Improving Dynamic Susceptibility Contrast MRI Measurement of Quantitative Cerebral Blood Flow using Corrections for Partial Volume and Nonlinear Contrast Relaxivity: A Xenon Computed Tomographic Comparative Study

Purpose: To test whether dynamic susceptibility contrast MRI-based CBF measurements are improved with arterial input function (AIF) partial volume (PV) and nonlinear contrast relaxivity correction, using a gold-standard CBF method, xenon computed tomography (xeCT). Materials and Methods: Eighteen patients with cerebrovascular disease underwent xeCT and MRI within 36 h. PV was measured as the ratio of the area under the AIF and the venous output function (VOF) concentration curves. A correction was applied to account for the nonlinear relaxivity of bulk blood (BB). Mean CBF was measured with both techniques and regression analyses both within and between patients were performed. Results: Mean xeCT CBF was 43.3 +/- 13.7 mL/100g/min (mean +/- SD). BB correction decreased CBF by a factor of 4.7 +/- 0.4, but did not affect precision. The least-biased CBF measurement was with BB but without PV correction (45.8 +/- 17.2 mL/100 g/min, coefficient of variation [COV] 32%). Precision improved with PV correction, although absolute CBF Was mildly underestimated, (34.3 +/- 10.8 mL/100 g/min, COV = 27%). Between patients correlation was moderate even with both corrections (R = 0.53). Conclusion: Corrections for AIF PV and nonlinear BB relaxivity improve bolus MRI-based CBF maps. However, there remain challenges given the moderate between-patient correlation, which limit diagnostic confidence of such measurements in individual patients.