Atrial Fibrillation ; Atrial Remodeling ; Diagnostic Imaging ; Heart Atria ; Humans

Objective To study characteristic findings and the diagnostic value of MRI in pituitary stalk interruption syndrome (PSIS). Methods Twenty-one patients with PSIS were included. Small field of view (FOV) MR1 scanning and clinic hormone detection were performed in all patients. Moreover, fluid attenuated inversion recovery (FLAIR)T,1 WI with fat-suppression sequence was performed in 8 cases. The appearance on FLAIR T1 WI and T2 WI were recorded. The shape of pituitary stalk and antehypophysis, and the signal intensity of posthypophysis were analyzed simultaneously. Results Growth hormone deficiency (GHD) was confirmed by clinic hormone detection in all 21 cases. The level of basal GH varied from 0. 03 μg,/L to 1.50 μg/L. The peak value under GH provocation was from 0. 13 μg/L to 4. 14 μg/L, and the GH was absolute default in all patients. Seventeen cases of them were combined pituitary hormone deficiency (CPHD), and 4 cases were isolated growth hormone deficiency (IGHD). The height of antepituitary was in the range from 1 mm to 3 mm, and the average value was (1.9±1.2) mm. Pituitary stalk was absent in 18 cases and showed as linear and discontinuous stalk in the other 3 cases. The high signal intensity was invisible in normal position in all cases, the high signal intensity spot in the region of infundibular recess of the third ventricle was shown in 19 cases, while it could not be found anywhere in 2 patients with diabetes insipidus. Conclusion PSIS often shows characteristic appearance on MRI, and a definite diagnosis can be made by using MRI combined with clinic hormone detection.

Objective To investigate the reliable methods for establishing models of acute radiation enteritis (ARE) and the criteria used to judge whether the model is successfully established.Methods A total of 98 rats were randomly divided into normal control group (group A),fractionated dose group B (4 Gy/fraction for 3 fractions),fractionated dose group C (4 Gy/fraction for 4 fractions),fractionated dose group D (4 Gy/fraction for 5 fractions),single fraction group E (12 Gy in a single fraction),single fraction group F (16 Gy in a single fraction),and single fraction group G (20 Gy in a single fraction).Abdominal irradiation was performed for all rats,and the changes in body weight and defecation were observed.Magnetic resonance imaging (MRI) was performed on days 3-5 after irradiation,and on the 4th day,anatomy was performed to measure the length of small intestine with edema,blood samples were collected to measure endotoxins,and the specimens of small intestine were collected to observe pathological changes.The independent-samples t-test was used for comparison between groups.Results After irradiation,groups D,E,F,and G experienced varying degrees of diarrhea and had positive results from endotoxins test.Group D had a longer length of small intestine with edema than group C (P=0.00) and had a similar length as group E (P=0.46).Groups E,F,and G showed dilation and dropsy in the intestinal canal on MRI,and groups F and G showed patchy signals of dropsy in the abdominal cavity.Groups F and G showed varying degrees of necrosis in the small intestine and died within 14 days after irradiation.Conclusions When the radiation dose is 33-46 Gy (biologically equivalent dose),both single dose and fractionated dose can successfully establish the model of ARE,while fractionated dose can be better controlled.

