Feasibility of MR spectroscopy for characterizing malignant breast lesions using a clinical 3-T scanner

To investigate the feasibility of in vivo proton magnetic resonance spectroscopy ((1)H-MRS) for characterizing malignant breast lesions using a clinical 3-T scanner, and to compare the measured total choline-containing compound (tCho) levels in this work with the previously published results at 1.5 T and 4 T.

Twenty-six patients (35-72 years old, mean age 53 years), with biopsy-confirmed breast cancer, underwent anatomical imaging, dynamic contrast-enhanced MR imaging, and single-voxel (1)H-MRS. The absolute tCho concentration in malignant tumors was calculated and was expressed as a concentration unit in mmol/kg. All lesions were divided into two groups (mass- and non-mass-type lesions), based on the morphological pattern of enhancement, and analyzed.

The measured tCho levels had a range of 0.10-10.1 (mean ± SD, 1.62 ± 2.29 mmol/kg) in 15 (58 %) of 26 malignant breast spectra, which was consistent with the previous in vivo estimates at 1.5 T and 4.0 T. There were 11 (42 %) false-negative cases, which resulted in 58 % sensitivity. The sensitivity of the (1)H-MRS in size-dependent subgroups (e.g., <2.0 and ≥2.0 cm) increased from 14 to 66 %, in a statistically significant manner (P = 0.019). In addition, the tCho detection rate was higher in mass-type lesions (14/21, 66 %) than in non-mass-type lesions (1/5, 20 %), reaching a significant level (P = 0.03). The sensitivity based on the dynamic contrast-enhanced kinetics was 100 %.

Quantitative in vivo (1)H-MRS at 3 T may provide useful information for quantifying tCho concentration levels and characterizing tumor types (e.g., mass vs diffuse) of breast cancer. However, its limitation in characterizing small lesions has to be considered.