Feasibility of Real-Time Myocardial Contrast Echocardiography to Detect Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients.

Background: Cardiac allograft vasculopathy (CAV) is an important adverse prognostic factor for pediatric heart transplant (HT) recipients. Invasive coronary angiography (ICA) is the gold standard for CAV detection but lacks sensitivity for early microvascular changes and cumulative radiation exposure is of concern. Real-time myocardial contrast echocardiography (RTMCE) using ultrasound enhancing (contrast) agents performed during dobutamine stress echocardiography (DSE) can assess myocardial function, perfusion, and microvascular integrity.

Photon trapping models for x-ray lasers.

Optimum methods for calculating the effects of photon trapping are discussed. An efficient line-transfer algorithm that can calculate trapping when there are overlapping and interacting lines is described. Escape probability formulas are shown to be appropriate for calculating photon trapping for isolated lines and for the highest-energy line in a group of lines in many situations.