Magnetic resonance imaging-based interpretation of degenerative changes in the lower lumbar segments and therapeutic consequences

Intervertebral disc degeneration and facet joint osteoarthritis of the lumbar spine are, among others, wellknown as a cause of low back and lower extremity pain. Together with their secondary disorders they set a big burden on health care systems and economics worldwide. Despite modern imaging modalities, such as magnetic resonance imaging, for a large proportion of patients with low back pain(LBP) it remains difficult to provide a specific diagnosis. The fact that nearly all the lumbar structures are possible sources of LBP, may serve as a possible explanation. Furthermore, our clinical experience confirms, that imaging alone is not a sufficient approach explaining LBP. Here, the Oswestry Disability Index, as the most commonly used measure to quantify disability for LBP, may serve as an easy-toapply questionnaire to evaluate the patient's ability to cope with everyday life. For therapeutic purposes, among the different options, the lumbar facet joint intraarticular injection of corticosteroids in combination with an anaesthetic solution is one of the most frequently performed interventional procedures. Although widely used the clinical benefit of intra-articular steroid injections remains controversial. Therefore, prior to therapy, standardized diagnostic algorithms for an accurate assessment, classification and correlation of degenerative changes of the lumbar spine are needed.

EVALUATION OF NEUROPROTECTIVE EFFECTS OF LONG-TERM LOW DOSE HORMONE REPLACEMENT THERAPY ON POSTMENOPAUSAL WO-MEN BRAIN HIPPOCAMPUS USING MAGNETIC RESONANCE SCANNER

To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol （E2 ） 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay （ELISA）. The gene types of apolipoprotein E （ApoE） were measured by polymerase chain reaction, and the subjects with susceptible genes （ ApoE ε3/ε4） of Alzheimer＇s disease （AD） were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging （MRI）, and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher （P 〈0. 05） except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 14 cases, control group 11 cases） showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group （0. 406 ± 0.028） was signiticantlyhigher than control gronp （0.369±0.031, P〈0.05）. Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 （ HRT group 12 cases, control group 11 cases） showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group （ 1.54±0. 08 ） were significantly higher than control group （ 1.45±0. 13, P 〈 0. 05）. Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.

Sacrum magnetic resonance imaging for low back and tail bone pain:A quality initiative to evaluate and improve imaging utility

As quality and cost effectiveness become essential in clinical practice,an evidencebased evaluation of the utility of imaging orders becomes an important consideration for radiology’s value in patient care.We report an institutional quality improvement project including a retrospective review of utility of sacrum magnetic resonance(MR)imaging for low back pain at our institution over a four-year period and follow-up results after physician education intervention.Sacral MR imaging for low back pain and tailbone pain were only positive for major findings in 2/98(2%)cases,and no major changes in patient management related to imaging findings occurred over this period,resulting in almost$500000 cost without significant patient benefit.We distributed these results to the Family Medicine department and clinics that frequently placed this order.An approximately 83%drop in ordering rate occurred over the ensuing 3 mo follow-up period.Sacrum MR imaging for low back pain and tail bone pain has not been a cost-effective diagnostic tool at our institution.Physician education was a useful tool in reducing overutilization of this study,with a remarkable drop in such studies after sharing these findings with primary care physicians at the institution.In conclusion,sacrum MR imaging rarely elucidates the cause of low back/tail pain diagnosed in a primary care setting and is even less likely to result in major changes in management.The practice can be adopted in other institutions for the benefit of their patients and improve cost efficiency.

Generalized Nonconvex Low-Rank Algorithm for Magnetic Resonance Imaging (MRI) Reconstruction

In recent years,utilizing the low-rank prior information to construct a signal from a small amount of measures has attracted much attention.In this paper,a generalized nonconvex low-rank(GNLR) algorithm for magnetic resonance imaging(MRI)reconstruction is proposed,which reconstructs the image from highly under-sampled k-space data.In the algorithm,the nonconvex surrogate function replacing the conventional nuclear norm is utilized to enhance the low-rank property inherent in the reconstructed image.An alternative direction multiplier method(ADMM) is applied to solving the resulting non-convex model.Extensive experimental results have demonstrated that the proposed method can consistently recover MRIs efficiently,and outperforms the current state-of-the-art approaches in terms of higher peak signal-to-noise ratio(PSNR) and lower high-frequency error norm(HFEN) values.

