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 r...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.展开更多
Lower back pain is one of the most common medical problems in the world and it is experienced by a huge percentage of people everywhere.Due to its ability to produce a detailed view of the soft tissues,including the s...Lower back pain is one of the most common medical problems in the world and it is experienced by a huge percentage of people everywhere.Due to its ability to produce a detailed view of the soft tissues,including the spinal cord,nerves,intervertebral discs,and vertebrae,Magnetic Resonance Imaging is thought to be the most effective method for imaging the spine.The semantic segmentation of vertebrae plays a major role in the diagnostic process of lumbar diseases.It is difficult to semantically partition the vertebrae in Magnetic Resonance Images from the surrounding variety of tissues,including muscles,ligaments,and intervertebral discs.U-Net is a powerful deep-learning architecture to handle the challenges of medical image analysis tasks and achieves high segmentation accuracy.This work proposes a modified U-Net architecture namely MU-Net,consisting of the Meijering convolutional layer that incorporates the Meijering filter to perform the semantic segmentation of lumbar vertebrae L1 to L5 and sacral vertebra S1.Pseudo-colour mask images were generated and used as ground truth for training the model.The work has been carried out on 1312 images expanded from T1-weighted mid-sagittal MRI images of 515 patients in the Lumbar Spine MRI Dataset publicly available from Mendeley Data.The proposed MU-Net model for the semantic segmentation of the lumbar vertebrae gives better performance with 98.79%of pixel accuracy(PA),98.66%of dice similarity coefficient(DSC),97.36%of Jaccard coefficient,and 92.55%mean Intersection over Union(mean IoU)metrics using the mentioned dataset.展开更多
Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear ma...Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear magnetic resonance(NMR)techniques.This review provides a comprehensive overview of the recent applications and advancements of non-invasive magnetic resonance imaging(MRI)techniques in LIBs.It initially introduces the principles and hardware of MRI,followed by a detailed summary and comparison of MRI techniques used for characterizing liquid/solid electrolytes,electrodes and commercial batteries.This encompasses the determination of electrolytes'transport properties,acquisition of ion distribution profile,and diagnosis of battery defects.By focusing on experimental parameters and optimization strategies,our goal is to explore MRI methods suitable to a variety of research subjects,aiming to enhance imaging quality across diverse scenarios and offer critical physical/chemical insights into the ongoing operation processes of LIBs.展开更多
Anterior cruciate ligament(ACL) reconstruction is one of the most common orthopedic procedures performed worldwide. In this regard, magnetic resonance imaging(MRI) represents a useful pre-operative tool to confirm a d...Anterior cruciate ligament(ACL) reconstruction is one of the most common orthopedic procedures performed worldwide. In this regard, magnetic resonance imaging(MRI) represents a useful pre-operative tool to confirm a disruption of the ACL and to assess for potential associated injuries. However, MRI is also valuable postoperatively, as it is able to identify, in a non-invasive way, a number of aspects and situations that could suggest potential problems to clinicians. Graft signal and integrity, correct tunnel placement, tunnel widening, and problems with fixation devices or the donor site could all compromise the surgical outcomes and potentially predict the failure of the ACL reconstruction. Furthermore, several anatomical features of the knee could be associated to worst outcomes or higher risk of failure. This review provides a practical guide for the clinician to evaluate the post-surgical ACL through MRI, and to analyze all the parameters and features directly or indirectly related to ACL reconstruction, in order to assess for normal or pathologic conditions.展开更多
BACKGROUND It has been reported that deep learning-based reconstruction(DLR)can reduce image noise and artifacts,thereby improving the signal-to-noise ratio and image sharpness.However,no previous studies have evaluat...BACKGROUND It has been reported that deep learning-based reconstruction(DLR)can reduce image noise and artifacts,thereby improving the signal-to-noise ratio and image sharpness.However,no previous studies have evaluated the efficacy of DLR in improving image quality in reduced-field-of-view(reduced-FOV)diffusionweighted imaging(DWI)[field-of-view optimized and constrained undistorted single-shot(FOCUS)]of the pancreas.We hypothesized that a combination of these techniques would improve DWI image quality without prolonging the scan time but would influence the apparent diffusion coefficient calculation.AIM To evaluate the efficacy of DLR for image quality improvement of FOCUS of the pancreas.METHODS This was a retrospective study evaluated 37 patients