Measurement of cerebral circulation by dynamic susceptibility contrast-enhanced MRI: effect of tracer delay

Cerebral blood flow (CBF) and mean transit time (MTT) can be determined by dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) and deconvolution with an arterial input function (AIF). However, deconvolution with a singular value decomposition (SVD) method is sensitive to the tracer delay that often occurs in patients with cerebrovascular disease. We developed a delay correction method that determines tracer delay by means of least-squares fitting pixel-by-pixel. The corrected CBF was determined by SVD deconvolution after time-shifting of the measured concentration curve. The simulations showed that the corrected CBF was insensitive to tracer delay irrespective of the vascular model, although CBF fluctuation increased slightly. We applied the delay correction to the CBF and MTT images acquired for a patient with hyperacute stroke and unilateral occlusion of the middle cerebral artery. The delay correction modulated the contrast of perfusion images. For hyperacute stroke patients, tracer delay correction is essential to obtain reliable CBF and MTT images when SVD deconvolution is used. [Copyright &y& Elsevier]