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Objective: To compare imaging characteristics of rat vitro maxilla based on X-ray absorption-contrast CT (ACCT) and X-ray phase-contrast CT (PCCT), and to explore the value of PCCT in evaluating rat periodontitis models. Methods: A total of 6 SD rats were randomly divided into periodontitis group and normal group (each n=3). In periodontitis group, "ligation of silk thread+high sugar feeding" method was used to establish periodontitis models, and the rats were given 10% high sugar viscous feed for 8 weeks, while rats in control group were given conventional feeding. After 8 weeks, ACCT and PCCT were performed on the right maxilla of rats in both groups, and imaging characteristics were analyzed. Then 3D images of the maxilla were reconstructed, and the distance between cemento-enamel junction and alveolar bone crest (CEJ-ABC) of rats were measured and compared between groups. Results: ACCT could not clearly display dental pulp, also difficult to distinguish the periodontal membrane soft tissue. The contrast of PCCT images were better, able to clearly show the microstructure of soft tissue and hard tissue of maxilla, and the quality of 3D images based on PCCT was better than that of ACCT. Compared with control group, CEJ-ABC increased significantly in periodontitis group (Z=-9.43, P<0.01). Conclusion: PCCT has more advantages in imaging of soft tissue and hard tissue of rat maxilla, which is of great value in assessment of maxilla in rat periodontitis models.
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Objective To investigate the value of multi-phase contrast enhanced MR in the diagnosis and differential diagnosis of thyroid nodules. Methods From September 2015 to January 2018,176 patients with 257 thyroid nodules(109 malignant and 148 benign)preoperatively evaluated by multi-phase contrast enhanced MR were included in the present study.The final diagnoses for all cases were proved by the final pathological reports in our hospital.The diagnostic value of multi-phase contrast enhanced MR in thyroid nodules was analyzed retrospectively. Results The outflow ring sign can be regarded as a specific sign of papillary thyroid carcinoma (χ2＝125.03,P＝0.000)and the diagnostic sensitivity,specificity,positive predictive value and negative predictive value were 66.06%,98.65%,97.30%and 79.78%,respectively.The obvious enhancement was more common in benign thyroid nodules (χ2＝33.45,P＝0.000)and it can be regarded as a specific sign of adenoma and adenomatoid nodule(χ2＝74.7 5 ,P＝0.000 ).Conclusion The multi-phase contrast enhanced MR has important clinical application value in the diagnosis and differential diagnosis of thyroid nodules.The outflow ring sign can be regarded as a specific sign of papillary thyroid carcinoma,and the obvious enhancement was an important feature of benign nodules,especially of adenoma and adenomatoid nodules.
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Objective To explore the monitoring of cerebrospinal fluid (CSF) dynamics in a model of brain herniation induced by acute intracranial hypertension in Guangxi Bama-Mini pigs by phasecontrast cine magnetic resonance imaging (PC cine MRI).Methods Femoral artery blood were extracted from 10 pigs,and injected into the frontal and temporal parietal lobe to make a model of brain herniation induced by acute intracranial hypertension.The mean arterial blood pressure (MAP),intracranial pressure (ICP),and cerebral perfusion pressure (CPP) were monitored.Routine T1WI,T2WI,coronal,sagittal and cerebrospinal fluid flow sequence (fast PC cine slice) which positioned on the cervical 3 (C3) vertebral body as the center and perpendicular to the spinal scans were performed on all experimental animals before and after blood injection with 3.0T Magnetic Resonance Imaging.The ICP,MAP,CPP,the absolute values of CSF peak flow velocity and the absolute value of carotid peak flow velocity before and after blood injection were compared.Results The ICP,MAP,CPP,and the absolute value of CSF peak flow velocity before injection of autologous arterial blood were statistically significant as compared with those after blood injection [(6.80±2.044) mmHg vs (52.20±1.619) mmHg,(76.80±7.068) mmHg vs (142.80±12.399) mmHg,(70.00±6.074) mmHg vs (90.50±12.250) mmHg,and the absolute value of CSF peak flow velocity was (243.20±77.671) mm/s vs (201.40±55.482) mm/s,respectively,P＜0.01].The absolute value of the peak velocity of the carotid artery before blood injection was not statistically significant compared with that after blood injection [(876.80±239.908) mm/s vs (799.40±241.829) mm/s,P＞0.05].Conclusion After the formation of brain herniation induced by acute intracranial hypertension,the CSF flow in the C3 level spinal canal showed a low dynamic change,and the CSF flow velocity waveform was disordered and malformed.The non-invasive measurement of CSF dynamics by PC cine MRI can provide an important basis for the change of CSF dynamics in the model of brain herniation induced by acute intracranial hypertension,and provide a theoretical basis for further research on damage control neurosurgery in the future.
