Disrupted resting-state brain functional network properties in non-neuropsychiatric systemic lupus erythematosus patients.

INTRODUCTION: Previous fMRI studies revealed that the abnormal functional connectivity (FC) was related to cognitive impairment in patients with SLE. However, it remains unclear how the disease severity affects the functional topological organization of the whole-brain network in SLE patients without neuropsychiatric symptoms (non-NPSLE). OBJECTIVE: We aim to examine the impairment of the whole-brain functional network in SLE patients without neuropsychiatric symptoms (non-NPSLE), which may improve the understanding of neural mechanism in SLE. METHODS: We acquired resting-state fMRI data from 32 non-NPSLE patients and 32 healthy controls (HC), constructed their whole-brain functional network, and then estimated the topological properties including global and nodal parameters by using graph theory. Meanwhile, we also investigated the differences in intra- and inter-network FC between the non-NPSLE patients and the HC. RESULTS: The non-NPSLE patients showed significantly lower clustering coefficient, global and local efficiency, but higher characteristic path length than the HC. The non-NPSLE patients had significantly lower nodal strength in two regions, ventromedial prefrontal cortex (vmPFC) and anterior PFC (aPFC) than the HC. We found the non-NPSLE patients had significantly lower intra-network FC within frontal-parietal network (FPN) and within default mode network (DMN), and significantly lower inter-network FC between DMN and FPN than the HC. The intra-network FC within DMN was negatively correlated with systemic lupus erythematosus disease activity index (SLEDAI). CONCLUSION: Abnormal whole-brain functional network properties and abnormal intra- and inter-network FC may be related to cognitive impairment and disease degree in the non-NPSLE patients. Our findings provide a network perspective to understand the neural mechanisms of SLE.

Kartogenin (KGN)/synthetic melanin nanoparticles (SMNP) loaded theranostic hydrogel scaffold system for multiparametric magnetic resonance imaging guided cartilage regeneration.

Cartilage regeneration after injury is still a great challenge in clinics, which suffers from its avascularity and poor proliferative ability. Herein we designed a novel biocompatible cellulose nanocrystal/GelMA (gelatin-methacrylate anhydride)/HAMA (hyaluronic acid-methacrylate anhydride)-blended hydrogel scaffold system, loaded with synthetic melanin nanoparticles (SMNP) and a bioactive drug kartogenin (KGN) for theranostic purpose. We found that the SMNP-KGN/Gel showed favorable mechanical property, thermal stability, and distinct magnetic resonance imaging (MRI) contrast enhancement. Meanwhile, the sustained release of KGN could recruit bone-derived mesenchymal stem cells to proliferate and differentiate into chondrocytes, which promoted cartilage regeneration in vitro and in vivo. The hydrogel degradation and cartilage restoration were simultaneously monitored by multiparametric MRI for 12 weeks, and further confirmed by histological analysis. Together, these results validated the multifunctional hydrogel as a promising tissue engineering platform for noninvasive imaging-guided precision therapy in cartilage regenerative medicine.

Parametric MRI Detects Aristolochic Acid Induced Acute Kidney Injury.

Exposure to aristolochic acid (AA) is of increased concern due to carcinogenic and nephrotoxic effects, and incidence of aristolochic acid nephropathy (AAN) is increasing. This study characterizes renal alterations during the acute phase of AAN using parametric magnetic resonance imaging (MRI). An AAN and a control group of male Wistar rats received administration of aristolochic acid I (AAI) and polyethylene glycol (PEG), respectively, for six days. Both groups underwent MRI before and 2, 4 and 6 days after AAI or PEG administration. T2 relaxation times and apparent diffusion coefficients (ADCs) were determined for four renal layers. Serum creatinine levels (sCr) and blood urea nitrogen (BUN) were measured. Tubular injury scores (TIS) were evaluated based on histologic findings. Increased T2 values were detected since day 2 in the AAN group, but decreased ADCs and increased sCr levels and BUN were not detected until day 4. Significant linear correlations were observed between T2 of the cortex and the outer stripe of outer medulla and TIS. Our results demonstrate that parametric MRI facilitates early detection of renal injury induced by AAI in a rat model. T2 mapping may be a valuable tool for assessing kidney injury during the acute phase of AAN.

Application of amide proton transfer imaging for the diagnosis of neonatal hypoxic-ischemic encephalopathy.

