Assisting Scalable Diagnosis Automatically via CT Images in the Combat against COVID-19

Introductory paragraphThe pandemic of coronavirus Disease 2019 (COVID-19) caused enormous loss of life globally. 1-3 Case identification is critical. The reference method is using real-time reverse transcription PCR (rRT-PCR) assays, with limitations that may curb its prompt large-scale application. COVID-19 manifests with chest computed tomography (CT) abnormalities, some even before the onset of symptoms. We tested the hypothesis that application of deep learning (DL) to the 3D CT images could help identify COVID-19 infections. Using the data from 920 COVID-19 and 1,073 non-COVID-19 pneumonia patients, we developed a modified DenseNet-264 model, COVIDNet, to classify CT images to either class. When tested on an independent set of 233 COVID-19 and 289 non-COVID-19 patients. COVIDNet achieved an accuracy rate of 94.3% and an area under the curve (AUC) of 0.98. Application of DL to CT images may improve both the efficiency and capacity of case detection and long-term surveillance.

A retrospective comparison of MRI, ultrasound and X-ray mammography in detecting breast ductal carcinoma in situ / 中华放射学杂志

Objective:To compare the efficacies of MRI, X-ray mammography (XMG) and Ultrasound (US) in detecting and diagnosing breast ductal carcinoma in situ (DCIS).Methods:Two hundred and forty one consecutive patients with pathology-confirmed DCIS were retrospectively recruited from January 2011 to December 2017 in PLA General Hospital. The imaging examination modalities included MRI and/or XMG and/or US.The breast imaging reporting and data system (BI-RADS) categorizations by MRI, XMG and US were compared and their sensitivities of detecting DCIS were calculated. The causes of underestimation on MRI were interpreted with the information of XMG and US. Chi-square test was used to compare the differences.Results:The diagnostic sensitivity of XMG, US and MRI was 65.9% (29/44), 71.6% (101/141) and 91.2% (145/159), respectively, with statistical significant differences (χ2 =24.034, P<0.001). Breast density and lesion type would influence the sensitivity of XMG. And the sensitivity of US was decreased because of non-mass lesion. Of the 14 cases under-evaluated as BI-RADS category 1 to 3 on MRI, 5 were corrected by XMG and/or US to BI-RADS category 4. The cause of underestimation on MRI was the coexistence of DCIS with adenoma or other benign lesion. Conclusion:The retrospective comparison of MRI, XMG and US in this study showed that MRI had significant higher sensitivity in detecting breast DCIS, while the false negative rates of XMG and US were un-negligible.

MRI Study of Strain Feature of Left Ventricular Long-axis Myocardium in Normal Young Adults / 中国医学影像学杂志

Purpose To measure the longitudinal and transverse strain and displacement parameters of each segment of long axis myocardium on cardiac MRI film images of normal young volunteers using feature tracking technique (FT), and to analyze the regularity of left ventricular long axis strain and establish peak and time to peak (TTP) reference range concerning the longitudinal and transverse strain and displacement. Materials and Methods Cardiac film images of 29 healthy volunteers aged 24 to 34 were collected using Philips Multiva 1.5T MRI scanner, including three typical long axis planes of the left ventricular long axis, left ventricular outflow tract, and four-chamber view. The MRI film images were analyzed drawing on myocardial feature tracking software TOMTEC, and the peak value and TTP of longitudinal and transverse strain and displacement of the 16 AHA segments excluding apex cordis were obtained thereby. The regularity of each parameter concerning the plane, layer, and segment was summarized and analyzed. Results The TTP of longitudinal strain, longitudinal displacement and transverse strain were consistent among each myocardial segment, which was a constant indicator in (41.24±12.51) ％ RR interphase. The peak value of longitudinal displacement was represented by apex cordis (2.56±0.89) mm < middle (6.09±2.03) mm < cardiac base (8.07±2.05) mm, and the peak value of transverse displacement was manifested as apex cordis (4.57±1.18) mm < middle (5.65±0.84) mm < cardiac base (8.48 ±1.18) mm, which was consistent with cardiac geometric deformation visually observed. The longitudinal strain showed consistency on 2CH-3CH-4CH plane, whose peak reference value was (-22.46±13.19)％; while the peak value of transverse strain displayed no consistency on different planes. Conclusion The longitudinal strain of the left ventricular on different planes has consistent peak value and TTP, suggesting good reference value.

