C-mode Virtual Image Display for a Matrix Array Ultrasound Sonic Flashlight

Abstract

Rationale and Objectives: Real Time Tomographic Reflection (RTTR) permits in situ visualization of tomographic images, so that natural hand-eye coordination can be employed directly during invasive procedures. The method uses a half-silvered mirror to merge the visual outer surface of the patient with a simultaneous scan of the patient? interior, without requiring a head-mounted display or any tracking. A viewpoint-independent virtual image is reflected precisely into its actual location. When applied to ultrasound, we call the resulting RTTR device the sonic flashlight. We have previously implemented the sonic flashlight using conventional 2D ultrasound scanners that produce B-mode slices. Real-time 3D ultrasound scanners have recently been developed that permit RTTR to be applied to slices with other orientations, including C-mode (parallel to the face of the transducer). Such slice orientation may offer advantages for image guided intervention. Materials and Methods: Using a prototype scanner developed at Duke University, whose matrix array electronically steers an ultrasound beam at high speed in 3D, we have implemented a sonic flashlight capable of displaying C-mode images in situ in real time. Results: We present the first images from the C-mode sonic flashlight, showing the bones of the hand and the cardiac ventricles. Conclusion: The extension of RTTR to matrix array Real-Time 3D ultrasound offers the ability to visualize in situ slices other than the conventional B-mode slice, including C-mode slices parallel to the face of the transducer. This orientation may provide a broader target facilitating certain interventional procedures. Future work is discussed including the display of slices with arbitrary orientation and the use of a holographic optical element instead of a mirror.