Performance study of aluminum shielded room for ultra-low-field magnetic resonance imaging based on SQUID： Simulations and experiments

The aluminum shielded room has been an important part of ultra-low-field magnetic resonance imaging （ULF MRI） based on the superconducting quantum interference device （SQUID）. The shielded room is effective to attenuate the external radio-frequency field and keep the extremely sensitive detector, SQUID, working properly. A high-performance shielded room can increase the signal-to-noise ratio （SNR） and improve image quality. In this study, a circular coil with a diameter of 50 cm and a square coil with a side length of 2.0 m was used to simulate the magnetic fields from the nearby electric apparatuses and the distant environmental noise sources. The shielding effectivenesses （SE） of the shielded room with different thicknesses of aluminum sheets were calculated and simulated. A room using 6-mm-thick aluminum plates with a dimension of 1.5 m x 1.5 m x 2.0 m was then constructed. The SE was experimentally measured by using three-axis SQUID magnetometers, with tranisent magnetic field induced in the aluminum plates by the strong pre-polarization pulses. The results of the measured SE agreed with that from the simulation. In addition, the introduction of a 0.5-mm gap caused the obvious reduction of SE indicating the importance of door design. The nuclear magnetic resonance （NMR） signals of water at 5.9 kHz were measured in free space and in a shielded room, and the SNR was improved from 3 to 15. The simulation and experimental results will help us design an aluminum shielded room which satisfies the requirements for future ULF human brain imaging. Finally, the cancellation technique of the transient eddy current was tried, the simulation of the cancellation technique will lead us to finding an appropriate way to suppress the eddy current fields.

Correlation of lumbar lateral recess stenosis in magnetic resonance imaging and clinical symptoms

AIM To assess the correlation of lateral recess stenosis(LRS) of lumbar segments L4/5 and L5/S1 and the Oswestry Disability Index(ODI).METHODS Nine hundred and twenty-seven patients with history of low back pain were included in this uncontrolled study.On magnetic resonance images(MRI) the lateral recesses(LR) at lumbar levels L4/5 and L5/S1 were evaluated and each nerve root was classified into a 4-point grading scale(Grade 0-3) as normal,not deviated,deviated or compressed.Patient symptoms and disability were assessed using ODI.The Spearman's rank correlation coefficient was used for statistical analysis(P < 0.05).RESULTS Approximately half of the LR revealed stenosis(grade 1-3;52% at level L4/5 and 42% at level L5/S1) with 2.2% and 1.9% respectively reveal a nerve root compression.The ODI score ranged from 0%-91.11% with an arithmetic mean of 34.06% ± 16.89%.We observed a very weak statistically significant positive correlation between ODI and LRS at lumbar levels L4/5 and L5/S1,each bilaterally(L4/5 left:rho < 0.105,P < 0.01;L4/5 right:rho < 0.111,P < 0.01;L5/S1 left:rho 0.128,P < 0.01;L5/S1 right:rho < 0.157,P < 0.001).CONCLUSION Although MRI is the standard imaging tool for diagnosing lumbar spinal stenosis,this study showed only a weak correlation of LRS on MRI and clinical findings.This can be attributed to a number of reasons outlined in this study,underlining that imaging findings alone are not sufficient to establish a reliable diagnosis for patients with LRS.

Spectrum of magnetic resonance imaging findings in congenital lumbar spinal stenosis

AIM: To investigate whether congenital lumbar spinal stenosis(CLSS) is associated with a specific degenerative changes of the lumbar spine. METHODS: The lumbar spine magnetic resonance imaging studies of 52 subjects with CLSS and 48 control subjects were retrospectively evaluated. In each examination, the five lumbar levels were assessed for the presence or absence of circumferential or shallow annular bulges, annular tears, anterior or posterior disc herniations, epidural lipomatosis, Schmorl's nodes,spondylolisthesis, pars defects, and stress reactions of the posterior vertebral elements. RESULTS: Compared to control individuals, subjects with CLSS exhibited increased incidence of circumferential and shallow annular bulges, annular tears, discherniations and spondylolisthesis(P < 0.05). CONCLUSION: CLSS is associated with increased incidence of degenerative changes in specific osseous and soft-tissue elements of the lumbar spine.

