Global, interhemispheric and intrahemispheric functional connection patterns in male adults with alcohol use disorder.

A growing body of evidence indicates the existence of abnormal local and long-range functional connection patterns in patients with alcohol use disorder (AUD). However, it has yet to be established whether AUD is associated with abnormal interhemispheric and intrahemispheric functional connection patterns. In the present study, we analysed resting-state functional magnetic resonance imaging data from 55 individuals with AUD and 32 healthy nonalcohol users. For each subject, whole-brain functional connectivity density (FCD) was decomposed into ipsilateral and contralateral parts. Correlation analysis was performed between abnormal FCD and a range of clinical measurements in the AUD group. Compared with healthy controls, the AUD group exhibited a reduced global FCD in the anterior and middle cingulate gyri, prefrontal cortex and thalamus, along with an enhanced global FCD in the temporal, parietal and occipital cortices. Abnormal interhemispheric and intrahemispheric FCD patterns were also detected in the AUD group. Furthermore, abnormal global, contralateral and ipsilateral FCD data were correlated with the mean amount of pure alcohol and the severity of alcohol addiction in the AUD group. Collectively, our findings indicate that global, interhemispheric and intrahemispheric FCD may represent a robust method to detect abnormal functional connection patterns in AUD; this may help us to identify the neural substrates and therapeutic targets of AUD.

T1 mapping as a quantitative imaging biomarker for diagnosing cervical cancer: a comparison with diffusion kurtosis imaging.

BACKGROUND: T1 mapping can potentially quantitatively assess the intrinsic properties of tumors. This study was conducted to explore the ability of T1 mapping in distinguishing cervical cancer type, grade, and stage and compare the diagnostic performance of T1 mapping with diffusion kurtosis imaging (DKI). METHODS: One hundred fifty-seven patients with pathologically confirmed cervical cancer were enrolled in this prospectively study. T1 mapping and DKI were performed. The native T1, difference between native and postcontrast T1 (T1diff), mean kurtosis (MK), mean diffusivity (MD), and apparent diffusion coefficient (ADC) were calculated. Cervical squamous cell carcinoma (CSCC) and adenocarcinoma (CAC), low- and high-grade carcinomas, and early- and advanced-stage groups were compared using area under the receiver operating characteristic (AUROC) curves. RESULTS: The native T1 and MK were higher, and the MD and ADC were lower for CSCC than for CAC (all p < 0.05). Compared with low-grade CSCC, high-grade CSCC had decreased T1diff, MD, ADC, and increased MK (p < 0.05). Compared with low-grade CAC, high-grade CAC had decreased T1diff and increased MK (p < 0.05). Native T1 was significantly higher in the advanced-stage group than in the early-stage group (p < 0.05). The AUROC curves of native T1, MK, ADC and MD were 0,772, 0.731, 0.715, and 0.627, respectively, for distinguishing CSCC from CAC. The AUROC values were 0.762 between high- and low-grade CSCC and 0.835 between high- and low-grade CAC, with T1diff and MK showing the best discriminative values, respectively. For distinguishing between advanced-stage and early-stage cervical cancer, only the AUROC of native T1 was statistically significant (AUROC = 0.651, p = 0.002). CONCLUSIONS: Compared with DKI-derived parameters, native T1 exhibits better efficacy for identifying cervical cancer subtype and stage, and T1diff exhibits comparable discriminative value for cervical cancer grade.

A multicenter study of cervical cancer using quantitative diffusion-weighted imaging.

BACKGROUND: Parameters from diffusion-weighted imaging (DWI) have been increasingly used as imaging biomarkers for the diagnosis and monitoring of treatment responses in cancer. The consistency of DWI measurements across different centers remains uncertain, which limits the widespread use of quantitative DWI in clinical settings. PURPOSE: To investigate the consistency of quantitative metrics derived from DWI between different scanners in a multicenter clinical setting. MATERIAL AND METHODS: A total of 193 patients with cervical cancer from four scanners (MRI1, MRI2, MRI3, and MRI4) at three centers were included in this retrospective study. DWI data were processed using the mono-exponential and intravoxel incoherent motion (IVIM) model, yielding the following parameters: apparent diffusion coefficient (ADC); true diffusion coefficient (D); pseudo-diffusion coefficient (D*); perfusion fraction (f); and the product of f and D* (fD*). Various parameters of cervical cancer obtained from different scanners were compared. RESULTS: The parameters D and ADC derived from MRI1 and MRI2 were significantly different from those derived from MRI3 or MRI4 (P <0.01 for all comparisons). However, there was no significant difference in cervical cancer perfusion parameters (D* and fD*) between the different scanners (P >0.05). The P values of comparisons of all DWI parameters (D, D*, fD*, and ADC) between MRI3 and MRI4 (same vendor in different centers) for cervical cancer were all >0.05, except for f (P = 0.05). CONCLUSION: Scanners of the same model by the same vendor can yield close measurements of the ADC and IVIM parameters. The perfusion parameters showed higher consistency among the different scanners.