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3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in 0.18° increments through 180°. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens (X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.
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Octopodiformes , SynchrotronsABSTRACT
OBJECTIVE: Multiple sclerosis (MS) is an inflammatory disease characterized by demyelinating plaques in the white matter. Chronic cerebrospinal venous insufficiency (CCSVI) has been proposed as a new hypothesis for the etiopathogenesis of MS disease. MS-CCSVI includes a significant decrease of cerebrospinal fluid (CSF) flow through the cerebral aqueduct secondary to an impaired venous outflow from the central nervous system. This study aimed to determine whether CSF flow dynamics are affected in MS patients and the contributions to differential diagnosis in active and chronic disease using phase-contrast magnetic resonance imaging (PC-MRI). MATERIALS AND METHODS: We studied 16 MS patients with chronic plaques (group 1), 16 MS patients with active plaques-enhanced on MRI (group 2), and 16 healthy controls (group 3). Quantitatively evaluation of the CSF flow was performed from the level of the cerebral aqueduct by PC-MRI. According to heart rates, 14–30 images were obtained in a cardiac cycle. Cardiac triggering was performed prospectively using finger plethysmography. RESULTS: No statistically significant difference was found between the groups regarding average velocity, net forward volume and the average flow (p > 0.05). Compared with the controls, group 1 and group 2, showed a higher peak velocity (5.5 ± 1.4, 4.9 ± 1.0, and 4.3 ± 1.3 cm/sec, respectively; p = 0.040), aqueductal area (5.0 ± 1.3, 4.1 ± 1.5, and 3.1 ± 1.2 mm2, respectively; p = 0.002), forward volume (0.039 ± 0.016, 0.031 ± 0.013, and 0.021 ± 0.010 mL, respectively; p = 0.002) and reverse volume (0.027 ± 0.016, 0.018 ± 0.009, and 0.012 ± 0.006 mL, respectively; p = 0.000). There were no statistical significance between the MS patients with chronic plaques and active plaques except for reverse volume. The MS patients with chronic plaques showed a significantly higher reverse volume (p = 0.000). CONCLUSION: This study indicated that CSF flow is affected in MS patients, contrary to the hypothesis that CCSVI-induced CSF flow decreases in MS patients. These findings may be explained by atrophy-dependent ventricular dilatation, which may occur at every stage of MS.
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Humans , Central Nervous System , Cerebral Aqueduct , Cerebrospinal Fluid , Chronic Disease , Diagnosis, Differential , Dilatation , Fingers , Heart Rate , Magnetic Resonance Imaging , Multiple Sclerosis , Plethysmography , Prospective Studies , Venous Insufficiency , White MatterABSTRACT
Congenital heart disease (CHD) is the most common congenital malformation.MRI plays an important role in evaluating postoperative cardiac function of CHD.The new technology of 4D flow can be used to encode phase flow coded cine based on 3 vertical dimensions at the same time.Meanwhile,4D flow can perform multi-parameter functional assessments of blood flow vector and peak flow velocity,also can visualize the structure and blood flow of the inner heart and the outer heart.The principle of 4D flow and its application in children with CHD were reviewed in this article.
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Objective To evaluate the changes of cerebrospinal fluid dynamics of Chiari malformation type I associated syringomyelia patients with phase-contrast MRI (PC-MRI).Methods Thirty cases diagnosed with Chiari malformation type Ⅰ associated with syringomyelia clinically underwent cisterna plasty treatment.Cerebrospinal fluid dynamics changes were measured before 24 h and 6 months after operation with PC-MRI.The stroke volume (SV),mean flow (MF),regurgitation fractions (RF) and the maximum peak flow velocity (Vmax) were analyzed.Results After operation,PC-MRI showed SV and MF increased,the bidirectional Vmax decreased,which had statistical difference compared with those of preoperation (all P＜0.05),and the C2-3 level was the most obvious.Conclusion PC-MRI can quantitative analysis of preoperative and postoperative changes of cerebrospinal fluid flow and peak velocity.