Magnetic resonance imaging-based deep learning model to predict multiple firings in double-stapled colorectal anastomosis

BACKGROUND Multiple linear stapler firings during double stapling technique(DST)after laparoscopic low anterior resection(LAR)are associated with an increased risk of anastomotic leakage(AL).However,it is difficult to predict preoperatively the need for multiple linear stapler cartridges during DST anastomosis.AIM To develop a deep learning model to predict multiple firings during DST anastomosis based on pelvic magnetic resonance imaging(MRI).METHODS We collected 9476 MR images from 328 mid-low rectal cancer patients undergoing LAR with DST anastomosis,which were randomly divided into a training set(n=260)and testing set(n=68).Binary logistic regression was adopted to create a clinical model using six factors.The sequence of fast spin-echo T2-weighted MRI of the entire pelvis was segmented and analyzed.Pure-image and clinical-image integrated deep learning models were constructed using the mask region-based convolutional neural network segmentation tool and three-dimensional convolutional networks.Sensitivity,specificity,accuracy,positive predictive value(PPV),and area under the receiver operating characteristic curve(AUC)was calculated for each model.RESULTS The prevalence of≥3 linear stapler cartridges was 17.7%(58/328).The prevalence of AL was statistically significantly higher in patients with≥3 cartridges compared to those with≤2 cartridges(25.0%vs 11.8%,P=0.018).Preoperative carcinoembryonic antigen level>5 ng/mL(OR=2.11,95%CI 1.08-4.12,P=0.028)and tumor size≥5 cm(OR=3.57,95%CI 1.61-7.89,P=0.002)were recognized as independent risk factors for use of≥3 linear stapler cartridges.Diagnostic performance was better with the integrated model(accuracy=94.1%,PPV=87.5%,and AUC=0.88)compared with the clinical model(accuracy=86.7%,PPV=38.9%,and AUC=0.72)and the image model(accuracy=91.2%,PPV=83.3%,and AUC=0.81).CONCLUSION MRI-based deep learning model can predict the use of≥3 linear stapler cartridges during DST anastomosis in laparoscopic LAR surgery.This model might help determine the best anastomosis strategy by avoiding DST when there is a high probability of the need for≥3 linear stapler cartridges.

High-resolution,three-dimensional magnetic resonance imaging axial load dynamic study improves diagnostics of the lumbar spine in clinical practice

BACKGROUND The response to axial physiological pressure due to load transfer to the lumbar spine structures is among the various back pain mechanisms.Understanding the spine adaptation to cumulative compressive forces can influence the choice of personalized treatment strategies.AIM To analyze the impact of axial load on the spinal canal’s size,intervertebral foramina,ligamenta flava and lumbosacral alignment.METHODS We assessed 90 patients using three-dimensional isotropic magnetic resonance imaging acquisition in a supine position with or without applying an axial compression load.Anatomical structures were measured in the lumbosacral region from L1 to S1 in lying and axially-loaded magnetic resonance images.A paired t test atα=0.05 was used to calculate the observed differences.RESULTS After axial loading,the dural sac area decreased significantly,by 5.2%on average(4.1%,6.2%,P<0.001).The intervertebral foramina decreased by 3.4%(2.7%,4.1%,P<0.001),except for L5-S1.Ligamenta flava increased by 3.8%(2.5%,5.2%,P<0.001),and the lumbosacral angle increased.CONCLUSION Axial load exacerbates the narrowing of the spinal canal and intervertebral foramina from L1-L2 to L4-L5.Cumulative compressive forces thicken ligamenta flava and exaggerate lumbar lordosis.

