Quantitative susceptibility mapping of the substantia nigra subregions in relapsing-remitting multiple sclerosis patients / 中华放射学杂志

Objective:To investigate the distribution of iron deposition in the substantia nigral (SN) subregions on quantitative susceptibility mapping (QSM) and the change of swallow tail sign (STS) in patients with relapsing-remitting multiple sclerosis (RRMS) of different disease stages.Methods:The clinical and imaging data of 53 patients with RRMS (case group) diagnosed at the First Hospital of Chongqing Medical University from November 2019 to December 2021 were retrospectively analyzed. The case group was divided into 0-5 years subgroup, 6-10 years subgroup, and >10 years subgroup according to the disease duration; another 37 age-and gender-matched healthy volunteers were recruited as the control group during the same period. All subjects underwent MRI and QSM reconstruction. First, the SN was divided into four subregions: rostral anterior-SN (aSNr), rostral posterior-SN (pSNr), caudal anterior-SN (aSNc), and caudal posterior-SN (pSNc) on the QSM, and the quantitative susceptibility value (QSV) of each subregion was measured, and then the STS of the SN was observed and scored on the susceptibility weighted imaging (SWI) generated by post-processing. ANOVA was used to compare the differences in the QSV of each subregion of SN among the groups, and the probability of abnormal STS was compared using the χ 2 test. Spearman′s test was used to analyze the correlation between the QSV of each subregion of SN and the STS score. Results:The differences in QSV of aSNr, pSNr, aSNc, and pSNc were statistically significant among the 0-5 years subgroup, 6-10 years subgroup,>10 years subgroup of RRMS patients and the control group ( P<0.05). The QSV of aSNr, pSNr, and aSNc in 0-5 years subgroup was higher than those in the control group ( P was 0.039, 0.008, 0.039, respectively). The QSV of aSNr, aSNc, and pSNc in the 6-10 years subgroup were higher than those in the 0-5 years subgroup ( P was <0.001, 0.020, 0.015, respectively). The QSV of the aSNc, pSNc in >10 years subgroup were lower than those in the 6-10 years subgroup ( P=0.037, 0.006). The QSV of aSNr, pSNr in >10 years subgroup were higher than those in the control group ( P was <0.001, 0.001). There were 7 cases of abnormal STS in the 0-5 years subgroup, 11 cases in the 6-10 years subgroup, 12 cases in >10 years subgroup, and 9 cases in the control subgroup, and there was a statistically significant difference in the probability of abnormal STS among the subgroups of the RRMS patients and the control subgroup (χ 2=16.20, P=0.011). Both the scores of STS in the 6-10 years subgroup and >10 years group were positively correlated with the QSV in pSNc ( r s=0.65, P=0.006; r s=0.48, P=0.045). Conclusions:In RRMS patients, SN iron deposition is concentrated on aSNr, pSNr, and aSNc in the 0-5 years subgroup and on aSNr, aSNc and pSNc in the 6-10 years subgroup. The QSVs of all SN subregions have a downward trend in >10 years subgroup compared with that in the 6-10 years subgroup. Both the QSVs of the pSNc in the 6-10 years group and >10 years group are positively related to STS scores. These help explore the potential progression pattern of SN iron deposition in RRMS patients and the cause of abnormal STS in RRMS patients.

Value of central vein sign and iron deposition to differentiate multiple sclerosis from neuromyelitis optica spectrum disorder / 中华放射学杂志

Objective:To investigate the value of central vein sign (CVS) and iron deposition on quantitative susceptibility imaging (QSM) of 3.0 T MRI in differentiating multiple sclerosis (MS) from neuromyelitis optica spectrum disease (NMOSD).Methods:This study was a retrospective study. A total of 54 MS patients and 49 NMOSD patients were enrolled from July 2018 to December 2020 in People′s Hospital of Leshan and the First Affiliated Hospital of Chongqing Medical University. All patients underwent conventional MRI and three-dimensional enhanced T 2*-weighted angiography (3D-ESWAN), and ESWAN-filtered phase and QSM were reconstructed from 3D-ESWAN data. First, brain lesions of MS and NMOSD were screened on proton density (PD)-T 2WI, and then the location of lesions, CVS and nodular/annular iron deposition were observed on phase and QSM images. The χ 2 test was used to compare the differences in intracranial lesion location, CVS and iron deposition between MS and NMOSD patients. Receiver operating characteristic curve and area under the curve (AUC) were used to assess the efficiency of CVS and QSM iron deposition to differentiate MS from NMOSD. Results:A total of 968 MS lesions were observed in 54 MS patients, of which CVSs were found in 354 lesions and 227 CVSs were located around the lateral ventricles, 117 in deep white matter (DWM) and 10 in the cortex/subcortex; 372 lesions showed nodular iron deposition, and 193 lesions ring iron deposition on QSM. Totally 247 brain lesions were observed in 41 of 48 patients with NMOSD, of which CVSs were found in 4 lesions and 1 located around the lateral ventricle, 3 located in the DWM; 3 lesions showed nodular iron deposition on QSM. There were significant differences in cortex/subcortex lesions, CVS and iron deposition between MS and NMOSD patients (χ 2 were 29.33, 115.66 and 258.21, respectively, all P<0.001). The AUC of CVS for differentiating MS from NMOSD was 0.941 (95%CI 0.887-0.994), with a sensitivity of 96.3% and a specificity of 91.8%; the AUC of iron deposition for differentiating MS from NMOSD was 0.969 (95%CI 0.930-1.000), with a sensitivity of 100% and a specificity of 93.9%. Conclusion:CVS and iron deposition on 3.0 T MRI are distinct radiologic features of MS lesions from those of NMOSD lesions, and have certain value in the differential diagnosis.

