Optically guided ultrasound imaging system
This study investigates the potential use of combining near infrared (NIR) diffuse light and ultrasound methods for early detection of small breast tumors. A novel imaging system which combines these two methods has been introduced. A NIR phased array positioner capable of providing the line-of-sight of a small heterogeneity in a scattering medium is incorporated into an ultrasound imaging system. This combined system has been tested using models consisting of few mm emulated tumors buried in a scattering phantom. In each test, the combined system was mechanically translated to scan for a small object. At each scanning position, optical amplitude and phase data and an ultrasound image were acquired. The object line-of-sight information was coded into ultrasound images after scanning. Ultrasound images without and with line-of-sight information were evaluated by 2 radiologists. ROC curves using ultrasound and combined methods are measured and the areas under the average ROC curves of ultrasound and combined methods are 49% and 82%, respectively. Thus the combined method affords a significant improvement in detection sensitivity and specificity compared with conventional ultrasound in this phantom study.