Objective: This study aimed to evaluate cerebral amide proton transfer signal intensity (SI) among controls, hypoxic-ischemic encephalopathy (HIE) neonates with normal conventional magnetic resonance imaging (HIE/MRI-) findings, and HIE neonates with abnormal conventional MRI (HIE/MRI+) findings. Methods: Forty neonates diagnosed with neonatal HIE and sixteen normal neonates were evaluated. All neonates underwent conventional MRI scans and APT imaging. Cerebral APT SIs were compared to identify cerebral regions with significant APT changes among sixteen controls, thirteen HIE/MRI- patients, and twenty-seven HIE/MRI+ patients. Results: Significantly increased APT SIs were observed in the HIE/MRI- group compared with controls, in the left insula, right occipital lobe, left cingulate gyrus (posterior part), and corpus callosum. Significantly increased APT SIs were found in the HIE/MRI+ group compared with controls, in the right anterior temporal lobe (medial part), anterior parts of the right parahippocampal and ambient gyri, left superior temporal gyrus (middle part), left insula, left cingulate gyrus (posterior part), and right lentiform nucleus. No significant APT SI differences were observed in the cerebellum and brainstem among the three groups. Conclusion: Amide proton transfer imaging plays an important role in detecting hypoxic-ischemic encephalopathy regardless of conventional MRI findings. Changes in APT signal intensity may provide important insights into the characterization of the cerebral internal environment. This study suggests that APT imaging could be used as a complement to conventional MRI in the detection of hypoxic-ischemic encephalopathy in clinical practice.

Quantitative evaluation of the characteristic of infrapatellar fat pad Fat Content and Unsaturation Index by using hydrogen proton MR spectroscopy.

OBJECTIVE: To investigate the characteristics of fat content and component in IFP using hydrogen proton MR spectroscopy (1H-MRS), and to explore the correlation with the severity of OA, Hoffa-synovitis, and knee pain. MATERIALS AND METHODS: 80 volunteers were enrolled. Subjects were grouped based on Kellgren-Lawrence (K-L) grading. Fat fraction (FF) and unsaturation index (UI) of IFP were measured using 1H-MRS. Hoffa-synovitis was evaluated based on the MRI Osteoarthritis Knee Score system (MOAKS). Knee pain was assessed by a self-administered Western Ontario and McMaster Osteoarthritis Index (WOMAC) questionnaire. One-way ANOVA or Kruskal-Wallis test and Spearman's correlation tests were applied for statistical analysis. RESULTS: After matching BMI, waistline, and K-L grade, a total of 64 knees were included and divided into 23 normal, 25 mild OA, and 16 advanced OA. The mean values were 76.79% ± 7.24%, 70.35% ± 7.42%, and 58.29% ± 10.32% for FF in the healthy controls, mild OA, and advanced OA group, and 6.36 ± 1.19%, 6.08 ± 1.35%, and 5.69 ± 1.78% for UI, respectively, the statistical difference was found for FF (p < 0.01). A good negative correlation was observed between the FF and the severity of OA, Hoffa-synovitis (r = -0.625, -0.758, respectively, p < 0.0001), and a weak inverse correlation with knee pain. CONCLUSION: FF alteration in IFP is associated with the severity of OA, Hoffa synovitis, and knee pain, and has the potential to be a new quantitative imaging biomarker in knee OA.

Combining Magnetic Resonance Diffusion-Weighted Imaging with Prostate-Specific Antigen to Differentiate Between Malignant and Benign Prostate Lesions.

