Linear discriminant analysis provided the most ad
equate combination of these variables for binary classifications of a biops
y between any two possible classes and in multiple choice comparisons, invo
lving the eight possible classes considered. Correct diagnosis was obtained
when the class selected by the computer matched the histological diagnosis
. In binary comparisons, consideration of the amino acid profile increased
the percentage of correct classifications, being always higher than 75% and
reaching 100% in many cases. In multilateral comparisons, scores were: hig
h-grade astrocytomas, 80%; low-grade astrocytomas, 74%; normal brain, 100%;
medulloblastomas, 100%; meningiomas, 94.5%; metastases, 86%; neurinomas, 1
00%; and oligodendrogliomas, 75%. These results indicate that statistical m
ultivariate procedures, combining H-1 MRS and amino acid analysis of tissue
extracts, provide a valuable classifier for the nonhistological diagnosis
of biopsies from brain tumors in vitro.