ObjectiveTo observe the change of cardiac function after acute myocardial infarction (AMI) in rabbit model,and to study MRI characteristics of left ventricular remodeling (LVR).Methods Forty-five japanese white rabbits underwent chest-opening coronary artery ligation surgery to obtain rabbit myocardial infarction model The animals were scanned on a 1.5 T MR scanner ( GE Healthcare,Chalfont St.Giles,UK) at six time-points as surgery,1,2,4,6,8 weeks after surgery. Cardiac function parameters were measured,including left ventricular end diastolic volume ( EDV ),stroke volume ( SV ),ejection fraction (EF),peak ejection rate ( PER ) and peak firing rate (PFR).At each time point,5 rabbits were randomly selected and performed re-thoracotomy to obtain heart specimen.Each specimen was examined by MRI with the diffusion tensor imaging ( DTI ).The value of ADC and fractional anisotropy (FA) were collected. Cardiac function data sets of different time points were analyzed using repeated measures data of ANOVA.The FA and ADC values of infarction myocardium set of different time points or different parts of the myocardium were analyzed using one-way ANOVA. The average was compared statistically between two adjacent groups using LSD-t test. Results Left ventricular EDV increased in progress with the time.It was increased from ( 2.21 ± 0.35 ) ml preoperatively to ( 3.15 ± 0.57 ) ml 8-week postoperatively.But the difference was not statistical significant ( F =1.384,P =0.220).EF was decreased from(57.31 ± 11.11 )％ to( 34.71 ± 8.72 )％.It dropped significantly and the difference was statistically significant (F =27.134,P =0.001 ).EF showed a downward trend with the increase of EDV.By linear regression analysis,an equation was set up with y =- 5.58x + 57.7 ( F =8.855,P =0.005 ).On the other hand,PER showed a progressive decline from (27.31 ± 13.06) ml/s to ( 17.31 ± 6.41 ) ml/s ( F =2.105,P =0.037 ),and PFR decreased from ( 23.79 ± 14.15 ) ml/s to ( 12.07 ± 6.91 ) ml/s ( F =2.366,P =0.011 ).FA value decreased from 0.442 ±0.093 to 0.107 ±0.037( F =12.61,P =0.001 ),and ADC valueshowed upward trend from (5.07 ± 1.15) ×10-4 mm2/s to(6.39 ±0.78) ×10-4 mm2/s (F=4.166,P =0.022 ).FA values of infarct,adjacent and remote region were 0.201 ± 0.049,0.316 ± 0.127 and 0.323 ± 0.117 respectively( F =3.896,P =0.004 ),and the ADC values in these regions were (6.19 ± 1.78 ) ×10 -4,(5.44 ± 2.63 ) × 1 0 -4,(5.29 ± 2.02 ) × 10 -4 mm2/s respectively ( F =3.248,P =0.018 ).FA and ADC values were significantly different between the infarct region and adjacent region ( t =7.327,P =0.001 ;t =3.292,P =0.005,respectively),but there was no significantly different between adjacent region and remote region ( t =1.024,P =0.129 ; t =1.467,P =0.164,respectively ).ConclusionsMRI measurement of parameters of cardiac function can be used to monitor the process of left ventricular function remodeling after AMI.The process of micro-structural remodeling of myocardium can be reflected by DTI.MRI provides a feasible imaging modality for LVR after AMI.

Objective To study the value of MR diffusion tensor imaging(DTI) in the staging of chronic kidney disease(CKD).Method MR diffusion tensor imaging was used on 26 CKD patients.All patients were diagnosed as CKD according to the criteria of clinical diagnostic.All MR images achieved diagnostic requirements.Diethylenetriamine pentaacetic acid(99mTc-DTPA) renal dynamic imaging was used to determine the unilateral renal function.CKD patients were determined as mildly renal impairment group and moderately to severely renal impairment group based on the glomerular filtration rate(GFR).Twenty healthy volunteers underwent DTI at the same time.The cortical and medullary ADC value and FA value were measured in all subjects who underwent conventional MRI and DTI.The paired Student's t test was used to compare the cortico-medullary difference of the mean ADC and FA values in all subjects.The oneway analysis of variance(ANOVA) was carried out to assess the difference among the medullary and cortical diffusion parameters(ADC,FA) of all the three groups,and LSD was used to assess multiple comparisons.The correlation of GFR and ADC value of the patients,and FA value of the patients were tested by Pearson correlation analysis.Results The cortical and medullary ADC values of 46 subjects were(2.25±0.25) × 10-3 and(2.10±0.20) × 10-3 mm2/s respectively,FA of them were(3.48±0.61) and(4.27±0.75) respectively(t =6.754,10.043 respectively; P＜0.01).The cortical ADC values of volunteers,mild renal impairment group,severely renal impairment group were(2.25±0.22) ×10-3,(2.31±0.19) ×103,(2.18±0.32) ×10-3mm2/s respectively.The medullary ADC value of the three groups were(2.09±0.19) × 10-3,(2.17±0.17) × 10-3,(2.06±0.24) × 10-3mm2/s respectively(F=0.968,0.882 respectively; P＞0.05).The cortical FA values of the three groups were 3.85± 0.47,3.18±0.62,3.20±0.52 respectively.The medullary FA of the three groups were 4.92±0.38,3.93±0.57,3.62 ± 0.53(F=8.725,33.705 respectively; P＜0.01).There was no correlation between cortical ADC,medullary ADC,cortical FA of the patients and GFR [(30.14±15.79) ml· min-1 · 1.73 m-2](r =0.243,0.197,0.196 respectively; P＞0.05).There was a positive correlation between medullary FA of the patients and GFR (r=0.556,P=0.003).Conclusion FA value has certain value in evaluating CKD early diagnosis and renal function.