with pancreatic cystic lesions who underwent magnetic resonance imaging between August 2021 and October 2021.We evaluated three types of FOCUS examinations:FOCUS with DLR(FOCUS-DLR+),FOCUS without DLR(FOCUS-DLR−),and conventional FOCUS(FOCUS-conv).The three types of FOCUS and their apparent diffusion coefficient(ADC)maps were compared qualitatively and quantitatively.RESULTS FOCUS-DLR+(3.62,average score of two radiologists)showed significantly better qualitative scores for image noise than FOCUS-DLR−(2.62)and FOCUS-conv(2.88)(P<0.05).Furthermore,FOCUS-DLR+showed the highest contrast ratio and 600 s/mm^(2)(0.72±0.08 and 0.68±0.08)and FOCUS-DLR−showed the highest CR between cystic lesions and the pancreatic parenchyma for the b-values of 0 and 600 s/mm2(0.62±0.21 and 0.62±0.21)(P<0.05),respectively.FOCUS-DLR+provided significantly higher ADCs of the pancreas and lesion(1.44±0.24 and 3.00±0.66)compared to FOCUS-DLR−(1.39±0.22 and 2.86±0.61)and significantly lower ADCs compared to FOCUS-conv(1.84±0.45 and 3.32±0.70)(P<0.05),respectively.CONCLUSION This study evaluated the efficacy of DLR for image quality improvement in reduced-FOV DWI of the pancreas.DLR can significantly denoise images without prolonging the scan time or decreasing the spatial resolution.The denoising level of DWI can be controlled to make the images appear more natural to the human eye.However,this study revealed that DLR did not ameliorate pancreatic distortion.Additionally,physicians should pay attention to the interpretation of ADCs after DLR application because ADCs are significantly changed by DLR.展开更多
Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods ...Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods In the outpatient department of our hospital(Sichuan Cancer Hospital,Chengdu,China),60 patients diagnosed with prostate disease were selected randomly and included in a prostate cancer group,60 patients with benign prostatic hyperplasia were included in a proliferation group,and 60 healthy subjects were included in a control group,from January 2013 to January 2017.Using Siemens Avanto 1.5 T high-field superconducting MRI for DCE-MRI and MRS scans,after the MRS scan was completed,we used the workstation spectroscopy tab spectral analysis,and eventually obtained the crest lines of the prostate metabolites choline(Cho),creatine(Cr),citrate(Cit),and the values of Cho/Cit,and(Cho+Cr)/Cit.Results Participants who had undergone 21-s,1-min,and 2-min dynamic contrast-enhanced MR revealed significant variations among the three groups.The spectral analysis of the three groups revealed a significant variation as well.DCE-MRI and MRS combined had a sensitivity of 89.67%,specificity of 95.78%,and accuracy of 94.34%.Conclusion DCE-MRI combined with MRS is of great value in the diagnosis of prostate cancer.展开更多
The state-of-the-art approaches for image reconstruction using under-sampled k-space data are compressed sensing based.They are iterative algorithms that optimize objective functions with spatial and/or temporal const...The state-of-the-art approaches for image reconstruction using under-sampled k-space data are compressed sensing based.They are iterative algorithms that optimize objective functions with spatial and/or temporal constraints.This paper proposes a non-iterative algorithm to estimate the un-measured data and then to reconstruct the image with the efficient filtered backprojection algorithm.The feasibility of the proposed method is demonstrated with a patient magnetic resonance imaging study.The proposed method is also compared with the state-of-the-art iterative compressed-sensing image reconstruction method using the total-variation optimization norm.展开更多
fMRI (Functional Magnetic Resonance Imaging) is a relatively new technique that uses MRI (Magnetic Resonance Imaging) to measure the hemodynamic response (change in blood flow) related to neural activity in the ...fMRI (Functional Magnetic Resonance Imaging) is a relatively new technique that uses MRI (Magnetic Resonance Imaging) to measure the hemodynamic response (change in blood flow) related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.展开更多
There is a large amount of fat in the postganglionic segment of the brachial plexus nerve.The use of short T1 inversion recovery pulse sequence may improve signal strength of the brachial plexus postganglionic segment...There is a large amount of fat in the postganglionic segment of the brachial plexus nerve.The use of short T1 inversion recovery pulse sequence may improve signal strength of the brachial plexus postganglionic segment.The present study revealed that the combination of three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence clearly displayed the anatomical morphology and structure of the brachial plexus nerve,together with maximum intensity projection,volume rendering and other three-dimensional reconstruction techniques.Our results suggested that this method is also suitable for providing accurate assessment and diagnosis of the site,severity and scope of brachial plexus injury.展开更多
Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestat...Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestations of HE are widely variable and involve a spectrum from mild subclinical disturbance to deep coma. Research interest has focused on the role of circulating gut-derived toxins, particularly ammonia, the development of brain swelling and changes in cerebral neurotransmitter systems that lead to global CNS depression and disordered function. Until recently the direct investigation of cerebral function has been difficult in man. However, new magnetic resonance imaging (MRI) techniques provide a non-invasive means of assessment of changes in brain volume (coregistered MRI) and impaired brain function (fMRI), while proton magnetic resonance spectroscopy (^1H MRS) detects changes in brain biochemistry, including direct measurement of cerebral osmolytes, such as myoinositol, glutamate and glutamine which govern processes intrinsic to cellular homeostasis, including the accumulation of intracellular water. The concentrations of these intracellular osmolytes alter with hyperammonaemia. MRS-detected metabolite abnormalities correlate with the severity of neuropsychiatric impairment and since MR spectra return towards normal after treatment, the technique may be of use in objective patient monitoring and in assessing the effectiveness of various treatment regimens.展开更多
Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound (TRUS)-guided biopsy has been used f...Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound (TRUS)-guided biopsy has been used for the diagnosis of prostate cancer for over 2 decades, but the technique is usually blind to cancer location. Moreover, the false negative rate of TRUS biopsy has been reported to be as high as 47%. Multiparametric magnetic resonance imaging (mp-MRI) includes T1- and T2-weighted imaging as well as dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI). mp-MRI is a major advance in the imaging of prostate cancer, enabling targeted biopsy of suspicious lesions. Evolving targeted biopsy techniquesmincluding direct in-bore biopsy, cognitive fusion and software-based MRI-ultrasound (MRI-US) fusion--have led to a several-fold improvement in cancer detection compared to the earlier method. Importantly, the detection of clinically significant cancers has been greatly facilitated by targeting, compared to systematic biopsy alone. Targeted biopsy via MRI-US fusion may dramatically alter the way prostate cancer is diagnosed and managed.展开更多
As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In...As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In clinical practice, magnetic resonance imaging (MRI) is one of the imaging tools for the evaluation of prostate cancer, the fusion of MRI or dynamic contrast-enhanced MRI (DCE-MRI) with magnetic resonance spectroscopic imaging (MRSI) is improving the evaluation of cancer locafon, size, and extent, while providing an indication of tumor aggressiveness. This review summarizes the role of MRI in the application of prostate cancer and describes molecular MRI techniques (including MRSI and DCE-MRI) for aiding prostate cancer management.展开更多
Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 ...Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 cases of NACC and summarized the magnetic resonance imaging (MRI) features. MR images of 10 patients with histologically validated NACC were reviewed by two experienced radiologists. The location, shape, margin, signal intensity, lesion texture, contrast enhancement patterns, local invasion, and cervical lymphadenopathy of all tumors were evaluated. Clinical and pathologic records were also reviewed. No patients were positive for antibodies against Epstein-Barr virus (EBV). The imaging patterns of primary tumors were classified into two types as determined by location, shape, and margin. Of all patients, 7 had tumors with a type 1 imaging pattern and 3 had tumors with a type 2 imaging pattern. The 4 tubular NACCs were all homogeneous tumors, whereas 3 (60%) of 5 cribriform NACCs and the sole solid NACC were heterogeneous tumors with separations or central necrosis on MR images. Five patients had perineural infiltration and intracranial involvement, and only 2 had cervical lymphadenopathy. Based on these results, we conclude that NACC is a local, aggressive neoplasm that is often negative for EBV infection and associated with a low incidence of cervical lymphadenopathy. Furthermore, MRI features of NACC vary in locations and histological subtypes.展开更多