Correlations between hippocampal functional connectivity,structural changes,and clinical data in patients with relapsing-remitting multiple sclerosis:a case-control study using multimodal magnetic resonance imaging

Multiple sclerosis is associated with structural and functional brain alterations leading to cognitive impairments across multiple domains including attention,memory,and the speed of information processing.The hippocampus,which is a brain important structure involved in memory,undergoes microstructural changes in the early stage of multiple sclerosis.In this study,we analyzed hippocampal function and structure in patients with relapsing-remitting multiple sclerosis and explored correlations between the functional connectivity of the hippocampus to the whole brain,changes in local brain function and microstructure,and cognitive function at rest.We retrospectively analyzed data from 20 relapsing-remitting multiple sclerosis patients admitted to the Department of Neurology at the China-Japan Union Hospital of Jilin University,China,from April 2015 to November 2019.Sixteen healthy volunteers were recruited as the healthy control group.All participants were evaluated using a scale of extended disability status and the Montreal cognitive assessment within 1 week before and after head diffusion tensor imaging and functional magnetic resonance imaging.Compared with the healthy control group,the patients with relapsing-remitting multiple sclerosis had lower Montreal cognitive assessment scores and regions of simultaneously enhanced and attenuated whole-brain functional connectivity and local functional connectivity in the bilateral hippocampus.Hippocampal diffusion tensor imaging data showed that,compared with the healthy control group,patients with relapsing-remitting multiple sclerosis had lower hippocampal fractional anisotropy values and higher mean diffusivity values,suggesting abnormal hippocampal structure.The left hippocampus whole-brain functional connectivity was negatively correlated with the Montreal cognitive assessment score(r=-0.698,P=0.025),and whole-brain functional connectivity of the right hippocampus was negatively correlated with extended disability status scale score(r=-0.649,P=0.042).The mean diffusivity value of the left hippocampus was negatively correlated with the Montreal cognitive assessment score(r=-0.729,P=0.017)and positively correlated with the extended disability status scale score(r=0.653,P=0.041).The right hippocampal mean diffusivity value was positively correlated with the extended disability status scale score(r=0.684,P=0.029).These data suggest that the functional connectivity and presence of structural abnormalities in the hippocampus in patients with relapse-remission multiple sclerosis are correlated with the degree of cognitive function and extent of disability.This study was approved by the Ethics Committee of China-Japan Union Hospital of Jilin University,China(approval No.201702202)on February 22,2017.

Application of nuclear magnetic resonance technology to carbon capture,utilization and storage:A review

Carbon capture,utilization and storage (CCUS) is considered as a very important technology for mitigating global climate change.Carbon dioxide (CO2) injected into an underground reservoir will induce changes in its physical properties and the migration of CO2 will be affected by many factors.Accurately understanding these changes and migration characteristics of CO2 is crucial for selecting a CCUS project site,estimating storage capacity and ensuring storage security.In this paper,the basic principles of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) technologies are briefly introduced in the context of laboratory experiments related to CCUS.The types of NMR apparatus,experimental samples and testing approaches applied worldwide are discussed and analyzed.Then two typical NMR core analysis systems used in CCUS field and a self-developed high-pressure,low-field NMR rock core flooding experimental system are compared.Finally,a summary of the current deficiencies related to NMR applied to CCUS field is given and future research plans are proposed.

Abnormal brain activity in adolescents with Internet addiction who attempt suicide: an assessment using functional magnetic resonance imaging

Internet addiction is associated with an increased risk of suicidal behavior and can lead to brain dysfunction among adolescents.However,whether brain dysfunction occurs in adolescents with Internet addiction who attempt suicide remains unknown.This observational cross-sectional study enrolled 41 young Internet addicts,aged from 15 to 20 years,from the Department of Psychiatry,the First Affiliated Hospital of Chongqing Medical University,China from January to May 2018.The participants included 21 individuals who attempted suicide and 20 individuals with Internet addiction without a suicidal attempt history.Brain images in the resting state were obtained by a 3.0 T magnetic resonance imaging scanner.The results showed that activity in the gyrus frontalis inferior of the right pars triangularis and the right pars opercularis was significantly increased in the suicidal attempt group compared with the non-suicidal attempt group.In the resting state,the prefrontal lobe of adolescents who had attempted suicide because of Internet addiction exhibited functional abnormalities,which may provide a new basis for studying suicide pathogenesis in Internet addicts.The study was authorized by the Ethics Committee of Chongqing Medical University,China(approval No.2017 Scientific Research Ethics(2017-157))on December 11,2017.

