"Sudden Drop" in Blood Pressure is Associated With Recanalization After Thrombolysis.

We aim to investigate whether the phenomenon of "sudden drop" in blood pressure (BP) within the first 2 hours is associated with vessel recanalization.We retrospectively examined clinical and imaging data from a consecutive series of patients with stroke with large vessel occlusion treated with intravenous thrombolysis (IVT). BP was monitored every 15 minutes during the first 2 hours, then every 30 minutes for 6 hours, and then every hour for 16 hours.We observed the phenomenon of "sudden drop" in systolic BP (≥20 mm Hg) in 82 (50.9%) patients in the first 2 hours and vessel recanalization in 87 (54.0%) patients 24 hours after treatment. This phenomenon was independently associated with recanalization (odds ratio 2.100; 95% confidence interval: 1.085-4.062; P = 0.028) after adjusting for the history of atrial fibrillation, coronary heart disease, and hypertension.The phenomenon of "sudden drop" in systolic BP with 20 mm Hg or greater between 2 continuous measurements within the first 2 hours is associated with recanalization after IVT in patients with large vessel occlusion, especially for middle cerebral artery occlusion

Minimizing L1 over L2 norms on the gradient

In this paper, we study the L1/L2 minimization on the gradient for imaging applications. Several recent works have demonstrated that L1/L2 is better than the L1 norm when approximating the L0 norm to promote sparsity. Consequently, we postulate that applying L1/L2 on the gradient is better than the classic total variation (the L1 norm on the gradient) to enforce the sparsity of the image gradient. To verify our hypothesis, we consider a constrained formulation to reveal empirical evidence on the superiority of L1/L2 over L1 when recovering piecewise constant signals from low-frequency measurements. Numerically, we design a specific splitting scheme, under which we can prove subsequential and global convergence for the alternating direction method of multipliers (ADMM) under certain conditions. Experimentally, we demonstrate visible improvements of L1/L2 over L1 and other nonconvex regularizations for image recovery from low-frequency measurements and two medical applications of MRI and CT reconstruction. All the numerical results show the efficiency of our proposed approach.Comment: 26 page