MRI measurement of left ventricle myocardial strain on short axis in normal youth / 中华放射学杂志

Objective To learn the endocardial strain patterns of the left ventricles on the short-axis views in normal youth volunteers using feature tracking techniques on cine cardiac MR imaging,and to build up the reference ranges of strain peak and time to peak (TTP) for endocardial strain analysis.Methods Twenty-nine normal youth volunteers aged from 24-34 years old were enrolled in the study in march 2015.The Cine MR imaging were acquired using balance FFE sequence with 24 phases for each cardiac cycle.The standard short-axis imaging planes were basal,mid-cavity and apical levels and divided into 16 segments.The peaks and TTPs of myocardial displacement and its velocity,radial and circumferential strain and strain rate and its velocity in each segment were calculated using feature tracking techniques.The data with normal distribution were analyzed by ANOVA and Student-Newman-Keuls (SNK) method,and Kruskal-Wallis and Wilcoxon rank sum test were used for the data without normal distribution.Results The peaks and TTPs of radial strain and strain rate differed in 16-segmental levels and basal,middle and apical plane levels and had no concordant reference ranges.The circumferential strain and strain rate were homogeneous at basal and middle plane levels [(-27.09 ±9.51)％,(1.94 ±0.98)/s,respectively].Their TTPs were homogenous [0.38 (0.08)RR,0.54 (0.08)RR,respectively],and there were no significant differences in planar-segments or inter-segment level.Except for middle level,the peaks of radial displacement and velocity differed in basal and apical levels and had no concordant reference ranges.But radial velocity TTPs were homogeneous in all 16 segments [0.21 (0.04)RR].Except for the radial strain rate,TTPs showed no significant difference between basal level and middle level.The measurements at apical level revealed high variance.No regular pattern could be found on individual peak and TTP curves of velocity and strain rate.Conclusion The peaks and TTPs of radial strain are different in segmental and planar levels without a concordant reference range.The peaks and TFPs of circumferential strain and the radial velocity rTTPs are homogeneous in middle and apical plane level and have homogeneous reference range.

Radiologist-technologist integration training program: Evaluation and practice / 医学研究生学报

The radiologist-technologist integration (RTI)training program involves radiologists′ participation in technologists′ scan and examination training and technologists′ participation in physicians′preparation of reports during their residency training.Based on the investigations in the PLA General Hospital, West China Hospital of Sichuan University, The SecondXiangyaHospitalofCentralSouthUniversity, International Hospital of Peking University, and The First Hospital of Qinhuangdao, the author evaluated the methods of and practice in RTItraining as well as the potential value of RTI and itsfacilitation of work quality.RTItraining has effectively enhanced the basic skills training of the residents, deepened their understanding of the imaging process, and promoted scientific research and clinical work.The RTI training program can cultivate the technologists′ abilities to identify lesions, design individual protocols, and achieve the targeted scan for diagnosis.Meanwhile, itmay contribute to the improvement of human resource management inthe radiology department and overall quality of radiological examinations.

A comparison of echocardiography with magnetic resonance imaging in measurement of cardiac function in patients with dilated cardiomyopathy / 中华地方病学杂志

