Quantitative susceptibility mapping of carotid plaques using nonlinear total field inversion: Initial experience in patients with significant carotid stenosis

Abstract

Purpose:To develop a nonlinear preconditioned total field-inversion algorithm using the MEDI toolbox (MEDInpt) for robust QSM of carotid plaques and evaluate its performance in comparison with a local field-inversion algorithm (STI Suite) previously applied to carotid QSM. Methods: Numerical simulation and in vivo carotid QSM were performed to compare the MEDInpt and STI Suite algorithms. Multicontrast MRI was used as the reference standard for detecting calcified plaque and intraplaque hemorrhage (IPH).A total of 5 healthy volunteers and 11 patients with at least one significant carotid artery stenosis were enrolled in this study. Results: In the numerical carotid phantom, the relative susceptibility errors for calcified plaque and IPH were reduced from −63.2% and −56.5% with STI Suite to −13.0% and −24.2% with MEDInpt, respectively. In humans, MEDInpt provided a higher QSM quality score and better detection of calcification and IPH than STI Suite. Although all calcifications and IPHs detected on multicontrast MRI could be seen on QSM obtained with MEDInpt, only 50% of calcified plaques and 83% of IPHs could be captured on QSM obtained with STI Suite. Conclusion: MEDInpt can resolve calcification and IPH in advanced atherosclerotic carotid plaques. Compared with STI Suite, MEDInpt provided better QSM quality and has the potential to improve the detection of these plaque components. K E Y W O R D S atherosclerosis, calcification, carotid plaques, intraplaque hemorrhage, quantitative susceptibility mapping (QSM) 1502 | NGUYEN Et al.

Diffusion tensor imaging and arterial tissue: establishing the influence of arterial tissue microstructure on fractional anisotropy, mean diffusivity and tractography

“…Despite the idealised ex vivo experimental set up, the work presented here highlights the promise for DTI metrics to yield valuable insight into arterial microstructure which could ultimately provide novel insight into diseased tissue morphologies. For example, recent in vivo studies have used quantitative susceptibility mapping to investigate gross morphological features [69][70][71] and inflammation 72 in atherosclerotic plaques, but this approach also has potential to provide markers of tissue microstructure and integrity 73 . Ideally, a combination of methods which allow for the full characterisation of the microstructure within the vessel wall would provide the insight needed to better inform the risk of atherosclerotic plaque rupture.…”

Multiecho complex total field inversion method (mcTFI) for improved signal modeling in quantitative susceptibility mapping

“…The more robust approach is to employ single‐step QSM algorithms 55‐58 . One of these methods, the preconditioned total field inversion method estimates the susceptibility distribution in the entire image volume directly from the total field using a preconditioner to improve convergence speed 55,59,60 …”

Diffusion tensor imaging and arterial tissue: establishing the influence of arterial tissue microstructure on fractional anisotropy, mean diffusivity and tractography

“…Despite the idealised ex vivo experimental set up, the work presented here highlights the promise for DTI metrics to yield valuable insight into arterial microstructure which could ultimately provide novel insight into diseased tissue morphologies. For example, recent in vivo studies have used quantitative susceptibility mapping to investigate gross morphological features [67][68][69] and inflammation 70 in atherosclerotic plaques, but this approach also has potential to provide markers of tissue microstructure and integrity 21 . Ideally, a combination of methods which allow for the full characterisation of the microstructure within the vessel wall would provide the insight needed to better inform the risk of atherosclerotic plaque rupture.…”