Introduction to proton (H) magnetic resonance spectroscopy of the breast

Proton magnetic resonance spectroscopy (¹H MRS) provides biochemical information about the tissue under investigation. The diagnostic value of ¹H MRS in cancer is typically based on the detection of elevated levels of choline compounds, which is a marker of active tumor [1]. Breast ¹H MRS is performed on a clinical magnet of 1.5 T or higher in field strength. A four or more channel breast coil is also needed, just as for imaging. The most widely used technique is the single voxel technique, which is limited to scan one lesion at a time. Magnetic resonance spectroscopic imaging provides information about the spatial distribution of metabolites and is useful for studying multiple lesions [2, 3]. The two main potential clinical applications of ¹H MRS include its use as an adjunct to breast MRI to improve the specificity in differentiating benign from malignant lesions and in monitoring or even predicting response to treatment in patients undergoing neoadjuvant chemotherapy. Studies have suggested that ¹H MRS may decrease the number of benign biopsies recommended by MRI [4, 5]. Also, in patients undergoing neoadjuvant chemotherapy, ¹H MRS may be able to predict response as early as 24 hours after the first dose [6]. Currently, several limitations exist that make the technique premature for clinical use [7]. Preliminary data are promising, warranting further evaluation with larger, preferably multicenter, trials.