Milestones on the road to higher resolution, quantitative, and functional ultrasonic imaging

Ultrasonography is evolving rapidly with important recent advances in high-density transducer arrays, one-and-one-half-dimensional transducers, broad-band transducers, increased scanner bandwidth, and more sophisticated image-formation routines. Technical advances have clearly improved accuracy of image readings, heightened contrast and resolution, reduced noise, and reduced image slice thickness. It is within this fertile environment that very high-frequency ultrasound, harmonic imaging, and ultrasound contrast agents have emerged. Clinical applications of ultrasonography have also been extended to new fields, such as skeletal status assessment, which have long been considered beyond ultrasound's reach, and over the past 15 years, quantitative ultrasound bone densitometry has become an important part of the armamentarium for osteoporosis diagnosis. The state of these innovations, their contributions to diagnostic and monitoring capabilities, as well as the new applications they bring into reach will be discussed. We will explore several applications currently under development including ultrasound biomicroscopy (eye, skin, small animals), quantitative perfusion assessment, and pathology evaluation. Thus, ongoing research has not only significantly added to diagnostic ultrasound's existing capabilities, but also promises to further broaden the range of its clinical and biological applications.