Development of three-dimensional power Doppler ultrasound imaging of fetoplacental vasculature

To develop an off-line system for three-dimensional (3-D) ultrasound (US) r econstruction of fetoplacental vasculature using colour segmentation and re construction software and to determine sources of error in fully freehand u ltrasound image acquisition. US images were acquired freehand with the Acus on Sequoia(TM) (5C 2-MHz transducer) using power Doppler. After digital tra nsfer to a personal computer, CQ Analysis software (Kinetic Imaging Ltd, Li verpool, UK) was used to segment the colour information from these images, and the resulting 8-bit grey-scale images were used for 3-D rendering using commercial software (VoxBlast(TM), Vaytek Inc., Fairfield, IA, USA). 2-D s canning, software and freehand acquisition accuracy were assessed using a l inear test rig and distance and volume phantoms (Dansk Phantom Service Ltd) ; 2-D scanning accuracy was within 1.3%, and software reconstruction accura cy within 1% for x and y planes and up to 3% for the z plane. Fully freehan d acquisition was associated with a 12% to 18% mean percentage error in dis tance measurement in the plane of acquisition. Volumetric reconstruction in accuracy was between 1.5% and 19.7% for precisely separated images and betw een 16.2% and 39.2% for fully freehand image acquisition. Rendered 3-D US v ascular images clearly delineated vascular anatomy within the placenta and cord. Fully freehand 3-D US does have a role in off-line reconstruction of vascular anatomy, although variability in the z plane precludes its use for volumetric measurement.