Fat Composition Measured by Proton Spectroscopy: A Breast Cancer Tumor Marker?

Almir Bitencourt,Elizabeth A Morris,Varadan Sevilimedu,Sunitha B Thakur,Katja Pinker

doi:10.3390/diagnostics11030564

Abstract

Altered metabolism including lipids is an emerging hallmark of breast cancer. The purpose of this study was to investigate if breast cancers exhibit different magnetic resonance spectroscopy (MRS)-based lipid composition than normal fibroglandular tissue (FGT). MRS spectra, using the stimulated echo acquisition mode sequence, were collected with a 3T scanner from patients with suspicious lesions and contralateral normal tissue. Fat peaks at 1.3 + 1.6 ppm (L13 + L16), 2.1 + 2.3 ppm (L21 + L23), 2.8 ppm (L28), 4.1 + 4.3 ppm (L41 + L43), and 5.2 + 5.3 ppm (L52 + L53) were quantified using LCModel software. The saturation index (SI), number of double bods (NBD), mono and polyunsaturated fatty acids (MUFA and PUFA), and mean chain length (MCL) were also computed. Results showed that mean concentrations of all lipid metabolites and PUFA were significantly lower in tumors compared with that of normal FGT (p ≤ 0.002 and 0.04, respectively). The measure best separating normal and tumor tissues after adjusting with multivariable analysis was L21 + L23, which yielded an area under the curve of 0.87 (95% CI: 0.75–0.98). Similar results were obtained between HER2 positive versus HER2 negative tumors. Hence, MRS-based lipid measurements may serve as independent variables in a multivariate approach to increase the specificity of breast cancer characterization.

Highlights

Fat information from magnetic resonance imaging (MRI) examinations is seldom used for diagnostic purposes
We have analyzed the fat profile of breast lesions and normal fibroglandular tissue from the contralateral healthy breast in a prospective in vivo MR spectroscopy (MRS) study
Invasive carcinomas are high in water content with very low levels of lipid when compared to normal fibroglandular tissue

Summary

Introduction

Fat information from magnetic resonance imaging (MRI) examinations is seldom used for diagnostic purposes. An emerging hallmark of breast cancer [10,11]. Approximately 80% of body fat exists in adipocytes, 10% in cell membranes, and another 10% in intracellular lipid droplets. It is likely that lipid content in adipocytes will reflect a “centralized” distribution which is less sensitive to local changes in the environment compared to lipid content in a tumor. While evidence for several changes in the overall lipid profiles of postmenopausal women with invasive ductal carcinoma (as evidenced by multi-spectral MRI imaging of breast adipose tissue) has recently emerged [6], it is the lipid composition local to the tumor that is more likely to change [9]

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