BACKGROUND Hepatocellular carcinoma(HCC)is a major cause of cancer-related mortality worldwide.Transcatheter arterial chemoembolization(TACE)has been performed as a palliative treatment for patients with HCC.However,H...BACKGROUND Hepatocellular carcinoma(HCC)is a major cause of cancer-related mortality worldwide.Transcatheter arterial chemoembolization(TACE)has been performed as a palliative treatment for patients with HCC.However,HCC is easy to recur after TACE.Magnetic resonance imaging(MRI)has clinical potential in evaluating the TACE treatment effect for patients with liver cancer.However,traditional MRI has some limitations.AIM To explore the clinical potential of diffusion kurtosis imaging(DKI)in predicting recurrence and cellular invasion of the peritumoral liver zone of HCC after TACE.METHODSSeventy-six patients with 82 HCC nodules were recruited in this study and underwent DKI afterTACE. According to pathological examinations or the overall modified response evaluationcriteria in solid tumors (mRECIST) criterion, 48 and 34 nodules were divided into true progressionand pseudo-progression groups, respectively. The TACE-treated area, peritumoral liver zone, andfar-tumoral zone were evaluated on DKI-derived metric maps. Non-parametric U test and receiveroperating characteristic curve (ROC) analysis were used to evaluate the prediction performance ofeach DKI metric between the two groups. The independent t-test was used to compare each DKImetric between the peritumoral and far-tumoral zones of the true progression group.RESULTSDKI metrics, including mean diffusivity (MD), axial diffusivity (DA), radial diffusivity (DR), axialkurtosis (KA), and anisotropy fraction of kurtosis (Fak), showed statistically different valuesbetween the true progression and pseudo-progression groups (P < 0.05). Among these, MD, DA,and DR values were higher in pseudo-progression lesions than in true progression lesions,whereas KA and FAk values were higher in true progression lesions than in pseudo-progressionlesions. Moreover, for the true progression group, the peritumoral zone showed significantlydifferent DA, DR, KA, and FAk values from the far-tumoral zone. Furthermore, MD values of theliver parenchyma (peritumoral and far-tumoral zones) were significantly lower in the trueprogression group than in the pseudo-progression group (P < 0.05).CONCLUSIONDKI has been demonstrated with robust performance in predicting the therapeutic response ofHCC to TACE. Moreover, DKI might reveal cellular invasion of the peritumoral zone by moleculardiffusion-restricted change.展开更多
The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MC...The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MCAO)in rats at 3T MRI,and to validate NODDI metrics with histology.A multi-shell diffusion MRI protocol was performed on 11 MCAO rats and 10 control rats at different post-operation time points of 0.5,2,6,12,24 and 72 h.NODDI orientation dispersion index(ODI)and intracellular volume fraction(V_(ic))metrics were compared between MCAO group and control group.The evolution of NODDI metrics was characterized and validated by histology.Infarction was consistent with significantly increased ODI and V_(ic)in comparison to control tissues at all time points(P<0.001).Lesion ODI increased gradually from 0.5 to 72 h,while its V_(ic)showed a more complicated and fluctuated evolution.ODI and V_(ic)were significantly different between hyperacute and acute stroke periods(P<0.001).The NODDI metrics were found to be consistent with the histological findings.In conclusion,NODDI can reflect microstructural changes of brain tissues in MCAO rats at 3T MRI and the metrics are consistent with histology.This study helps to prepare NODDI for the diagnosis and management of ischemic stroke in translational research and clinical practice.展开更多
Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and t...Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and therapeutic response.Magnetic resonance imaging(MRI)endoscopy is a newer idea employing tiny catheter-mounted detectors connected to the MRI scanner.It can see through vessel walls and provide soft-tissue sensitivity,but its slow imaging speed limits practical applications.Our goal is highresolution MRI endoscopy with real-time imaging speeds comparable to existing modalities.Methods.Intravascular(3 mm)transmit-receive MRI endoscopes were fabricated for highly undersampled radial-projection MRI in a clinical 3-tesla MRI scanner.Iterative nonlinear reconstruction was accelerated using graphics processor units connected via a single ethernet cable to achieve true real-time endoscopy visualization at the scanner.MRI endoscopy was performed at 6-10 frames/sec and 200-300μm resolution in human arterial specimens and porcine vessels ex vivo and in vivo and compared with fully sampled 0.3 frames/sec and three-dimensional reference scans using mutual information(MI)and structural similarity(3-SSIM)indices.Results.High-speed MRI endoscopy at 6-10 frames/sec was consistent with fully sampled MRI endoscopy and histology,with feasibility demonstrated in vivo in a large animal model.A 20-30-fold speed-up vs.0.3 frames/sec reference scans came at a cost of~7%in MI and~45%in 3-SSIM,with reduced motion sensitivity.Conclusion.High-resolution MRI endoscopy can now be performed at frame rates comparable to those of X-ray and optical endoscopy and could provide an alternative to existing modalities,with MRI’s advantages of soft-tissue sensitivity and lack of ionizing radiation.展开更多