Idiopathic Parkinson's disease (IPD) is a progressive, neurodegenerative movement disorder characterized by bradykinesia, muscular rigidity, pos- tural instability and tremor. IPD is usually diagnosed based on clin...Idiopathic Parkinson's disease (IPD) is a progressive, neurodegenerative movement disorder characterized by bradykinesia, muscular rigidity, pos- tural instability and tremor. IPD is usually diagnosed based on clinical findings, but diagnoses are only 75-90% accurate when compared with autopsy results. Improving diagnostic accuracy is critical for the early dif- ferentiation of IPD from other Parkinsonism-related disorders because of differences in their prognoses and treatment. Furthermore, IPD is clinically heterogeneous, with variable prognosis. Although the biological function of neuromelanin has not yet been determined, the selective vulnerability of neuromelanin-containing neurons in patients with IPD suggests a role for this pigment in neurodegeneration. Recently developed ultra-high-field magnetic resonance imaging (MRI) systems produce Tl-weighted neuro- melanin-sensitive images with very high spatial resolution, enabling the de- piction of tissue containing neuromelanin. Here we review recent advances in neuromelanin-sensitive MRI in IPD and related conditions suggesting that neuromelanin may be a potential diagnostic biomarker for IPD.展开更多
The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imagi...The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, 19F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of 19F imaging has exploded. In part, this is due to advances in MRI instrumentation, ~gF/1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of ~gF into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfluorocarbon compound-based agents.展开更多
Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uteri...Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uterine cervical cancer to radiochemotherapy(CRT).Methods This prospective study was approved by the institutional review board, and informed consent was obtained from all patients. A total of 23 patients with primary cervical cancer who were undergoing CRT and 16 age-matched healthy subjects were prospectively recruited for IVIM(b = 0–800 s/mm2) and standard pelvic MRI. Bi-exponential analysis was performed to derive f(perfusion fraction), D*(pseudo-diffusion coefficient), and D(true molecular diffusion coefficient) in cervical cancer(n = 23) and the normal cervix(n = 16). The apparent diffusion coefficient(standard ADC) was calculated. The independent-samples t-test and paired-samples t-test were used for comparisons.Results Pre-treatment cervical cancer had the lowest standard ADC(1.15 ± 0.13 × 10-3 mm2/s) and D(0.89 ± 0.10 × 10-3 mm2/s) values, and these were significantly different from the normal cervix and posttreatment cervical cancer(P = 0.00). The f(16.67 ± 5.85%) was lowest in pre-treatment cervical cancer and was significantly different from the normal cervix and post-treatment cervical cancer(p = 0.012 and 0.00, respectively). No difference was observed in D*.Conclusion IVIM is potentially promising for differentiating between the normal cervix and cervical cancer because pre-treated cervical cancer has low perfusion and diffusion IVIM characteristics. Further, the standard ADC, D, and f of cervical cancer showed a tendency to normalize after CRT; thus, IVIM may be useful for monitoring the response to CRT in cervical cancer.展开更多
Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients wit...Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues.展开更多
Objective: To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging(DCEMRI) for predicting tumor response to radiotherapy in patients with suspected primary central nervous system(CNS) ...Objective: To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging(DCEMRI) for predicting tumor response to radiotherapy in patients with suspected primary central nervous system(CNS) germ cell tumors(GCTs).Methods: DCE-MRI parameters of 35 patients with suspected primary CNS GCTs were obtained prior to diagnostic radiation, using the Tofts and Kermode model. Radiosensitivity was determined in tumors diagnosed 2 weeks after radiation by observing changes in tumor size and markers as a response to MRI. Taking radiosensitivity as the gold standard, the cut-off value of DCE-MRI parameters was measured by receiver operating characteristic(ROC) curve. Diagnostic accuracy of DCE-MRI parameters for predicting radiosensitivity was evaluated by ROC curve.Results: A significant elevation in transfer constant(K^trans) and extravascular extracellular space(Ve)(P=0.000), as well as a significant reduction in rate constant(Kep)(P=0.000) was observed in tumors. K^trans, relative K^trans, and relative Kep of the responsive group were significantly higher than non-responsive groups. No significant difference was found in Kep, Ve, and relative Ve between the two groups. Relative K^trans showed the best diagnostic value in predicting radiosensitivity with a sensitivity of 100%, specificity of 91.7%, positive predictive value(PPV) of 95.8%, and negative predictive value(NPV) of 100%.Conclusions: Relative K^trans appeared promising in predicting tumor response to radiation therapy(RT). It is implied that DCE-MRI pre-treatment is a requisite step in diagnostic procedures and a novel and reliable approach to guide clinical choice of RT.展开更多
基金National Natural Science Foundations of China(Nos.61362001,61365013,51165033)the Science and Technology Department of Jiangxi Province of China(Nos.20132BAB211030,20122BAB211015)+1 种基金the Jiangxi Advanced Projects for Postdoctoral Research Funds,China(o.2014KY02)the Innovation Special Fund Project of Nanchang University,China(o.cx2015136)
文摘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.
