Paroxysmal supraventricular tachycardia includes atrioventricular node reentry tachycardia, atrioventricular reentry tachycardia and atrial tachycardia.At present, the commonly used methods in clinical diagnosis include ventricular pacing in tachycardia, pre ventricular stimulation in refractory/non refractory period of his bundle, pacing in different parts of the atrium, parahisian pacing in sinus rhythm and stimulation in different parts of the ventricle.Ventricular pacing is one of the most commonly used methods in clinical diagnosis.However, it may lead to " false V-A-A-V" sequence after pacing.The ventricular pre phase stimulation of his bundle refractory period may appear false negative or lead to termination of tachycardia, which is not condutive to differential diagnosis.The results may be affected by pacing position, bypass position and refractory period when parahisian pacing and ventricular stimulation at different sites/frequencies are performed in sinus rhythm.Because of their respective advantages and limitations, it is necessary to integrate a variety of identification methods to improve the accuracy of diagnosis and the success rate of operation.

Objective To detect different activated patterns of heavy smokers in different states as well as between smokers and non-smokers. Methods Seventeen subjects including 12 heavy smokers and 5 non-smokers (controls) were examined with functional magnetic resonance imaging (fMRI) performing smoking-related olfactory cue tasks. The data were processed with SPM2. These different patterns were compared between the two groups. Results When smokers were exposed to the smoking olfactory cue in the abstinent state, activation was found on the left superior frontal gyrus (BA8, 9, 10, 11), left middle frontal gyrus (BA8, 10, 11, 46), left inferior frontal gyrus (BA9), left medial frontal gyrus (BA6, 8, 10,11), right superior frontal gyrus (BA10), right middle frontal gyrus (BA8, 9), right inferior frontal gyrus (BA45, 47), right medial frontal gyrus (BA9, 11), left callosal gyrus (BA24, 31), right callosal gyrus (BA24, 37), right middle temporal gyrus (BA21) and both sides of the thalamus and cerebellum. When smokers were exposed to the smoking olfactory cue in the satiated state, activation could be found on both sides of the prefrontal lobe and cerebellar hemisphere, while there was no activation on the other brain regions. No activation was found on the whole brain of the nonsmokers,except for a little small volume active points appeared in individual subjects, possibly caused by the picture noise. Conclusion The Limbic system (cingulate cortex, thalamus) and the prefrontal lobe play an important role in the cue-induced smoking craving approved from the new perspective of the olfactory. It is feasible to research smoking addicts' brain activation and the role of neural mechanisms using olfactory stimulation with clinical 1.5T MRI equipment.

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.

Objective To investigate the value of kinetic features measured by computer-aided diagnosis (CAD)for breast MRI.Methods One hundred and sixty four lesions diagnosed pathologically by operation or biopsy comprised the analysis set.Automated lesion kinetic information from CADStream programs for breast MRI was identified.Three CAD variables were compared for benign and malignant lesions: initial phase peak enhancement (greatest percentage of signal intensity increase on first contrast enhanced sequence),delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement (washout,plateau,or persistent),and delayed phase enhancement categorized by single most suspicious type of kinetics (any washout ＞ any plateau ＞ any persistent).Morphological characteristics of breast lesions were described according to breast imaging and reporting data system (BI-RADS).Initial phase peak enhancement mean values between benign and malignant breast lesions were compared by using Wilcoxon rank-sum test,delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement or by single most suspicious type of kinetics between benign and malignant breast lesions were compared by using Chi-square test.Results There were 72 benign and 92 malignant breast lesions.A total of 123 (75.0％) mass lesions were identified,and the other 41 (25.0％) lesions showed no mass.Thirty lesions were BI-RADS-MRI 2,68 lesions were BI-RADS-MRI 3,43 lesions were BI-RADS-MRI 4,23 lesions were BI-RADS-MRI 5.Initial phase peak enhancement mean values of benign and malignant lesions were 237％ (69％ to 629％)and 336％ (86％ to 793％),respectively.There was no significant difference between benign and malignant lesions in initial peak enhancement mean value (Z =-1.626,P =0.104).Delayed phase enhancement categorized by single most suspicious type of kinetics (any washout ＞ any plateau ＞ any persistent) for benign and malignant lesions were 15,10,47 and 2,3,87 respectively.There was a significant difference between benign and malignant lesions (x2 =23.562,P =0.000).Initial peak enhancement value ＜ 100％ or ≥100％ were 5 and 67 for benign lesions,3 and 89 for malignant lesions,respectively.There was no significant difference between benign and malignant lesions at 100％ threshold (x2 =1.181,P =0.277).Delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement (washout,plateau,or persistent) for benign and malignant lesions were 48,6,18 and 47,15,30 respectively.There was no significant difference between benign and malignant lesions (x2 =4.496,P =0.106).Conclusions Of CAD kinetics analyzed,only delayed enhancement categorized by most suspicious type is helpful for the differentiation between benign and malignant lesions.However,there is significant overlap between initial peak enhancement at 100％ threshold or delayed kinetics categorized by largest percentage enhancement types of benign and malignant lesions,so lesion morphologic features should be considered.

