Objective To investigate the application of cardiovascular magnetic resonance feature tracking(CMR-FT)in assessing myocardial strain in dilated cardiomyopathy(DCM)patients residing at high altitudes.Methods We retrospectively enrolled 29 DCM patients living at high altitudes(DCM-H),27 DCM patients living in a low-altitude plain environment(DCM-P),23 healthy volunteers living at a high altitude(HV-H),and 24 healthy volunteers living in a low-altitude plain environment(HV-P).All subjects underwent cine MRI scanning using a 3.0T rapid steady-state free precession sequence.The CMR images thus acquired were analyzed using cvi42,a post-processing software,to obtain left ventricular function and myocardial strain parameters.Results Compared with the HV-H group,the DCM-H group showed higher left ventricle end-diastolic volume(LVEDV)and left ventricle end-systolic volume(LVESV),and lower left ventricular ejection fraction(LVEF)and stroke volume(LVSV)(all P＜0.01).No significant difference was observed in cardiac function between the DCM-H and DCM-P groups(all P＞0.05).The absolute values of global radial strain(GRS),global circumferential strain(GCS),and global longitudinal strain(GLS)in the DCM-H group were lower than those in the HV-P group([14.5±6.5]％vs.[34.2±10.7]％,[-11.1±4.4]％vs.[-19.9±2.8]％,and[-7.7±3.2]％vs.[-13.6±4.1]％,respectively),with the differences being statistically significant(all P＜0.001).The DCM-H group had higher absolute GRS,GCS,and GCS values than the DCM-P group did([14.5±6.5]％vs.[7.0±2.7]％,[-11.1±4.4]％vs.[—5.4±2.2]％,and[—7.7±3.2]％vs.[—4.3±1.7]％,respectivley,all P＜0.01).Conclusion Myocardial strain in DCM patients living at a high altitude is lower than that in healthy volunteers living at a high altitude,but higher than that in DCM patients living in a low-altitude plain environment.CMR-FT can be used to quantitatively assess myocardial contractility in DCM patients living at a high altitude,showing promise for clinical application.

Purpose To explore the cardioprotective effect of cang-ai volatile oil(CAVO)on rats with cardiac function impairment model under low-pressure and low-oxygen environment in Tibet Plateau based on 7.0T cardiovascular magnetic resonance(CMR)imaging.Materials and Methods Forty SD rats were randomly divided into the normal group,the high altitude model group,the CAVO-treated group and the rhodiola rosea-treated group,with 10 rats in each group.Except for the normal group,the rats in other groups were transferred from the plain(500 m above sea level)to the Tibet Plateau(4 250 m above sea level)for two months,and then administered with the corresponding drugs by gavage for 14 d.The left ventricle function was measured by using a 7.0T high-field strength CMR and myocardial strain was analysed by using tissue tracing technique.HE staining was used to observe the morphology of cardiomyocytes,Masson staining to observe interstitial fibrosis,wheat germ agglutinin staining to observe cardiomyocyte hypertrophy,and transmission electron microscopy to observe the morphological changes of mitochondria in each group.Serum levels of creatine kinase,creatine kinase isoenzyme,lactate dehydrogenase,cardiac troponin T,superoxide dismutase,malondialdehyde and glutathione peroxidase were detected.Intracellular reactive oxygen species levels were detected using flow cytometry.Results The left ventricular ejection fraction of rats in the CAVO-treated group was higher than that of the high altitude model group[(66.61±1.38)％vs.(60.94±3.21)％;t=3.969,P=0.032];meanwhile,the global circumferential strain of the left ventricle in the CAVO-treated group was higher than that of the high altitude model group(-25.68±1.30 vs.-22.84±1.17;t=3.967,P=0.003).HE,Masson and wheat germ agglutinin staining showed hypertrophy and necrosis as well as interstitial fibrosis and ultrastructural disruption of cardiomyocytes in the high altitude model group,which improved after CAVO treatment.The level of cardiac troponin T in the serum of rats with CAVO treatment group was significantly decreased compared with that of the high altitude model group[(314.03±20.05)pg/ml vs.(518.30±18.13)pg/ml;1=13.090,P=0.001].Conclusion CAVO treatment can reduce cardiac injury caused by low-pressure hypoxia in high altitude,and its effect can be detected dynamically and non-invasively by 7.0T high-field strength CMR.