A Novel Model of Predicting Archie's Cementation Factor from Nuclear Magnetic Resonance(NMR) Logs in Low Permeability Reservoirs

The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin, Northwest China, illustrate that the cementation factors are not agminate, but vary from 1.335 to 1.749. This leads to a challenge for the estimation of water and hydrocarbon sa- turation. Based on the analysis of Purcell equation and assumption that rock resistivity is determined by the parallel connection of numerous capillary resistances, a theoretical expression of cementation factor in terms of porosity and permeability is established. Then, cementation factor can be calculated if the parameters of porosity and permeability are determined. In the field application, porosity can be easily obtained by conventional logs. However, it is a tough challenge to estimate permeability due to the strong heterogeneity of low permeability reservoirs. Thus, the Schlumberger Doll Research （SDR） model derived from NMR logs has been proposed to estimate permeability. Based on the analysis of the theoretical expressions of cementation factor and SDR model, a novel cementation factor prediction model, which is relevant to porosity and logarithmic mean of NMR T2 spectrum （T21m）, is derived. The advantage of this model is that all the input information can be acquired from NMR logs accurately. In order to confirm the credibility of the novel model, the resistivity and corresponding laboratory NMR measurements of 27 core samples are conducted. The credibility of the model is confirmed by compar- ing the predicted cementation factors with the core analyzed results. The absolute errors for all core samples are lower than 0.071. Once this model is extended to field application, the accuracy of water and hydrocarbon saturation estimation will be significantly improved.

Analysis of the differences in brain function response after acupuncture and moxibustion at Zusanli(足三里ST36)in the patients with functional dyspepsia based on fractional amplitude of low frequency fluctuation of rest functional magnetic resonance imaging

Objective:To explore the differences in the central response after acupuncture and moxibusbution at Zusanli(足三里ST36) in treatment of functional dyspepsia(FD) based on the analysis of fractional amplitude of low frequency fluctuation(fALFF) of resting-state functional magnetic resonance imaging(rfMRI).Methods:A total of 60 patients with FD were randomized into an acupuncture group and a moxibustion group,30 cases in each one.In the acupuncture group,acupuncture was applied to bilateral ST36.In the moxibustion group,moxibustion was exerted at bilateral ST36.The treatment was given once a day,5 times a week,totally for 4 weeks in each group,including 20 treatments with acupuncture or moxibustion.Separately,before and at the end of treatment,rfMRI scanning was conducted in two groups.Using data processing assistant for resting-state fMRI(DPARSF) software and MATLAB data platform,rfMRI data were collected for preprocessing and fALFF analysis.Results:Compared with the data before treatment,after treated with acupuncture at ST36 in FD patients,fALFF value was reduced in the right superior frontal gyrus,left superior frontal gyrus,left inferior frontal gyrus,right cuneus,left precuneus,right middle occipital gyrus,left middle occipital gyrus,etc.,and it was increased in the left parahippocampus,right parahippocampus,left cerebellum,etc(all P <0.01).After treated with moxibustion,the remarkable increase of fALFF was not discovered in brain areas,but fALFF decreased significantly in the left superior parietal gyrus(P <0.01).Compared with moxibustion at ST36,after acupuncture at ST36 in FD patients,the increase of fALFF appeared in the right putamen and the decrease of it occurred in the middle occipital gyrus,indicating the statistical significance(both P <0.05).Conclusion:The differences in central function responses are induced in treamtent with acupuncture and moxibustion,which is probably related to the resting-state default network associated with targeted regulation and ventral attention of brain areas in functional dyspepsia.