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Objective To measure middle cerebral artery (MCA) hemodynamic parameters of chronic cerebral ischemia in middle aged and elderly people with phase contrast magnetic resonance imaging (PCMRI),and to explore cerebral blood flow dynamic pattern in different degrees of chronic cerebral ischemia patients.Methods Middle aged and elderly people underwent conventional MRI scan,and were divided into 12 cases of the normal group,16 cases of mild cerebral ischemia group and 13 cases of obvious cerebral ischemia group.All groups underwent bilateral MCA PCMRI.Bilateral MCA hemodynamic parameters and phase-velocity curve in a heartbeat cycle were obtained by QFLOW analysis software on the workstation for post-processing.Bilateral MCA vascular area,peak velocity (PV),mean velocity (MV) and mean flow (MF) were recorded.The differences of bilateral MCA hemodynamic parameters among the three groups were compared by SPSS17.0 software.Results Bilateral MCA vascular area,MV,MF and right MCA PV among three groups were statistically significant by one-Way ANOVA (P＜0.05).Compared with normal group,systolic peak of bilateral MCA phase-velocity curve was low,dull,widen,and the connection between the diastolic peak and systolic peak became flattened in chronic cerebral ischemia patients.Conclusion PCMRI can reflect the differences of the cerebral blood flow dynamic change pattern between different degrees of chronic cerebral ischemia.
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4D Flow MRI is a new phase contrast MR technique,which can spatially encode velocity in three-direction,collect multi-directional blood flow data,and result in complex three-dimensional dynamic parameters.4D Flow MRI is more accurate and comprehensive than 2D phase contrast MRI and Doppler echocardiography.However,4D Flow MRI have some disadvantages,such as long scanning time,noise,etc.,which are the future key technical issues to be addressed.4D Flow MRI technology has a great potential in clinical applications,such as intracranial vascular diseases,cardiac magnetic resonance imaging,and other aspects of aortic diseases.Research advances in clinical application of 4D Flow MRI were reviewed in this paper.
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Objective To evaluate aorta's compliance after repair of coarctation of the aorta (CoA)using the pulse wave velocity (PWV)of MRI.Methods A retrospective analysis of cardiac MR images in 22 patients after repair of CoA was performed.PWV was measured and calculated with phase contrast MRI,and echocardiography was performed to measure both ventricular function and myocardial thickness during the same period.Age and sex-matched 22 normal subjects were served as a control group and their aortic PWVs were measured.Results The averaged PWV in study group was significantly higher than that in control group [(4 .42 ± 3 .02 )m/s vs (2 .73 ± 0 .76 )m/s,P =0.02].In study group,the PWV value of children with moderate anastomotic stenosis was the highest. ROC curve analysis showed the highest sensitivity and specificity could be achieved to distinguish the mild or moderate anastomotic stenosis when the threshold for PWV was 3.37 m/s.No significant correlations were found between left ventricular end-diastolic volume,left ventricular end-systolic volume,ejection fraction,left ventricular thickness and PWV.Conclusion PWV is increased in children after repair of CoA.Significant aortic remodelling can be observed in patients with moderate anastomotic stenosis.
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Objective To evaluate aorta's compliance after repair of coarctation of the aorta (CoA)using the pulse wave velocity (PWV)of MRI.Methods A retrospective analysis of cardiac MR images in 22 patients after repair of CoA was performed.PWV was measured and calculated with phase contrast MRI,and echocardiography was performed to measure both ventricular function and myocardial thickness during the same period.Age and sex-matched 22 normal subjects were served as a control group and their aortic PWVs were measured.Results The averaged PWV in study group was significantly higher than that in control group [(4 .42 ± 3 .02 )m/s vs (2 .73 ± 0 .76 )m/s,P =0.02].In study group,the PWV value of children with moderate anastomotic stenosis was the highest. ROC curve analysis showed the highest sensitivity and specificity could be achieved to distinguish the mild or moderate anastomotic stenosis when the threshold for PWV was 3.37 m/s.No significant correlations were found between left ventricular end-diastolic volume,left ventricular end-systolic volume,ejection fraction,left ventricular thickness and PWV.Conclusion PWV is increased in children after repair of CoA.Significant aortic remodelling can be observed in patients with moderate anastomotic stenosis.
