Letter by Knight et al Regarding Article, “Validation of In Vivo Magnetic Resonance Imaging Blood–Brain Barrier Permeability Measurements by Comparison With Gold Standard Histology”

Abstract

To the Editor: We read with great interest the recent paper by Hoffmann et al1 on the validation of magnetic resonance imaging (MRI) measurements of blood-brain barrier (BBB) permeability. The authors reported that they measured changes in BBB permeability in rodent models of focal cerebral ischemia using MRI methods in conjunction with a Gd-based MRI contrast agent; they then validated these measures by comparing them with Cresyl violet histology and Evans Blue extravasation. The MRI-based estimates of vascular leakage were obtained using the Patlak graphical method to calculate the blood-to-brain transfer constant (Ki). In recent years, there has been a great deal of interest in the development of noninvasive imaging techniques capable of accurately measuring changes in acute BBB permeability after stroke to predict probability …