Feasibility and Diagnostic Performance of Voxelwise Computed Diffusion-Weighted Imaging in Breast Cancer

Abstract

Background: Conventional diffusion-weighted imaging (DWI) with high b-values may improve lesion conspicuity, but with a low signal intensity and thus a low signal-to-noise ratio (SNR). The voxelwise computed DWI (vcDWI) may generate high-quality images with a strong lesion signal and low background.

Purpose: To evaluate the feasibility and diagnostic performance of vcDWI.

Study type: Retrospective.

Population: In all, 67 patients with 72 lesions, 33 malignant and 39 benign.

Field strength/sequence: 3T, including T₂ /T₁ , DWI with two b-values, and dynamic contrast-enhanced MRI (DCE-MRI).

Assessment: Computed DWI (cDWI) with high b-values of 1500, 2000, 2500 s/mm² (cDWI₁₅₀₀ , cDWI₂₀₀₀ , cDWI₂₅₀₀ ) and vcDWI were generated from measured DWI (mDWI). The mDWI, cDWIs and vcDWI were evaluated by three readers independently to determine lesion conspicuity, background signal suppression, overall image quality using 1-5 rating scales, as well as to give BI-RADS scores. The mean apparent diffusion coefficient (ADC) value for each lesion was measured.

Statistical tests: Agreement among the three readers was evaluated by the intraclass correlation coefficient. Receiver operating characteristic (ROC) analysis was performed to compare the diagnostic performance based on reading of mDWI, cDWIs, vcDWI, and the measured ADC values.

Results: vcDWI provided the best lesion conspicuity compared with mDWI and cDWIs (P < 0.005). For overall image quality, vcDWI was significantly better than cDWI (P < 0.005), but not significantly better compared with mDWI for two readers (P = 0.037 and P = 0.013) and significantly worse for the third reader (P < 0.005). Background signal suppression was the best on cDWI₂₅₀₀ , and better on vcDWI than on mDWI, cDWI₁₅₀₀ , and cDWI₂₀₀₀ . The AUC value for differential diagnosis was 0.868 for mDWI, 0.862 for cDWI₁₅₀₀ , 0.781 for cDWI₂₀₀₀ , 0.704 for cDWI₂₅₀₀ , 0.946 for vcDWI, 0.704 for ADC value, and 0.961 for DCE-MRI. DATA CONCLUSION: vcDWI was implemented without increasing scanning time, and it provided excellent lesion conspicuity for detection of breast lesions and assisted in differentiating malignant from benign breast lesions.

Level of evidence: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

Keywords: breast cancer diagnosis; computed diffusion weighted imaging (cDWI); diffusion weighted imaging (DWI); voxelwise cDWI (vcDWI.