His research has focused on the basic physics and clinical applications of medical ultrasound. Some of his achievements include the development and clinical introduction of power Doppler, a method that is now widely used in multiple clinical situations for evaluating blood flow and has become a standard function on most diagnostic ultrasound machines. He was also instrumental in introducing ultrasound into the neurosurgical operating room for real-time guidance during intracranial and spinal surgery. His most recent interests relate to blood volume flow measurements using ultrasound and the use of ultrasound for assessing placental function. The volume flow method employs 3D ultrasound along with Gauss’s divergence theorem to quantify true blood flow. The most recent implementation of this method permits total brain blood flow measurements in neonates. The placental measurement technique analyzes umbilical venous Doppler spectra in order to determine the placenta’s response to the maternal and fetal arterial input flows. Both the maternal and fetal inputs are assessed simultaneously. This method provides a means for evaluating placental function and structure in new ways.