BACKGROUND We aimed to develop a combined model of quantitative parameters derived from 3 different magnetic resonance imaging (MRI) diffusion models and laboratory data related to prostate-specific antigen (PSA) for differentiating between prostate cancer (PCa) and benign lesions. MATERIAL AND METHODS Eighty-four patients pathologically confirmed as having PCa or benign disease were enrolled. All patients underwent multiparametric MRI before biopsy, added intravoxel incoherent motion (IVIM) imaging, and diffusion kurtosis imaging (DKI). The following data were collected: quantitative parameters of diffusion-weighted imaging (DWI), IVIM, and DKI, preoperative total PSA, free/total PSA ratio, and PSA density (PSAD) values. A combined logistic regression model was established by above MRI quantitative parameters and PSA data to diagnose PCa. The Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) was used to assess the lesions for comparison. RESULTS Thirty-two patients had PCa and 52 patients had benign lesions. In multivariate logistic regression analysis, only apparent diffusion coefficient (ADC) and PSAD were significant variables (P<0.05) and were thus retained in the model. The area under curve value of the combined model (0.911) was higher than that of ADC, PSAD, and PI-RADS v2 (0.887, 0.861, and 0.859, respectively) in univariate analysis, but without any statistically significant differences. The combined model generated greater clinical benefit than the independent application of ADC, PSAD, and PI-RADS v2. CONCLUSIONS ADC and PSAD were the 2 most important metrics for distinguishing PCa from benign lesions. The combined model of ADC and PSAD demonstrated satisfactory discrimination and improved clinical net benefit.

Use of intravoxel incoherent motion MRI to assess placental perfusion in normal and Fetal Growth Restricted pregnancies on their third trimester.

INTRODUCTION: Intravoxel Incoherent Motion (IVIM) MRI is a non-invasive, in vivo techniques which can assess placental perfusion quantitatively, and be useful for evaluating placental microcirculation. Our primary aim was to investigate whether fetal growth restriction (FGR) pregnancies have different placental perfusion and diffusion compared with normal pregnancies using IVIM. A secondary aim was to investigate correlations between placental IVIM parameters and gestational age in normal pregnancy. METHODS: This study population included 17 FGR pregnancies and 36 normal pregnancies between 28 + 3 to 38 + 0 weeks. All women underwent a MRI examination including an IVIM sequence with 9 b-values on a 3.0 T MRI system. The standard diffusion coefficeint (D), pseudodiffusion (D*) and perfusion fraction (f) were calculated. RESULTS: Placental f was significantly lower in the FGR group than that in the normal group (33.96 ± 2.62(%) vs 38.48 ± 5.31(%), p = 0.002). Placental D and D* in two groups showed no statistical significance (P > 0.05). Placental f moderately increased with increasing gestational age in normal pregnancies (r = 0.411, p = 0.013), and there existed a negative correlation between D values and gestational age (r = -0.390, p = 0.019). DISCUSSION: The f values are able to distinguish FGR from normal pregnancies. It can be uses as a feasible index to evaluate placenta perfusion. Gestational age-associated changes in placental IVIM parameters likely reveal trajectories of microvascular perfusion fraction and diffusion characteristics in the normal developing placenta.

Carotid arterial wall MRI of apolipoprotein e-deficient mouse at 7 T using DANTE-prepared variable-flip-angle rapid acquisition with relaxation enhancement.

PURPOSE: To optimize a sequence combining the delay alternating with nutation for tailored excitation (DANTE) preparative module with the variable-flip-angle rapid acquisition with relaxation enhancement (VF-RARE) sequence (DANTE-VF-RARE) and to investigate its feasibility for vessel wall imaging in Apolipoprotein E-Deficient (ApoE-/-) mouse at 7 Tesla (T). MATERIALS AND METHODS: Specific T1/T2 values were used for producing a sharper vessel wall in the variable-flip-angle optimization scheme. The DANTE RF pulse flip angle and pulse train length were optimized for maximizing the wall-lumen contrast. ApoE-/- (fed high fat diet for 20/40/ 60 weeks, n = 9/4/4) and wild-type mice (controls, n = 3) were imaged at 7 T using VF-RARE, DANTE-VF-RARE, time-of-flight (TOF) angiography, and multi-slice T1-weighted 2D RARE coupled with inflow outflow saturation bands (IOSB-RARE). Wall-lumen contrast-to-noise-ratio efficiency (CNReff), lumen area (LA), and wall area (WA) were compared between DANTE-VF-RARE and 2D IOSB-RARE sequences. Additionally, linear regression analysis was conducted between MR measurements and histomorphometric planimetry results. RESULTS: Residual blood signal was observed in the four out of eighteen carotids on VF-RARE images, whereas it was significantly suppressed on DANTE-VF-RARE images. Compared with IOSB-RARE, DANTE-VF-RARE offered significantly improved CNReff (P < 0.001). The LA and WA were both comparable (P = 0.085 and 0.112, respectively) and showed excellent agreement between DANTE-VF-RARE and IOSB-RARE (ICC = 0.96 and 0.95, respectively). The luminal stenosis identified by DANTE-VF-RARE was in consistent with the results of TOF. Strong correlations were found between MR measurements and histopathological analysis for both WA (DANTE-VF-RARE: r = 0.92, slope = 0.94, P < 0.001; IOSB-RARE: r = 0.93, slope = 0.94, P < 0.001) and LA (DANTE-VF-RARE: r = 0.82, slope = 0.54, P < 0.001; IOSB-RARE: r = 0.78, slope = 0.50, P < 0.001). CONCLUSION: DANTE-VF-RARE achieves effective blood signal suppression and is a feasible approach for the 3D carotid arterial wall imaging of ApoE-/- mouse at 7 T.

