Theoretical Basis of Hemodynamic MR Imaging Techniques to Measure Cerebral Blood Volume, Cerebral Blood Flow, and Permeability
Cerebrovascular hemodynamic assessment adds new information to standard anatomic MR imaging and improves patient care. This article reviews the theoretic underpinnings of several potentially quantitative MR imaging-based methods that shed light on the hemodynamic status of the brain, including cerebral blood flow (CBF), cerebral blood volume (CBV), and contrast agent permeability. Techniques addressed include dynamic susceptibility contrast (which most simply and accurately estimates CBV), arterial spin labeling (a powerful method to measure CBF), and contrast-enhanced methods to derive permeability parameters such as the transport constant Ktrans.
In the pilot study on the treatment of polyvinyl chloride centrifugal mother liquid wastewater by using a combination of MBR and RO,the removal efficiency of organics and suspending solid together with the capability to resist the impact of the system were researched.The changes of the biological phase in the MBR and the membrane fouling of both membranes were observed.The experiment results show that the total removal efficiency of COD was over 95%,the effluent less than 40 mg/L can meet the requirement of wastewater discharge standard.Furthermore,the effluent of the MBR can reach the polymerization reuse water standard with a water recovery more than 70% after being treated by antiosmosis,Ion exchange or EDI.Film properties are in a good state during the experiment.