Contrast Imaging

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This page provides some insight into how the system can be setup to perform contrast enhanced imaging and flash features.

Contrast imaging consists of using micro-bubbles that flow through the bloodstream. Their reflections produce B mode images that show flow, similar to an enhanced B-Flow mode. Contrast microbubbles can be destroyed by intense ultrasound and the scattered signal level can increase abruptly for a short time during microbubble destruction, resulting in sudden increase in echogenicity (acoustical "flash"). Intermittent imaging with high acoustic output utilizes the unique property of contrast microbubbles to improve blood-to-tissue image contrast by imaging intermittently at very low frame rates instead of the conventional 30 frames per second. The frame rate is usually reduced to about one frame per second, or it is synchronized with cardiac cycles so that enough contrast microbubbles can flow into the imaging site where most microbubbles have been destroyed by the previous acoustic pulse. Because bubbles are destroyed by ultrasound, controlling the delay time between frames produces images whose contrast emphasizes regions with rapid blood flow or regions with high or low blood volume.

For an ultrasound system to have Contrast Imaging, it typically requires:

  • Harmonic imaging
  • A flash mode