The utility of quantitative susceptibility mapping in the diagnosis of Wilson′s disease / 中华神经科杂志

Early diagnosis and treatment is the key to improve the prognosis and reduce the disability of Wilson′s disease. Conventional magnetic resonance imaging sequences are difficult to detect early brain lesions in Wilson′s disease, especially in preclinical patients. Quantitative susceptibility mapping (QSM) is a recently developed magnetic resonance post-processing technique, which is very sensitive to magnetic metal deposition in the brain. QSM can be used for quantitative analysis of metal deposition in the basal ganglia of Wilson′s disease and is expected to be an imaging technique for early diagnosis and condition assessment of Wilson′s disease.

Quantitative evaluation of renal injury in the early diabetic nephropathy with quantitative susceptibility mapping / 中华放射学杂志

Objective:To explore the value of quantitative susceptibility mapping (QSM) in evaluating renal injury in patients with early diabetic nephropathy (DN).Methods:From October 2019 to December 2020, 32 patients with early DN were prospectively enrolled in the Third Affiliated Hospital of Soochow University. According to the estimated glomerular filtration rate (eGFR), they were divided into three groups: DN1 (eGFR≥90 ml·min -1·1.73 m -2, 11 cases), DN2 (60-<90 ml·min -1·1.73 m -2, 11 cases) and DN3 (30-<60 ml·min -1·1.73 m -2, 10 cases). At the same time, 32 normal volunteers were recruited as the control group. Both kidneys were scanned by QSM to measure the susceptibility of renal cortex and medulla. Paired samples t-test was used to compare the differences of the susceptibility between left and right kidneys and between cortex and medulla. One-way analysis of variance was performed to compare the differences of corresponding susceptibility values among different groups, and LSD- t was used for the pairwise comparison. Pearson correlation test was performed between the susceptibility value of the medulla and eGFR. The ROC curve was used to analyze the diagnostic efficacy of QSM parameters in the diagnosis of DN and different degrees of severity of DN. Results:The susceptibility values of bilateral renal medulla in normal volunteers and patients with DN were lower than those of renal cortex (all P<0.001). There was no significant difference in the susceptibility value between left and right renal cortex (all P>0.05). There was significant difference in the susceptibility value between left and right medulla (all P<0.05). There was no significant difference in the susceptibility value of bilateral renal cortex among the control group and the DN1－DN3 groups (both P>0.05). The susceptibility values of left renal medulla in control group, DN1, DN2 and DN3 groups were (-4.46±1.16)×10 -2, (-5.96±0.97)×10 -2, (-7.97±1.25)×10 -2, (-9.58±1.45)×10 -2 ppm, of right renal medulla were (-3.70±0.65)×10 -2, (-5.06±1.28)×10 -2, (-7.33±1.46)×10 -2, (-9.09±2.22)×10 -2 ppm, respectively. The overall difference of the susceptibility value of bilateral renal medulla was statistically significant (both P<0.05), and there were significant differences between each two groups (all P<0.05). The linear positive correlation were found between the susceptibility values of renal medulla and the corresponding eGFR (left kidney r=0.732, P<0.001; right kidney r=0.684, P<0.001). The areas under the ROC curve (AUC) of left and right renal medulla susceptibility value in diagnosis of normal and DN were 0.931 and 0.943, of DN1 and DN (2 and 3) were 0.952 and 0.883, of DN (1 and 2) and DN3 were 0.888 and 0.831, respectively. Conclusion:The susceptibility value of QSM quantitative parameter has a certain value in the staging and differential diagnosis of early DN, among which the susceptibility value of renal medulla has higher diagnostic efficiency.