Prediction of Recurrent Cervical Cancer in 2-Year Follow-Up After Treatment Based on Quantitative and Qualitative Magnetic Resonance Imaging Parameters: A Preliminary Study.

PURPOSE: This study investigated predictors of cervical cancer (CC) recurrence from native T1 mapping, conventional imaging, and clinicopathologic metrics. PATIENTS AND METHODS: In total, 144 patients with histopathologically confirmed CC (90 with and 54 without surgical treatment) were enrolled in this prospective study. Native T1 relaxation time, conventional imaging, and clinicopathologic characteristics were acquired. The association of quantitative and qualitative parameters with post-treatment tumor recurrence was assessed using univariate and multivariate Cox proportional hazard regression analyses. Independent risk factors were combined into a model and individual prognostic index equation for predicting recurrence risk. The receiver operating characteristic (ROC) curve determined the optimal cutoff point. RESULTS: In total, 12 of 90 (13.3%) surgically treated patients experienced tumor recurrence. Native T1 values (X1) [hazard ratio (HR) 1.008; 95% confidence interval (CI) 1.001-1.016], maximum tumor diameter (X2) (HR 1.065; 95% CI 1.020-1.113), and parametrial invasion (X3) (HR 3.930; 95% CI 1.013-15.251) were independent tumor recurrence risk factors. The individual prognostic index (PI) of the established recurrence risk model was PI = 0.008X1 + 0.063X2 + 1.369X3. The area under the ROC curve (AUC) of the Cox regression model was 0.923. A total of 20 of 54 (37.0%) non-surgical patients experienced tumor recurrence. Native T1 values (X1) (HR 1.012; 95% CI 1.007-1.016) and lymph node metastasis (X2) (HR 4.064; 95% CI 1.378-11.990) were independent tumor recurrence risk factors. The corresponding PI was calculated as follows: PI = 0.011X1 + 1.402X2; the Cox regression model AUC was 0.921. CONCLUSIONS: Native T1 values combined with conventional imaging and clinicopathologic variables could facilitate the pretreatment prediction of CC recurrence.

T1 mapping and extracellular volume fraction measurement to evaluate the poor-prognosis factors in patients with cervical squamous cell carcinoma.

PURPOSE: To evaluate the clinical feasibility of T1 mapping and extracellular volume fraction (ECV) measurement in assessing prognostic factors in patients with cervical squamous cell carcinoma (CSCC). MATERIALS AND METHODS: A total of 117 CSCC patients and 59 healthy volunteers underwent T1 mapping and diffusion-weighted imaging (DWI) on a 3 T system. Native T1 , contrast-enhanced T1 , ECV, and apparent diffusion coefficient (ADC) were calculated and compared based on surgico-pathologically verified deep stromal infiltration, parametrial invasion (PMI), lymphovascular space invasion (LVSI), lymph node metastasis, stage, histologic grade, and the Ki-67 labeling index (LI). RESULTS: Native T1 , contrast-enhanced T1 , ECV, and ADC values were significantly different between CSCC and the normal cervix (all p < 0.05). No significant differences were observed in any parameters of CSCC when the tumors were grouped by stromal infiltration or lymph node status, respectively (all p > 0.05). In subgroups of the tumor stage and PMI, native T1 was significantly higher for advanced-stage (p = 0.032) and PMI-positive CSCC (p = 0.001). In subgroups of the grade and Ki-67 LI, contrast-enhanced T1 was significantly higher for high-grade (p = 0.012) and Ki-67 LI ≥ 50% tumors (p = 0.027). ECV was significantly higher in LVSI-positive CSCC than in LVSI-negative CSCC (p < 0.001). ADC values showed a significant difference for the grade (p < 0.001) but none for the other subgroups. CONCLUSION: Both T1 mapping and DWI could stratify the CSCC histologic grade. In addition, T1 mapping and ECV measurement might provide more quantitative metrics for noninvasively predicting poor prognostic factors and aiding in preoperative risk assessment in CSCC patients.