Objective:To investigate the electrocardiographic characteristics of left and right ventricles origin of premature ventricular contractions(PVCs) during V3 transition of precordial leads, right ventricular outflow tract (RVOT) anterior septum and right coronary sinus (RCC), and RVOT middle-posterior septum and left coronary sinus (LCC).Methods:From January 2017 to September 2019, 91 patients with ventricular extrasystole of outflow tract who had V3 transition in precordial lead and had successful radiofrequency ablation in RVOT anterior septum, middle posterior septum, LCC and RCC were selected for retrospective case control study.The electrocardiography measurements of PVCs were compared between the anteroseptal RVOT group and RCC group, as well as the middle-posterior septal RVOT group and the LCC group, respectively.The measurements included the R-wave amplitude in lead Ⅰ, Ⅱ, Ⅲ and aVF, R amplitude ratio in leads Ⅲ to Ⅱ, Q-wave amplitude in lead aVL and aVR, Q amplitude ratio in leads aVL to aVR, R-wave and S-wave amplitude from leads V1 to V3, the V2S/V3R index, the transition zone index, and the V2 transition ratio.Results:Thirty-six cases originated from the anteroseptal RVOT, and 11 from the LCC.Lead I R-wave amplitude in anterior septal RVOT was higher than LCC group((0.22±0.25) mV vs.(-0.17±0.33) mV; P=0.003). R-wave amplitude in lead Ⅱ was lower than that in the LCC group((1.59±0.35) mV vs.(1.76±0.27) mV; P=0.035). R-wave amplitude in lead aVF was lower compared with the LCC group((1.53±0.35) mV vs.(1.78±0.39) mV; P=0.050). The V2S/V3R index showed a significant difference between these two groups(1.99±0.66 vs.0.76±0.38; P<0.001). The V2 transition ratio also appeared a significant difference between the two groups(0.69±0.43 vs.1.05±0.35; P=0.005). PVCs arose from the middle-posterior septal RVOT in 32 cases, and from the RCC in 12 cases.Compared with RCC group, lead Ⅰ R-wave amplitude showed lower ((0.25±0.31) mV vs.(0.57±0.12) mV; P<0.001); R amplitude ratio in leads Ⅲ to Ⅱ higher (0.89±0.14 vs.0.72±0.18; P=0.002); Q amplitude in lead aVL((0.72±0.24) mV vs.(0.51±0.16) mV; P=0.002)higher, and Q amplitude ratio in leads aVL to aVR higher in the middle-posterior septal RVOT(0.76±0.23 vs.0.50±0.21; P=0.002). Conclusion:Among the cases with lead V3 transition, PVCs originated from the anteroseptal RVOT show significantly different R wave in lead Ⅰ, Ⅱ, aVF, V2S/V3R index, and the V2 transition ratio compared with those from the LCC.The PVCs from the middle-posterior septal RVOT and the RCC have different R wave in lead Ⅰ, R amplitude ratio in leads Ⅱ and Ⅲ, Q amplitude ratio in leads aVL and aVR.Combined with its different characteristics, it can help to identify the origin of left and right ventricles.

