Relaxometry and Contrast-Free Cerebral Microvascular Quantification using Balanced Steady-State Free Precession MR Fingerprinting

Motivation: Most MR methods for quantifying microvascular properties involve the injection of exogenous contrast agents (CA).

Goal(s): We propose an innovative MRI method that simultaneously maps the deoxygenated cerebral blood volume (CBV), microvascular geometry (averaged vessel radius), and relaxometry ($T_1$, $T_2$) without CA injection.

Approach: Acquisitions are made using a multi-echo, phase-cycled, bSSFP-sequence acquired in transient and pseudo-steady-state regimes. Reconstruction of the maps is made under the MRFingerprinting framework using realistic 3D microvessel representations. Magnetic field distributions ($B_1$, $B_0$) are also taken into account.

Results: Preliminary results on five healthy volunteers are in line with previous measurements made with MRF and PWI with gadolinium injection.

Impact: We propose a contrast-free quantification technique of microvascular properties and relaxation times. It could be useful for functional experiments as well as clinical investigations of several cerebrovascular pathologies including stroke and cancer.