[Clinical characteristics and genetic analysis of a case with adult neuronal ceroid lipofuscinosis type 7 due to variant of MFSD8 gene].

OBJECTIVE: To explore the clinical characteristics and genetic variants in a patient with adult ceroid lipofuscinosis neuronal type 7 (ACLN7). METHODS: A female patient diagnosed with ACLN7 in Henan Provincial People's Hospital in June 2021 was selected as the study subject. Clinical data, auxiliary examination and result of genetic testing were retrospectively analyzed. RESULTS: The patient, a 39-year-old female, has mainly presented progressive visual loss, epilepsy, cerebellar ataxia and mild cognitive decline. Neuroimaging analysis has revealed generalized brain atrophy, prominently cerebellum. Fundus photography has revealed retinitis pigmentosa. Ultrastructural skin examination has revealed granular lipofuscin deposits in the periglandular interstitial cells. Whole exome sequencing revealed that she has harbored compound heterozygous variants of the MSFD8 gene, namely c.1444C>T (p.R482*) and c.104G>A (p.R35Q). Among these, c.1444C>T (p.R482*) was a well established pathogenic variant, while c.104G>A (p.R35Q) was a missense variant unreported previously. Sanger sequencing confirmed that the daughter, son and elder brother of the proband have respectively carried heterozygous c.1444C>T (p.R482*), c.104G>A (p.R35Q), and c.104G>A (p.R35Q) variants of the same gene. The family has therefore fit with the autosomal recessive inheritance pattern of the CLN7. CONCLUSION: Compared with previously reported cases, this patient has the latest onset of the disease with a non-lethal phenotype. Her clinical features have involved multiple systems. Cerebellar atrophy and fundus photography may be indicative of the diagnosis. The c.1444C>T (p.R482*) and c.104G>A (p.R35Q) compound heterozygous variants of the MFSD8 gene probably underlay the pathogenesis in this patient.

Encephalitis in Kikuchi-Fujimoto disease being immune-mediated.

INTRODUCTION: Histiocytic necrotizing lymphadenitis, also known as Kikuchi-Fujimoto disease, is a rare benign self-limiting inflammatory disease often seen in young adults. The main clinical features are fever with cervical lymphadenopathy. Neurological complications of Kikuchi-Fujimoto disease were occasionally reported although the specific pathogenesis was not clear. The condition could be severe when encephalitis coexists. METHODS: Here we reported a young case of Kikuchi-Fujimoto disease with subsequent severe autoimmune encephalitis. RESULTS: The symmetric striatal and limbic MRI lesions combined with psycho-cognitive, epileptic symptoms supported encephalitis. Tissue-based immunofluorescence revealed widely cytoplasmic fluorescence in rat cerebellar and hippocampal neurons, which provide evidence for immune-mediated encephalitis. The clinical outcome was satisfactory after immunosuppressive therapy with MRI lesions largely disappeared. CONCLUSION: The encephalitis complication of Kikuchi disease may be autoimmune and mediated by cytotoxic T cells.

Adult-onset autosomal dominant leukodystrophy and neuronal intranuclear inclusion disease: lessons from two new Chinese families.

INTRODUCTION: Adult-onset autosomal dominant leukodystrophy (ADLD) is a rare genetic leukoencephalopathy caused by duplication of the lamin B1 gene (LMNB1) or LMNB1 upstream deletions. Neuronal intranuclear inclusion disease (NIID) is another leukoencephalopathy due to GGC repeat expansion in the 5'-untranslated region of the NOTCH2NLC gene. Here, we report two Chinese ADLD families with neuroimaging and clinical features mimicking NIID. METHODS: We conducted detailed medical history inquiry, neurological examinations, and magnetic resonance imaging in the two families. Candidate gene sequencing and whole exome sequencing (WES) with copy number variation analysis were used to screen the genetic variations. The special points on the clinical and neuroimaging findings in the current families and differential diagnosis of ADLD with NIID are discussed. RESULTS: The two families presented with slowly progressive, multiple central nervous system symptoms, including spastic paraplegia, autonomic dysfunction, ataxia, deep sensory loss, and tremor. Clinical phenotypes were consistent within the family. Transient hypoglycemia and transient dilated pupils indicating autonomic dysfunctions were recorded for the first time in ADLD. Brain MRI showed band-like hyperintensities at the cortico-medullary junction on DWI, typical for NIID. Skin biopsy and genetic sequencing of the NOTCH2NCL gene did not support the diagnosis of NIID. Further whole exome sequencing (WES) identified the duplication mutation spanning the entire LMNB1 gene. CONCLUSIONS: The novel feature of transient hypoglycemia and dilated pupils broadens the spectrum of autonomic dysfunction in ADLD. Clinical manifestations and neuroimaging of ADLD can mimic NIID. Although ADLD is even rarer than NIID, the differential diagnosis of these two diseases should not be confused.

