Osman Mir, MD
Liu HS, Chung HW, Chou MC, Liou M, Wang CY, Kao HW. Effects of Microvascular Permeability Changes on Contrast-Enhanced T1and Pharmacokinetic MR Imagings After Ischemia. Stroke. 2013
Liu et al explored the effects of microvascular permeability on T1 contrast enhancement on MRI after ischemic stroke and its relationship with hemorrhagic transformation.
It has been previously shown that reperfusion in the setting of ischemia might be related to Hemmorhagic transformation(HT) of ischemic tissue. They wanted to further elucidate this finding with the help of contrast enhancement. Contrast enhancement in AIS(acute ischemic stroke) is typically in the sub-acute phase and associated with breakdown of Blood Brain Barrier(BBB). Liu et al have used contrast enhancement by doing multiple MRI’s of different patients at different time points to better assess breakdown of BBB and also to look at Microvascular Permeability.
This is a retrospective study in which they looked at 26 patients getting MRI’s in hyperacute to chronic phases exploring the relationship. They found that Endothelial transfer constant ktran, an indirect measure of Microvascular permeability, is a better predictor of Parechymal enhancement in the ischemic tissue rather than Cerebral blood volume in hyperacute and acute settings. Parenchymal enhancement as seen on T1 images is related more to luxury perfusion in later stages.
Also in patients with HT there was increase in ktran compared to patients with non HT. This probably needs further investigatation in a large patient population in a prospective fashion. However, it does raise interesting questions regarding application of perfusion imaging and ktran in hyperacute stroke patients going for reperfusion therapy.