The Association between Choline Concentration Measured by 1 H MR Spectroscopy with Clinical Characteristics and Biomarkers of Breast Cancer

Introduction: Proton Magnetic Resonance Spectroscopy (H-MRS) of the breast is an adjunct to the Magnetic Resonance Imaging (MRI) to improve the specificity in distinguishing benign from malignant breast tumors. The diagnostic value of H-MRS is typically based on the detection of elevated level of choline containing compounds (tCho), which is a marker of cell proliferation thus indicating the level of aggressiveness in cell division. However, in vivo breast H-MRS has shown a variable sensitivity (46% 100%) from study to study [1]. Since choline level represents a proliferative marker, many biological factors may affect its concentration within the tumor. Since this issue has not been studied using a systematic approach we set out to investigate the association between choline and the clinical characteristics and biomarker status of breast cancer. Choline was measured using single-voxel technique with an internal reference method to calculate the absolute concentration in mmol/kg. The other considered lesion characteristics measured on MRI included lesion phenotype (presenting as mass lesions or non-mass type enhancements), and the contrast enhancement kinetic pattern (showing washout or not). Clinical variables considered included: patient age, tumor histological type, tumor grade, biomarker status (ER-estrogen receptor, PR-progesterone receptor, and HER-2). In order to minimize the impact of partial volume effect, which is known to affect the spectral quality thus compromising the accuracy of choline concentration measurements, lesions smaller than 1.5cm were excluded from this study.