Feasibility of quantitative measurement of brain iron by Brainnetome Atlas based on magnetic susceptibility mapping / 中国医学影像技术

Objective: To explore the feasibility of quantitative measurement of cerebral iron using brain network atlas based on quantitative susceptibility mapping (QSM). Methods QSM images of 43 right-handed healthy adult volunteers were registered, which were smoothed and mapped to the standard brain using Matlab software. ROI of bilateral globus pallidus, putamen, caudate nucleus, hippocampus, thalamus, frontal cortex, parietal cortex and occipital cortex were selected from Brainnetome Atlas. The magnetic susceptibility was measured using Matlab software, and ROI of the above areas were manually sketched and measured. The correlation of the magnetic susceptibility values measured with the above 2 methods and the iron concentration results obtained from brain tissue staining of autopsy were analyzed, and the correlation between the magnetic susceptibility values and age were analyzed. Results: The highest measurement value of brain magnetic susceptibility values from Matlab and manually drawn ROI were all found in globus pallidus, then in the putamen, and the lowest was in hippocampus. The brain magnetic susceptibility values measured with Matlab and manual ROI were all highly consistent with autopsy results (r=0.920, P=0.003; r=0.856, P=0.014). The magnetic susceptibility values of male at frontal cortex measured from Matlab ROI was higher than that of female (P0.05), nor between left and right hemispheres brain regions measured with 2 methods (all P>0.05). Conclusion: Quantitative measurement of cerebral iron based on QSM imaging and Brainnetome Atlas has high accuracy and feasibility. The content of brain iron tends to increase with aging. The magnetic susceptibility values of frontal cortex have sex differences.

Reproducibility analysis of quantitative susceptibility mapping of cerebral subcortical nuclei in healthy adults / 南方医科大学学报

OBJECTIVE@#To investigate the intra- and inter-scanner reproducibility of quantitative susceptibility mapping (QSM) of cerebral subcortical nuclei in healthy adults.@*METHODS@#QSM was performed in 21 healthy adults on two different 3.0T MR scanners, and the region of interest (ROI) method was used to measure the magnetic susceptibility value of the left subcortical nuclei (the head of the caudate, putamen, globus pallidus, thalamus, substantia nigra and red nucleus). The intraclass correlation coefficient (ICC) and Bland-Altman method were used to evaluate the inter-scanner and intra-scanner reliability.@*RESULTS@#The ICCs of the susceptibility value ranged from 0.90 to 0.99 for all the subcortical gray nuclei except for the head of the caudate nucleus measured on the same MR scanner by the same observer. Bland-Altman analysis revealed that the points with susceptibility differences for all the subcortical gray nuclei except for substantia nigra located in the 95% CI of limits of agreement for the same MR scanner. The ICCs of the susceptibility value for the inter-scanner was 0.49 (0.08-0.75) for the head of the caudate nuleus, 0.80 (0.57-0.91) for the putamen, 0.77 (0.51-0.90) for the globus pallidus, 0.78 (0.54-0.91) for the thalamus, 0.80 (0.56-0.91) for the substantia nigra and 0.93 (0.83-0.97) for the red nucleus. The points with susceptibility difference (95.2%, 20/21) located in the 95% CI of limits of agreement for the putamen and the thalamus measured on two different MR scanners.@*CONCLUSIONS@#The intra-scanner reproducibility of QSM of the subcortical gray nuclei is superior to the inter-scanner reproducibility in healthy adults.

Relationship between Abnormal Hyperintensity on T2-Weighted Images Around Developmental Venous Anomalies and Magnetic Susceptibility of Their Collecting Veins: In-Vivo Quantitative Susceptibility Mapping Study

OBJECTIVE: A developmental venous anomaly (DVA) is a vascular malformation of ambiguous clinical significance. We aimed to quantify the susceptibility of draining veins (χvein) in DVA and determine its significance with respect to oxygen metabolism using quantitative susceptibility mapping (QSM). MATERIALS AND METHODS: Brain magnetic resonance imaging of 27 consecutive patients with incidentally detected DVAs were retrospectively reviewed. Based on the presence of abnormal hyperintensity on T2-weighted images (T2WI) in the brain parenchyma adjacent to DVA, the patients were grouped into edema (E+, n = 9) and non-edema (E−, n = 18) groups. A 3T MR scanner was used to obtain fully flow-compensated gradient echo images for susceptibility-weighted imaging with source images used for QSM processing. The χvein was measured semi-automatically using QSM. The normalized χvein was also estimated. Clinical and MR measurements were compared between the E+ and E− groups using Student's t-test or Mann-Whitney U test. Correlations between the χvein and area of hyperintensity on T2WI and between χvein and diameter of the collecting veins were assessed. The correlation coefficient was also calculated using normalized veins. RESULTS: The DVAs of the E+ group had significantly higher χvein (196.5 ± 27.9 vs. 167.7 ± 33.6, p = 0.036) and larger diameter of the draining veins (p = 0.006), and patients were older (p = 0.006) than those in the E− group. The χvein was also linearly correlated with the hyperintense area on T2WI (r = 0.633, 95% confidence interval 0.333–0.817, p < 0.001). CONCLUSION: DVAs with abnormal hyperintensity on T2WI have higher susceptibility values for draining veins, indicating an increased oxygen extraction fraction that might be associated with venous congestion.

