New lens on breast health: harnessing high-b-value synthetic diffusion-weighted imaging for breast lesion...

This study aims to evaluate the diagnostic efficacy of synthetic diffusion-weighted imaging (sDWI) at various high b-values in distinguishing malignant from benign breast lesions and to compare its performance with that of conventional DWI (cDWI).

After the exclusion of 22 lesions, 63 women (age range, 24-99 years; mean age, 53.7 ± 15.1 years) with 68 suspicious breast lesions on ultrasound who underwent multiparametric breast magnetic resonance imaging before biopsy between January 2021 and April 2023 were included in this retrospective study. According to the pathological results, lesions were classified as malignant or benign. Volumetric mask images were defined. The lesion signal/normal breast signal ratio [relative signal intensity (rSI)] was measured on different diffusion-weighted images (cDWI at b = 800 and 1500 s/mm²; sDWI at b = 1500-5000 s/mm²), and lesion SI on apparent diffusion coefficient (ADC) 0-800 and ADC0-1500 maps (mADC) was calculated. The diagnostic performances of these parameters were evaluated using a receiver operating characteristic curve analysis and the DeLong test in both the mass and non-mass lesion groups.

A total of 32 (47.06%) benign and 36 (52.94%) malignant lesions were identified. Malignant lesions exhibited significantly higher rSI values on cDWI800, cDWI1500, sDWI1500, sDWI2000, and sDWI3000 (P values: <0.001, <0.001, <0.001, <0.001, <0.001, 0.03) and lower mADC800 and mADC1500 values (P values: 0.01 and 0.03). In mass lesions, synthetic b1500 and conventional b1500 demonstrated diagnostic accuracy comparable with that of routine mADC800 and mADC1500. However, in non-mass lesions, high-b-value DWI maps (b ≥ 2000 s/mm²) significantly outperformed mADC and cDWI in differentiating malignant from benign lesions. The highest diagnostic accuracy in non-mass lesions was observed with rSIC4000 [area under the curve (AUC) = 0.87], whereas in mass lesions, rSIC1500 exhibited the highest diagnostic performance (AUC = 0.79).

The optimal b-value for DWI differs between mass and non-mass breast lesions, emphasizing the need for separate evaluation protocols. Although high-b-value sDWI provides limited added diagnostic value in mass lesions, it significantly improves malignancy detection in non-mass lesions, outperforming cDWI and ADC mapping.

This study underscores the need for a tailored DWI protocol for optimal breast lesion characterization, particularly for non-mass lesions, where high-b-value synthetic imaging enhances diagnostic accuracy.