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Objective To investigate the cellular fragments and particle image changes of inventory aleucocytic suspending RBC produced by the storage time extension ,RBC damage or hemolysis in order to provide the revelatory experimental basis for the transfusion safety .Methods The supernatant was prepared from different stored days (3 ,7 ,14 ,21 d) of stock aleukocytic suspen‐ding RBC .The particles in supernatant were observed and morphologically analyzed by using the microscopic static image analytic technology .Results There were a small amounts of visible particles in the sample supernatant preserved for 3 ,7 d and the parti‐cles′sizes are similar to cells′;the number of particles began to significantly increase from 14 d and the diameter became smaller . The particles filled the entire field until 21 d ,showing fragmentary status .Conclusion The cellular fragments and particles in the supernatants of stock aleukocytic suspending RBC with the storage period exceeding 14 d are significantly increased and have signif‐icant difference compared with those stored for less than 14 d .These exogenous fragments and particles may become antigens and induce the body immune response ,lead to transfusion adverse reactions .It is recommended that the patients should be transfused with stock aleukocytic suspending RBC within a storage period of 14 d .
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Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions.
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Biomarkers , Hemodynamics , Hydrodynamics , Magnetic Resonance ImagingABSTRACT
Objective To observe the characteristics of different level of normal abdominal aorta’s time-flow,time-velocity curve and to investigate the hemodynamic factors in role of the occurrence and development of abdominal aorta’s disease.Methods PC-MRI scanning was performed on 60 normal volunteers T12/L1-L4/5 disc at the level of abdominal aorta,time-flow and time-veloci-ty curve were generated respectively.The characteristics of blood flow curves at different levels of abdominal aorta were observed. Results The time-flow,time-velocity curve of the normal abdominal aorta in different levels have 2nd phase (no diastolic reflux) and 3rd phase (diastolic reflux).Conclusion The characteristics of blood flow curves of different levels of abdominal aorta are dif-ferent.
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Objective To compare the value of UF‐1000i urinary sediment analyzer and phase‐contrast microscopy in identify source of hematuria .Methods A total of 98 patients diagnosed as hematuresis from December 2013 to May 2014 in the Affiliated Hospital of Putian Institute were enrolled in this study .Both the urinary sediment examination and phase‐contrast microscopy ex‐amination were conducted on the patients .According to clinical diagnosis results ,the sensitivity and specificity of the two methods were calculated and compared .Results The sensitivity of UF‐1000i urinary sediment analyzer (95 .3% ) was higher than that of the phase contrast microscope (81 .9% ) ,the difference was significant (P < 0 .05) ,while the specificity of phase contrast microscope (92 .3% ) was higher than that of UF‐1000i urinary sediment analyzer(89 .2% ) ,the difference was significant(P < 0 .05) .Conclu‐sion Combining application of UF‐1000i urinary sediment analyzer and phase contrast microscope has great clinical significance .
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Objective To investigate jugular vein morphological changes with three dimension phase contrast magnetic resonance venography(3D PC MRV),and to explore hemodynamic features using MR phase contrast cine (MR PC cine).Methods Sixty-five healthy volunteers performed 3D PC MRV and MR PC-cine sannings.MRV ranged from torcular herophili to brachiocephalic veins, and the raw data of PC-cine was acquired at cervical 2-3(C2-C3)level perpendicular to the Jugular veins(JVs)with the maximum encoding velocity of 50 cm/sec.Jugular vein showing absent or tip shape(cross-sectional area less than 12.5 mm2 )was considered abnormal,and flat,crescent,oval,round shapes were considered normal.Data of PC-cine was processed by computer to evaluate the hemodynamic features.Results Nine (13.85%)of 65 cases were abnormal that unilateral jugular vein showing needle-pointed narrow or absent,and 8 cases on the left,and one case on the right;Weak correlation was found between jugular veins pattern and the age.The right sided values in volunteers were higher than that of the left side.Conclusion The morphology and hemodynamics of jugular veins in volunteers showed significant difference between sides,and weak correlation is found between the morphology and aging.
