Human breast lesions: characterization with proton MR spectroscopy

Abstract

Purpose: To assess the clinical usefulness of spatially localized hydrogen-1 magnetic resonance (MR) spectroscopy in distinguishing benign from malignant lesions on the basis of total choline levels.

Materials and methods: These studies were performed at 1.5 T with a four-channel multicoil that compresses the breast sagittally. Contrast material-enhanced MR imaging and single-voxel H-1 MR spectroscopy were performed in 17 patients (age range, 25-68 years) who had nonspecific mammographic findings. Histopathologic correlations were made from biopsy or surgical specimens. Ten patients had various malignant breast lesions 1-4 cm in diameter, and seven patients had benign processes.

Results: Most studies were performed with nominal voxel sizes (< 2 cm3). Spectra obtained with an echo time of 31 msec showed resonances from water and mobile fatty acids and, in some cases, the N-trimethyl resonance of choline-containing compounds (Cho) at 3.2 ppm. The absolute concentration of Cho in each lesion was determined with a phantom containing 1 mmol/L Cho as an external reference. On the basis of reference measurements, the least detectable level of Cho was 0.2 mmol/L. With this threshold, seven of 10 malignant lesions showed detectable levels of Cho. In contrast, Cho was seen in only one patient with an extremely rare benign process, a tubular adenoma. The remaining six patients with benign processes demonstrated no detectable Cho levels.

Conclusion: Spatially localized H-1 MR spectroscopy can provide sufficient sensitivity and spectral resolution at 1.5 T to demonstrate Cho in human breast lesions with a spectroscopic protocol that provides up to 1-cm3 resolution. Determining the presence of Cho may provide a useful test for malignancy.