Figure 3
From: Quantitative tissue perfusion imaging using nonlinear ultrasound localization microscopy
Nonlinear imaging is necessary to describe tissue perfusion. Single frames reconstructed with the linear (a) or nonlinear (b) signal component are displayed for a representative sparse acquisition (i.e., low microbubble concentration) in the thoracic spinal cord. The linear case solely shows tissue clutter, whereas individual circulating microbubbles are visible in the nonlinear case without any additional filtering or processing. To illustrate the unique utility of nonlinear imaging in describing tissue perfusion, SVD segmented contrast-enhanced Doppler images of a representative dense acquisition (i.e., high microbubble concentration) are displayed. These were acquired following contusion injury. The low projections in the linear case (c) are corrupted generally by tissue clutter and more prominently by hematoma in the injury center (yellow arrow). With nonlinear imaging (d), tissue clutter and hematoma are cancelled, revealing a perfusion deficit at the contusion center. Both linear and nonlinear imaging (e,f) can image larger vasculature and associated hypoperfusion following contusion SCI.