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OBJECTIVE: To evaluate the image characteristics of subtraction magnetic resonance venography (SMRV) from time-resolved contrast-enhanced MR angiography (TRMRA) compared with phase-contrast MR venography (PCMRV) and single-phase contrast-enhanced MR venography (CEMRV). MATERIALS AND METHODS: Twenty-one patients who underwent brain MR venography (MRV) using standard protocols (PCMRV, CEMRV, and TRMRA) were included. SMRV was made by subtracting the arterial phase data from the venous phase data in TRMRA. Co-registration and subtraction of the two volume data was done using commercially available software. Image quality and the degree of arterial contamination of the three MRVs were compared. In the three MRVs, 19 pre-defined venous structures (14 dural sinuses and 5 cerebral veins) were evaluated. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the three MRVs were also compared. RESULTS: Single-phase contrast-enhanced MR venography showed better image quality (median score 4 in both reviewers) than did the other two MRVs (p < 0.001), whereas SMRV (median score 3 in both reviewers) and PCMRV (median score 3 in both reviewers) had similar image quality (p ≥ 0.951). SMRV (median score 0 in both reviewers) suppressed arterial signal better than did the other MRVs (median score 1 in CEMRV, median score 2 in PCMRV, both reviewers) (p < 0.001). The dural sinus score of SMRV (median and interquartile range [IQR] 48, 43-50 for reviewer 1, 47, 43-49 for reviewer 2) was significantly higher than for PCMRV (median and IQR 31, 25-34 for reviewer 1, 30, 23-32 for reviewer 2) (p < 0.01) and did not differ from that of CEMRV (median and IQR 50, 47-52 for reviewer 1, 49, 45-51 for reviewer 2) (p = 0.146 in reviewer 1 and 0.123 in reviewer 2). The SNR and CNR of SMRV (median and IQR 104.5, 83.1-121.2 and 104.1, 74.9-120.5, respectively) were between those of CEMRV (median and IQR 150.3, 111-182.6 and 148.4, 108-178.2) and PCMRV (median and IQR 59.4, 49.2-74.9 and 53.6, 43.8-69.2). CONCLUSION: Subtraction magnetic resonance venography is a promising MRV method, with acceptable image quality and good arterial suppression.
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Adult , Aged , Female , Humans , Male , Middle Aged , Cerebral Veins/diagnostic imaging , Cranial Sinuses/diagnostic imaging , Magnetic Resonance Angiography/instrumentation , Signal-To-Noise RatioABSTRACT
Objective To establish a three-dimensional (3D) visualization model for the vessel system of rabbit eyes using X-ray phase contrast imaging（XPCI）technique, and observe the morphological characteristics of iris vessels of the rabbit eyes. Methods Angiography on vessels of the New Zealand rabbit eyes was conducted using Barium sulfate as the contrast medium. The projected images of in vitro rabbit eye samples with high precision were obtained by XPCI technique, and then converted to tomography images by filter back projection. The 3D reconstruction of the rabbit eyes was completed by commercial visualization software Amira 5.2.2. Results The main blood vessels of the rabbit eyes were clear and coherent in the projection images, and the distribution and trend of some small vessels could be observed, with the smallest distinguishable blood vessel diameter being about 10 μm. The 3D model for vessel network of the rabbit eyes was built after 3D reconstruction of CT scan images. The major arterial circle of the iris could be observed at level 4 branch structure of vessels in the fundus, and the minimum diameter of vessels that could be identified was 40 μm. Conclusions The vessels of the rabbit eyes can be clearly observed and 3D visualization of vessel network can be constructed by using XPCI technique, which would provide basis for the analysis on hemodynamics of blood vessels in the eye and reference for the clinical study of glaucoma.
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Although digital subtraction angiography (DSA) has been used as the gold standard for the diagnosis of intracranial aneurysms, its clinical use is somewhat limited by its invasiveness, high medical cost and potential risk of nephrotoxicity. For the past three decades, the magnetic resonance angiography (MRA) techniques have been developed rapidly. As a non-invasive technique with high resolution ability, MRA can replace DSA for the diagnosis of intracranial aneurysms in most clinical situations. The time-of-flight MRA (TOF-MRA) carries a diagnostic sensitivity of up to 98.2%-98.7%for tiny intracranial aneurysms ( 5 mm) reaches as high as 100%. All the above mentioned MRA techniques can clearly display the intracranial aneurysms although their imaging characteristics and clinical applications are different from each other. This paper aims to make a brief review concerning the principles, clinical applications and recent progress of some MRA techniques.
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The proximity of thoracic aortic aneurysm to the left subclavian artery (LSA) has made the coverage of LSA during thoracic endovascular aortic repair (TEVAR) be essential. Despite controversy concerning the safety of LSA coverage and the indications for LSA revascularizations, the cerebral hemodynamic change after LSA coverage has not been demonstrated. We prospectively examined two patients who would undergo TEVAR with LSA coverage by using 2D cine phase contrast MR imaging. After LSA coverage, the left subclavian steal was properly compensated by the increased flow volumes of both carotid arteries and right vertebral artery, which is the major collateral supply. The total brain supply after TEVAR did not lessen, which showed good correlation with uneventful clinical outcome. Therefore, 2D phase contrast MR imaging can be recommended as a useful technique to evaluate the hemodynamic change of the LSA coverage during TEVAR and to triage the candidate for LSA revascularization.