Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium.It is trapped in the middle ear and can lead to bony erosion.The disease is treated surgically often followed by a second-look proc...Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium.It is trapped in the middle ear and can lead to bony erosion.The disease is treated surgically often followed by a second-look procedure to check for residual tissue or recurrence.Cholesteatoma has specific signal-intensity characteristics on magnetic resonance imaging with very high signal intensity on diffusion weighted imaging(DWI).Various DWI techniques exist:Echo-planar imaging(EPI)-based and non-EPI-based techniques as well as new approaches like multi-shot EPI DWI.This article summarizes all techniques,discusses the significance in detecting cholesteatoma and mentions actual studies.Further recommendations for daily clinical practise are provided.展开更多
Objective:To evaluate the value of apparent diffusion coefficients(ADC)in Magnetic Resonance diffusion weighted imaging(MR DWI)with echo-planar technique in depicting the tumor cellularity and grading of astrocytomas....Objective:To evaluate the value of apparent diffusion coefficients(ADC)in Magnetic Resonance diffusion weighted imaging(MR DWI)with echo-planar technique in depicting the tumor cellularity and grading of astrocytomas.Methods:Thirty-four patients with astrocytomas(18 male,16 female,ages from 10-73 with average of 38.41)were examined by MRI and proved by surgery and pathology,and the number of gradeⅠ-Ⅱ(low-grade)and gradeⅢ-Ⅳ(high-grade)is 26 and 8 respectively.ADC values of astrocytomas were determined on MR DWI.Cellularity of astrocytomas was analyzed with Adobe Photoshop 7.0 software.Results:Mean ADC values of high-grade astrocytomas(7.34±2.95)×10^(-4)mm^(2)/s were significantly different from that of lowgrade astrocytomas(13.76±3.31)×10^(-4)mm^(2)/s(t=4.913,P<0.001).Cellularity of high-grade astrocytomas(19.81±9.73)%were significantly higher than that of low-grade astrocytomas(4.74±2.96)%(t=4.32,P=0.003).ADC values of astrocytomas significantly negatively correlated with their cellularities(r=-0.535,P=0.001).Conclusion:The cellularities of astrocytomas contribute very much to ADC values in MR DWI.MR DWI is very valuable in predicting and evaluating the cellularity of astrocytomas.MR DWI might have a potential in predicting the degree of astrocytomas.展开更多
Purpose: To evaluate the impact of field strength and respiratory motion control on diffusion-weighted MR imaging (DWI) of the liver at 1.5 and 3 T. Material and Methods: Three DWI sequences using seven b-values from ...Purpose: To evaluate the impact of field strength and respiratory motion control on diffusion-weighted MR imaging (DWI) of the liver at 1.5 and 3 T. Material and Methods: Three DWI sequences using seven b-values from 20 - 400 s/mm2 were designed with identical parameters but with different handling of respiratory motion [respiratory triggered (RT), free breathing (FB), breath hold (BH)] on 3 T and 1.5 T. Thirteen volunteers were examined at a 3 T and six of them also at a 1.5 T magnet. DW images were analyzed quantitatively and qualitatively. Regions of interest were placed in cranial, middle and caudal parts of the right liver lobe (RLL) and ADC and SNR were calculated. Results: ADC in RLL tended to be lower at 3 T MRI. Least inter-subject ADC variability was found with RT in the middle RLL at 3 T. Highest ADCs were found caudally in the RLL. Significant differences in ADC between middle and caudal RLL were calculated in FB and RT at 3 T and FB and BH at 1.5 T, respectively. No significant difference in SNR was found between 3 T and 1.5 T. There were significantly more artifacts in the left liver lobe (LLL) compared to the RLL in all sequences and in the LLL at 3 T compared to 1.5 T. Conclusion: Our study suggests that longitudinal hepatic ADC measurements should be performed using equivalent field strength, b-values, and acquisition technique, given influence of these factors on ADC measurements.展开更多
Objective：To label rat bone marrow mesenchymal stem cells （BMSCs） with superparamagnetic iron oxide （SPIO） in vitro, and to monitor the survival and location of these labeled BMSCs in a rat model of traumatic bra...Objective：To label rat bone marrow mesenchymal stem cells （BMSCs） with superparamagnetic iron oxide （SPIO） in vitro, and to monitor the survival and location of these labeled BMSCs in a rat model of traumatic brain injury （TBI） by susceptibility weighted imaging （SWI）sequence.Methods：BMSCs were cultured in vitro and then labeled with SPIO. Totally 24 male Sprague Dawley （SD） rats weighing 200-250 g were randomly divided into 4 groups： Groups A-D （n=6 for each group）. Moderate TBI models of all the rats were developed in the left hemisphere following Feeney＇s method. Group A was the experimental group and stereotaxic transplantation of BMSCs labeled with SPIO into the region nearby the contusion was conducted in this group 24 hours after TBI modeling. The other three groups were control groups with transplantation of SPIO, unlabeled BMSCs and injection of nutrient solution respectively conducted in Groups B, C and D at the same time. Monitoring of these SPIO-labeled BMSCs by SWI was performed one day,one week and three weeks after implantation.Results： Numerous BMSCs were successfully labeled with SPIO. They were positive for Prussian blue staining and intracytoplasm positive blue stained particles were found under a microscope （×200）. Scattered little iron particles were observed in the vesicles by electron microscopy （×5000）. MRI of the transplantation sites of the left hemisphere demonstrated a low signal intensity on magnitude images,phase images and SWI images for all the test rats in Group A, and the lesion in the left parietal cortex demonstrated a semicircular low intensity on SWI images, which clearly showed the distribution and migration of BMSCs in the first and third weeks. For Group B, a low signal intensity by MRI was only observed on the first day but undetected during the following examination. No signals were observed in Groups C and D at any time points.Conclusion：SWI sequence in vivo can consecutively and noninvasively trace and demonstrate the status and distribution of BMSCs labeled with SPIO in the brain of TBI model rats.展开更多
文摘Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium.It is trapped in the middle ear and can lead to bony erosion.The disease is treated surgically often followed by a second-look procedure to check for residual tissue or recurrence.Cholesteatoma has specific signal-intensity characteristics on magnetic resonance imaging with very high signal intensity on diffusion weighted imaging(DWI).Various DWI techniques exist:Echo-planar imaging(EPI)-based and non-EPI-based techniques as well as new approaches like multi-shot EPI DWI.This article summarizes all techniques,discusses the significance in detecting cholesteatoma and mentions actual studies.Further recommendations for daily clinical practise are provided.