Abnormal intrinsic brain activity in amnestic mild cognitive impairment revealed by amplitude of low-frequency fluctuation： a resting-state functional magnetic resonance imaging study

Background Previous studies have shown that brain functional activity in the resting state is impaired in Alzheimer＇s disease （AD） patients. However, alterations in intrinsic brain activity patterns in mild cognitive impairment （MCI） patients are poorly understood. This study aimed to explore the differences in regional intrinsic activities throughout the whole brain between aMCI patients and controls. Methods In the present study, resting-state functional magnetic resonance imaging （fMRI） was performed on 18 amnestic MCI （aMCI） patients, 18 mild AD patients and 20 healthy elderly subjects. And amplitude of low-frequency fluctuation （ALFF） method was used. Results Compared with healthy elderly subjects, aMCI patients showed decreased ALFF in the right hippocampus and parahippocampal cortex, left lateral temporal cortex, and right ventral medial prefrontal cortex （vMPFC） and increased ALFF in the left temporal-parietal junction （TPJ） and inferior parietal Iobule （IPL）. Mild AD patients showed decreased ALFF in the left TPJ, posterior IPL （plPL）, and dorsolateral prefrontal cortex compared with aMCI patients. Mild AD patients also had decreased ALFF in the right posterior cingulate cortex, right vMPFC and bilateral dorsal MPFC （dMPFC） compared with healthy elderly subjects. Conclusions Decreased intrinsic activities in brain regions closely related to episodic memory were found in aMCI and AD patients. Increased TPJ and IPL activity may indicate compensatory mechanisms for loss of memory function in aMCI patients. These findings suggest that the fMRI based on ALFF analysis may provide a useful tool in the study of aMCI patients.

Gradient-Based Low Rank Method for Highly Undersampled Magnetic Resonance Imaging Reconstruction

Recently, exploiting low rank property of the data accomplished by the non-convex optimization has shown great potential to decrease measurements for compressed sensing. In this paper, the low rank regularization is adopted to gradient similarity minimization, and applied for highly undersampled magnetic resonance imaging(MRI) reconstruction, termed gradient-based low rank MRI reconstruction(GLRMRI). In the proposed method,by incorporating the spatially adaptive iterative singular-value thresholding(SAIST) to optimize our gradient scheme, the deterministic annealing iterates the procedure efficiently and superior reconstruction performance is achieved. Extensive experimental results have consistently demonstrated that GLRMRI recovers both realvalued MR images and complex-valued MR data accurately, especially in the edge preserving perspective, and outperforms the current state-of-the-art approaches in terms of higher peak signal to noise ratio(PSNR) and lower high-frequency error norm(HFEN) values.

Combining quantitative and qualitative magnetic resonance imaging features to differentiate anorectal malignant melanoma from low rectal cancer

Background:Distinguishing anorectal malignant melanoma from low rectal cancer remains challenging because of the overlap of clinical symptoms and imaging findings.We aim to investigate whether combining quantitative and qualitative magnetic resonance imaging(MRI)features could differentiate anorectal malignant melanoma from low rectal cancer.Methods:Thirty-seven anorectal malignant melanoma and 98 low rectal cancer patients who underwent preoperative rectal MRI from three hospitals were retrospectively enrolled.All patients were divided into the primary cohort(N=84)and validation cohort(N=51).Quantitative image analysiswas performed on T1-weighted(T1WI),T2-weighted(T2WI),and contrast-enhanced T1-weighted imaging(CE-T1WI).The subjective qualitative MRI findings were evaluated by two radiologists in consensus.Multivariable analysis was performed using stepwise logistic regression.The discrimination performance was assessed by the area under the receiver operating characteristic curve(AUC)with a 95%confidence interval(CI).Results:The skewness derived from T2WI(T2WI-skewness)showed the best discrimination performance among the entire quantitative image features for differentiating anorectal malignant melanoma from low rectal cancer(primary cohort:AUC=0.852,95%CI 0.788–0.916;validation cohort:0.730,0.645–0.815).Multivariable analysis indicated that T2WI-skewness and the signal intensity of T1WI were independent factors,and incorporating both factors achieved good discrimination performance in two cohorts(primary cohort:AUC=0.913,95%CI 0.868–0.958;validation cohort:0.902,0.844–0.960).Conclusions:Incorporating T2WI-skewness and the signal intensity of T1WI achieved good performance for differentiating anorectal malignant melanoma from low rectal cancer.The quantitative image analysis helps improve diagnostic accuracy.

