The added value of quantitative multi-voxel MR spectroscopy in breast magnetic resonance imaging.

Abstract

To determine whether quantitative multivoxel MRS improves the accuracy of MRI in the assessment of breast lesions. Twenty-five consecutive patients with 26 breast lesions ≥ 1 cm assessed as BI-RADS 3 or 4 with mammography underwent quantitative multivoxel MRS and contrast-enhanced MRI. The choline (Cho) concentration was calculated using the unsuppressed water signal as a concentration reference. ROC analysis established the diagnostic accuracy of MRI and MRS in the assessment of breast lesions. Respective Cho concentrations in 26 breast lesions re-classified by MRI as BI-RADS 2 (n = 5), 3 (n = 8), 4 (n = 5) and 5 (n = 8) were 1.16 ± 0.43 (mean ± SD), 1.43 ± 0.47, 2.98 ± 2.15 and 4.94 ± 3.10 mM. Two BI-RADS 3 lesions and all BI-RADS 4 and 5 lesions were malignant on histopathology and had Cho concentrations between 1.7 and 11.8 mM (4.03 ± 2.72 SD), which were significantly higher (P = 0.01) than that in the 11 benign lesions (0.4-1.5 mM; 1.19 ± 0.33 SD). Furthermore, Cho concentrations in the benign and malignant breast lesions in BI-RADS 3 category differed (P = 0.01). The accuracy of combined multivoxel MRS/breast MRI BI-RADS re-classification (AUC = 1.00) exceeded that of MRI alone (AUC = 0.96 ± 0.03). These preliminary data indicate that multivoxel MRS improves the accuracy of MRI when using a Cho concentration cut-off ≤ 1.5 mM for benign lesions. Quantitative multivoxel MR spectroscopy can improve the accuracy of contrast-enhanced breast MRI. Multivoxel-MRS can differentiate breast lesions by using the highest Cho-concentration. Multivoxel-MRS can exclude patients with benign breast lesions from further invasive diagnostic procedures.