Objective To establish a hypobaric hypoxia rat model in a real high-altitude environment,to investigate the effects of the real high-altitude environment on rat bone mass and bone microstructure using multiple methods such as Micro CT,blood biochemistry,and pathology,and to explore the potential mechanisms involved.Methods Sprague Dawley(SD)rats were transported to the Yushu Plateau Laboratory(at 4250 m above sea level)in Qinghai Province and kept there for 4,or 8,or 18 months.These groups were designated as H-4,H-8,and H-18,respectively.Upon completion of the high-altitude exposure,these animals were transported to the Molecular Imaging Laboratory,West China Hospital,Sichuan University(at 500 m above sea level)in Chengdu for relevant testing and comparison with the control animals raised in a low-altitude environment for the same durations(designated L-4,L-8,and L-18).The tests performed included blood biochemistry,Micro CT imaging,and pathological assessments such as ELISA,Western blot,and HE and TRAP staining.Results Compared with that of the control group,the body mass of rats in the H-4 and H-18 groups decreased significantly(H-4 group vs.L-4 group:[513.75±35.10]g vs.[649.18±60.03]g,P＜0.01;H-18 group vs.L-18 group:[535.58±66.65]g vs.[670.86±44.96]g,P＜0.01).The serum Ca2+concentration was higher in the H-8 group and H-18 group compared to that in the control group(H-8 group vs.L-8 group:[2.48±0.09]mmol/L vs.[2.38±0.07]mmol/L,P＜0.05;H-18 group vs.L-18 group:[2.55±0.11]mmol/L vs.[2.13±0.27]mmol/L,P＜0.05).No statistically significant difference was observed in the concentration of P3+.Bone metabolism indicator cross-linked carboxy-terminal telopeptide of type Ⅰ collagen(CTX-Ⅰ)was significantly increased in all high-altitude groups compared to the low-altitude groups(H-4 group vs.L-4 group:[1.44±0.08]ng/mL vs.[0.70±0.13]ng/mL,P＜0.01;H-8 group vs.L-8 group:[1.52±0.10]ng/mL vs.[0.75±0.10]ng/mL,P＜0.01;H-18 group vs.L-18 group:[2.70±0.13]ng/mL vs.[1.94±0.15]ng/mL,P＜0.01).In addition,CT results showed a decrease in bone volume fraction of trabecular bone in the three high-altitude groups(H-4 group vs.L-4 group:[7.48±2.35]％vs.[10.40±2.93]％,P＜0.05;H-8 group vs.L-8 group:[7.17±2.68]％vs.[10.09±2.95]％,P＜0.05;H-18 group vs.L-18 group:[2.90±2.91]％vs.[8.68±4.11]％,P＜0.01),and increased trabecular separation in the three high-altitude groups(H-4 group vs.L-4 group:[0.70±0.12]mm vs.[0.60±0.06]mm,P＜0.05;H-8 group vs.L-8 group:[0.68±0.07]mm vs.[0.59±0.05]mm,P＜0.01;H-18 group vs.L-18 group:[0.80±0.09]mm vs.[0.70±0.09]mm,P＜0.05).TRAP staining showed an increase in osteoclasts in the H-4 and H-18 groups.Western blot results indicated an increase in the expression of receptor activator of nuclear factor-κB ligand(RANKL)and hypoxia inducible factor-1α(HIF-1α)in high-altitude environment,while the expression of osteoprotegerin(OPG)was inhibited.Conclusion The impact of high-altitude environment on rat femurs is characterized primarily by a reduction in trabecular bone mass and damage to bone microstructure.