Objective To compare the difference of echocardiography and magnetic resonance imaging (MRI) in measurement of cardiac function in patients with dilated cardiomyopathy (DCM).Methods Totally 41 patients with DCM underwent echocardiography and MRI to measure cardiac function,the parameters included left ventricular end-diastolic volume (LVEDV),end systolic volume (LVESV),left ventricular ejection fraction (LVEF) and stroke volume (SV).The vertical long axis (VLA),horizontal long axis (HLA) and short axis (SA) of heart were measured by echocardiography.The differences of echocardiography and MRI were compared by linear regression and linear correlation.Results ①The value of LVEDV and LVESV obtained by the two methods:the value of LVEDV [(262.6 ± 117.0) ml] and LVESV [(196.4 ± 109.8) ml] obtained by MRI were higher than those of echocardiography [(211.4 ± 90.6),(216.5 ± 71.5),(219.1 ± 80.1) ml;(153.3 ± 76.1),(153.9 ± 54.1),(157.0 ± 61.1) ml,all P ＜ 0.05].②The value of SV and LVEF obtained by the two methods:the value of SV[(66.2 ± 21.3) ml] obtained by MRI was higher than that of echocardiography VLA [(58.1 ± 14.4) ml,P ＜ 0.05].The value of LVEF [(25.2 ±7.2)％] obtained by MRI was lower than those of echocardiography HLA and echocardiography SA [(28.9 ± 6.1)％,(28.3 ± 6.1)％,all P ＜ 0.05].③The value of LVEDV and LVESV obtained by echocardiography SA were associated with those obtained by MRI (r =0.785,0.653,all P ＜ 0.05).The value of LVEF obtained by echocardiography VLA was associated with it obtained by MRI (r =0.690,P ＜ 0.05).The value of SV obtained by echocardiography HLA and echocardiography SA were associated with those obtained by MRI (r =0.734,0.701,all P ＜ 0.05).Conclusion There are differences in accuracy and reliability using echocardiography and MRI when measuring dilated cardiomyopathy heart function,which must be treated differently.

Statistical Analysis of Publications in Chinese Journal of Medical Imaging from 2013 to 2015 / 中国医学影像学杂志

Purpose A systematic analysis of the articles published in the Chinese Journal of Medical Imaging from year 2013 to 2015 was performed to investigate its features of acceptance and publication for future decision making.Methods The printed journal and retrieved data from the Chinese Hospital Knowledge Database was analyzed using biometrical index,including the number of the papers,subspecialties,publication types,medical imaging modalities,MeSH frequency,citation and download.Results From year 2013 to 2015,there were 770 papers published,21.4 articles per issue and 0.267 articles per page in average.The top three subspecialty were abdominal imaging,chest imaging and reviews/comments,accounting for 17.27％,9.61％,9.48％,respectively.The top three modalities were CT,ultrasound and MRI,accounting for 39.61％,38.31％,29.87％,respectively.The original research papers were 584,accounting for 75.84％.The frequent MeSH subjects were differential diagnosis,angiography,pathology,computer-assisted image processing and contrast agents.Totally,there were 2395 citations and averagely 3.11 citation for each paper.The top citation was 36.There were 71317 downloads and 92.62 for each paper in average,the top download was 499.Conclusions The publications and its density per page increased annually from 2013 to 2015.The subspecialty were fully covered,the papers focus on original researches and clinical applications.The publication theme could follow the tendency of the imaging technology and had good and steady effects in the field.

Efifcacy of A Multi-parametric MRI Protocol for BI-RADS Categorization of Breast Lesions / 中国医学影像学杂志

