Impact of Non-Contrast Enhanced Imaging Input Sequences on the Generation of Virtual Contrast-Enhanced Breast MRI Scans using Neural Networks

Abstract

ABSTRACTBackgroundVirtual contrast-enhanced (vCE) imaging techniques are an emerging topic of research in breast MRI.PurposeTo investigate how different combinations of T1-weighted (T1w), T2-weighted (T2w), and diffusion-weighted imaging (DWI) impact the performance of vCE breast MRI.Materials and MethodsThe IRB-approved, retrospective study included 1064 multiparametric breast MRI scans (age:52±12 years) obtained from 2017-2020 (single site, two 3T MRI). Eleven independent neural networks were trained to derive vCE images from varying input combinations of T1w, T2w, and multi-b-value DWI sequences (b-value=50–1500s/mm2). Three readers evaluated the vCE images with regards to qualitative scores of diagnostic image quality, image sharpness, satisfaction with contrast/signal-to-noise-ratio, and lesion/non-mass enhancement conspicuity. Quantitative metrics (SSIM, PSNR, NRMSE, and median symmetrical accuracy) were analyzed and statistically compared between the input combinations for the full breast volume and both enhancing and non-enhancing target findings.ResultsThe independent test set consisted of 187 cases. The quantitative metrics significantly improved in target findings when multi-b-value DWI sequences were included during vCE training (p<.05). Non-significant effects (p>.05) were observed for the quantitative metrics on the full breast volume when comparing input combinations including T1w. Using T1w and DWI acquisitions during vCE training is necessary to achieve high satisfaction with contrast/SNR and good conspicuity of the enhancing findings. The input combination of T1w, T2w, and DWI sequences with three b-values showed the best qualitative performance.ConclusionvCE breast MRI performance is significantly influenced by input sequences. Quantitative metrics and visual quality of vCE images significantly benefit when a multi b-value DWI is added to morphologic T1w-/T2w-sequences as input for model training.Key ResultsThe inclusion of diffusion-weighted imaging significantly improves the conspicuity of lesions/non-mass enhancements and satisfaction with the image contrast in virtual contrast-enhanced breast MRI.The quality of virtual contrast-enhanced breast MRI scans benefits from the inclusion of high-resolution morphologic T1-weighted image acquisitions.Quantitative metrics such as the structural similarity index and peak signal-to-noise ratio calculated over the entire breast volume insufficiently reflect variations in lesion/non-mass enhancement’s individual characteristics.