Objective To explore clinical value of cardiac MRI feature tracking (CMR-FT) in evaluation of left ventricular global and regional myocardial strain in hypertrophic cardiomyopathy (HCM).Methods Totally 60 patients with HCM (HCM group) and 10 healthy volunteers (control group) were enrolled and underwent cardiac MR.MR Sequences included fast imaging employing steady state acquisition (FIESTA) and late gadalinum enhancement (LGE) at ventricular short-axis,two-chamber and four-chamber planes.The patients in HCM group were divided into LGE negative subgroup and LGE positive subgroup.CMR-FT processing software was used to measure myocardial global radial peak strain (GPSR),global circumferential peak strain (GPSC) and global longitudinal peak strain (GPSL).The radial,circumferential and longitudinal peak strain (PSR,PSC and PSL) at the apex,middle and basal parts of left ventricular were also measured as well.Resuits GPSR,GPSC,GPSL in LGE positive subgroup,LGE negative subgroup and control group had significant differences (all P＜0.05),and showed upward trends.Except PSL at the apex had no significent difference among three groups,PSR,PSC and PSL at the apex,middle and basal parts had significant differences (all P＜0.05),and also showed upward trends.There were positive correlations between the LVEF,SV and GPSR,GPSC,GPSL (all P＜0.05).The area under ROC curve of GPSR,GPSC and GPSL in diagnosis of HCM were 0.79,0.82,0.77 (all P＜0.05),and the area under ROC curve of GPSC was the largest.Conclusion The CMR-FT technology can find myocardial strain dysfunction in HCM sensitively,and the longitudinal strain is damaged earlier or worse than circumferential and radial strains.

Objective To evaluate the coronary microvascular dysfunction in patients with hypertrophic cardiomyopathy(HCM) by MR first-pass perfusion and late gadolinium enhancement. Methods From January 2011 to May 2015, 47 cases with HCM (HCM group) from the second affiliated hospital of Nanchang University were retrospectively analyzed. Additionally, 21 healthy volunteers were recruited as the control group. HCM group and control group underwent cardiac MR examinations at rest, including short axial cine, first-pass myocardial perfusion and late gadolinium enhancement scanning. Time to peak(tpeak), maximal upslope of time-intensity curve(Slopemax), peak signal intensity(SIpeak), myocardial thickening, and late myocardial gadolinium enhancement(LGE) were assessed for each myocardial segment. HCM group were divided into LGE segments group and non-LGE segments group. LGE segments group were divided into mild, moderate and severe LGE segments group. The SIpeak, Slopemax and tpeak in multiple groups were compared by one-way ANOVA and Kruskal-Wallis test. Spearman correlation tests were used to determine the relationships between perfusion parameter and LGE. Results The average values of tpeak in non-LGE segments group (527 segments), LGE segments group (225 segments) and control group (336 segments) were (67.0 ± 27.4), (79.4 ± 27.4), (59.7 ± 21.6)s, respectively. The average values of Slopemax in the three groups were 17.2±7.0, 16.4±7.4, 20.4±6.3, respectively. The average values of SIpeak in the three groups were 442.7 ± 143.2, 465.1 ± 138.4, 521.9 ± 146.7, respectively. Compared to the control group, tpeak increased and Slopemax, SIpeak decreased in non-LGE segments group and LGE segments group (P<0.01), while tpeak increased more significantly in LGE segments group. The Slopemax and SIpeak showed no statistically significant differences between non-LGE segments group and LGE segments group (P>0.05). There were significant differences among LGE segments groups, as the tpeak and SIpeak increased with increasing degrees of myocardial LGE (P<0.01). The Slopemax showed no statistically significant difference among them (P>0.05). The degree of LGE were positively correlated with tpeak (r=0.237, P<0.01). Conclusions 3.0 T magnetic resonance myocardial perfusion imaging can show microvascular dysfunction accurately and reliably in non-LGE segments. It may be helpful in the early diagnosis of coronary microvascular dysfunction for HCM.