文摘Lower back pain is one of the most common medical problems in the world and it is experienced by a huge percentage of people everywhere.Due to its ability to produce a detailed view of the soft tissues,including the spinal cord,nerves,intervertebral discs,and vertebrae,Magnetic Resonance Imaging is thought to be the most effective method for imaging the spine.The semantic segmentation of vertebrae plays a major role in the diagnostic process of lumbar diseases.It is difficult to semantically partition the vertebrae in Magnetic Resonance Images from the surrounding variety of tissues,including muscles,ligaments,and intervertebral discs.U-Net is a powerful deep-learning architecture to handle the challenges of medical image analysis tasks and achieves high segmentation accuracy.This work proposes a modified U-Net architecture namely MU-Net,consisting of the Meijering convolutional layer that incorporates the Meijering filter to perform the semantic segmentation of lumbar vertebrae L1 to L5 and sacral vertebra S1.Pseudo-colour mask images were generated and used as ground truth for training the model.The work has been carried out on 1312 images expanded from T1-weighted mid-sagittal MRI images of 515 patients in the Lumbar Spine MRI Dataset publicly available from Mendeley Data.The proposed MU-Net model for the semantic segmentation of the lumbar vertebrae gives better performance with 98.79%of pixel accuracy(PA),98.66%of dice similarity coefficient(DSC),97.36%of Jaccard coefficient,and 92.55%mean Intersection over Union(mean IoU)metrics using the mentioned dataset.
基金supported by the National Key R&D Program of China,Grant No.2021YFB2401800。
文摘Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear magnetic resonance(NMR)techniques.This review provides a comprehensive overview of the recent applications and advancements of non-invasive magnetic resonance imaging(MRI)techniques in LIBs.It initially introduces the principles and hardware of MRI,followed by a detailed summary and comparison of MRI techniques used for characterizing liquid/solid electrolytes,electrodes and commercial batteries.This encompasses the determination of electrolytes'transport properties,acquisition of ion distribution profile,and diagnosis of battery defects.By focusing on experimental parameters and optimization strategies,our goal is to explore MRI methods suitable to a variety of research subjects,aiming to enhance imaging quality across diverse scenarios and offer critical physical/chemical insights into the ongoing operation processes of LIBs.
文摘Anterior cruciate ligament(ACL) reconstruction is one of the most common orthopedic procedures performed worldwide. In this regard, magnetic resonance imaging(MRI) represents a useful pre-operative tool to confirm a disruption of the ACL and to assess for potential associated injuries. However, MRI is also valuable postoperatively, as it is able to identify, in a non-invasive way, a number of aspects and situations that could suggest potential problems to clinicians. Graft signal and integrity, correct tunnel placement, tunnel widening, and problems with fixation devices or the donor site could all compromise the surgical outcomes and potentially predict the failure of the ACL reconstruction. Furthermore, several anatomical features of the knee could be associated to worst outcomes or higher risk of failure. This review provides a practical guide for the clinician to evaluate the post-surgical ACL through MRI, and to analyze all the parameters and features directly or indirectly related to ACL reconstruction, in order to assess for normal or pathologic conditions.
