A new method to reduce false positive results in breast MRI by evaluation of multiple spectral regions in proton MR-spectroscopy.

OBJECTIVES

To investigate whether the evaluation of multiple spectral regions can increase the diagnostic performance of H-MRS of the breast and reduce false positive findings.

METHODS

93 patients (mean age 56 years, range 23-79) undergoing breast MRI for routine clinical indications on a 1.5T scanner were eligible for this IRB-approved prospective study. Suspicious enhancing lesions ≥8mm underwent single-voxel point-resolved H-MRS (PRESS, TR=2000ms, TE=272ms). Histology showed 69 malignant and 24 benign lesions. The Signal-to-Noise ratio of choline, olefinic acids and the water-to-methylene ratio were measured. The area under the ROC-curve (AUC) was used to evaluate single measurements. Combined diagnostic accuracy was explored using a 10-fold cross-validated Chi-squared automatic interaction detection (CHAID) analysis. Inter-reader agreement was evaluated in a subset of patients.

RESULTS

A significant AUC for differentiation between benign and malignant lesions was identified for choline (0.733, P=0.001), olefinic acids (0.769, P=0.0001) and water-to-methylene ratio (0.704, P=0.003). All three variables were included in a classification algorithm using CHAID methodology. Using this classification, 70.8% (17/24) false positive diagnoses in benign lesions would have been avoided. Inter-reader agreement was almost perfect.

CONCLUSIONS

The combined evaluation of multiple spectral regions can increase the diagnostic performance of H-MRS and potentially reduce false positive findings.