PurposeTo investigate a multi-parametric protocol for breast MRI examination and lesions assessment correlated to the American College of Radiology (ACR) breast imaging reporting and data system (BI-RADS) categorization, and to improve the management of the breast lesions.Materials and Methods 301 pathologically confirmed lesions on 278 patients were retrospectively included. The scan protocol used a dynamic contrast enhancement sequence (DCE) of 1 mm×1 mm×1 mm spatial resolution, 120 temporal resolution and a diffusion weighted imaging (DWI) of b=1000 s/mm2. The malignant morphological features on the early-enhanced images, type II or III time intensity curve and the apparent diffusion coefficient (ADC) value less than benign/malignant threshold was equally weighted. Each was given 1 point when present malignant features and treated different on mass and non-mass-like enhancement lesions. When the sum of score was ≥2 points, the lesion was categorized as BI-RADS 5. When the sum of score was 1 point, the lesion was categorized as BI-RADS 4. When the sum of score was <1 point, the lesion was categorized as BI-RADS 3. The other specific benign findings were categorized as BI-RADS 2. No abnormality on DWI, DCE, T2WI and T1WI was categorized as BI-RADS 1. The final categories were correlated to the pathological grades as benign (B), high risk (HR) and malignant (M).Results When grouped HR as malignant (M+HR), the area under curve (AUC) of the ROC was 0.860. When grouped HR as benign (B+HR), the AUC of the ROC was 0.876, and the optimized sensitivity, specificity and accuracy was 85.3%, 86.8% and 85.1%, respectively, which were better than the other grouping. If the management of HR lesions could be lumptoectomy or short-term follow-up, the positive predictive value (PPV) of BI-RADS 5 for excisable lesions (M+HR) was 93.2%, the PPV of BI-RADS 4 for excisable lesions (M+HR) was 46.9% and the biopsy was essential. The PPV of BI-RADS 3 and below for follow-up lesions (B+HR) was 90.4%.Conclusion A simple diagnosis algorithm was established, which equally weighted the DCE morphological feature, DCE-TIC and DWI-ADC. The diagnosis protocol was well consistent with BI-RADS categorization and could predict the benign, high risk and malignant lesions in pathology as well as the proper management.

Correlation Between Apparent Diffusion Coefifcient Value on MR Diffusion-weighted Imaging and Prognostic Factors in Breast Invasive Ductal Carcinomas / 中国医学影像学杂志

PurposeTo explore the correlation between apparent diffusion coefficient (ADC) value on MR diffusion-weighted imaging (DWI) and prognostic factors in breast invasive ductal carcinomas.Materials and Methods 103 patients with pathology-proven invasive breast ductal carcinomas underwent DWI MR scan using b=1000 s/mm2. The minimum ADC values of the lesions were determined. Histopathological specimens were analyzed for tumor size, lymph node metastasis, pathological grade (traditional prognostic factors) and the expression of prognostic factors including Ki-67, ToPo-IIα, P53 and CyclinD1. The correlations between ADC values and these prognostic factors were evaluated.Results In 103 breast invasive ductal carcinomas, there was no significant relationship between tumor size, lymph node metastasis, pathological grade and mean ADC values (P>0.05). The correlations between mean ADC values and the biological prognostic factors were not significant (P>0.05). However, positive correlations were observed between pathological grade and the expression of Ki-67 as well as ToPo-IIα(P<0.05).Conclusion ADC values cannot serve as a prognostic factor for invasive ductal breast carcinomas. However, the expression of Ki-67 and ToPo-IIα in breast invasive ductal carcinomas may be important in evaluating prognosis of the tumor and guiding clinical therapy.

Analysis of clinical and imaging features of cardiac amyloidosis: a multicenter study / 南方医科大学学报

<p><b>OBJECTIVE</b>To summarize the features of clinical manifestations, laboratory tests and imaging findings of patients with cardiac amyloidosis (CA).</p><p><b>METHODS</b>A total of 60 CA patients (including 41 male and 19 female patients) from 4 centers admitted between May, 2012 and November, 2013 were included in the study. The demographic data, medical history, clinical manifestations, laboratory test data, ECG, cardiac ultrasound, and cardiac magnetic resonance (CMR) imaging of the patients were analyzed.</p><p><b>RESULTS</b>Two-thirds of the 60 CA patients, were middle-aged or elderly men, and 47% of the patients had AL-CA. The clinical manifestations included exertional dyspnea (73%), pedal edema (47%), hypotension (47%), and hypertrophy of the tongue (22%); abnormal laboratory test results included albuminuria (53%) and liver (15%) and kidney (28%) dysfunction; blood routine, urine and serum immunoglobulin quantification and immunofixation electrophoresis could help the screening of AL-CA. Kidney (53%) and liver (15%) involvement was common, and 86% of AL-CA patients had kidney involvement. Typical ECG characteristics included poor R wave progression (35%), low voltage in limb leads (33%), and a pseudo infarct Q wave (30%); the latter two were more frequent in AL-CA. The characteristics of ultrasound findings included left ventricle thickening (100%), left atrial enlargement (87%) and enhanced echo of the myocardial granules(92%), and diastolic dysfunction was obvious in all the CA patients regardless of the systolic function. The DT and E/e' of the mitral annulus could be used as an index to evaluate diastolic dysfunction in early stage of the disease. Left ventricular (LV) global subendocardial late gadolinium enhancement (LGE, 81%) accompanied by right ventricular (RV) and atrial LGE was the typical characteristic of CMR, and the range of LGE in the RV and the two atria was wider in AL-CA than in non-AL-CA. NT-proBNP (97%) and cardiac troponin (53%) in CA patients were both elevated, which helped in diagnosing and assessing the severity of cardiac involvement, according to which 50% of the patients were found to be at a high risk, 43% at an intermediate risk, and 7% at a low risk.</p><p><b>CONCLUSION</b>The combination of the features of clinical, laboratory tests and imaging findings of CA have important diagnostic and prognostic value for CA.</p>