Inflow-based vascular-space-occupancy (iVASO) might potentially predict IDH mutation status and tumor grade in diffuse cerebral gliomas.

PURPOSE: The aim of the study is to assess the diagnostic performance of inflow-based vascular-space-occupancy (iVASO) MR imaging for differentiating glioblastomas (grade IV, GBM) and lower-grade diffuse gliomas (grade II and III, LGG) and its potential to predict IDH mutation status. METHODS: One hundred and two patients with diffuse cerebral glioma (56 males; median age, 43.5 years) underwent iVASO and dynamic susceptibility contrast (DSC) MR imaging. The iVASO-derived arteriolar cerebral blood volume (CBVa), relative CBVa (rCBVa), and the DSC-derived relative cerebral blood volume (rCBV) were obtained, and these measurements were compared between the GBM group (n = 43) and the LGG group (n = 59) and between the IDH-mutation group (n = 54) and the IDH-wild group (n = 48). RESULTS: Significant correlation was observed between rCBV and CBVa (P < 0.001) or rCBVa (P < 0.001). Both CBVa (P < 0.001) and rCBVa (P < 0.001) were higher in the GBM group. Both CBVa (P < 0.001) and rCBVa (P < 0.001) were lower in the IDH-mutation group compared to the IDH-wild group. Receiver operating characteristic analyses showed the area under curve (AUC) of 0.95 with CBVa and 0.97 with rCBVa in differentiating GBM from LGG. The AUCs were 0.82 and 0.85 for CBVa and rCBVa in predicting IDH gene status, respectively, which were lower than that of rCBV (AUC = 0.90). Combined rCBV and rCBVa significantly improved the diagnostic performance (AUC = 0.95). CONCLUSIONS: iVASO MR imaging has the potential to predict IDH mutation and grade in glioma.

Diffusion-weighted magnetic resonance imaging in rat kidney using two-dimensional navigated, interleaved echo-planar imaging at 7.0 T.

The purpose of this study was to investigate the feasibility of two-dimensional (2D) navigated, interleaved multishot echo-planar imaging (EPI) to enhance kidney diffusion-weighted imaging (DWI) in rats at 7.0 T. Fully sampled interleaved four-shot EPI with 2D navigators was tailored for kidney DWI (Sprague-Dawley rats, n = 7) on a 7.0-T small bore preclinical scanner. The image quality of four-shot EPI was compared with T2 -weighted rapid acquisition with relaxation enhancement (RARE) (reference) and single-shot EPI (ss-EPI) without and with parallel imaging (PI). The contrast-to-noise ratio (CNR) was examined to assess the image quality for the EPI approaches. The Dice similarity coefficient and the Hausdorff distance were used for evaluation of image distortion. Mean diffusivity (MD) and fractional anisotropy (FA) were calculated for renal cortex and medulla for all DWI approaches. The corticomedullary difference of MD and FA were assessed by Wilcoxon signed-rank test. Four-shot EPI showed the highest CNR among the three EPI variants and lowest geometric distortion versus T2 -weighted RARE (mean Dice: 0.77 for ss-EPI without PI, 0.88 for ss-EPI with twofold undersampling, and 0.92 for four-shot EPI). The FA map derived from four-shot EPI clearly identified a highly anisotropic region corresponding to the inner stripe of the outer medulla. Four-shot EPI successfully discerned differences in both MD and FA between renal cortex and medulla. In conclusion, 2D navigated, interleaved multishot EPI facilitates high-quality rat kidney DWI with clearly depicted intralayer and interlayer structure and substantially reduced image distortion. This approach enables the anatomic integrity of DWI-MRI in small rodents and has the potential to benefit the characterization of renal microstructure in preclinical studies.

