Quantification of cerebral perfusion using the “bookend technique”: an evaluation in CNS tumors

We present a method of quantifying cerebral blood volume using dynamic susceptibility contrast. Our approach combines T2-weighted echo planar imaging (EPI) pulse sequences and reference scans that determine the parenchymal T1 changes resulting from an injection of a gadolinium chelate. This combined T2- and T1-weighted approach (the “bookend” technique) has been shown to be effective in the quantification of gradient-echo (GRE) (T2*-weighted) perfusion images but has not been applied to spin-echo EPI (SE-EPI) (T2-weighted) images. The physics related to blood volume measurement based on T2- and T2*-weighted EPI sequences is known to be different, and there is a question as to whether the bookend approach is effective with SE-EPI. We have compared the quantitative SE-EPI with GRE-EPI in a series of patients with central nervous system (CNS) tumors. We found that quantitative cerebral blood volume (qCBV) values for SE-EPI and GRE-EPI are in agreement with each other and with historical reference values. A subjective evaluation of image quality showed that image quality in the SE-EPI scans was high and exhibited high interreader agreement. We conclude that measuring qCBV using the bookend technique with SE-EPI images is possible and may be a viable alternative to GRE-EPI in the evaluation of CNS tumors.