Objective To evaluate the deep brain venous blood oxygen content changes in patients with multiple sclerosis(MS) using susceptibility weighted imaging (SWI), and to explore the ability of SWI in reflecting the clinical condition. Methods Forty-four MS patients were prospectively enrolled in the study. All the clinical-proved patients meeting the McDonald standards (2005 revised) underwent conventional MRI, SWI, and 12 cases of them underwent MRI review from 12 to 16 months interval. all the patients' clinical condition were quantified according to the expanded disability status scale(EDSS). The score was 0.5—6.5. Sixty-five age- and gender- matched healthy volunteers underwent conventional MRI and SWI. The blood oxygen content of the deep brain venous were estimated by the veins phase value, and differential phase values of blood vessels and surrounding tissues (Δφ) were processed with SPIN software. The blood vessels consist of bilateral BV, SMCV, ICV, STV and FMV, PMV, OMV. The difference of Δφvalue in different veins between MS patients and the controls was compared using independent sample t-test, and the Δφ value comparison of MS patients in different time were performed by using paired t test; The correlation ofΔφvalue between MS and EDSS was analyzed using Spearman correlation. Results TheΔφvalue of BV, SMCV, ICV, STV were 856.6 ± 246.4, 600.6 ± 155.2, 965.9 ± 205.4, 844.2 ± 149.7 in MS, and 767.6±145.1, 536.2±123.5, 892.8±156.3, 783.1±148.5 in controls, respectively. TheΔφvalue was higher in MS patients than the controls (t=2.157, 2.303, 2.005, 2.103,P<0.05). The twelve patients'Δφvalues of BV, ICV,STV were 729.4±275.1, 906.1±219.2, 737.2±159.1 in the first time, and 923.2±211.6, 1017.3±211.1, 919.3 ± 165.9 in the second time, and all the values increased in the review of the interval of 12 to 16 months (t=-3.092,-6.420,-3.972,P<0.05). The phase value of PMV and OMV had significant positive correlation with EDSS scores(r=0.638, 0.642,P<0.01). Conclusions The state of hypoxia of the brain parenchyma appears in MS patients, and hypoxia may become worse with the extension of course. The extent of hypoxia can reflect the disability of the patients.

Objective To evaluate CT imaging and pathological features of maxillofacial malignant myoepithelioma (MME). Methods A total of eight patients with pathologically confirmed MME of the maxillofacial region were underwent non-enhanced and contrast-enhanced CT scans.CT features of the lesions were assessed as follows:location,number,shape,size,enhancement pattern and CT number on non-enhanced and contrast-enhanced scan.CT features were compared with the pathological results.Results All the lesions were unilateral,in which mixed type with clear cells and spindle cells in 5 cases,mixed type with epithelioid cells and plas-ma cells in 2 cases,and clear cell type in one case.8 cases were manifested as lobulated mass.On non-enhanced scan,the density of all the lesions were hetergeneous with cystic area,1 case with calcification and 2 cases with bone destruction.On the contrast-en-hanced CT,all the lesions were showed hetergeneously moderate or obvious enhancement,and cystic,line and crack areas without the enhancement were observed.Minor vessel and spiculate protuberance of marginal zone on the arterial phase were observed in most le-sions.Conclusion MME has different pathological subtypes and characteristic CT features.CT is an effective method to diagnose MME.

Objective To optimize protocol in one-stop whole brain CT perfusion imaging (CTP) combined with CTA.Methods Totally 45 subjects underwent one-stop whole brain CTP combined with CTA with three different scanning protocols and 22 phases.CTA images were reconstructed from CTP original data at the tenth phase,the protocols of three scanning groups were as follows:Group A using automatic tube current modulation technique (ATCM) with low noise index (NI;NI=2),group B with fixed tube current (325 mA) and group C using ATCM with slightly low NI (NI=2.5),and the other phases of three groups were performed with ATCM and NI=8.Tube voltage of all three scanning protocols was 100 kV.The radiation dose and related parameters were recorded.Objective parameters including image noise (SD),SNR,CNR and perfusion parameters in different parts of the brain parenchyma and subjective scores of CTA,CTP image quality were compared among three groups.Results There was significant difference of effective dose (ED) among three groups (P＜0.05).ED of group A was higher than that of group B and C (P=0.043,0.001).No difference was found in CTA image noise,SNR,CNR nor subjective scores among three groups (P=0.218,0.545,0.575,0.900),neither of CTP images among three groups (P＞ 0.05).Conclusion Using ATCM and increasing NI appropriately may reduce radiation dose in one-stop CTP combined with CTA.