Value of assessing left ventricular longitudinal systolic peak strain in differential diagnosis of primary cardiac amyloidosis from hypertrophic cardiomyopathy / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the endocardial, myocardial, and epicardial longitudinal systolic strain (LSsys) in the left ventricle (LV) segments and walls in patients with cardiac involvement due to primary amyloidosis (AL-CA) and hypertrophic cardiomyopathy (HCM).</p><p><b>METHODS</b>Twenty patients with biopsy-proven AL-CA, 20 with asymmetric HCM, and 20 age-matched healthy volunteers were analyzed for their clinical characteristics and underwent conventional echocardiography for evaluating LV wall thickness, left atrial and ventricle size, systolic and diastolic function and 2-dimensional velocity vector imaging for evaluating the endocardial, myocardial and epicardial LSsys of the LV segments and walls. AL-CA and HCM patients also underwent cardiac magnetic resonance to evaluate the late gadolinium enhancement (LGE) features.</p><p><b>RESULTS</b>Compared with the control group, AL-CA and HCM groups, with similar clinical symptoms and physical signs, both showed increased LV wall thickness, left atrial diameter, E/A ratio, septal E/e' ratio and the prevalence of granular sparkling. LV segments and walls endocardial LSsys were significantly lower in AL-CA patients than in HCM patients and the control subjects. The endocardial-epicardial LSsys difference in all the left ventricle walls were significantly smaller in AL-CA group than in the control group, but this difference appeared variable in HCM group. The LGE also presented with different features in AL-CA and HCM: AL-CA group showed subendocardial LGE in almost all the LV walls, but HCM group showed patchy LGE with a regional, multifocal distribution.</p><p><b>CONCLUSION</b>AL-CA is characterized by a significantly reduced endocardial LSsys in the LV segments and an uniform decrease of the endocardial-epicardial LSsys difference in all the LV walls, but the changes in HCM appear variable, and 2-dimensional velocity vector imaging is therefore a useful modality to differentiate AL-CA from HCM.</p>

Optimization of b-value in breast diffusion-weighted 1.5 T MR imaging ZHANG Jing / 中华放射学杂志

ObjectiveTo optimize the b-value of breast diffusion-weighted MRI (DW-MRI) at 1.5T by applying a range of b values and comparing the apparent diffusion coefficient (ADC) and signal-to-noise ratio (SNR) on a phantom,disease-free breast tissues,and benign and malignant lesions.Methods A phantom and 32 women with pathologically confirmed malignant ( 18 ) and benign ( 14 ) lesions were examined using EPI-DWI with different b values on a 1.5 T MR scanner.The b-value of EPI-DWI was 0,50,100,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,and 2600 s/mm2,respectively.The SNR and ADC values of the phantom,disease-free breast tissues,and benign and malignant lesions were measured.The correlation between the b-value and ADC or SNR of each image was analyzed.ResultsThe SNR of DWIdecreased as the b-valueincreased,showing aninversecorrelation (r =-0.802,P ＜0.01 ).The ADC values of benign and malignant lesion decreased as the b-value increased (r =-0.923 and -0.855,P ＜0.01 ).The maximum difference in ADC between malignant and benign lesions was observed when the b-value is between 800 and 1000 s/mm2 and diminished when the b-value was greater than 1400 s/mm2.ConclusionFor good image quality and valid differentiation between malignant and benign lesions,the optimized b-value of DWI at 1.5 T is between 800 s/mm2 and 1000 s/mm2.

