Spectroscopic Imaging of Breast Cancer

Single voxel magnetic resonance spectroscopy (MRS) has been the standard in human breast tumour studies published to date. This method is hampered by the impossibility to study tissue heterogeneity or compare the metabolite signals in breast lesion directly to those in unaffected tissue. Multivoxel MRS studies, frequently referred to as spectroscopic imaging, while potentially allowing for truly quantitative tissue characterization, have up to now also been far from quantitative with, for example, the signal-to-noise ratio of the choline (Cho) signal serving as a measure of tumour activity. Demonstrated in this study is that in a standard clinical setting with a regular 1.5 T MR scanner, it is possible to perform quantitative multivoxel MRS. Using a pre-measurement to map the distributions of water and fat, and literature values for the T1 and T2 relaxation times of Cho and water in fibroglandular breast tissue and tumours, one can determine the concentrations of Cho in different tumour compartments and surrounding tissues in two brief multivoxel MRS measurements. Quantitative diagnostic and follow-up studies of focal breast pathology are now possible.