Objective:To assess the value of amide proton transfer weighted (APTw) imaging in the evaluation of pH changes in infarct core (IC) and ischemic penumbra (IP) in subacute cerebral infarction.Methods:The data of twenty-three subacute cerebral infarction patients with unilateral steno-occlusive disease of the middle cerebral artery (subacute infarction group) from April to November 2019 in the First Affiliated Hospital of Dalian Medical University were prospectively analyzed. Fifteen healthy volunteers were enrolled in this study as the control group. All subjects underwent conventional MRI, DWI, 3D-pseudo continuous arterial spin labeling (3D-pCASL) and APTw sequences. Based on DWI images, relative cerebral blood flow (rCBF) and APTw images to determine the region of IC, blood flow penumbra [cerebral blood flow(CBF)-DWI mismatch area, IP CBF] and metabolic penumbra (APTw-DWI mismatched area, IP APT). 3D ROIs were used to semi-automatically measure the APTw signals and the volume of IC and IP CBF of the patients in subacute infarction group. The comparison of APTw signals between the infarct side and the contralateral side in the subacute infarction group, the comparison of bilateral APTw signals in the control group, and the comparison of APTw signals in the IC and IP CBF regions were performed by paired-sample t test or Wilcoxon signed-rank test. The paired-sample t test or Mann-Whitney U test was used to compare the APTw signals between the two groups. The Friedman test was applied to compare the difference of volumes among IP CBF1.5, IP CBF2.5 and IP APT . Results:There was no significant difference of the APTw signals among the IC, the contralateral side in the subacute infarction group and the control group ( P>0.05). The APTw signals of IP CBF and IC of the infarction group were statistically different ( P<0.05). Compared with the contralateral side of IP CBF1.5 (3.7±1.7, -1.84±1.48, 5.57±2.75), the APTwmax (3.07±1.41, t=-3.012, P=0.006), APTw min [-1.30 (-1.74, -0.57), Z=-2.099, P=0.036], and APTwmax-min(4.51±2.58, t=-3.273, P=0.003) signals in the IP CBF1.5 were decreased ( P<0.05). Compared with the contralateral side of IP CBF2.5 [-1.53 (-2.80, -0.91), 5.31±2.61], the APTw min [-1.08 (-1.60, -0.49), Z=-2.616, P=0.009] and APTwmax-min (4.41±2.72, t=-3.228, P=0.004) signals in the IP CBF2.5 were decreased. The volumes of IP CBF1.5 [107.51(50.08, 138.61)mm 3], IP APT [99.00 (53.27, 121.335) mm 3] and IP CBF2.5 [89.91 (51.53, 139.87) mm 3] were successively reduced (χ2=7.913, P=0.019), and the volume of IP CBF2.5 was significantly smaller than that of IP CBF1.5 ( P=0.037). Conclusion:The acid-base metabolism in the IC of subacute cerebral infarction is not obvious, but the blood flow penumbra has local acid-base metabolism imbalance, and the range of metabolic penumbra coincides with the blood flow penumbra.

Objective To make correct diagnosis for Rathke cleft cyst(RCC)and cystic pituitary adenomas(CPA)through retrospective analysis of characteristics of MRI.Methods RCC (n=30)and CPA (n=30)confirmed by surgery and pathology were analyzed retrospectively.Following characteristics of lesions were observed:morphology,size,location,range,T1WI signal intensity and patterns of enhancement,presence of intracystic fluid level,septum,nodule,hypointense rim on T2WI and change of the pituitary stalk.The independent sample t-test and χ2 test were used respectively to analyze differences between two groups of continuous variables and categorical variables.Results Most of RCC were oval,less than 2 cm3,under the optic chiasm and within the bilateral cavernous sinus,various for signal intensity,without or with thin-walled contrast enhancement.Intracystic nodule accounted for 40% of cases and there were double cystic nodules in 1 case.Obvious contrast enhancement of intracystic nodule was found in 1 case.Pituitary stalk was in center.Most of CPA were snowman shaped,bigger than 2 cm3,off middle line location,with compression of the optic chiasm and sellar base,had thick-walled contrast enhancement,with intracystic fluid level and septum,had hypointense rim on T2WI.The pituitary stalk was shifted.Conclusion The MRI findings of RCC and CPA are significant differences in the shape,size,intracapsular structure,enhanced performance and changes of surrounding structure.