Quantitative susceptibility mapping of ultra-high resolution monkey brain in vivo at 9.4 T / 生物医学工程学杂志

Quantitative susceptibility mapping (QSM) can provide tissue susceptibility information and has been adapted for clinical research and diagnosis. QSM of monkey brain at 9.4 T has not been demonstrated so far. In this study 9.4 T monkey brain QSM was performed with 200 μm isotropic high-resolution. It was found that the inherent singularity problem for QSM diverged significantly at ultra-high image resolution during regularization process and resulted in severe image artifacts. The K-space division (TKD) was applied to eliminate the artifacts, with an optimal threshold level between 0.2 and 0.3. High resolution QSM of monkey brain can thus provide a novel tool for brain research.

Research progresses of MR quantitative magnetic susceptibility imaging in neurodegenerative diseases / 中国医学影像技术

Iron is an important trace element in human body, and too much or too little iron can lead to corresponding pathological changes. Although there is no direct evidence that the destruction of iron homeostasis leads to neurodegenerative diseases, it is undeniable that the abnormal iron content is involved in the pathogenesis of most diseases. Having high resolution and sensitivity, quantitative susceptibility mapping (QSM) imaging is able to detect abnormal iron depositions in the early stage of most neurodegenerative diseases, therefore it is used as the main method to quantitatively measure iron content in vivo brain tissue in the study of neurodegenerative diseases in recent years. QSM imaging research progresses of iron metabolism in Alzheimer disease, Parkinson disease, Huntington disease, multiple sclerosis and amyotrophic lateral sclerosis were reviewed in this article.

Discussion and improvement methods of quantitative susceptibility mapping reconstruction / 生物医学工程学杂志

To assess the background field removal method usually used in quantitative susceptibility mapping (QSM), and to analyze the cause of serious artifacts generated in the truncated -space division (TKD) method, this paper discusses a variety of background field removal methods and proposes an improved method to suppress the artifacts of susceptibility inversion. Firstly, we scanned phase images with the gradient echo sequence and then compared the quality and the speed of reconstructed images of sophisticated harmonic artifact reduction for phase data (SHARP), regularization enable of SHARP (RESHARP) and laplacian boundary value (LBV) methods. Secondly, we analyzed the reasons for reconstruction artifacts caused by the multiple truncations and discontinuity of the TKD method, and an improved TKD method was proposed by increasing threshold truncation range and improving data continuity. Finally, the result of susceptibility inversion from the improved and original TKD method was compared. The results show that the reconstruction of SHARP and RESHARP are very fast, but SHARP reconstruction artifacts are serious and the reconstruction precision is not high and implementation of RESHARP is complicated. The reconstruction speed of LBV method is slow, but the detail of the reconstructed image is prominent and the precision is high. In the QSM inversion methods, the reconstruction artifact of the original TKD method is serious, while the improved method obtains good artifact suppression image and good inversion result of artifact regions.

Generating Motion- and Distortion-Free Local Field Map Using 3D Ultrashort TE MRI: Comparison with T₂* Mapping