Background: The aim of this study was to evaluate the feasibility of a dualbolus protocol, where a first bolus of an intravascular tracer is used to measure perfusion, followed by a second bolus of a freely filtered g...Background: The aim of this study was to evaluate the feasibility of a dualbolus protocol, where a first bolus of an intravascular tracer is used to measure perfusion, followed by a second bolus of a freely filtered gadolinium-containing agent to measure filtration capacity. Methods: The study was conducted in mice subjected to complete unilateral ureteral obstruction (UUO), and sham operated mice were used as controls. Dynamic contrast- en-hanced MRI was performed 2 days after surgery. Results and discussions: Mean signal-time curves of the renal cortex, renal medulla and abdominal aorta were used to calculate the relative renal blood flow (rRBF), relative renal blood volume (rRBV), mean transit time (MTT) and the glomerular transfer rate Ktrans. We demonstrated that kidneys suffering from two days of UUO showed a decrease in cortical as well as medullary rRBF compared to kidneys from sham-operated mice. Further, we found no changes in rRBV and MTT among groups, neither in the cortex nor in the medulla. The renal functional parameter Ktrans showed a tendency (but statistically insignificant) to be reduced in the ob-structed kidney compared to the sham-operated mice. Conclusions: We showed our first experiences with the consecutive use of intra- and extra-vascularly distributed agents in a renal-diseased mouse model, allowing analysis of both functional haemo- dyamics and filtration capacity in kidneys.展开更多
Amblyopia is the most common cause of vision loss in children and can persist into adulthood in the absence of effective intervention.Previous clinical and neuroimaging studies have suggested that the neural mechanism...Amblyopia is the most common cause of vision loss in children and can persist into adulthood in the absence of effective intervention.Previous clinical and neuroimaging studies have suggested that the neural mechanisms underlying strabismic amblyopia and anisometropic amblyopia may be different.Therefore,we performed a systematic review of magnetic resonance imaging studies investigating brain alterations in patients with these two subtypes of amblyopia;this study is registered with PROSPERO(registration ID:CRD42022349191).We searched three online databases(PubMed,EMBASE,and Web of Science) from inception to April 1,2022;39 studies with 633 patients(324patients with anisometropic amblyo pia and 309 patients with strabismic amblyopia) and 580 healthy controls met the inclusion criteria(e.g.,case-control designed,pee r-reviewed articles) and were included in this review.These studies highlighted that both strabismic amblyopia and anisometropic amblyopia patients showed reduced activation and distorted topological cortical activated maps in the striate and extrastriate co rtices during tas k-based functional magnetic resonance imaging with spatial-frequency stimulus and retinotopic representations,respectively;these may have arisen from abnormal visual experiences.Compensations for amblyopia that are reflected in enhanced spontaneous brain function have been reported in the early visual cortices in the resting state,as well as reduced functional connectivity in the dorsal pathway and structural connections in the ventral pathway in both anisometro pic amblyopia and strabismic amblyopia patients.The shared dysfunction of anisometro pic amblyopia and strabismic amblyopia patients,relative to controls,is also chara cterized by reduced spontaneous brain activity in the oculomotor co rtex,mainly involving the frontal and parietal eye fields and the cerebellu m;this may underlie the neural mechanisms of fixation instability and anomalous saccades in amblyopia.With regards to specific alterations of the two forms of amblyo pia,anisometropic amblyo pia patients suffer more microstructural impairments in the precortical pathway than strabismic amblyopia patients,as reflected by diffusion tensor imaging,and more significant dysfunction and structural loss in the ventral pathway.Strabismic amblyopia patients experience more attenuation of activation in the extrastriate co rtex than in the striate cortex when compared to anisometropic amblyopia patients.Finally,brain structural magnetic resonance imaging alterations tend to be lateralized in the adult anisometropic amblyopia patients,and the patterns of brain alterations are more limited in amblyopic adults than in childre n.In conclusion,magnetic resonance imaging studies provide important insights into the brain alterations underlying the pathophysiology of amblyopia and demonstrate common and specific alte rations in anisometropic amblyo pia and strabismic amblyopia patients;these alterations may improve our understanding of the neural mechanisms underlying amblyopia.展开更多