Objective To study the correlation between the diffusion-weighted imaging (DWI) measurements and glomerular filtration rate (GFR), Katafuchi scores in IgA nephropathy. Methods Thirty-five patients with IgA nephropathy (IgAN group) and twenty healthy volunteers (control group) were enrolled in this study. All of the subjects underwent bilateral renal DWI measurements with 3.0T MRI scanner. The values of apparent diffusion coefficient (ADC) of renal cortex and medulla were measured. GFR of IgAN group was detected with 99Tcm-DTPA scintigraphy. Based on the Lee classification and the Katafuchi score system, the pathological grading was carried out in patients of IgAN group. The ADC values were compared between control group and different grades of IgAN group. The correlations between ADC and GFR values were analysed in defferent groups. The correlations between ADC values and Katafuchi scores were analysed in IgAN group. Results The renal cortical ADC values were significantly higher than medulla ADC values in both control group and IgAN group (P < 0.05). There were statistically significant differences in renal cortical ADC values and medulla ADC values between control group and IgAN subgroups (P<0.05). But there was no significant difference in renal cortical ADC value between IgANⅠgroup and control group (P>0.05). There was a positive correlation between the renal cortical and medulla ADC values and the GFR values in IgAN group (P<0.01). Negative correlation was found between the renal cortical and
medulla ADC values and the Katafuchi scores in IgAN group (P<0.05). Conclusion The diffusion-weighted imaging can reflect the physiological functions of kidney. It was feasible for application DWI in IgA nephropathy, which can be used for assessing the renal filtration function and the pathological damage. However, DWI measurement is not sensitive to early renal disease.

Objective: To investigate the application value of cardiovascular magnetic resonance tissue-tracking (CMR-TT) in the quantitative assessment of global and segmental myocardial strain after myocardial infarction. Methods: From June 2013 to June 2017, 45 patients with chronic myocardial infarction from the Second Affiliated Hospital of Nanchang University and eighteen normal volunteers as a control group were included in our research. All participants received CMR examination on a 3.0 T MRI scanner. Imaging protocol including FIESTA cine sequence (left ventricle short-axis planes, four chamber and two chamber long-axis planes) and late gadolinium enhancement (LGE). CMR-TT was undertaken using cvi 42 dedicated commercial software, global peak systolic circumferential, longitudinal, radial strains (GPCS, GPLS, GPRS) and segmental peak systolic circumferential, longitudinal, radial strains (PCS, PLS, PRS) in accordance with the American Heart Association's sixteen segment model were all derived. All segments were divided into five groups according to transmural extent expressed as enhanced area per segment: 0% as non-LGE segments group, 1 %-25 % as mild LGE segments group, 26%-50 % as moderate LGE segments group, 51%-75% as severe LGE segments group and >75% as complete LGE segments group. Two-independent samples t-test and Kruskal-Wallis H test were used, respectively, to compare means of 2 and 3 or more groups of continuous variables. Variables with normal distribution were presented as ±s, non-normal variables were reported as median (interquartile range). Results: Patients showed significant lower GPRS, GPCS and GPLS than the control group (15.13%±8.18%, -8.25%±3.23%, -7.11%±2.41% versus 32.41%±12.99%, -14.92%±3.32%, -11.50%±2.51%). PRS, PCS and PLS statistically significantly decreased with increasing extent of myocardial enhancement (t=-6.35,7.33,6.44, P<0.001).Segmental peak systolic strains of five groups were:PRS:24.87% (10.95%,39.02%), 13.26%(5.94%,24.24)%, 9.47%(4.01%,18.40%), 5.98%(-3.74%,11.86%), -2.65%(-6.62%,8.59%), respectively; PCS: -11.84%±5.34%, -8.60%±5.48%, -7.32%±5.59%, -5.30%±5.52%, -2.74%±5.24%, respectively; PLS: -9.47%±6.82%, -7.72%±6.22%, -7.07%±6.49%, -5.55%±5.95%, -3.54%±5.44%, respectively. The differences in the groups were statistically significant (H=164.47,166.61, 59.06, P<0.001). GPRS was positively correlated with LVEF(r=0.543, P<0.001), while GPCS and GPLS were both negatively associated with LVEF (r=-0.654, P<0.001; r=-0.682, P<0.001, respectively). Conclusions CMR-TT can quantitatively assess the severity of myocardial infarction accurately and reliably.Strain parameters have a good correlation with cardiac function indexes, this may be helpful in the recognition of left ventricular remodel after MI.