Objective To explore the therapeutic effect of Cang-ai volatile oil(CAVO)on rats with myocardial hypertrophy(MH)exposed to the hypobaric hypoxic environment of the Qinghai-Tibet Plateau using 7.0-tesla(7.0T)cardiac magnetic resonance imaging(CMR).Methods A total of 50 male specific pathogen-free(SPF)Sprague-Dawley(SD)rats were randomly assigned to a low-altitude control(CON)group,hypobaric hypoxia(HH)group,myocardial hypertrophy modeling(MH)group,MH modeling plus CAVO treatment(MH+CAVO)group,and MH modeling plus benadryl hydrochloride treatment(MH+RX)group,with 10 rats in each group.Except for the CON group,the rats in all the groups were kept and fed in the standard way for 8 weeks in a high-altitude environment(at 4250 m above sea level),and then given the corresponding treatment drugs by gastric gavage.Afterwards,7.0T high field strength CMR was used to measure left ventricular(LV)function and myocardial strain.Hematoxylin-eosin(HE)staining and Masson staining were performed to observe myocardial interstitial fibrosis.Wheat germ agglutinin(WGA)staining was performed to analyze the cross-sectional area of cardiomyocytes.Transmission electron microscopy was used to observe the ultrastructural changes of the myocardium.Serum levels of cardiac troponin T(cTnT),superoxide dismutase(SOD),malondialdehyde(MDA),and glutathione peroxidase(GSH-PX)were measured by ELISA.Results Compared with those of the control group,the MH group had significantly lower left ventricular global circumferential strain(LVGCS)at(-18.85±1.67)％and left ventricular global longitudinal strain(LVGLS)at(-20.39±1.48)％(P＜0.05).However,the MH+CAVO group had significantly higher LVGCS at(-22.10±1.08)％and LVGLS at(-24.60±1.72)％compared with those of the MH group(both P＜0.05),indicating that CAVO treatment improved LV function.The MH group had a decreased level of serum glutathione peroxidase(GSH-Px)in comparison with the CON group([1173.49±27.10]U/mL vs.[300.83±47.25]U/mL,P＜0.01),a decreased SOD level in comparison with the CON group([302.27±3.65]U/mL vs.[105.96±4.03]U/mL,P＜0.01),and an increased level of serum malondialdehyde(MDA)in comparison with the CON group([57.91±1.13]μmol/L vs.[6.65±2.99]μmol/L,P＜0.01),suggesting that the antioxidant capacity of rats in the MH group was decreased.After CAVO intervention,rats in the MH+CAVO group exhibited an increase in the serum levels of SOD at(278.51±5.97)U/mL and GSH-Px at(961.82±17.56)U/mL,as well as a decrease in MDA at(17.79±1.33)μmol/L(all P＜0.05).Conclusion CAVO can effectively improve cardiac function in rats with cardiac hypertrophy exposed to high-altitude environment by modulating oxidative stress and ameliorating cardiac hypertrophy.

Objective: The occurrence of intramyocardial hemorrhage (IMH) and microvascular obstruction (MVO) in myocardial infarction (MI), known as severe ischemia/reperfusion injury (IRI), has been associated with adverse remodeling. APT102, a soluble human recombinant ecto-nucleoside triphosphate diphosphohydrolase-1, can hydrolyze extracellular nucleotides to attenuate their prothrombotic and proinflammatory effects. The purpose of this study was to temporally evaluate the therapeutic effect of APT102 on IRI in rats and to elucidate the evolution of IRI in the acute stage using cardiovascular magnetic resonance imaging (CMRI). Materials and Methods: Fifty-four rats with MI, induced by ligation of the origin of the left anterior descending coronary artery for 60 minutes, were randomly divided into the APT102 (n = 27) or control (n = 27) group. Intravenous infusion of APT102 (0.3 mg/kg) or placebo was administered 15 minutes before reperfusion, and then 24 hours, 48 hours, 72 hours, and on day 4 after reperfusion. CMRI was performed at 24 hours, 48 hours, 72 hours, and on day 5 post-reperfusion using a 7T system and the hearts were collected for histopathological examination. Cardiac function was quantified using cine imaging and IMH/edema using T2 mapping, and infarct/MVO using late gadolinium enhancement. Results: The extent of infarction (p < 0.001), edema (p < 0.001), IMH (p = 0.013), and MVO (p = 0.049) was less severe in the APT102 group than in the control group. IMH size at 48 hours was significantly greater than that at 24 hours, 72 hours, and 5 days after reperfusion (all p < 0.001). The left ventricular ejection fraction (LVEF) was significantly greater in the APT102 group than in the control group (p = 0.006). There was a negative correlation between LVEF and IMH (r = -0.294, p = 0.010) and a positive correlation between IMH and MVO (r = 0.392, p < 0.001). Conclusion APT102 can significantly alleviate damage to the ischemic myocardium and microvasculature. IMH size peaked at 48 hours post reperfusion and IMH is a downstream consequence of MVO. IMH may be a potential therapeutic target to prevent adverse remodeling in MI.

