On a fractional order calculus model in diffusion weighted breast imaging to differentiate between malignant and benign breast lesions detected on X-ray screening mammography

<div><p>Objective</p><p>To evaluate a fractional order calculus (FROC) model in diffusion weighted imaging to differentiate between malignant and benign breast lesions in breast cancer screening work-up using recently introduced parameters (<i>β</i>_FROC, <i>D</i>_FROC and <i>μ</i>_FROC).</p><p>Materials and methods</p><p>This retrospective analysis within a prospective IRB-approved study included 51 participants (mean 58.4 years) after written informed consent. All patients had suspicious screening mammograms and indication for biopsy. Prior to biopsy, full diagnostic contrast-enhanced MRI examination was acquired including diffusion-weighted-imaging (DWI, b = 0,100,750,1500 s/mm²). Conventional apparent diffusion coefficient <i>D</i>_app and FROC parameters (<i>β</i>_FROC, <i>D</i>_FROC and <i>μ</i>_FROC) as suggested further indicators of diffusivity components were measured in benign and malignant lesions. Receiver operating characteristics (ROC) were calculated to evaluate the diagnostic performance of the parameters.</p><p>Results</p><p>29/51 patients histopathologically revealed malignant lesions. The analysis revealed an AUC for <i>D</i>_app of 0.89 (95% CI 0.80–0.98). For FROC derived parameters, AUC was 0.75 (0.60–0.89) for <i>D</i>_FROC, 0.59 (0.43–0.75) for <i>β</i>_FROC and 0.59 (0.42–0.77) for <i>μ</i>_FROC. Comparison of the AUC curves revealed a significantly higher AUC of <i>D</i>_app compared to the FROC parameters <i>D</i>_FROC (p = 0.009), <i>β</i>_FROC (p = 0.003) and <i>μ</i>_FROC (p = 0.001).</p><p>Conclusion</p><p>In contrast to recent description in brain tumors, the apparent diffusion coefficient <i>D</i>_app showed a significantly higher AUC than the recently proposed FROC parameters <i>β</i>_FROC, <i>D</i>_FROC and <i>μ</i>_FROC for differentiating between malignant and benign breast lesions. This might be related to the intrinsic high heterogeneity within breast tissue or to the lower maximal b-value used in our study.</p></div