PURPOSE: To generate phase images with free of motion-induced artifact and susceptibility-induced distortion using 3D radial ultrashort TE (UTE) MRI.MATERIALS AND METHODS: The field map was theoretically derived by solving Laplace's equation with appropriate boundary conditions, and used to simulate the image distortion in conventional spin-warp MRI. Manufacturer's 3D radial imaging sequence was modified to acquire maximum number of radial spokes in a given time, by removing the spoiler gradient and sampling during both rampup and rampdown gradient. Spoke direction randomly jumps so that a readout gradient acts as a spoiling gradient for the previous spoke. The custom raw data was reconstructed using a homemade image reconstruction software, which is programmed using Python language. The method was applied to a phantom and in-vivo human brain and abdomen. The performance of UTE was compared with 3D GRE for phase mapping. Local phase mapping was compared with T₂* mapping using UTE.RESULTS: The phase map using UTE mimics true field-map, which was theoretically calculated, while that using 3D GRE revealed both motion-induced artifact and geometric distortion. Motion-free imaging is particularly crucial for application of phase mapping for abdomen MRI, which typically requires multiple breathold acquisitions. The air pockets, which are caught within the digestive pathway, induce spatially varying and large background field. T₂* map, that was calculated using UTE data, suffers from non-uniform T₂* value due to this background field, while does not appear in the local phase map of UTE data.CONCLUSION: Phase map generated using UTE mimicked the true field map even when non-zero susceptibility objects were present. Phase map generated by 3D GRE did not accurately mimic the true field map when non-zero susceptibility objects were present due to the significant field distortion as theoretically calculated. Nonetheless, UTE allows for phase maps to be free of susceptibility-induced distortion without the use of any post-processing protocols.

Simultaneous Unwrapping Phase and Error Recovery from Inhomogeneity (SUPER) for Quantitative Susceptibility Mapping of the Human Brain

PURPOSE: The effect of global inhomogeneity on quantitative susceptibility mapping (QSM) was investigated. A technique referred to as Simultaneous Unwrapping Phase with Error Recovery from inhomogeneity (SUPER) is suggested as a preprocessing to QSM to remove global field inhomogeneity-induced phase by polynomial fitting. MATERIALS AND METHODS: The effect of global inhomogeneity on QSM was investigated by numerical simulations. Three types of global inhomogeneity were added to the tissue susceptibility phase, and the root mean square error (RMSE) in the susceptibility map was evaluated. In-vivo QSM imaging with volunteers was carried out for 3.0T and 7.0T MRI systems to demonstrate the efficacy of the proposed method. RESULTS: The SUPER technique removed harmonic and non-harmonic global phases. Previously only the harmonic phase was removed by the background phase removal method. The global phase contained a non-harmonic phase due to various experimental and physiological causes, which degraded a susceptibility map. The RMSE in the susceptibility map increased under the influence of global inhomogeneity; while the error was consistent, irrespective of the global inhomogeneity, if the inhomogeneity was corrected by the SUPER technique. In-vivo QSM imaging with volunteers at 3.0T and 7.0T MRI systems showed better definition in small vascular structures and reduced fluctuation and non-uniformity in the frontal lobes, where field inhomogeneity was more severe. CONCLUSION: Correcting global inhomogeneity using the SUPER technique is an effective way to obtain an accurate susceptibility map on QSM method. Since the susceptibility variations are small quantities in the brain tissue, correction of the inhomogeneity is an essential element for obtaining an accurate QSM.

Susceptibility weighted imaging: current clinical applications and development prospects / 中华神经科杂志

As a routine scanning method of magnetic resonance imaging nowadays , susceptibility weighted imaging provides very important diagnostic information for daily medical treatment in clinical departments such as neurology , neurosurgery, and emergency departments.With the continuous improvement and upgrading , the scope of its clinical application has been further expanded , such as analysis of quantitative susceptibility mapping , perinatal fetal monitoring and neonatal disease diagnosis , guiding clinical therapy strategies and so on.Owing to the great potential and scientific value of this technology , its future development prospects will be new sequence improvement , multiple body parts'application, functional image research, etc.

Analysis of magnetic susceptibility of normal brain of young adults by quantitative susceptibility mapping / 中国医学影像技术

Objective To explore the changes of susceptibility of different sides and gender in healthy young adults with quantitative susceptibility mapping (QSM).Methods Totally 41 healthy young right-handed adults underwent conventional brain MRI and QSM scan,and the susceptibility maps were obtained by the image post-processing software.Then the ROI of the bilateral frontal grey matter (FGM),frontal white matter (FWM),caudate (CA),globus pallidus (GP),putamen (PU),thalamus (TH),substantia nigra (SN),red nucleus (RN),dentate nucleus (DN),pons (PO),corpus callosum (CC) were manually drawn to obtain magnetic susceptibility on the susceptibility map.The magnetic susceptibility of each ROI was compare between both sides,as well as gender by Mann-Whitney test.Results The magnetic susceptibility of the bilateral ROI of GP was the highest,and SN was followed,FWM was minimum.The susceptibility of bilateral FGM,FWM,CA,GP,PU,TH,SN,RN,DN,PO,CC had no statistically significant differences (all P＞0.05).The magnetic susceptibility in CA of different gender had statistically significant difference (P＜0.05).Conclusion The brain magnetic susceptibility.can be measured by QSM,and it can assess brain iron content quantitatively.