Quantitative evaluation of bone marrow fat content and unsaturated fatty index in young male soccer players using proton magnetic resonance spectroscopy (1H-MRS): a preliminary study.

BACKGROUND: Marrow fat exists as a distinct adipose tissue and plays a critical role in affecting both the quantity and quality of bone. However, the effect of soccer training on marrow fat has been rarely reported. This study aims to evaluate and characterize the marrow fat content and composition in different bone areas of soccer players and age-matched healthy subjects using proton magnetic resonance spectroscopy (1H-MRS). METHODS: Between May 2020 and June 2020, 20 professional soccer players (20.7±0.9 years) and 20 age-matched healthy subjects (21.2±0.8 years) were enrolled in this cross-sectional study. The 1H-MRS were acquired from the 3rd lumbar vertebrae, bilateral femoral necks, and distal tibias of all subjects using a single-voxel point-resolved spatially localized spectroscopy (PRESS) sequence. Four soccer players underwent a second magnetic resonance (MR) examination within a 30-minute interval after the initial scan to evaluate test-retest reproducibility. Inter- and intra-observer measurement reliabilities were assessed using 10 randomly selected spectra from the soccer players group. All spectra were processed using the jMRUI software package (http://www.jmrui.eu/). Quantified water and lipid signals were used to calculate fat content (FC) and the unsaturated fatty index (UI). RESULTS: Compared with healthy subjects, we found that soccer players had a lower FC in L3 and bilateral femoral necks and higher UI in the left femoral neck (P<0.05). All FC and UI values of the bilateral distal tibias showed no significant differences between the two groups (P>0.05). The UI values of the right femoral neck or distal tibia were markedly higher than the left side in both inactive subjects and soccer players (P<0.05, except for the femoral neck in players), and there were notable ΔUI differences in the lower limbs between the soccer players and the healthy subjects (P<0.05). CONCLUSIONS: Soccer practice can be considered a positive sport that contributes to decreasing FC in lumbar vertebrae and femoral necks and increasing the UI in femoral necks. Quantitative MRS provides an ideal modality to predict marrow fat metabolism caused by mechanical stimulation.

Value of Magnetic Resonance Cholangiopancreatography in Santorinicele and Wirsungocele.

BACKGROUND: Former studies showed that magnetic resonance cholangiopancreatography (MRCP) is useful in diagnosing the presence of santorinicele; however, few studies have evaluated MRCP in diagnosing wirsungocele and the association between pancreatitis and santorinicele or wirsungocele. The purpose of the study was to explore the performance of MRCP in diagnosing santorinicele and wirsungocele and investigate the potential association among pancreatitis, pancreas divisum, and santorinicele or wirsungocele. METHODS: Sixty-five patients (mean age, 55.68 years; range, 11-82 years) with santorinicele or wirsungocele were included and sorted into two groups: the santorinicele group (n = 48) and the wirsungocele group (n = 17). All patients underwent MRCP. The images were evaluated for the appearance and size of santorinicele or wirsungocele. The diagnostic sensitivity of MRCP was assessed. Additionally, whether two groups are correlated with pancreas divisum or pancreatitis were investigated. RESULTS: The sensitivity of MRCP in detecting santorinicele and wirsungocele showed no difference (68.8% and 76.5%, respectively). The proportion of patients who developed pancreatitis in santorinicele and wirsungocele groups were 60.4% and 11.8%, respectively (p < 0.05). Pancreas divisum accounted for 77.1% and 11.8% of the patients in the santorinicele and wirsungocele groups, respectively (p < 0.05). Patients with santorinicele and pancreas divisum tended to be older when they acquired pancreatitis. CONCLUSION: MRCP could be an alternative imaging method to detect cystic dilation of the pancreatic duct. Pancreatitis is more common in patients with santorinicele than in those with wirsungocele. Moreover, santorinicele is more closely associated with pancreatitis than with pancreas divisum.

Physiological system analysis of the kidney by high-temporal-resolution T2∗ monitoring of an oxygenation step response.