文摘Objective:To evaluate the value of apparent diffusion coefficients(ADC)in Magnetic Resonance diffusion weighted imaging(MR DWI)with echo-planar technique in depicting the tumor cellularity and grading of astrocytomas.Methods:Thirty-four patients with astrocytomas(18 male,16 female,ages from 10-73 with average of 38.41)were examined by MRI and proved by surgery and pathology,and the number of gradeⅠ-Ⅱ(low-grade)and gradeⅢ-Ⅳ(high-grade)is 26 and 8 respectively.ADC values of astrocytomas were determined on MR DWI.Cellularity of astrocytomas was analyzed with Adobe Photoshop 7.0 software.Results:Mean ADC values of high-grade astrocytomas(7.34±2.95)×10^(-4)mm^(2)/s were significantly different from that of lowgrade astrocytomas(13.76±3.31)×10^(-4)mm^(2)/s(t=4.913,P<0.001).Cellularity of high-grade astrocytomas(19.81±9.73)%were significantly higher than that of low-grade astrocytomas(4.74±2.96)%(t=4.32,P=0.003).ADC values of astrocytomas significantly negatively correlated with their cellularities(r=-0.535,P=0.001).Conclusion:The cellularities of astrocytomas contribute very much to ADC values in MR DWI.MR DWI is very valuable in predicting and evaluating the cellularity of astrocytomas.MR DWI might have a potential in predicting the degree of astrocytomas.
文摘Purpose: To evaluate the impact of field strength and respiratory motion control on diffusion-weighted MR imaging (DWI) of the liver at 1.5 and 3 T. Material and Methods: Three DWI sequences using seven b-values from 20 - 400 s/mm2 were designed with identical parameters but with different handling of respiratory motion [respiratory triggered (RT), free breathing (FB), breath hold (BH)] on 3 T and 1.5 T. Thirteen volunteers were examined at a 3 T and six of them also at a 1.5 T magnet. DW images were analyzed quantitatively and qualitatively. Regions of interest were placed in cranial, middle and caudal parts of the right liver lobe (RLL) and ADC and SNR were calculated. Results: ADC in RLL tended to be lower at 3 T MRI. Least inter-subject ADC variability was found with RT in the middle RLL at 3 T. Highest ADCs were found caudally in the RLL. Significant differences in ADC between middle and caudal RLL were calculated in FB and RT at 3 T and FB and BH at 1.5 T, respectively. No significant difference in SNR was found between 3 T and 1.5 T. There were significantly more artifacts in the left liver lobe (LLL) compared to the RLL in all sequences and in the LLL at 3 T compared to 1.5 T. Conclusion: Our study suggests that longitudinal hepatic ADC measurements should be performed using equivalent field strength, b-values, and acquisition technique, given influence of these factors on ADC measurements.
文摘Objective：To label rat bone marrow mesenchymal stem cells （BMSCs） with superparamagnetic iron oxide （SPIO） in vitro, and to monitor the survival and location of these labeled BMSCs in a rat model of traumatic brain injury （TBI） by susceptibility weighted imaging （SWI）sequence.Methods：BMSCs were cultured in vitro and then labeled with SPIO. Totally 24 male Sprague Dawley （SD） rats weighing 200-250 g were randomly divided into 4 groups： Groups A-D （n=6 for each group）. Moderate TBI models of all the rats were developed in the left hemisphere following Feeney＇s method. Group A was the experimental group and stereotaxic transplantation of BMSCs labeled with SPIO into the region nearby the contusion was conducted in this group 24 hours after TBI modeling. The other three groups were control groups with transplantation of SPIO, unlabeled BMSCs and injection of nutrient solution respectively conducted in Groups B, C and D at the same time. Monitoring of these SPIO-labeled BMSCs by SWI was performed one day,one week and three weeks after implantation.Results： Numerous BMSCs were successfully labeled with SPIO. They were positive for Prussian blue staining and intracytoplasm positive blue stained particles were found under a microscope （×200）. Scattered little iron particles were observed in the vesicles by electron microscopy （×5000）. MRI of the transplantation sites of the left hemisphere demonstrated a low signal intensity on magnitude images,phase images and SWI images for all the test rats in Group A, and the lesion in the left parietal cortex demonstrated a semicircular low intensity on SWI images, which clearly showed the distribution and migration of BMSCs in the first and third weeks. For Group B, a low signal intensity by MRI was only observed on the first day but undetected during the following examination. No signals were observed in Groups C and D at any time points.Conclusion：SWI sequence in vivo can consecutively and noninvasively trace and demonstrate the status and distribution of BMSCs labeled with SPIO in the brain of TBI model rats.
