Update on Color Flow Imaging in Obstetrics.

Color flow imaging (CFI), being non-invasive, is commonly used in obstetrics to study the fetal and placental circulations. The conventional CFI modes include color Doppler flow imaging (CDFI) and power Doppler imaging (PDI). In recent years, there is increasing use of new modes, including high-definition flow imaging (HDFI), radiant flow, microvascular flow imaging (MVFI), and three-/four-dimensional rendering in glass-body mode. Compared to CDFI, HDFI can show a higher resolution and sensitivity and allow the detection of slower flows. MVFI increases the sensitivity to fine or low-flow vessels while producing little or no motion artifacts. Radiant flow shows the blood flow with a sense of depth and reduces blood overflow. Glass-body mode, showing both gray-scale and color-flow information, can demonstrate the heart-cycle-related flow events and the vessel spatial relationship. In this review, the characteristics and applications of the various CFI modes in obstetrics are discussed. In particular, how these new technologies are integrated in detailed diagnostic and early morphology scans is presented.