Watch out for neuromyelitis optica spectrum disorder after inactivated virus vaccination for COVID-19.

With recent availability of COVID-19 vaccine, post-vaccination neurological complications had been occasionally reported. Here, we reported for the first time a case of neuromyelitis optica spectrum disorder (NMOSD) that developed after the first dose of inactivated virus vaccine for COVID-19. The patient developed mild fever, vomiting, diarrhea, and cough after receiving the first dose of inactivated virus vaccine. Two months later, she experienced dizziness and unsteady walking. MRI scanning of the brain revealed lesions in area postrema and bilateral hypothalamus, typical for NMOSD. Serum antibodies for AQP4, ANA, SSA, SSB, Ro-52, and p-ANCA were positive. The patient was diagnosed as AQP4-positive NMOSD with coexisting systemic autoimmunity. After treatment with methylprednisolone (500 mg for 5 days), symptoms were greatly relieved. As NMOSD is seriously harmful and curative, it is important to be aware of the NMOSD symptoms after vaccination. Cautions should be given for those with preexisting systemic autoimmune abnormalities in vaccination for COVID-19.

Effects of acute mild hypoxia on cerebral blood flow in pilots.

BACKGROUND: Pilots often face and need to overcome a diverse range of unfavorable conditions, of which hypoxic exposure is the most common. Studies have reported that hypoxia can induce a decrease in cerebral blood flow (CBF) in the brains of both humans and animals. Hypoxia and the associated cerebral hemodynamic changes can contribute to cognitive performance deficits that may endanger flight safety and increase the risk of accidents. AIM: In this study, we aimed to identify region-specific alterations in CBF in male pilots after exposure to hypoxia. MATERIAL AND METHODS: We used 3D pseudo-continuous arterial spin labeling sequences in 35 healthy male pilots (mean age: 30.6 ± 4.82 years) under simulated hypoxic conditions with a 3.0-T magnetic resonance imaging scanner. The generated CBF maps were measured and averaged in several regions of interest. RESULTS: Hypoxia decreased CBF in various brain regions, including the right temporal and bilateral occipital lobes, the anterior and posterior lobes of the cerebellum, the culmen and declive, and the inferior semilunar lobule of the cerebellum. CONCLUSION: These changes may impact the functional activity of the brains of pilots experiencing hypoxia in flight, but the related mechanisms require further investigation.

Combined Diagnosis of Whole-Lesion Histogram Analysis of T1- and T2-Weighted Imaging for Differentiating Adrenal Adenoma and Pheochromocytoma: A Support Vector Machine-Based Study.

PURPOSE: This study aimed to determine whether a combined diagnosis of whole-lesion histogram analysis of T1- and T2-weighted imaging based on support vector machine (SVM) can distinguish pheochromocytoma from adrenal adenoma. METHODS: A pathology database was retrospectively appraised over a period of 7 years and we obtained 40 histopathologically proven adrenal adenomas and 20 pheochromocytomas with magnetic resonance images. The T1-weighted imaging (T1WI, including both in phase and opposed phase) and T2-weighted imaging (T2WI) images of each patients were analyzed using Mazda software. Nine parameters were selected as indicators of comparison: variance, skewness, kurtosis, mean, 1st percentile, 10th percentile, 50th percentile, 90th percentile, and 99th percentile. The parameters with differential-diagnosis significance were used to establish the combined diagnostic model of SVM. RESULTS: Among the 9 parameters extracted using histogram analysis, the 1st percentile, 10th percentile, and 50th percentile of T1WI (in phase) and the skewness of T2WI and almost all parameters of T1WI (opposed phase), except variance and 99th percentile, showed statistical significance between groups. Among the above parameters, the area under the curve (AUC) of 10th percentile of T1WI (opposed phase) was the largest with the value of 0.909 (100.0% sensitivity and 80.0% specificity). After the analysis of combined diagnosis was performed, the AUC of SVM model in testing set showed the value of 0.917 (85.0% accuracy). CONCLUSIONS: Whole-lesion histogram analysis of T1WI and T2WI may help differentiate adrenal adenomas from pheochromocytomas. Furthermore, the combined diagnosis of T1WI and T2WI histogram based on SVM was more effective than most of individual histogram parameters.

