3D contrast ultrasound dispersion imaging by mutual information for prostate cancer localization

Prostate cancer (PCa) is the most occurring type of cancer in the Western World. Yet, the most common diagnostic tool, systematic biopsy, is invasive and has low sensitivity. Recently, contrast-ultrasound dispersion imaging (CUDI) by spatiotemporal similarity analysis on contrast-enhanced ultrasound (CEUS) has been proposed as a promising, non-invasive alternative for PCa localization. It was shown that increased mutual information (MutI) between the indicator dilution curves in a block kernel and its central pixel relates to the presence of PCa. However, until now CUDI by MutI has been investigated in 2-D only, requiring a separate contrast injection for each imaging plane. Moreover, out-of-plane contrast flow could not be taken into account. In this work, we implemented CUDI by MutI using 4-D CEUS to overcome the aforementioned issues. We tested its feasibility to perform 3-D CUDI by comparison with 12-core systematic biopsies in 3 patients. The mean MutI for the patient with only one positive biopsy sample was significantly lower than that for the other two patients with more than 6 positive samples. This result encourages refinement and validation of the presented method in a larger patient group.