OBJECTIVE: A failed electrocardiography (ECG)-trigger often leads to a long acquisition time (TA) and deterioration in image quality. The purpose of this study was to evaluate and optimize the technique of self-gated (SG) cardiovascular magnetic resonance (CMR) for cardiac late gadolinium enhancement (LGE) imaging of rats with myocardial infarction/reperfusion. MATERIALS AND METHODS: Cardiovascular magnetic resonance images of 10 rats were obtained using SG-LGE or ECG with respiration double-gating (ECG-RESP-gating) method at 7T to compare differences in image interference and TA between the two methods. A variety of flip angles (FA: 10°–80°) and the number of repetitions (NR: 40, 80, 150, and 300) were investigated to determine optimal scan parameters of SG-LGE technique based on image quality score and contrast-to-noise ratio (CNR). RESULTS: Self-gated late gadolinium enhancement allowed successful scan in 10 (100%) rats. However, only 4 (40%) rats were successfully scanned with the ECG-RESP-gating method. TAs with SG-LGE varied depending on NR used (TA: 41, 82, 154, and 307 seconds, corresponding to NR of 40, 80, 150, and 300, respectively). For the ECG-RESP-gating method, the average TA was 220 seconds. For SG-LGE images, CNR (42.5 ± 5.5, 43.5 ± 7.5, 54 ± 9, 59.5 ± 8.5, 56 ± 13, 54 ± 8, and 41 ± 9) and image quality score (1.85 ± 0.75, 2.20 ± 0.83, 2.85 ± 0.37, 3.85 ± 0.52, 2.8 ± 0.51, 2.45 ± 0.76, and 1.95 ± 0.60) were achieved with different FAs (10°, 15°, 20°, 25°, 30°, 35°, and 40°, respectively). Optimal FAs of 20°–30° and NR of 80 were recommended. CONCLUSION: Self-gated technique can improve image quality of LGE without irregular ECG or respiration gating. Therefore, SG-LGE can be used an alternative method of ECG-RESP-gating.
Animals ; Electrocardiography ; Gadolinium* ; Magnetic Resonance Imaging ; Methods ; Myocardial Infarction* ; Rats* ; Respiration

OBJECTIVE: Whether blood-brain barrier (BBB) disruption induced by chronic spontaneous hypertension is associated with beta-amyloid (Aβ) accumulation in the brain remains poorly understood. The purpose of this study was to investigate the relationship between BBB disruption and Aβ influx and accumulation in the brain of aged rats with chronic spontaneous hypertension. MATERIALS AND METHODS: Five aged spontaneously hypertensive rats (SHRs) and five age-matched normotensive Wistar-Kyoto (WKY) rats were studied. The volume transfer constant (Ktrans) obtained from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used to evaluate BBB permeability in the hippocampus and cortex in vivo. The BBB tight junctions, immunoglobulin G (IgG), Aβ, and amyloid precursor protein (APP) in the hippocampus and cortex were examined with immunohistochemistry. RESULTS: As compared with WKY rats, the Ktrans values in the hippocampus and cortex of the SHRs increased remarkably (0.316 ± 0.027 min−1 vs. 0.084 ± 0.017 min−1, p < 0.001 for hippocampus; 0.302 ± 0.072 min−1 vs. 0.052 ± 0.047 min−1, p < 0.001 for cortex). Dramatic occludin and zonula occludens-1 losses were detected in the hippocampus and cortex of SHRs, and obvious IgG exudation was found there. Dramatic Aβ accumulation was found and limited to the area surrounding the BBB, without extension to other parenchyma regions in the hippocampus and cortex of aged SHRs. Alternatively, differences in APP expression in the hippocampus and cortex were not significant. CONCLUSION: Blood-brain barrier disruption is associated with Aβ influx and accumulation in the brain of aged rats with chronic spontaneous hypertension. DCE-MRI can be used as an effective method to investigated BBB damage.
Alzheimer Disease ; Amyloid ; Animals ; Blood-Brain Barrier* ; Brain* ; Hippocampus ; Hypertension* ; Immunoglobulin G ; Immunohistochemistry ; Magnetic Resonance Imaging* ; Methods ; Occludin ; Permeability ; Rats* ; Rats, Inbred SHR ; Rats, Inbred WKY ; Tight Junctions