Novel T2 Mapping for Evaluating Cervical Cancer Features by Providing Quantitative T2 Maps and Synthetic Morphologic Images: A Preliminary Study.

BACKGROUND: The application value of T2 mapping in evaluating cervical cancer (CC) features remains unclear. PURPOSE: To investigate the role of T2 values in evaluating CC classification, grade, and lymphovascular space invasion (LVSI) in comparison to apparent diffusion coefficient (ADC), and to compare synthetic T2 -weighted (T2 W) images calculated from T2 values to conventional T2 W images for CC staging. STUDY TYPE: Retrospective. POPULATION: Sixty-three patients with histopathologically confirmed CC. FIELD STRENGTH/SEQUENCE: 3T, conventional T2 W turbo spin-echo, diffusion-weighted echo-planar, and accelerated T2 mapping sequence. ASSESSMENT: T2 and ADC values between different pathological features of CC were compared. The diagnostic accuracies of conventional and synthetic T2 W images in staging were also compared. STATISTICAL TESTS: Parameters were compared using an independent t-test, Wilcoxon signed-rank test, and the chi-square test. Receiver operating characteristic analysis was performed. RESULTS: The T2 values varied significantly between well/moderately differentiated and poorly differentiated tumors ([92.8 ± 9.5 msec] vs. [83.8 ± 9.5 msec], P < 0.05) and between LVSI-positive and LVSI-negative CC ([82.2 ± 8.2 msec] vs. [93.9 ± 9.1 msec], P < 0.05). The ADC values showed a significant difference for grade ([0.76 ± 0.10 × 10-3 mm2 /s] vs. [0.65 ± 0.11 × 10-3 mm2 /s], P < 0.05) and no difference for LVSI status ([0.71 ± 0.11× 10-3 mm2 /s] vs. [0.73 ± 0.12× 10-3 mm2 /s], P = 0.472). There was no significant difference in T2 and ADC values between squamous cell carcinoma and adenocarcinoma (P = 0.378 and P = 0.661, respectively). In MRI staging, the conventional and synthetic T2 W images resulted in a similar accuracy (71% vs. 68%, P = 0.698). DATA CONCLUSION: The accelerated T2 mapping sequence may facilitate grading and staging of CC by providing quantitative T2 maps and synthetic T2 W images in one acquisition. T2 values may be superior to ADC in predicting LVSI. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2 J. MAGN. RESON. IMAGING 2020;52:1859-1869.

Differentiating skull base chordomas and invasive pituitary adenomas with conventional MRI.

Background It is difficult to distinguish between invasive pituitary adenomas (IPAs) and skull base chordomas based on tumor location and clinical manifestations. Purpose To investigate the value of the apparent diffusion coefficient (ADC), T2-weighted (T2W) imaging, and dynamic contrast enhancement (DCE) in differentiating skull base chordomas and IPAs. Material and Methods Data for 21 patients with skull base chordomas and 27 patients with IPAs involving the paranasal sinus were retrospectively reviewed, and all diagnoses were pathologically confirmed. Each patient underwent conventional 3.0 T magnetic resonance imaging (MRI), including, ADC, T2W imaging, and DCE sequences. Regions of interest were drawn in the mass and in normal white matter on ADC maps and T2W imaging. The mean ADC, normal ADC, T2W imaging signal intensity (SI), and relative T2-weighted (rT2W) imaging values were measured. DCE parameters, including types of time signal-intensity curves (TIC), enhancement peak (EP), and maximum contrast enhancement ratio (MCER), were calculated. Differences between skull base chordomas and IPAs were evaluated using the independent samples t-test. Receiver operating characteristic (ROC) curve analyses were also performed. Results When comparing IPAs and chordomas, there were significant differences in mean ADC, normal ADC, rT2W imaging values, TIC, EP, and MCER ( P < 0.01). The areas under curves in the ROC analyses for normal ADC, mean ADC, T2W imaging, rT2W imaging, TIC, EP, and MCER were 1.0, 0.996, 1.0, 0.81, 0.987, and 0.987, respectively. Conclusion ADC, T2W imaging SI, and DCE-related parameters can contribute to the differential diagnosis of skull base chordomas and IPAs.

