Morphology-adaptive total variation for the reconstruction of quantitative susceptibility map from the magnetic resonance imaging phase

Regional high iron deposition on quantitative susceptibility mapping correlates with cognitive decline in type 2 diabetes mellitus

Objective

To quantitatively evaluate the iron deposition and volume changes in deep gray nuclei according to threshold-method of quantitative susceptibility mapping (QSM) acquired by strategically acquired gradient echo (STAGE) sequence, and to analyze the correlation between the magnetic susceptibility values (MSV) and cognitive scores in type 2 diabetes mellitus (T2DM) patients.

Methods

Twenty-nine patients with T2DM and 24 healthy controls (HC) matched by age and gender were recruited in this prospective study. QSM images were used to evaluate whole-structural volumes (V_wh), regional magnetic susceptibility values (MSV_RII), and volumes (V_RII) in high-iron regions in nine gray nuclei. All QSM data were compared between groups. Receiver operating characteristic (ROC) analysis was used to assess the discriminating ability between groups. The predictive model from single and combined QSM parameters was also established using logistic regression analysis. The correlation between MSV_RII and cognitive scores was further analyzed. Multiple comparisons of all statistical values were corrected by false discovery rate (FDR). A statistically significant P-value was set at 0.05.

Results

Compared with HC group, the MSV_RII of all gray matter nuclei in T2DM were increased by 5.1-14.8%, with significant differences found in bilateral head of caudate nucleus (HCN), right putamen (PUT), right globus pallidus (GP), and left dentate nucleus (DN) (P < 0.05). The V_wh of most gray nucleus in T2DM group were decreased by 1.5-16.9% except bilateral subthalamic nucleus (STN). Significant differences were found in bilateral HCN, bilateral red nucleus (RN), and bilateral substantia nigra (SN) (P < 0.05). V_RII was increased in bilateral GP, bilateral PUT (P < 0.05). V_RII/V_wh was also increased in bilateral GP, bilateral PUT, bilateral SN, left HCN and right STN (P < 0.05). Compared with the single QSM parameter, the combined parameter showed the largest area under curve (AUC) of 0.86, with a sensitivity of 87.5% and specificity of 75.9%. The MSV_RII in the right GP was strongly associated with List A Long-delay free recall (List A LDFR) scores (r = -0.590, P = 0.009).

Conclusion

In T2DM patients, excessive and heterogeneous iron deposition as well as volume loss occurs in deep gray nuclei. The MSV in high iron regions can better evaluate the distribution of iron, which is related to the decline of cognitive function.

Data-Driven Quantitative Susceptibility Mapping Using Loss Adaptive Dipole Inversion (LADI)

BACKGROUND

Quantitative susceptibility mapping (QSM) uses prior information to reconstruct maps, but prior information may not show pathology and introduce inconsistencies with susceptibility maps, degrade image quality and inadvertently smoothing image features.

PURPOSE

To develop a local field data-driven QSM reconstruction that does not depend on spatial edge prior information.

STUDY TYPE

Retrospective.

SUBJECTS, ANIMAL MODELS

A dataset from 2016 ISMRM QSM Challenge, 11 patients with glioblastoma, a patient with microbleeds and porcine heart.

SEQUENCE/FIELD STRENGTH

3D gradient echo sequence on 3T and 7T scanners.

ASSESSMENT

Accuracy was compared to Calculation of Susceptibility through Multiple Orientation Sampling (COSMOS), and several published techniques using region of interest (ROI) measurements, root-mean-squared error (RMSE), structural similarity index metric (SSIM), and high-frequency error norm (HFEN). Numerical ranking and semiquantitative image grading was performed by three expert observers to assess overall image quality (IQ) and image sharpness (IS).

STATISTICAL TESTS

Bland-Altman, Friedman test, and Conover multiple comparisons.

RESULTS

Loss adaptive dipole inversion (LADI) (β = 0.82, R² = 0.96), morphology-enabled dipole inversion (MEDI) (β = 0.91, R² = 0.97), and fast nonlinear susceptibility inversion (FANSI) (β = 0.81, R² = 0.98) had excellent correlation with COSMOS and no bias was detected (bias = 0.006 ± 0.014, P < 0.05). In glioblastoma patients, LADI showed consistently better performance (IQ_Grade = 2.6 ± 0.4, IS_Grade = 2.6 ± 0.3, IQ_Rank = 3.5 ± 0.4, IS_Rank = 3.9 ± 0.2) compared with MEDI (IQ_Grade = 2.1 ± 0.3, IS_Grade = 2 ± 0.5, IQ_Rank = 2.4 ± 0.5, IS_Rank = 2.8 ± 0.2) and FANSI (IQ_Grade = 2.2 ± 0.5, IS_Grade = 2 ± 0.4, IQ_Rank = 2.8 ± 0.3, IS_Rank = 2.1 ± 0.2). Dark artifact visible near the infarcted region in MEDI (Inf_MEDI = -0.27 ± 0.06 ppm) was better mitigated by FANSI (Inf_FANSI-TGV = -0.17 ± 0.05 ppm) and LADI (Inf_LADI = -0.18 ± 0.05 ppm).

CONCLUSION

For neuroimaging applications, LADI preserved image sharpness and fine features in glioblastoma and microbleed patients. LADI performed better at mitigating artifacts in cardiac QSM.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY STAGE: 1 J. Magn. Reson. Imaging 2020;52:823-835.