Objective:To explore the technical feasibility of CT feature tracking (CT-FT) technique in evaluating left ventricular myocardial strain and evaluate the change of myocardial strain in patients with coronary heart disease.Methods:Eighty-one patients with coronary heart disease (lesion group) and 33 patients with normal coronary artery (control group) matched with age and sex were collected retrospectively from the Second Affiliated Hospital of Nanchang University from April 2019 to October 2020. The lesion group was first divided into single vessel stenosis group (42 cases) and multi vessel stenosis group (39 cases) according to the number of coronary artery stenosis branches, and the global myocardial strains of the left ventricle between the groups were analyzed. Lesion site included the left anterior descending branch (LAD), right coronary artery (RCA) and left circumflex branch (LCX), respectively. According to the degree of vascular stenosis, the lesion groups were divided into normal group, mild stenosis group, moderate stenosis group and severe stenosis group. The segmental myocardial strains of the branch segment of LAD, RCA or LCX were analyzed between groups. All CCTA examinations were performed with retrospective electrocardiogram gating. CVI 42 cardiac postprocessing software was used to obtain myocardial strain parameters, including global peak longitudinal strain (GPLS), global peak circumferential strain (GPCS), global peak radial strain (GPRS), and the segmental myocardial strains of the branch segment of LAD, RCA or LCX. The segmental myocardial strains included the peak longitudinal strain (PLS), peak circumferential strain (PCS) and peak radial strain (PRS). One way ANOVA or Kruskal Wallis H test were used for multi group analysis. Results:With the increased number of coronary artery stenosis branches, the absolute value of GPLS gradually decreased. The GPLS of the control group, single vessel stenosis group and multi vessel stenosis group were -14.1%±2.7%, -11.5%±2.3% and -8.8%±2.0%, respectively. The difference of GPLS between the 3 groups or any 2 groups was statistically significant (all P<0.001). The absolute values of GPRS and GPRS in multi vessel stenosis group were significantly lower than those in control group and single vessel stenosis group (all P<0.001). There was no significant difference in GPRS or GPRS between single vessel stenosis group and control group ( P=0.083, 0.118). And there were significant differences in the segmental myocardial strains of the branch segment of LAD, RCA or LCX among 3 groups ( P<0.001). In severe stenosis group, the absolute values of PRS, PCS and PLS in LAD, RCA or LCX were significantly lower than those in moderate stenosis group, mild stenosis group and normal group (all P<0.05). In the moderate stenosis group, the absolute value of PLS in each branch segment was lower than that of the mild stenosis and normal group (all P<0.05), and there was no significant difference in any 2 other myocardial strain parameters of each branch (all P>0.05). Conclusions:CT-FT technique was feasible to evaluate left ventricular myocardial function. With the increased number or degree of coronary artery stenosis, the global and segmental myocardial strain parameters of left ventricle gradually decreased, and the longitudinal strain was more sensitive.