A novel SYNE1 gene mutation in a Chinese family of Emery-Dreifuss muscular dystrophy-like.

BACKGROUND: In the present study, a novel mutation in exon 46 at codon 2304 (G2304R) of the SYNE1 gene is described in a Chinese family (proband, mother, and sister) with Emery-Dreifuss muscular dystrophy-like, which clinically manifests as muscle weakness, muscle atrophy, joint contracture, and without significant cardiac abnormalities. METHODS: Clinical examination and neuroimaging of the captured target region and high-throughput sequencing were performed in a family of four generations. Muscle changes were evaluated using magnetic resonance imaging and muscle biopsies. RESULTS: Target region capture sequencing yielded a novel missense mutation in codon 2304 (G2304R), which is a heterozygous A to G point mutation at position 6910 (c.6910A > G) in exon 46 of SYNE1 leading to a glycine-to-arginine substitution (p.Gly2304Arg). The results were also identified by Sanger sequencing in three family members but not in the other three unaffected family members and 100 control subjects. CONCLUSIONS: This mutation is probably pathogenic and is the first of its kind reported in a familial Emery-Dreifuss muscular dystrophy-like.

[Research for the antiapoptotic mechanisms of bone marrow mesenchymal stem cells in the treatment of brain ischemia stroke].

OBJECTIVE: To evaluate the anti-apoptosis role of bone marrow mesenchymal stem cells (BMMCs) transplantation to cell cerebral brain ischemia mice. METHODS: BMMCs were separated through Ficoll from bone marrow, after amplified in vitro, flow cytometry was used to identify the surface markers. Then cells were transplanted into Middle cerebral artery occlusion (MACO) mice, in situ cell death detection kit and Western blot were used to examine the cell apoptosis. Immunofluorescence and Western blot were used to detect the expression of eNOS, ICAM-1, CD31 which are related to the repair of vascular endothelial cells. RESULTS: After BMMCs transplantation, the number of apoptosis cells was decreased from (78.2±1.4) to (12.8±3.0), P<0.05. The expression of eNOS (80.0±6.2 vs 31.2±1.6, P<0.01) and CD31 (85±3 vs 45±5, P<0.01), were higher than MACO, while ICAM-1 was lower than MACO (34.1±2.2 vs 85.2±2.8, P<0.01). CONCLUSION: BMMCs reduce the cell apoptosis of ischemia mice through regulate the expression of vascular endothelial cells relate genes.

Solid-State Electrolyte for Lithium-Air Batteries: A Review.

Traditional lithium-air batteries (LABs) have been seriously affected by cycle performance and safety issues due to many problems such as the volatility and leakage of liquid organic electrolyte, the generation of interface byproducts, and short circuits caused by the penetration of anode lithium dendrite, which has hindered its commercial application and development. In recent years, the emergence of solid-state electrolytes (SSEs) for LABs well alleviated the above problems. SSEs can prevent moisture, oxygen, and other contaminants from reaching the lithium metal anode, and their inherent performance can solve the generation of lithium dendrites, making them potential candidates for the development of high energy density and safety LABs. This paper mainly reviews the research progress of SSEs for LABs, the challenges and opportunities for synthesis and characterization, and future strategies are addressed.

Mechanism of groundwater recharge in the thick loess deposits by multiple environmental tracers.