Objective This study aimed to noninvasively characterize the metabolic alterations in ischemic brain tissues using Z-spectrum-fitted multiparametric chemical exchange saturation transfer-weighted magnetic resonance im...Objective This study aimed to noninvasively characterize the metabolic alterations in ischemic brain tissues using Z-spectrum-fitted multiparametric chemical exchange saturation transfer-weighted magnetic resonance imaging(CEST-MRI).Methods Three sets of Z-spectrum data with saturation power(B_(1))values of 1.5,2.5,and 3.5µT,respectively,were acquired from 17 patients with ischemic stroke.Multiple contrasts contributing to the Z-spectrum,including fitted amide proton transfer(APT_(fitted)),+2 ppm peak(CEST@2ppm),concomitantly fitted APT_(fitted) and CEST@2ppm(APT&CEST@2ppm),semisolid magnetization transfer contrast(MT),aliphatic nuclear Overhauser effect(NOE),and direct saturation of water(DSW),were fitted with 4 and 5 Lorentzian functions,respectively.The CEST metrics were compared between ischemic lesions and contralateral normal white matter(CNWM),and the correlation between the CEST metrics and the apparent diffusion coefficient(ADC)was assessed.The differences in the Z-spectrum metrics under varied B1 values were also investigated.Results Ischemic lesions showed increased APTfitted,CEST@2ppm,APT&CEST@2ppm,NOE,and DSW as well as decreased MT.APT&CEST@2ppm,MT,and DSW showed a significant correlation with ADC[APT&CEST@2ppm at the 3 B_(1) values:R=0.584/0.467/0.551;MT at the 3 B_(1) values:R=−0.717/−0.695/−0.762(4-parameter fitting),R=−0.734/−0.711/−0.785(5-parameter fitting);DSW of 4-/5-parameter fitting:R=0.794/0.811(2.5µT),R=0.800/0.790(3.5µT)].However,the asymmetric analysis of amide proton transfer(APT_(asym))could not differentiate the lesions from CNWM and showed no correlation with ADC.Furthermore,the Z-spectrum contrasts varied with B_(1).Conclusion The Z-spectrum-fitted multiparametric CEST-MRI can comprehensively detect metabolic alterations in ischemic brain tissues.展开更多
基金the Greater Bay Area Institute of Precision Medicine,No.KCH2310094Shanghai Sailing Program,No.22YF1405000+1 种基金Research Startup Fund of Huashan Hospital Fudan University,No.2021QD035and Clinical Research Plan of SHDC,No.SHDC2020CR3020A.
文摘BACKGROUND Hepatocellular carcinoma(HCC)is a major cause of cancer-related mortality worldwide.Transcatheter arterial chemoembolization(TACE)has been performed as a palliative treatment for patients with HCC.However,HCC is easy to recur after TACE.Magnetic resonance imaging(MRI)has clinical potential in evaluating the TACE treatment effect for patients with liver cancer.However,traditional MRI has some limitations.AIM To explore the clinical potential of diffusion kurtosis imaging(DKI)in predicting recurrence and cellular invasion of the peritumoral liver zone of HCC after TACE.METHODSSeventy-six patients with 82 HCC nodules were recruited in this study and underwent DKI afterTACE. According to pathological examinations or the overall modified response evaluationcriteria in solid tumors (mRECIST) criterion, 48 and 34 nodules were divided into true progressionand pseudo-progression groups, respectively. The TACE-treated area, peritumoral liver zone, andfar-tumoral zone were evaluated on DKI-derived metric maps. Non-parametric U test and receiveroperating characteristic curve (ROC) analysis were used to evaluate the prediction performance ofeach DKI metric between the two groups. The independent t-test was used to compare each DKImetric between the peritumoral and far-tumoral zones of the true progression group.RESULTSDKI metrics, including mean diffusivity (MD), axial diffusivity (DA), radial diffusivity (DR), axialkurtosis (KA), and anisotropy fraction of kurtosis (Fak), showed statistically different valuesbetween the true progression and pseudo-progression groups (P < 0.05). Among these, MD, DA,and DR values were higher in pseudo-progression lesions than in true progression lesions,whereas KA and FAk values were higher in true progression lesions than in pseudo-progressionlesions. Moreover, for the true progression group, the peritumoral zone showed significantlydifferent DA, DR, KA, and FAk values from the far-tumoral zone. Furthermore, MD values of theliver parenchyma (peritumoral and far-tumoral zones) were significantly lower in the trueprogression group than in the pseudo-progression group (P < 0.05).CONCLUSIONDKI has been demonstrated with robust performance in predicting the therapeutic response ofHCC to TACE. Moreover, DKI might reveal cellular invasion of the peritumoral zone by moleculardiffusion-restricted change.