文摘BACKGROUND It has been reported that deep learning-based reconstruction(DLR)can reduce image noise and artifacts,thereby improving the signal-to-noise ratio and image sharpness.However,no previous studies have evaluated the efficacy of DLR in improving image quality in reduced-field-of-view(reduced-FOV)diffusionweighted imaging(DWI)[field-of-view optimized and constrained undistorted single-shot(FOCUS)]of the pancreas.We hypothesized that a combination of these techniques would improve DWI image quality without prolonging the scan time but would influence the apparent diffusion coefficient calculation.AIM To evaluate the efficacy of DLR for image quality improvement of FOCUS of the pancreas.METHODS This was a retrospective study evaluated 37 patients with pancreatic cystic lesions who underwent magnetic resonance imaging between August 2021 and October 2021.We evaluated three types of FOCUS examinations:FOCUS with DLR(FOCUS-DLR+),FOCUS without DLR(FOCUS-DLR−),and conventional FOCUS(FOCUS-conv).The three types of FOCUS and their apparent diffusion coefficient(ADC)maps were compared qualitatively and quantitatively.RESULTS FOCUS-DLR+(3.62,average score of two radiologists)showed significantly better qualitative scores for image noise than FOCUS-DLR−(2.62)and FOCUS-conv(2.88)(P<0.05).Furthermore,FOCUS-DLR+showed the highest contrast ratio and 600 s/mm^(2)(0.72±0.08 and 0.68±0.08)and FOCUS-DLR−showed the highest CR between cystic lesions and the pancreatic parenchyma for the b-values of 0 and 600 s/mm2(0.62±0.21 and 0.62±0.21)(P<0.05),respectively.FOCUS-DLR+provided significantly higher ADCs of the pancreas and lesion(1.44±0.24 and 3.00±0.66)compared to FOCUS-DLR−(1.39±0.22 and 2.86±0.61)and significantly lower ADCs compared to FOCUS-conv(1.84±0.45 and 3.32±0.70)(P<0.05),respectively.CONCLUSION This study evaluated the efficacy of DLR for image quality improvement in reduced-FOV DWI of the pancreas.DLR can significantly denoise images without prolonging the scan time or decreasing the spatial resolution.The denoising level of DWI can be controlled to make the images appear more natural to the human eye.However,this study revealed that DLR did not ameliorate pancreatic distortion.Additionally,physicians should pay attention to the interpretation of ADCs after DLR application because ADCs are significantly changed by DLR.
文摘Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods In the outpatient department of our hospital(Sichuan Cancer Hospital,Chengdu,China),60 patients diagnosed with prostate disease were selected randomly and included in a prostate cancer group,60 patients with benign prostatic hyperplasia were included in a proliferation group,and 60 healthy subjects were included in a control group,from January 2013 to January 2017.Using Siemens Avanto 1.5 T high-field superconducting MRI for DCE-MRI and MRS scans,after the MRS scan was completed,we used the workstation spectroscopy tab spectral analysis,and eventually obtained the crest lines of the prostate metabolites choline(Cho),creatine(Cr),citrate(Cit),and the values of Cho/Cit,and(Cho+Cr)/Cit.Results Participants who had undergone 21-s,1-min,and 2-min dynamic contrast-enhanced MR revealed significant variations among the three groups.The spectral analysis of the three groups revealed a significant variation as well.DCE-MRI and MRS combined had a sensitivity of 89.67%,specificity of 95.78%,and accuracy of 94.34%.Conclusion DCE-MRI combined with MRS is of great value in the diagnosis of prostate cancer.
基金supported by American Heart Association,No.18AJML34280074.
文摘The state-of-the-art approaches for image reconstruction using under-sampled k-space data are compressed sensing based.They are iterative algorithms that optimize objective functions with spatial and/or temporal constraints.This paper proposes a non-iterative algorithm to estimate the un-measured data and then to reconstruct the image with the efficient filtered backprojection algorithm.The feasibility of the proposed method is demonstrated with a patient magnetic resonance imaging study.The proposed method is also compared with the state-of-the-art iterative compressed-sensing image reconstruction method using the total-variation optimization norm.
文摘fMRI (Functional Magnetic Resonance Imaging) is a relatively new technique that uses MRI (Magnetic Resonance Imaging) to measure the hemodynamic response (change in blood flow) related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.
文摘There is a large amount of fat in the postganglionic segment of the brachial plexus nerve.The use of short T1 inversion recovery pulse sequence may improve signal strength of the brachial plexus postganglionic segment.The present study revealed that the combination of three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence clearly displayed the anatomical morphology and structure of the brachial plexus nerve,together with maximum intensity projection,volume rendering and other three-dimensional reconstruction techniques.Our results suggested that this method is also suitable for providing accurate assessment and diagnosis of the site,severity and scope of brachial plexus injury.
