Q-space trajectory imaging with positivity constraints (QTI+)

NeuroImage

Tom Dela Haije¹  Carl-Fredrik Westin²  Deneb Boito³  Aasa Feragen⁴  Magnus Herberthson⁵  Evren Özarslan⁶ 

[1] Center for Medical Image Science and Visualization, Linköping University, Linköping, Sweden;Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark;Department of Biomedical Engineering, Linköping University, Linköping, Sweden;Department of Computer Science, University of Copenhagen, Copenhagen, Denmark;Department of Mathematics, Linköping University, Linköping, Sweden;Laboratory for Mathematics in Imaging, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA;

关键词: Diffusion;    MRI;    Constrained;    Positive definite;    QTI;    Multidimensional;   

DOI  :  

来源: DOAJ

【 摘 要 】

Q-space trajectory imaging (QTI) enables the estimation of useful scalar measures indicative of the local tissue structure. This is accomplished by employing generalized gradient waveforms for diffusion sensitization alongside a diffusion tensor distribution (DTD) model. The first two moments of the underlying DTD are made available by acquisitions at low diffusion sensitivity (b-values). Here, we show that three independent conditions have to be fulfilled by the mean and covariance tensors associated with distributions of symmetric positive semidefinite tensors. We introduce an estimation framework utilizing semi-definite programming (SDP) to guarantee that these conditions are met. Applying the framework on simulated signal profiles for diffusion tensors distributed according to non-central Wishart distributions demonstrates the improved noise resilience of QTI+ over the commonly employed estimation methods. Our findings on a human brain data set also reveal pronounced improvements, especially so for acquisition protocols featuring few number of volumes. Our method’s robustness to noise is expected to not only improve the accuracy of the estimates, but also enable a meaningful interpretation of contrast in the derived scalar maps. The technique’s performance on shorter acquisitions could make it feasible in routine clinical practice.

【 授权许可】

Unknown