The loess-covered region accounts for ∼10 % of global land surface. Because of dry climate and thick vadose zones, the subsurface water flux is low but the water storage is relatively large . As a result, the groundwater recharge mechanism is complicated and currently controversial (e.g., piston flow or dual mode with piston and preferential flow). Taking typical tablelands in China's Loess Plateau as example study area, this study aims to qualitatively and quantitively evaluate the forms/rates and controls of groundwater recharge considering space and time. We collected 498 precipitation, soil water and groundwater samples in 2014-2021 for hydrochemical and isotopic analysis (Cl-, NO3-, δ18O, δ2H, 3H and 14C). A graphical method was employed to determine appropriate model to correct 14C age. Dual model exhibited in the recharge: regional-scale piston flow and local-scale preferential flow. Piston flow dominated groundwater recharge with a proportion of 77 %-89 %. Preferential flow gradually declined with increasing water table depths, and the upper depth limit may be <40 m. The dynamics of tracers proved that mixing and dispersion effects of aquifers limited the ability of tracers to capture preferential flow at short-time scales. Long-term average potential recharge (79 ± 49 mm/year) was close to actual recharge (85 ± 41 mm/year) at the regional scale, indicating the hydraulic equilibrium between unsaturated and saturated zones. The thickness of vadose zone controlled recharge forms, and precipitation dominated the potential and actual recharge rates. Land-use change can also affect the potential recharge rates at point and field scales but maintain the dominance of piston flow. The revealed spatially-varied recharge mechanism is useful for groundwater modeling and the method can be referred for studying recharge mechanism in thick aquifers.

Synthetic MRI for the quantitative and morphologic assessment of head and neck tumors: a preliminary study.

OBJECTIVES: To evaluate the feasibility of synthetic MRI for quantitative and morphologic assessment of head and neck tumors and compare the results with the conventional MRI approach. METHODS AND MATERIALS: A total of 92 patients with different head and neck tumor histology who underwent conventional and synthetic MRI were retrospectively recruited. The quantitative T1, T2, proton density (PD), and apparent diffusion coefficient (ADC) values of 38 benign and 54 malignant tumors were measured and compared. Diagnostic efficacy for differentiating malignant and benign tumors was evaluated with receiver operating characteristic (ROC) analysis and integrated discrimination index. The image quality of conventional and synthetic T1W/T2W images on a 5-level Likert scale was also compared with Wilcoxon signed rank test. RESULTS: T1, T2 and ADC values of malignant head and neck tumors were smaller than those of benign tumors (all p < 0.05). T2 and ADC values showed better diagnostic efficacy than T1 for distinguishing malignant tumors from benign tumors (both p < 0.05). Adding the T2 value to ADC increased the area under the curve from 0.839 to 0.886, with an integrated discrimination index of 4.28% (p < 0.05). In terms of overall image quality, synthetic T2W images were comparable to conventional T2W images, while synthetic T1W images were inferior to conventional T1W images. CONCLUSIONS: Synthetic MRI can facilitate the characterization of head and neck tumors by providing quantitative relaxation parameters and synthetic T2W images. T2 values added to ADC values may further improve the differentiation of tumors.

[Temporal and Spatial Distribution Characteristics and Source Analysis of Nitrate in Surface Water of Wuding River Basin].

The Wuding River Basin is a first-class tributary of the Yellow River, and the quality of its water ecological environment has a profound impact on the ecological protection and high-quality development of the Yellow River Basin. In order to identify the source of nitrate pollution in the Wuding River Basin, surface water samples of the Wuding River were collected from 2019 to 2021, and the temporal and spatial distribution characteristics and influencing factors of nitrate concentration in surface water in the basin were explored. Nitrogen and oxygen isotope tracer technology and the MixSIAR model were used to qualitatively and quantitatively determine the sources of surface water nitrate and their contribution rates. The results showed that there were significant spatial and temporal differences in nitrate concentrations in the Wuding River Basin. In terms of time, the mean concentration of NO-3-N in surface water in the wet season was higher than that in the flat-water period; spatially, the mean concentration of NO-3-N in the downstream surface water was higher than that in the upstream. The spatial and temporal differences in surface water nitrate concentrations were mainly affected by rainfall runoff, soil types, and land use types. The main sources of nitrates in the surface water of the Wuding River Basin during the wet season were domestic sewage, manure, chemical fertilizers, and soil organic nitrogen, whose contribution rates were 43.3%, 27.6%, and 22.1%, respectively, and the contribution rate of precipitation was only 7.0%. There were differences in the contribution rate of nitrate pollution sources in surface water of different river sections. The contribution rate of soil nitrogen in the upstream was significantly higher than that in the downstream, which was 26.5%. The contribution rate of domestic sewage and manure in the downstream was significantly higher than that in the upstream, which was 48.9%. To provide a basis for the analysis of nitrate sources and pollution control in Wuding River and even rivers in arid and semi-arid regions.