Quick injection combining with slow infusion of contrast media on coronary MR angiography / 中华放射学杂志

Objective To evaluate the effect of quick injection combining with slow infusion of Gd-DTPA on T1 relaxation of the blood. Methods Fifteen volunteers were recruited for coronary MRA study using a navigator-gated 3D-FIESTA sequence. Coronary MRA were acquired on the same segments two times at 5 minutes and 15 minutes after Gd-DTPA administration. Contrast agent was injected biphasically with 10 ml at a flow rate of 1.5 ml/s and 20 ml at 0. 05 ml/s to prolong the T1 relaxation effect. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated pre- and post-contrast MRA. Image quality was compared using t-test. Results The SNR and CNR at 5 minutes after contrast injection (35.37 ±6. 84 and 21.57 ± 6. 08 ) were significantly higher than that of pre-contrast MRA ( 27.38 ± 6. 24 and 13.19 ±6. 50). The SNR at 15 minutes after contrast injection (33. 81 ±9. 43) was higher than that of precontrast MRA, but there was no statistically difference(t = 1. 885 ,P =0. 074). The CNR at 15 minutes after contrast injection (21.20 ± 7.65) was significantly higher than that of pre-contrast MRA. The SNR and CNR at 15 minutes after contrast injection were no significant different compared with those at 5 minutes after contrast injection. Conclusion T1-shorting effect in the blood can be prolonged by quick injection combining with slow infusion of Gd-DTPA ,which meet with the need of multiple scans of coronary MRA.

Characteristics of hippocampal 3-dimensional magnetic resonance imaging in amnestic mild cognitive impairment / 中华神经科杂志

Objective To identify the characteristics of hippocampal 3-dimensional MRI in patients diagnosed as having subtypes of amnestic mild cognitive impairment(aMCI)using hippocampal surfacebased analytic technique.Methods Fifry aMCI patients and 16 healthy controls who were equivalent in age and education(NC)were recruited.Every subiect carried out a 3-dimensional MRI scan.After the imaging data were acquired.the borders of the hippocampus were manually traced in coronal vlew using the software of InsightSNAP1.4.1. Hippocampal volume was computed automatically and statistically analysed.Hippocampal 3-dimension MRI were transformed into 3-dimension parametric surface mesh models of 400×200 prids.Hippocampal radial distance measures which was the distance from the surface point to the central axis were statistically compared between two groups.The radial atrophy significance maps were acquired and adjusted for multiple comparisons.Hippocampal morphological difference maps of aMCI in contrast with NC were acquired.Results The average normalized volume of left hippocampus were(3247.5±600.2)mm3 in aMCI patients and(3467.9±451.3)mm3 in NC subjects.The average normalized volume of right hippocampus were(3416.8±699.1)mm3 in aMCI patients and(3469.1±358.9)mm3 in NC subjects.Comparison of hippocampal volume did not differ significantly between aMCI patients and NC subjects(t=1.161,P=0.255;U=0.178,P=0.859).By using hippocampal surface-based morphologic analytic technique,3-dimension hippocampal morphological difference maps between two groups were acquired,showing significant atrophy on the lateral and inferior hippocampal surface which corresponded to CA1 and subiculum hippocampal subfields bilaterally in aMCI patients compared with NC subjects. Conclusions aMCI patients do not have significant volume loss in the hippocampus. Through hippocampal surface-based morphologic analyses, partial regional atrophy of hippocampus at some degree is found, mainly localizing in the lateral and inferior hippocampal regions which correspond to CA1 and subiculum hippocampal subfields bilaterally in aMCI compared with NC. These results may reflect the early image marker in aMCI.