基金Supported by grants from BUPA, the Royal College of Physicians of London and Paddington Charitable Trust, St Mary's,London. The European Association for the Study of the Liver, the British Medical Research Council (G9900178)Philips Medical Systems (Cleveland, Ohio, USA) and the United Kingdom Department of Health provided support for some of the studies outlined
文摘Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestations of HE are widely variable and involve a spectrum from mild subclinical disturbance to deep coma. Research interest has focused on the role of circulating gut-derived toxins, particularly ammonia, the development of brain swelling and changes in cerebral neurotransmitter systems that lead to global CNS depression and disordered function. Until recently the direct investigation of cerebral function has been difficult in man. However, new magnetic resonance imaging (MRI) techniques provide a non-invasive means of assessment of changes in brain volume (coregistered MRI) and impaired brain function (fMRI), while proton magnetic resonance spectroscopy (^1H MRS) detects changes in brain biochemistry, including direct measurement of cerebral osmolytes, such as myoinositol, glutamate and glutamine which govern processes intrinsic to cellular homeostasis, including the accumulation of intracellular water. The concentrations of these intracellular osmolytes alter with hyperammonaemia. MRS-detected metabolite abnormalities correlate with the severity of neuropsychiatric impairment and since MR spectra return towards normal after treatment, the technique may be of use in objective patient monitoring and in assessing the effectiveness of various treatment regimens.
文摘Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound (TRUS)-guided biopsy has been used for the diagnosis of prostate cancer for over 2 decades, but the technique is usually blind to cancer location. Moreover, the false negative rate of TRUS biopsy has been reported to be as high as 47%. Multiparametric magnetic resonance imaging (mp-MRI) includes T1- and T2-weighted imaging as well as dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI). mp-MRI is a major advance in the imaging of prostate cancer, enabling targeted biopsy of suspicious lesions. Evolving targeted biopsy techniquesmincluding direct in-bore biopsy, cognitive fusion and software-based MRI-ultrasound (MRI-US) fusion--have led to a several-fold improvement in cancer detection compared to the earlier method. Importantly, the detection of clinically significant cancers has been greatly facilitated by targeting, compared to systematic biopsy alone. Targeted biopsy via MRI-US fusion may dramatically alter the way prostate cancer is diagnosed and managed.
文摘As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In clinical practice, magnetic resonance imaging (MRI) is one of the imaging tools for the evaluation of prostate cancer, the fusion of MRI or dynamic contrast-enhanced MRI (DCE-MRI) with magnetic resonance spectroscopic imaging (MRSI) is improving the evaluation of cancer locafon, size, and extent, while providing an indication of tumor aggressiveness. This review summarizes the role of MRI in the application of prostate cancer and describes molecular MRI techniques (including MRSI and DCE-MRI) for aiding prostate cancer management.
文摘Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 cases of NACC and summarized the magnetic resonance imaging (MRI) features. MR images of 10 patients with histologically validated NACC were reviewed by two experienced radiologists. The location, shape, margin, signal intensity, lesion texture, contrast enhancement patterns, local invasion, and cervical lymphadenopathy of all tumors were evaluated. Clinical and pathologic records were also reviewed. No patients were positive for antibodies against Epstein-Barr virus (EBV). The imaging patterns of primary tumors were classified into two types as determined by location, shape, and margin. Of all patients, 7 had tumors with a type 1 imaging pattern and 3 had tumors with a type 2 imaging pattern. The 4 tubular NACCs were all homogeneous tumors, whereas 3 (60%) of 5 cribriform NACCs and the sole solid NACC were heterogeneous tumors with separations or central necrosis on MR images. Five patients had perineural infiltration and intracranial involvement, and only 2 had cervical lymphadenopathy. Based on these results, we conclude that NACC is a local, aggressive neoplasm that is often negative for EBV infection and associated with a low incidence of cervical lymphadenopathy. Furthermore, MRI features of NACC vary in locations and histological subtypes.
文摘Idiopathic Parkinson's disease (IPD) is a progressive, neurodegenerative movement disorder characterized by bradykinesia, muscular rigidity, pos- tural instability and tremor. IPD is usually diagnosed based on clinical findings, but diagnoses are only 75-90% accurate when compared with autopsy results. Improving diagnostic accuracy is critical for the early dif- ferentiation of IPD from other Parkinsonism-related disorders because of differences in their prognoses and treatment. Furthermore, IPD is clinically heterogeneous, with variable prognosis. Although the biological function of neuromelanin has not yet been determined, the selective vulnerability of neuromelanin-containing neurons in patients with IPD suggests a role for this pigment in neurodegeneration. Recently developed ultra-high-field magnetic resonance imaging (MRI) systems produce Tl-weighted neuro- melanin-sensitive images with very high spatial resolution, enabling the de- piction of tissue containing neuromelanin. Here we review recent advances in neuromelanin-sensitive MRI in IPD and related conditions suggesting that neuromelanin may be a potential diagnostic biomarker for IPD.