基金National Natural Science Foundation of China(No.81570462,No.81730049,and No.81801666).
文摘The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MCAO)in rats at 3T MRI,and to validate NODDI metrics with histology.A multi-shell diffusion MRI protocol was performed on 11 MCAO rats and 10 control rats at different post-operation time points of 0.5,2,6,12,24 and 72 h.NODDI orientation dispersion index(ODI)and intracellular volume fraction(V_(ic))metrics were compared between MCAO group and control group.The evolution of NODDI metrics was characterized and validated by histology.Infarction was consistent with significantly increased ODI and V_(ic)in comparison to control tissues at all time points(P<0.001).Lesion ODI increased gradually from 0.5 to 72 h,while its V_(ic)showed a more complicated and fluctuated evolution.ODI and V_(ic)were significantly different between hyperacute and acute stroke periods(P<0.001).The NODDI metrics were found to be consistent with the histological findings.In conclusion,NODDI can reflect microstructural changes of brain tissues in MCAO rats at 3T MRI and the metrics are consistent with histology.This study helps to prepare NODDI for the diagnosis and management of ischemic stroke in translational research and clinical practice.
基金supported by grants R01 EB007829 from the National Institutes of Health,Siemens Medical SystemsRussell H Morgan Professorship in Radiology。
文摘Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and therapeutic response.Magnetic resonance imaging(MRI)endoscopy is a newer idea employing tiny catheter-mounted detectors connected to the MRI scanner.It can see through vessel walls and provide soft-tissue sensitivity,but its slow imaging speed limits practical applications.Our goal is highresolution MRI endoscopy with real-time imaging speeds comparable to existing modalities.Methods.Intravascular(3 mm)transmit-receive MRI endoscopes were fabricated for highly undersampled radial-projection MRI in a clinical 3-tesla MRI scanner.Iterative nonlinear reconstruction was accelerated using graphics processor units connected via a single ethernet cable to achieve true real-time endoscopy visualization at the scanner.MRI endoscopy was performed at 6-10 frames/sec and 200-300μm resolution in human arterial specimens and porcine vessels ex vivo and in vivo and compared with fully sampled 0.3 frames/sec and three-dimensional reference scans using mutual information(MI)and structural similarity(3-SSIM)indices.Results.High-speed MRI endoscopy at 6-10 frames/sec was consistent with fully sampled MRI endoscopy and histology,with feasibility demonstrated in vivo in a large animal model.A 20-30-fold speed-up vs.0.3 frames/sec reference scans came at a cost of~7%in MI and~45%in 3-SSIM,with reduced motion sensitivity.Conclusion.High-resolution MRI endoscopy can now be performed at frame rates comparable to those of X-ray and optical endoscopy and could provide an alternative to existing modalities,with MRI’s advantages of soft-tissue sensitivity and lack of ionizing radiation.
文摘Background: The aim of this study was to evaluate the feasibility of a dualbolus protocol, where a first bolus of an intravascular tracer is used to measure perfusion, followed by a second bolus of a freely filtered gadolinium-containing agent to measure filtration capacity. Methods: The study was conducted in mice subjected to complete unilateral ureteral obstruction (UUO), and sham operated mice were used as controls. Dynamic contrast- en-hanced MRI was performed 2 days after surgery. Results and discussions: Mean signal-time curves of the renal cortex, renal medulla and abdominal aorta were used to calculate the relative renal blood flow (rRBF), relative renal blood volume (rRBV), mean transit time (MTT) and the glomerular transfer rate Ktrans. We demonstrated that kidneys suffering from two days of UUO showed a decrease in cortical as well as medullary rRBF compared to kidneys from sham-operated mice. Further, we found no changes in rRBV and MTT among groups, neither in the cortex nor in the medulla. The renal functional parameter Ktrans showed a tendency (but statistically insignificant) to be reduced in the ob-structed kidney compared to the sham-operated mice. Conclusions: We showed our first experiences with the consecutive use of intra- and extra-vascularly distributed agents in a renal-diseased mouse model, allowing analysis of both functional haemo- dyamics and filtration capacity in kidneys.