PURPOSE: Examine the feasibility of characterizing the regulation of renal oxygenation using high-temporal-resolution monitoring of the T2∗ response to a step-like oxygenation stimulus. METHODS: For T2∗ mapping, multi-echo gradient-echo imaging was used (temporal resolution = 9 seconds). A step-like renal oxygenation challenge was applied involving sequential exposure to hyperoxia (100% O2 ), hypoxia (10% O2 + 90% N2 ), and hyperoxia (100% O2 ). In vivo experiments were performed in healthy rats (N = 10) and in rats with bilateral ischemia-reperfusion injury (N = 4). To assess the step response of renal oxygenation, a second-order exponential model was used (model parameters: amplitude [A], time delay [Δt], damping constant [D], and period of the oscillation [T]) for renal cortex, outer stripe of the outer medulla, inner stripe of the outer medulla, and inner medulla. RESULTS: The second-order exponential model permitted us to model the exponential T2∗ recovery and the superimposed T2∗ oscillation following renal oxygenation stimulus. The in vivo experiments revealed a difference in Douter medulla between healthy controls (D < 1, indicating oscillatory recovery) and ischemia-reperfusion injury (D > 1, reflecting aperiodic recovery). The increase in Douter medulla by a factor of 3.7 (outer stripe of the outer medulla) and 10.0 (inner stripe of the outer medulla) suggests that this parameter might be rather sensitive to (patho)physiological oxygenation changes. CONCLUSION: This study demonstrates the feasibility of monitoring the dynamic oxygenation response of renal tissues to a step-like oxygenation challenge using high-temporal-resolution T2∗ mapping. Our results suggest that the implemented system analysis approach may help to unlock questions regarding regulation of renal oxygenation, with the ultimate goal of providing imaging means for diagnostics and therapy of renal diseases.

T1 mapping and feature tracking imaging of left ventricular extracellular remodeling in severe aortic stenosis.

BACKGROUND: Left ventricular (LV) extracellular remodeling is a critical process in aortic stenosis (AS), which is related to functional abnormalities. Data regarding the use of combined T1 mapping and feature tracking (FT) to assess LV extracellular remodeling in severe AS are scarce. This study aimed to investigate the ability of T1-derived and FT-derived parameters to identify and assess the changes in process of LV extracellular remodeling in patients with severe AS. METHODS: A total of 49 patients with severe AS and 20 healthy volunteers were prospectively recruited. Modified look-locker inversion-recovery T1 mapping and FT imaging were performed in all participants using 3.0-T cardiac magnetic resonance imaging. The degree of myocardial fibrosis was quantified using Masson trichrome stain in biopsy specimens obtained intraoperatively from 13 patients and expressed as collagen volume fraction (CVF). Patients were divided into subgroups according to preserved LV ejection fraction (LVEF) (LVEF ≥50%) or reduced LVEF (LVEF <50%). RESULTS: Regarding the diffuse fibrosis burden, extracellular volume (ECV) was statistically insignificant between patients with preserved LVEF) and controls (28.0%±3.3% vs. 26.5%±2.3%, P>0.05). ECV in the reduced LVEF group (n=20) was significantly higher than that in the preserved LVEF group (n=29) (30.4%±3.9% vs. 28.0%±3.3%, P<0.05). Regarding the myocardial strain, global longitudinal strain (GLS) showed increasing impairment from the control group to the preserved LVEF AS group to the reduced LVEF AS group (-23.4%±3.3% vs. -18.6%±3.8% vs. -11.2%±4.8%, P<0.05). A significant correlation was found between ECV and CVF (r=0.64, P=0.020), whereas the correlation between GLS and CVF was insignificant. Significant correlations were observed between GLS and LV mass index (r=0.72, P=0.006) and LVEF (r=0.82, P<0.001). However, no correlations were found between ECV and LV mass index (P=0.172) and between ECV and LVEF (P=0.339). Discrimination of patients with preserved LVEF from controls, GLS yielded the best diagnostic performance as defined by the area of under the curve (-0.83), and GLS, ECV, and post-T1 were significant discriminators after regression analysis. CONCLUSIONS: In the process of LV extracellular remodeling in severe AS, ECV is the structural marker of extracellular fibrosis burden, and GLS is the functional marker before the fibrosis burden intensifies.

Applying Amide Proton Transfer-Weighted Imaging (APTWI) to Distinguish Papillary Thyroid Carcinomas and Predominantly Solid Adenomatous Nodules: Comparison With Diffusion-Weighted Imaging.

