Has Arterial Spin Labeling Removed the Need for Contrast Enhanced Perfusion Studies?

Magnetic resonance (MR) cerebral perfusion imaging can be performed using dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) perfusion imaging. DSC is routinely used in clinical practice for assessment of perfusion. It involves injection of a gadolinium contrast agent and acquisition of T2 or T2*-weighted images. Although DSC is a fast and convenient method, patients with poor renal function are at risk of nephrogenic systemic fibrosis with the use of gadolinium contrast. Arterial spin labeling is a non-exogenous contrast technique that can serve as an alternative method, as it images perfusion by magnetically labeling the blood with radiofrequency pulses. Clinical applications of MR perfusion imaging include cerebrovascular diseases, CNS neoplasms, epilepsy and degenerative diseases. This review focuses on the applications on acute ischemic stroke, tumor grading and tumor type differentiation. Studies show comparable results between DSC and ASL data. However, ASL is considered unsuitable for acute ischemic stroke treatment assessment but shows potential in stroke treatment follow-up and tumor grading. More studies using ASL for tumor type differentiation are needed. In conclusion, the need for DSC has not been entirely removed, but ASL can be applied when more suitable.