High resolution MR imaging of porcine coronary arterial wall in vitro / 中国医学影像技术

Objective To get a MR imaging protocol for coronary arterial wall in vitro. Methods MR examinations were performed in 10 fresh porcine hearts. Three dimensional fast imaging employing steady state acquisition (3D FIESTA) was used to delineate left anterior descending artery (LAD), while 2D spin-echo T1W was performed with 8-channel head surface coil, temporomandibular surface coil and knee coil with the same parameters. T1WI was obtained with 384×256 and 512×512 in matrix using temporomandibular surface coil, and then T1WI, PDW and T2WI with fat saturation were obtained with different NEX using temporomandibular surface coil after injecting Resovist in LAD. Signal of the LAD wall, lumen, fat tissue adjacent to LAD, myocardium of anterior part of interventricular septum and noise were respectively measured. Signal-to-noise ratio (SNR) of image, contrast to noise ratio (CNR) between the wall and lumen (CNR1), CNR between the wall and surrounding fatty tissue (CNR2) were calculated. Results The SNR and CNR1, CNR2 of SE T1WI with temporomandibular coil were higher than those with 8-channel head surface coil and knee coil. SNR and CNR1, CNR2 of SE T1WI with 384×256 matrix were higher than those with 512×512 matrix. SNR and CNR1, CNR2 using 3 NEX were the highest. Conclusion Good SNR and CNR of porcine coronary wall can be achieved using temporomandibular surface coil, 384×256 in matrix and NEX of 3.

Clinical application of respiratory navigator echo triggered black blood contrast cardiac MRI / 中华放射学杂志

Objective To investigate the application of respiratory navigator echo triggered black blood contrast FSE in cardiac MRI. Methods The respiratory navigator echo trigger technique combining with black blood FSE (NAV-FSE) was tested on 11 volunteers and 5 patients in free breathing,using breath-hold FSE (BH-FSE) with the same imaging protocals as control. The imaging efficiency and the image sharpness were compared between NAV-FSE and BH-FSE and t-test was used for the statistics. Results All NAV-FSE acquisitions were completed in sixteen subjects while 4 BH-FSE acquisitions failed because of poor breath holding. The efficiencies of NAV-FSE were (42. 95±11.50)%, (56. 14±11.40)% and (55.25± 14. 70)% when echo train length (ETL) were 24, 16 and 8, respectively. When ETL were 16 and 24, the sharpness of NAV-FSE ( 0. 43±0. 02 vs 0. 36±0. 02 ) and BH-FSE ( 0. 36±0. 03 vs 0. 35±0. 02 ) were statistically different (t =4. 26, 5. 53 ,respectively; P <0. 05). NAV-FSE could have a shorter ETL setting without consideration of breath holding. Conclusion The navigator echo trigger technique could be compatible with black blood contrast FSE to image the heart without the restriction of breath holding and it allows to optimize the parameters to improve the image quality.

In vivo MR tracking of Feridex labeled bone marrow mononuclear cells in canine myocardial infarction / 中国医学影像技术

Objective To track the magnetically labeled bone marrow mononuclear stem cells (BM-MNCs) in canine myocardial infarction (MI) model with MR. Methods BM-MNCs were labeled with Feridex effectively in vitro and then injected intramyocardially in 8 MI model dogs. Serial MR was performed with 1.5T MR scanner to show the location of the labeled cells compared with histology. Results The injection sites of labeled BM-MNCs could be located on the 1st and 2nd week, but disappeared on the 4th week. Corresponding to these sites, Prussian blue staining consistently showed that large clusters of cells were labeled by dense intracellular iron at the scar tissue. Conclusion Feridex labeling BM-MNCs enables ready detection in the beating heart on a conventional MR scanner after transplantation into canine infarcted myocardium.