Background: Amide proton transfer-weighted (ATPw) imaging is a novel MRI technique that has been used to identify benign and malignant tumors. The present study evaluated the role of APTw imaging in differentiating papillary thyroid carcinoma from predominantly solid adenomatous nodule. Methods: This study included 24 cases of solitary papillary thyroid carcinoma, and 20 cases of solid adenomatous nodules. Normal thyroid tissues were examined in 12 healthy subjects. The healthy subjects, eight cases of adenomatous nodule with cystic degeneration, and 12 cases of thyroid goiter, were only considered in the descriptive analysis, not included in our statistical analysis. The mean APTw value and the apparent diffusion coefficients (ADCs) of papillary thyroid carcinoma and solid adenomatous nodule were compared via a Mann-Whitney U test and receiver operating characteristic (ROC)-curve analyses. Results: The adenomatous nodule (3.3 ± 1.3%) exhibited significantly higher APTw value (p < 0.05) than that of the papillary thyroid carcinoma (1.8 ± 0.7%). The optimal cut-off value of the mean APTw value in differentiating papillary thyroid carcinoma from adenomatous nodule was 3.15%, with a sensitivity of 60% and a specificity of 100%. The mean ADC of papillary thyroid carcinoma (1.2 ± 0.2 × 10-3 mm2/s) was significantly lower than that of adenomatous nodule (2.0 ± 0.4 × 10-3 mm2/s). The optimal cut-off value of the mean ADC was 1.35 × 10-3 mm2/s, with a sensitivity of 100% and a specificity of 75%. Based on the ROC-curve analysis of APT and ADC, the ADC showed a higher area under the curve (AUC) than that of APT (AUCAPT = 0.84, AUCADC = 0.95). Conclusion: APTw imaging may be as useful as DWI for the differentiation of papillary thyroid carcinoma from predominantly solid adenomatous nodule. Although the sensitivity of ADC was greater than that of APT, APT had greater specificity.

Non-Gaussian Diffusion Models and T1 rho Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in Rats.

BACKGROUND: Non-Gaussian diffusion models and T1 rho quantification may reflect the changes in tissue heterogeneity in hepatic sinusoidal obstruction syndrome (SOS). PURPOSE: To investigate the feasibility of diffusion kurtosis imaging (DKI), stretched exponential model (SEM), and T1 rho quantification in detecting and staging SOS in a monocrotaline (MCT)-induced rat model. STUDY TYPE: Animal study. POPULATION: Thirty male Sprague-Dawley rats gavaged with MCT to induce hepatic SOS and six male rats without any intervention. FIELD STRENGTH/SEQUENCE: 3.0T, DWI with five b-values (0-2000 s/mm2 ) and T1 rho with five spin lock times (1-60 msec). ASSESSMENT: MRI was performed 1 day before and 1, 3, 5, 7, and 10 days after MCT administration. The corrected apparent diffusion coefficient (Dapp ), kurtosis coefficient (Kapp ), distributed diffusion coefficient (DDC), and intravoxel water molecular diffusion heterogeneity (α) were calculated from the corresponding non-Gaussian diffusion model. The T1 rho value was calculated using a monoexponential model. Specimens obtained from the six timepoints were categorized into normal liver (n = 6), early-stage (n = 16), and late-stage (n = 14) SOS in accordance with the pathological score. STATISTICAL TESTS: Parametric statistical methods and receiver operating characteristic (ROC) curves were employed to determine diagnostic accuracy. RESULTS: The Dapp , Kapp , DDC, α, and T1 rho values were correlated with pathological score with r values of -0.821, 0.726, -0.828, -0.739, and 0.714 (all P < 0.001), respectively. DKI (combined Dapp and Kapp ) and SEM (combined DDC and α) were better than T1 rho for staging SOS. The areas under the ROC curve of DKI, SEM, and T1 rho for differentiating normal liver and early-stage SOS were 0.97, 1.00, and 0.79, whereas those of DKI, SEM, and T1 rho for differentiating early-stage and late-stage SOS were 1.00, 0.97, and 0.92, respectively. DATA CONCLUSION: DKI, SEM, and T1 rho may be helpful in staging SOS. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:1110-1121.

Combination of hepatocyte fraction and diffusion-weighted imaging as a predictor in quantitative hepatic fibrosis evaluation.