基金supported in whole or part by grants from the National Institutes of Health (CA154737, CA199092, HL122471, HL112518, HL113392, and HHSN26820140042C for Gregory M.Lanza AR067491, DK102691, and HL073646 for Samuel A.Wickline)We appreciate the further support provided the Barnes-Jewish Research Foundation
文摘The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, 19F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of 19F imaging has exploded. In part, this is due to advances in MRI instrumentation, ~gF/1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of ~gF into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfluorocarbon compound-based agents.
基金Supported by grants from the the National Natural Science Foundation of China(No.81371524,81271529)the Hubei Provincial Natural Science Foundation of China(No.2014CFB298)
文摘Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uterine cervical cancer to radiochemotherapy(CRT).Methods This prospective study was approved by the institutional review board, and informed consent was obtained from all patients. A total of 23 patients with primary cervical cancer who were undergoing CRT and 16 age-matched healthy subjects were prospectively recruited for IVIM(b = 0–800 s/mm2) and standard pelvic MRI. Bi-exponential analysis was performed to derive f(perfusion fraction), D*(pseudo-diffusion coefficient), and D(true molecular diffusion coefficient) in cervical cancer(n = 23) and the normal cervix(n = 16). The apparent diffusion coefficient(standard ADC) was calculated. The independent-samples t-test and paired-samples t-test were used for comparisons.Results Pre-treatment cervical cancer had the lowest standard ADC(1.15 ± 0.13 × 10-3 mm2/s) and D(0.89 ± 0.10 × 10-3 mm2/s) values, and these were significantly different from the normal cervix and posttreatment cervical cancer(P = 0.00). The f(16.67 ± 5.85%) was lowest in pre-treatment cervical cancer and was significantly different from the normal cervix and post-treatment cervical cancer(p = 0.012 and 0.00, respectively). No difference was observed in D*.Conclusion IVIM is potentially promising for differentiating between the normal cervix and cervical cancer because pre-treated cervical cancer has low perfusion and diffusion IVIM characteristics. Further, the standard ADC, D, and f of cervical cancer showed a tendency to normalize after CRT; thus, IVIM may be useful for monitoring the response to CRT in cervical cancer.
基金Supported by Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant(No.20152225)Shanghai Hospital Development Center Research Grant(No.SHDC12013103)
文摘Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues.
基金supported by Beijing Natural Science Foundation(No.7122029)
文摘Objective: To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging(DCEMRI) for predicting tumor response to radiotherapy in patients with suspected primary central nervous system(CNS) germ cell tumors(GCTs).Methods: DCE-MRI parameters of 35 patients with suspected primary CNS GCTs were obtained prior to diagnostic radiation, using the Tofts and Kermode model. Radiosensitivity was determined in tumors diagnosed 2 weeks after radiation by observing changes in tumor size and markers as a response to MRI. Taking radiosensitivity as the gold standard, the cut-off value of DCE-MRI parameters was measured by receiver operating characteristic(ROC) curve. Diagnostic accuracy of DCE-MRI parameters for predicting radiosensitivity was evaluated by ROC curve.Results: A significant elevation in transfer constant(K^trans) and extravascular extracellular space(Ve)(P=0.000), as well as a significant reduction in rate constant(Kep)(P=0.000) was observed in tumors. K^trans, relative K^trans, and relative Kep of the responsive group were significantly higher than non-responsive groups. No significant difference was found in Kep, Ve, and relative Ve between the two groups. Relative K^trans showed the best diagnostic value in predicting radiosensitivity with a sensitivity of 100%, specificity of 91.7%, positive predictive value(PPV) of 95.8%, and negative predictive value(NPV) of 100%.Conclusions: Relative K^trans appeared promising in predicting tumor response to radiation therapy(RT). It is implied that DCE-MRI pre-treatment is a requisite step in diagnostic procedures and a novel and reliable approach to guide clinical choice of RT.