Peri-Procedural Arterial Spin Labeling
Claude Nguyen, MD
Nael K, Meshksar A, Liebeskind DS, Wang DJJ, Ellingson BM, Salamon N, et al. Periprocedural Arterial Spin Labeling and Dynamic Susceptibility Contrast Perfusion in Detection of Cerebral Blood Flow in Patients With Acute Ischemic Syndrome. Stroke. 2013.
The optimal imaging modality to identify patients with perfusion-diffusion mismatch who are suitable candidates for revascularization remains elusive. There has been a renewed interest in arterial spin-labeled (ASL) perfusion imaging for this purpose. Compared to dynamic susceptibility contrast (DSC) perfusion, ASL does not use gadolinium, and therefore does not carry the risk of nephrogenic systemic fibrosis. In addition, recent technical advances in its quality and acquisition speed have made ASL more appealing.
Nael et al. sought to compare ASL and DSC perfusion in detection of cerebral blood flow (CBF) changes. They performed a retrospective analysis of patients who underwent endovascular recanalization using intra-arterial tPA (<6 hrs) or clot retrieval (<9 hrs), looking at those who had both ASL and DSC images before and after the procedure. The studies were evaluated for image quality, location, and type of perfusion abnormality. Quantitative analysis was also done by comparing ratio of relative CBF in core and hypoperfused regions with respect to the contralateral hemisphere.
In their sample size of 25 patients, Nael et al. found that the image quality of ASL was significantly lower than DSC for both pre- and post-recanalization images. Although Nael et al. found that changes in rCBF were concordant between ASL and DSC both before and after recanalization, they showed that ASL was still limited in image quality, less sensitive in detecting rCBF changes with respect to hyperperfusion compared to DSC.
Ultimately, the selection of patients who may benefit the most from endovascular recanalization will depend partly on advanced neuroimaging selection to detect perfusion-diffusion mismatch. This work from Nael et al. helps clinicians understand the current limitations of ASL compared to DSC, and highlights the need for further work to optimize ASL before it can be applied to the acute clinical setting.