Characterization of brain metastases using high‐resolution magic angle spinning MRS

Abstract

The objectives of this study were to (a) explore the spectral characteristics of brain metastases, focusing on the origin of the primary cancer, and (b) evaluate the correlation with clinical outcome using multivariate analysis. High-resolution magic angle spinning (HR-MAS) MR spectra (n = 26) were obtained from 16 patients with brain metastases using a Bruker Avance DRX600 instrument. Standard pulse-acquired and spin-echo (TE 32 and 285 ms) (1)H spectra were obtained. These were examined using principal component analysis (PCA) and partial least squares regression analysis (PLS) relating spectral data to clinical outcome. The PCA score plot of pulse-acquired HR-MAS spectra showed a trend of clustering due to the origin of the metastases, mainly based on differences in the lipid signals at 1.3 and 0.9 ppm. With PLS, spectra of patients who died less than 5 months after surgery appeared to cluster in the lower left quadrant of the score plot. These preliminary results on brain metastasis classification and prediction of survival must be validated in a larger patient cohort. However, the possibility of differentiating metastases according to origin and predicting survival on the basis of HR-MAS spectra suggests that this method may be useful for diagnosing and planning treatment for brain metastases and also for guiding decisions about terminating further treatment.

Identification of mobile lipids in human cancer tissues by ex vivo diffusion edited HR-MAS MRS

“…The assignments were in agreement with the literature and were confirmed by comparison of the MR spectra of Sigma standard lipid compounds [Chol, CholE, TG, phosphatidylcholine (PhC), saturated fatty acids and poly-unsaturated fatty acids (PUFAs)]. (17), has become essential to outline intact human tissues metabolic profiles (9,(18)(19)(20)(21)(22). In a previous study performed in our laboratory (22), using HR-MAS technique, we characterized the human gastric adenocarcinomas biochemical profile.…”

“…In both cases, diffusion edited HR-MAS sequence, due to higher signal-tonoise ratio and to the fact that signals are not spread over the whole spectrum, as in in vivo MRS, allows to determine that MR visible MLs resonances receive contribution from: i) FA esterified in TG; ii) FA esterified in PhC; iii) Chol, which has been found to be present as CholE in experimental and human gliomas (11). This opportunity appears particularly important considering, for example, that lipid content, revealed by a conventional single pulse HR-MAS MRS experiment, only from the FA signals at 1.30 and 0.90 ppm, has been found to be an important factor to separate the metastasis spectra originating from different primary tumours and was also correlated with clinical outcome (19).…”

Use of 1H and 31P HRMAS to evaluate the relationship between quantitative alterations in metabolite concentrations and tissue features in human brain tumour biopsies

“…The use of HRMAS improves the resolution, allowing the detection and quantification of a great number of metabolites and FA [1][2][3][4], but sometimes the 1D 1 H spectra are too crowded to allow an unequivocal identification of some overlapped resonances.…”

“…to obtain detailed metabolic profiles of human brain tumours [1][2][3][4][5][6]. There is a widespread use of 1 H 1D spectra to quantify the metabolites [1-3, 6, 7].…”

“…There is a widespread use of 1 H 1D spectra to quantify the metabolites [1-3, 6, 7]. 2D 1 H -1 H homonuclear or 1 H - 13 C heteronuclear experiments have improved the assignments in HRMAS spectra [3][4][5]8] but the quantitative metabolic information comes mainly from the 1 H 1D spectra. The use of 31 P NMR spectroscopy has also been demonstrated to be useful in the metabolomic study of brain cancer since there are 31 P-containing metabolites that can provide valuable information complementary to 1 H NMR in metabolic studies [9][10][11].…”