Comparison of NMR spectroscopy and proton MR spectroscopy for quantification of choline metabolites in breast cancer

Abstract

Purpose: To examine correlation between nuclear magnetic resonance (NMR) spectroscopy using biopsy specimen and magnetic resonance (MR) spectroscopy for quantification of choline metabolites in breast cancer and to assess clinical role of these spectroscopy for breast cancer research. Materials and Methods: After institutional review board approval and informed consent were obtained for this study. Breast MR spectroscopy (3.0T) was performed in patients with biopsy-proven malignant lesions measuring 1cm or larger at imaging. The total choline (tCho) and signal to noise ratio (SNR) of tCho peak were quantified by single-voxel 1H MR spectroscopic data. Concentrations and metabolic ratios of multiple choline metabolites were estimated by NMR spectroscopy (11.7T) using biopsy specimens. NMR spectroscopic values were then compared with MR spectroscopic values. Additionally, NMR and MR spectroscopic values were compared according to clinicopathologic variables.Results: A total 34 patients (age range, 34-68 years) with 36 malignant lesions (mean size, 29.7mm) were imaged. NMR spectroscopy quantified and discriminated choline metabolites in all samples of 36 lesions, however, MR spectroscopy quantified that in 32 lesions. The free choline (Cho)/Creatine (Cr) on NMR spectroscopy was significantly correlated with normalized tCho (r=0.354, p=0.04) and SNR of tCho peak (r=0.403, p=0.03) on MR spectroscopy. In addition, the glycerophosphocholine (GPC)/Cr (r=0.412, p=0.02) and tCho/Cr (r=0.353, p=0.04) significantly correlated with SNR of tCho peak, We found several metabolite markers (Cho, Cr, taurine, s-inositol, m-inositol, tCho, phosphocholine (PC), glycine, Cho/Cr, tCho/Cr, PC/Cr) on NMR spectroscopy to correlate with histopathologic prognostic factors [ER (estrogen receptor), PR (progesterone receptor), HER2 (a receptor for human epidermal growth factor), triple negativity, Ki-67, and poor prognosis group (detection of axillary lymph node metastasis, tumor size with diameter >2cm, or negative for ER or PR)].Conclusion: MR spectroscopic values relatively correlate with several NMR spectroscopic values in breast cancer, indicating MR spectroscopy may be used to aid in vivo assessment of choline metabolites of breast cancer. NMR spectroscopic values were correlated with the histologic prognostic markers (ER, PR, HER, triple negativity, Ki-67, prognosis group), indicating NMR spectroscopy may be helpful for detection of reliable markers of characterization of breast cancer.