Standardization of relative cerebral blood volume (rCBV) image maps for ease of both inter‐ and intrapatient comparisons

Relative cerebral blood volume (rCBV) measured using dynamic susceptibility contrast MRI suffers from interpatient and interstudy variability for the same tissue type. Traditionally, when a more quantitative assessment of rCBV is required, as for comparison across studies and patients, the rCBV values are normalized to the rCBV in a reference region such as normal-appearing white matter. However, this technique of normalization is subjective and time consuming and introduces user-dependent variability. In this study, we demonstrate that a method called standardization, applied to rCBV maps, is an objective means of translating all rCBV values to a consistent scale. This approach reduces interpatient and interstudy variability for the same tissue type, thus enabling easy and accurate visual and quantitative comparison across studies. One caveat to this approach is that it is not appropriate for the evaluation of global changes in blood volume, since systematic differences are removed in the process of standardization.