OBJECTIVE: To investigate the performance of the combined hepatocyte fraction (HepF) and apparent diffusion coefficient (ADC) values to stage hepatic fibrosis (HF) in patients with hepatitis B/C. MATERIALS AND METHODS: A total of 281 patients with hepatitis B/C prospectively underwent gadoxetate disodium-based T1 mapping and diffusion-weighted imaging. HepF was determined from pre and postcontrast T1 mapping with pharmacokinetics. The independent predictors of the HF stage (S0-4) were identified from HepF, ADC, conventional T1-based parameters, and age using a logistic regression analysis. The performances of independent and combined predictors in diagnosing various HF stages were compared by analyzing receiver operating characteristic curves. The intraclass correlation coefficient (ICC) was used to assess the interobserver reproducibility of each predictor. RESULTS: In total, 167 patients with various stages of HF were included. All measurements had excellent interobserver agreement (ICC ≥ 0.75). The hepatic relative enhancement, HepF ,and ADC values were significantly different among various HF stages (p < 0.05). The HepF and ADC were independent predictors of > S0, > S1, > S2 , and > S3 disease (p < 0.05). T1Liver, T1Spleen, and T1Liver/Spleen were independent predictors of S > 2 disease (p < 0.05). The performance of HepF combined with the ADC (area under the curve (AUC) = 0.84-0.95) was higher than HepF (AUC = 0.79-0.92) or ADC (AUC = 0.82-0.89) alone in diagnosing > S0, > S1, > S2 , and > S3 disease. CONCLUSION: The combined predictor of HepF and ADC shows acceptable performance for staging HF.

A robust electrical conductivity imaging method with total variation and wavelet regularization.

PURPOSE: This study aims to develop and evaluate a robust conductivity imaging method that combines total variation and wavelet regularization to enhance the accuracy of conductivity maps. THEORY AND METHODS: The proposed approach is based on a gradient-based method. The central equation is derived from Maxwell's equation and describes the relationship between conductivity and the transceive phase. A linear system equation is obtained via a finite-difference method and solved using a least-squares method. Total variation and wavelet transform regularization terms are added to the minimization problem and solved using the Split Bregman method to improve reconstruction stability. The proposed approach is compared with conventional and gradient-based methods. Numerical simulations are performed to validate the accuracy of the developed method, and the effects of noise are determined. Phantom and in vivo experiments are conducted at 3 T to verify the clinical applicability of the proposed method. RESULTS: Numerical simulations show that the proposed method is more robust than other methods and can suppress the effects of noise. The quantitative conductivity value of the phantom experiment agrees with the measured value. The in vivo experiment results present a clear structure, and the conductivity value of the tumor region is significantly higher than that around healthy tissues. CONCLUSION: The proposed electrical conductivity imaging method can improve the quality of conductivity reconstruction, and thus, has future clinical applications.

NiSe2/Ni(OH)2 Heterojunction Composite through Epitaxial-like Strategy as High-Rate Battery-Type Electrode Material.

Constructing heterojunction is a promising way to improve the charge transfer efficiency and can thus promote the electrochemical properties. Herein, a facile and effective epitaxial-like growth strategy is applied to NiSe2 nano-octahedra to fabricate the NiSe2-(100)/Ni(OH)2-(110) heterojunction. The heterojunction composite and Ni(OH)2 (performing high electrochemical activity) is ideal high-rate battery-type supercapacitor electrode. The NiSe2/Ni(OH)2 electrode exhibits a high specific capacity of 909 C g-1 at 1 A g-1 and 597 C g-1 at 20 A g-1. The assembled asymmetric supercapacitor composed of the NiSe2/Ni(OH)2 cathode and p-phenylenediamine-functional reduced graphene oxide anode achieves an ultrahigh specific capacity of 303 C g-1 at 1 A g-1 and a superior energy density of 76.1 Wh kg-1 at 906 W kg-1, as well as an outstanding cycling stability of 82% retention for 8000 cycles at 10 A g-1. To the best of our knowledge, this is the first example of NiSe2/Ni(OH)2 heterojunction exhibiting such remarkable supercapacitor performance. This work not only provides a promising candidate for next-generation energy storage device but also offers a possible universal strategy to fabricate metal selenides/metal hydroxides heterojunctions.