文摘Amblyopia is the most common cause of vision loss in children and can persist into adulthood in the absence of effective intervention.Previous clinical and neuroimaging studies have suggested that the neural mechanisms underlying strabismic amblyopia and anisometropic amblyopia may be different.Therefore,we performed a systematic review of magnetic resonance imaging studies investigating brain alterations in patients with these two subtypes of amblyopia;this study is registered with PROSPERO(registration ID:CRD42022349191).We searched three online databases(PubMed,EMBASE,and Web of Science) from inception to April 1,2022;39 studies with 633 patients(324patients with anisometropic amblyo pia and 309 patients with strabismic amblyopia) and 580 healthy controls met the inclusion criteria(e.g.,case-control designed,pee r-reviewed articles) and were included in this review.These studies highlighted that both strabismic amblyopia and anisometropic amblyopia patients showed reduced activation and distorted topological cortical activated maps in the striate and extrastriate co rtices during tas k-based functional magnetic resonance imaging with spatial-frequency stimulus and retinotopic representations,respectively;these may have arisen from abnormal visual experiences.Compensations for amblyopia that are reflected in enhanced spontaneous brain function have been reported in the early visual cortices in the resting state,as well as reduced functional connectivity in the dorsal pathway and structural connections in the ventral pathway in both anisometro pic amblyopia and strabismic amblyopia patients.The shared dysfunction of anisometro pic amblyopia and strabismic amblyopia patients,relative to controls,is also chara cterized by reduced spontaneous brain activity in the oculomotor co rtex,mainly involving the frontal and parietal eye fields and the cerebellu m;this may underlie the neural mechanisms of fixation instability and anomalous saccades in amblyopia.With regards to specific alterations of the two forms of amblyo pia,anisometropic amblyo pia patients suffer more microstructural impairments in the precortical pathway than strabismic amblyopia patients,as reflected by diffusion tensor imaging,and more significant dysfunction and structural loss in the ventral pathway.Strabismic amblyopia patients experience more attenuation of activation in the extrastriate co rtex than in the striate cortex when compared to anisometropic amblyopia patients.Finally,brain structural magnetic resonance imaging alterations tend to be lateralized in the adult anisometropic amblyopia patients,and the patterns of brain alterations are more limited in amblyopic adults than in childre n.In conclusion,magnetic resonance imaging studies provide important insights into the brain alterations underlying the pathophysiology of amblyopia and demonstrate common and specific alte rations in anisometropic amblyo pia and strabismic amblyopia patients;these alterations may improve our understanding of the neural mechanisms underlying amblyopia.
基金supported by grants from the Guangzhou General Guidance Project of Health Science and Technology(No.20231A011013)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110737).
文摘Objective This study aimed to noninvasively characterize the metabolic alterations in ischemic brain tissues using Z-spectrum-fitted multiparametric chemical exchange saturation transfer-weighted magnetic resonance imaging(CEST-MRI).Methods Three sets of Z-spectrum data with saturation power(B_(1))values of 1.5,2.5,and 3.5µT,respectively,were acquired from 17 patients with ischemic stroke.Multiple contrasts contributing to the Z-spectrum,including fitted amide proton transfer(APT_(fitted)),+2 ppm peak(CEST@2ppm),concomitantly fitted APT_(fitted) and CEST@2ppm(APT&CEST@2ppm),semisolid magnetization transfer contrast(MT),aliphatic nuclear Overhauser effect(NOE),and direct saturation of water(DSW),were fitted with 4 and 5 Lorentzian functions,respectively.The CEST metrics were compared between ischemic lesions and contralateral normal white matter(CNWM),and the correlation between the CEST metrics and the apparent diffusion coefficient(ADC)was assessed.The differences in the Z-spectrum metrics under varied B1 values were also investigated.Results Ischemic lesions showed increased APTfitted,CEST@2ppm,APT&CEST@2ppm,NOE,and DSW as well as decreased MT.APT&CEST@2ppm,MT,and DSW showed a significant correlation with ADC[APT&CEST@2ppm at the 3 B_(1) values:R=0.584/0.467/0.551;MT at the 3 B_(1) values:R=−0.717/−0.695/−0.762(4-parameter fitting),R=−0.734/−0.711/−0.785(5-parameter fitting);DSW of 4-/5-parameter fitting:R=0.794/0.811(2.5µT),R=0.800/0.790(3.5µT)].However,the asymmetric analysis of amide proton transfer(APT_(asym))could not differentiate the lesions from CNWM and showed no correlation with ADC.Furthermore,the Z-spectrum contrasts varied with B_(1).Conclusion The Z-spectrum-fitted multiparametric CEST-MRI can comprehensively detect metabolic alterations in ischemic brain tissues.
