1H-MR spectroscopy of suspicious breast mass lesions at 3T: a clinical experience.

OBJECTIVES: To test 3T proton magnetic resonance spectroscopy (1H-MRS) for breast mass lesions. METHODS: Patients with BI-RADS 4-5 lesions at mammography/ultrasound were prospectively enrolled. After contrast-enhanced breast MRI, single-voxel MRS (point-resolved volume selection, PRESS); pencil-beam shimming; volume of interest 1 cm3; TR/TE = 3000/135 ms) was performed. Spectra were considered reliable if the full width at half maximum (FWHM) of the water peak was ≤45 Hz. A signal-to-noise ratio of the total choline (tCho) peak at 3.21 ppm ≥2 was used as cutoff for malignancy. All lesions underwent needle sampling. Final pathology was available for all malignant lesions; for benign lesions the reference standard was final pathology or at least 1-year negative follow-up. RESULTS: Reliable spectra were obtained in 115/127 lesions (91%), with a mean FWHM of 32.4 Hz (range 8-45 Hz). A tCho peak SNR ≥2 was detected in 66 malignant lesions (62 invasive cancers; 4 ductal carcinoma in situ) and in 3 benign lesions. Excluding lesions located ≤1 cm from the skin (n = 3) or pectoral muscle (n = 11), sensitivity was 65/73 [89%, 95% confidence interval (CI): 80-95%], and specificity 25/28 (89%) (95% CI: 72-98%). Considering only invasive cancers, sensitivity reached 61/68 (90%, 95% CI: 81-96%). MRS additional time was 8 min. CONCLUSIONS: When lesions close to the skin or pectoral muscle are excluded, 3T 1H-MRS of mass lesions ≥1 cm showed a high diagnostic performance, however, insufficient to avoid needle biopsy.

High-field MR spectroscopy in the multiparametric MRI evaluation of breast lesions.

INTRODUCTION: The aim of this work was to assess the role of 3T-MR spectroscopy (MRS) in the multi-parametric MRI evaluation of breast lesions, using a pattern-recognition based classification method. METHODS: 291 patients (301 lesions, median 2.3cm3) were enrolled in the study (age 18-85y, mean 54.2y). T1-TSE (TR/TE=400/10ms) and T2-STIR imaging (TR/TE=5000/60ms), dynamic-contrast-enhanced MRI (DCE-MRI), apparent diffusion coefficient (ADC) (b=0-800s/mm2), and single-voxel MRS (10×10×10mm3, PRESS, TR/TE=3000ms/135ms) were performed by means of a 3T scanner. MRS results were accepted if the FWHM of the water peak was ⩽45Hz. Total choline (tCho) was considered detected if the signal-to-noise ratio (SNR) of the 3.2ppmpeak was ⩾2. A classifier-based analysis (support-vector-machines, SVM) was performed with 4-dimensional vectors including type of margin, DCE-MRI kinetic curve type, ADC mean value, and tCho SNR. A comparison with 3-dimensional vectors (without tCho SNR) was used to assess MRS impact on sensitivity, specificity, and positive-negative predictive values (PPV-NPV) for malignancy. RESULTS: 228 lesions (180 malignant/48 benign) showed acceptable spectral quality. Comparison of classification results with histopathological examination of surgical specimens showed sensitivity=93.7%, specificity=84.9%, PPV=95.2%, NPV=81.5% without the inclusion of MRS in the SVM analysis. When MRS was included, the figures increased to 95.1%, 90.7%, 97.2%, and 85.0%, respectively. CONCLUSIONS: Inclusion of 3T-MRS in the multi-parametric MRI evaluation of breast lesions improved the performance of the SVM-based classifier, showing a possible role of high-field MR spectroscopy in the differential diagnosis between benign and malignant breast lesions. Further research is however needed to confirm this initial evidence.