High‐resolution dynamic susceptibility contrast perfusion imaging using higher‐order temporal smoothness regularization

PURPOSE: To improve image quality and resolution of dynamic susceptibility contrast perfusion weighted imaging (DSC‐PWI) by developing acquisition and reconstruction methods exploiting the temporal regularity property of DSC‐PWI signal. THEORY AND METHODS: A novel regularized reconstruction is proposed that recovers DSC‐PWI series from interleaved segmented spiral k‐space acquisition using higher order temporal smoothness (HOTS) properties of the DSC‐PWI signal. The HOTS regularization is designed to tackle representational insufficiency of the standard first‐order temporal regularizations for supporting higher accelerations. The higher accelerations allow for k‐space coverage with shorter spiral interleaves resulting in improved acquisition point spread function, and acquisition of images at multiple TEs for more accurate DSC‐PWI analysis. RESULTS: The methods were evaluated in simulated and in‐vivo studies. HOTS regularization provided increasingly more accurate models for DSC‐PWI than the standard first‐order methods with either quadratic or robust norms at the expense of increased noise. HOTS DSC‐PWI optimized for noise and accuracy demonstrated significant advantages over both spiral DSC‐PWI without temporal regularization and traditional echo‐planar DSC‐PWI, improving resolution and mitigating image artifacts associated with long readout, including blurring and geometric distortions. In context of multi‐echo DSC‐PWI, the novel methods allowed ∼4.3× decrease of voxel volume, providing 2× number of TEs compared to the previously published results. CONCLUSIONS: Proposed HOTS reconstruction combined with dynamic spiral sampling represents a valid mechanism for improving image quality and resolution of DSC‐PWI significantly beyond those available with established fast imaging techniques.