Comparison of whole body MR diffusion weighted imaging and skeletal scintigraphy In detecting bone metastasis / 中华放射学杂志

0bjective To evaluate the application of whole body MR diffusion weighted imaging (DWI)in the detection of bone metastasis using skeletal scintigraphy as the referenee.Methods Fonv.two healthy volunteers and 38 patients with malignant tumors were enrolled in our studv.A11 the patients received MR examination and skeletal scintigraphy within one week.MR examination was performed on GE signa 3.0T MR scanner using a build.in body coil.The skeletal system Was divided into eight regons and the images of the whole body MR DWI and skeletal seintigraphy were reviewed to compare the two modalities patient by patient and region by region.The images were reviewed separately by two radiologists and two nuclear medicine physicians,who were blinded to the results of another imaging modality.Results A total of 169 metastatic lesions in 69 regions of 30 patients were detected by whole body MR DWI while 156 lesions in 68 regions of 29 patients were identified by skeletal seintigraphy.There were two cases negative in scintigraphy but positive in whole body MR DWI and one case positive in scintigraphy only.There were eight lesions negative in scintigraphy but positive in whole body MR DWI,mainly located in the spine.pelvis and femur.Seven 1esions were only detected by scintigraphy,mainly located in the skull.sternum.clavicle and scapula.Conclusion The whole body MR DWI reveals excellent consistency with skeletal scintigraphy regarding bone metastasis.and the two modalities are complementary for each Other.

Efficiency of breath-hold three-dimensional fast imaging employing steady state acquisition sequence for coronary stenoses detection / 中华放射学杂志

Objective To evaluate the efficiency of coronary magnetic resonance angiography (CMRA) for stenoses detection by using breath-hold three-dimensional fast imaging employing steady state acquisition (FIESTA) sequence with the reference of conventional coronary catheter angiography. Methods~Consecutive 33 patients accepted CMRA examination within 3 weeks after the catheter angiography. Coronary stenoses was graded in 5 levels as 0%, 0%-25%, 25%-50%, 50%-75%, and 75%-100%, respectively, and CMRA and catheter angiogram were compared segment by segment. Results For the differentiation of the stenoses 50%, the accuracy, sensitivity, and specificity of CMRA was 84.3%, 84.8%, and 84.1%, respectively, and the negative prediction value was 92.3%. The accuracy, sensitivity, and specificity for the differentiation of stenoses between 50%-75% and 75%-100% were all 61.5%. Conclusion The breath-holding three-dimensional FIESTA sequence for CMRA was practical to exclude hemodynamic significant coronary stenoses but limited in detail grading.

Localization strategy for magnetic resonance coronary angiography / 中华放射学杂志

Objective To develop a localization strategy for magnetic resonance coronary angiography (MRCA). Methods In 89 subjects, the standard 4-chamber view and long-axis view of left and right ventricle were acquired using Fast-Imaging-Employing-Steady-State-Acquisition (FIESTA) sequence in CINE mode, and the trigger-delay time for mid-diastolic phase was determined. Coronary vessels including right coronary artery (RCA), left main (LM), left anterior descending (LAD), and left circumflex (LCX) were localized and imaged using 3-dimensional fat-suppressed FIESTA sequence during end-expiration. The reproducibility of the localization strategy was evaluated by taking the standard of coronary segmentation system recommended by American Heart Association. Results Eighty-six subjects completed the examination with full respiratory co-operation and the indication ratio was 96.63%. Nine planes were optimized as the standard to target the main branches of coronary arteries, and a comprehensive reproducibility reached 100% in demonstrating the proximal and middle segment of RCA (AHA-18, 19), LM (AHA-1, 2), proximal and middle segment of LAD (AHA-3, 5, 7), and proximal LCX (AHA-10). The reproducibility for the demonstration of distal segments of LAD, LCX, and RCA (AHA-9, 14, 21) was 94.19%, 72.09%, and 96.51%, respectively. Conclusion This is a simple and practical localization strategy for MRCA. It could image the proximal and middle segments of the coronary arteries with good reproducibility, which indicates the potential for clinical application.