利用低场核磁共振技术探究机械损伤对蓝莓果实内部水分状态的影响

本研究采用自制损伤装置制作不同损伤等级样本(DI组(撞击1次)和DII组(撞击不同位置2次)),利用低场核磁共振技术,在4℃和25℃两种贮存温度条件下,采集蓝莓损伤发生0、6、24 h的波谱信息和质子密度图像信息。结果表明,损伤显著改变了蓝莓内部水分状态与分布。随着时间的延长,受损蓝莓细胞壁水含量A21减少,而细胞质水含量A22在损伤发生后逐渐上升,特别在损伤程度高的DII组,损伤发生24 h后A22增至0 h的1.45倍以上,而液泡水含量A23和总水分含量A2大幅度下降,表明蓝莓损伤后水分重新分配和向外界环境迅速转移。随着损伤程度上升,液泡水主峰整体呈现显著下降和右移的趋势,同时温度的升高进一步加剧了该变化。在25℃条件下,损伤发生6 h和24 h时,出现了4个弛豫峰,弛豫峰的增加标志着蓝莓品质显著劣变。相比于室温(25℃),4℃低温贮存有利于保持果实的完整性,并减缓受损蓝莓水分流失速率。实验结果可为实现蓝莓机械损伤的快速检测和损伤机理研究提供理论基础和数据参考。

油炸条件对猪里脊品质和杂环胺形成的影响

猪肉含有丰富的膳食蛋白质、维生素及矿物质等营养素,食用历史悠久,在中国的饮食文化中占据举足轻重的地位。高蛋白食品在高温热加工过程中易产生杂环胺类风险因子,国内外对于禽肉及牛肉中杂环胺的产生已有丰富研究,但是关于猪里脊在高温油炸加工条件下杂环胺的变化规律研究较为缺乏。该文研究了不同油炸温度(150、160、170、180和190℃)和油炸时间(1、2、3、4和5 min)对油炸猪里脊的pH、烹饪损失、水分、颜色、质构、水分分布、油炸温度、感官评价以及杂环胺(heterocyclic aromatic amines,HAA)含量的影响。结果表明,随着油炸温度和油炸时间的增加,猪里脊中的水分含量、自由水含量、b^(*)和L^(*)显著降低,表面中心温度、烹饪损失、a^(*)、硬度、内聚性、油脂含量和HAA含量增加。在170℃下油炸3 min的熟度、质构品质相对较好,且HAA含量相对较低。在相对较高油炸温度(180~190℃)和较长油炸时间(4~5 min)下,猪里脊中的HAA含量相对较高。相关性分析表明,杂环胺生成与油炸温度、时间和猪里脊品质显著相关。综合分析不同油炸参数对猪里脊品质和HAA的含量的影响,在160~170℃下油炸2~3 min是制备油炸猪里脊的最适条件。该文为消费者和餐饮机构提供关于肉类油炸时间和温度的建议,以确保油炸猪里脊产品的高质量和安全性。

基于边界元逆问题法的超低场磁共振大鼠脑部成像双通道射频线圈优化设计

目前超低场磁共振成像(MRI)质量较差,为提升图像信噪比,射频线圈需尽可能贴近成像区域从而提升信噪比。该文采用间接边界元法并从逆问题角度求出线圈流函数分布,再利用线性规划寻找最优线圈结构。为验证超低场MRI诊断颅脑疾病的有效性,采用上述方法,在54 mT下针对大鼠头-脑几何形状设计了双通道射频接收线圈,并对大鼠脑卒中及脑外伤模型进行成像试验研究。试验结果表明,54mTMRI能够检出水肿和血肿病变,且与病理切片或临床3T MRI图像结果相符。同时,通过脑外伤模型7天的追踪观察,54 mT图像中病变的信号演变规律与高场影像一致。针对特定成像对象和非规则布线曲面,该文利用间接边界元逆问题法设计高信噪比射频接收线圈,大鼠模型试验证明超低场磁共振成像技术具有脑卒中与脑外份早期诊断与床旁影像监护潜力与价值。