Objective To explore the best multiplicities of infection (MOI),the expression of the target gene and in vitro MR imaging of adenovirus vector-mediated transferrin receptor (TFRC) reporter gene transfection of human colorectal cancer Lovo cells.Methods Lovo cells were transfected with recombinant adenovirus (Ad-TFRC) at 5,10,50,100 MOI to determine the best MOI,and quantitative real-time PCR was performed to detect the eDNA of TFRC.The transfected cells were incubated in the culture medium including Tf-USPIO of various concentrations,and were observed by Prussian blue staining,then the cell viability was evaluated via Trypan blue staining.The labeled cells were scanned with 7.0T MR T2W,T2 map,T2* map sequences,and the signal intensities were analyzed.Results Ad-TFRC were successfully transfected into Lovo cells.The best MOI was 50,and the efficiency of infection was more than 90％.The relative expression amount of TFRC in transfected cells was higher than that in control Lovo cells by real-time quantitive PCR (P＜ 0.01).Prussian blue staining showed numerous blue iron particles in transfected cells when the best labeling concentration was 1.5 μg/ml.Trypan blue staining results of transfected Lovo cells and control Lovo cells was (93.80± 1.60)％ and (95.10±2.30) ％,respectively (P＞0.05).MR imaging in vitro showed that compared with control Lovo cells,the signal intensity decreased on T2WI,T2 map and T2* map sequences in transfected Lovo cells (P＜0.05).Conclusion TFRC reporter gene can be efficiently mediated by adenovirus for expression in Lovo cells.After magnetization labeling,7.0T MR imaging of Lovo cells can be successfully achieved in vitro.

Objective To investigate the character of aquaporin-1(AQP-1)expression in adrenal gland in diabetes mellitus and evaluate adrenal gland damage and function alterations by DWI with multiple b values. Methods Twenty male Sprague-Dawley rats were randomly selected by computer and randomized into 2 groups:untreated controls(n=10)and diabetes(DM)(n=10). Rats in diabetes group were fed with high-sucrose and high-fat diet, controls were fed with common diet. After fed with high-sucrose and high-fat diet for 4 weeks, rats in diabetes group were injected with streptozotocin(STZ). Forty days after diabetes induction with streptozotocin(STZ), MR imaging was performed in a 7.0 T scanner. Venous blood from the tails was collected before MRI scan to measure blood glucose, blood glucose more than 16.7 mmol/L wasregarded as diabetic status. All the rats underwent DWI with 18 b values(0 to 4500 s/mm2). Maps of pure diffusion coefficients(D), pseudo-diffusion coefficients(D*)and ultra-high ADC(ADCuh)were acquired. Rats were sacrificed after MRI scan for adrenal gland histopathology, AQP-1 immunohistochemistry analysis and AQP-1 optical density(OD)measurements. Student t test was used to compare the difference of D*, D, ADCuh and OD of AQP-1 between two groups. Results Eight diabetic animals developed hyperglycemia(two rats died during the modeling process). MRI scan was performed in all of the 18 rats. Signal intensity of D*map, D map and ADCuh map decreased gradually. ADCuh increased significantly in DM animals(0.24 ± 0.06) × 10-3mm2/s compared with control animals(0.18 ± 0.07) × 10-3 mm2/s(P<0.05), whereas there was no significant difference found between the two groups in their respective D*and D values(P>0.05). There was a noticeable increase in the AQP-1 labeling in the adrenal cell membrane and cytoplasm in DM animals compared with control animals. DM rats showed an increased OD value of AQP-1 in adrenal gland compared with the control animals(P<0.05). Conclusions We found significantly higher AQP-1 expression in adrenal gland in DM animals compared with controls. Ultra-high b-Values DWI may work as a useful way for noninvasive evaluation the change of adrenal function in DM.

OBJECTIVE: To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. MATERIALS AND METHODS: Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). RESULTS: Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 × 10(-4) mm2/s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 × 10(-4) mm2/s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°-11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°-53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°-66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°-64.9 ± 4.3°). CONCLUSION: Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey's models.
Anisotropy ; Coronary Vessels ; Diffusion* ; Endocardium ; Haplorhini ; Heart ; Ligation ; Macaca mulatta* ; Magnetic Resonance Imaging* ; Methods ; Myocardial Infarction* ; Water