| Objective1. To discuss the image quality of the pulmonary vein imaging by the dual-source CT (DSCT) coronary angiography imaging sequence, and its relationship with heart rate.2. To analyze the anatomical type of pulmonary vein by the DSCT scan.3. To dicusss the applications in diameter measurement of the pulmonary vein ostium by the DSCT Best phase software in coronary angiography imaging sequence.Materials and methods1. The general information1.1 The image quality evaluation and anatomical type of pulmonary vein by DSCT coronary angiography imaging sequence150 patients underwent the pulmonary vien imaging of DSCT coronary angiography imaging sequence. There were 104 male and 46 female, average age was 57.89±11.55 years old. All candidates were classified to have sinus rhythm, the range of heart rate was 40-136bpm and the average heart rate was 74.70±15.68bpm. Exclusive criteria were the patients who had coronary heart disease, non-sinus rhythm or obvious arrhythmia, bad breathing, can not cope with the scan, heart and renal dysfunction and allergy to iodine contrast agent, thoracic deformity, mediastinal tumor and pulmonary fibrosis caused by concurrent chemoradiation, lung consolidation, atelectasis, pericardial effusion and pleural effusion, severe vascular disease and congenital heart disease which can influence or change the shape and diameter of the pulmonary vein. The informed consent must be signed for the enhanced scanning.1.2 Diameter measurement of the pulmonary vein ostium Inclusive criteria:85 patients of pulmonary vein type was classified as the "standard" group (that is, each patient had 4 separate pulmonary veins imported to left atrium) in 150 cases by the first study. An exclusive criterion for this study was described as above section. There were 66 males and 19 females within the 85 candidates, their ages range from 29 to 79 years old and their mean ages are 55.84±11.24 years old. All subjects who had sinus rhythm, heart rate ranged 46～118 bpm and the average heart rate was 73.55±14.82 bpm.2. Instruments and MethodsInstruments:Using the Siemens Somatom Definition's dual source CT, using retrospective ECG gating techniques for coronary heart imaging scan of the pulmonary vein. Using the DSCT scanning bed built ECG for ECG monitoring. Use the U.S. MALLINCKRODT binocular injector and 370mgI/ml non-ionic contrast agent.Scanning preparation:Fasting and water prohibition for 4 to 8 hours are required before scanning. Do not use the drugs such as (3-blocker which can reduce the heart rate. The sublingual nitroglycerin aerosol spray at 5min have to be used routinely before scanning and need to be 1 spray per time. All candidates must have breathing training.Scanning method and parameters:Selected coronary artery imaging scan sequence (DS_Coronary CTA Routine_Adult), ECG Cable had been positioned properly before scaning. Data acquisition was performed at collimation of 32×0.6mm,120 kV and 550mA, the thickness of level acquisition was 64×0.6mm, tube rotation time was 0.33s, pitch was 0.20-0.47(automatic adjustment by the heart rate changing), effective thickness was 0.75 mm, reconstruction interval was 0.5mm and the scanning time was 7-13s. The 18G trocar was used for injection with superficial vein in the elbow to 4.5～5.5 ml/s flow of 60～80ml non-ion iodic contrast medium(370mgI/ml), followed by injection of 50～60ml saline. A timing bolus scan (TBS) was obtained at the level of the aortic root with the administration, trigger threshold 100 HU, delayed scaning after 6s. Scan range:from tracheal bifurcation to the heart about 1cm under the diaphragm.3. Image reconstruction, image post-processing and observation evaluation3.1 Pulmonary vein imaging assessment of image qualityAfter the scan was completed, the systolic(BestSyst phase) images and diastolic (BestDiast phase) images were reconstructed by the "best phase" software. Reconstructed image slice thickness was 0.75mm, layers from 0.5mm, convolution function value was B26f, image matrix was 512x512. After re-processing this two-phase imaging data by the DSCT post-processing workstation, the postero-anterior view was selected to observe and combined with cross-sectional images to show on the left atrium, pulmonary veins and their ostiums. These had used a variety of imaging methods which included volume rendering(VR), multiplanar reformation(MPR) and maximum intensity projection(MIP), etc.The overall quality for all images was assessed by two experienced radiologist using the blinded and randomized analogy under the consensus agreement. Peer review may be used if opinion was on discrepancy. The image quality of the four pulmonary veins (LSPV, LIPV, RSPV and RIPV)was scored and it was used to calculate the average score (total score of the four PV divided by 4) of each case. This represented their integrated scoring level of image quality.Image quality assessment criteria:4 point=Excellent, clear and sharp edges, no motion artifacts, can be complete the imaging evaluation; 3 point=Good, minor artifacts, showed as slightly local edge fuzzy or slightly staggered, it has fine diagnostic quality and can be imaging evaluation; 2 points=Acceptable, moderate artifacts, vascular edge bluring or appear split-level, but the image quality can still be accepted, and can still meet the diagnosis; 1 point:Can not be evaluated, serious artifacts, impact on the accurate evaluation of PV lumen and ostium.3.2 Observation of pulmonary vein anatomical typeAll patients were selected on the reorganization of the best systolic image raw data by DSCT post-processing workstation. The data of BestSyst phase reorganization was imported into Inspace software to progress the VR, MPR and MIP images respectively. Using the bone removal technology "Bone Removal", which is part of the Inspace software tools package, was applied to eliminate the useless image and extract the pulmonary veinsand store the images for further observation and analysis.3.3 Measurement of pulmonary vein ostiumThe reorganization of the best systolic and diastolic image raw data was imported to Inspase software of DSCT post-processing workstation. The PV image was extracted on VR images by the Bone Removal technology from Inspace software. Then, through the vascular lumen measurement ("Lumen to Vessel" measurement) of the vessel analysis software (syngo InSpace 4D with Advanced Vessel Analysis) was utilized to measure the diameter of four pulmonary veins ostium, such as maximum diameter, minimum diameter, the average diameter, cross-sectional area. The opening index was also calculated (i.e. the minimum diameter/maximum diameter,0＜ratio≤1, open index=1, it represents the shape of ostium become a circle). Statistical analysis was undergone for the data of these two groups.4. GroupingAll patients were divided into two groups:low heart rate group (heart rate≤75bpm) and high heart rate group (heart rate> 75bpm). According to the best phase of the reconstructed image by the DSCT Bestphase software, it was divided into two groups: BestSyst phase group and BestDiast phase group.5. Data recording and statistical analysis5.1 Image quality assessment of pulmonary vein imaging and its relationship with heart rateAll statistical analysis was analyzed using SPSS 13.0 version. Measurement data was presented with mean±standard deviation. All the patients were divided into low heart rate group and high heart rate group. Independent sample t tests were used to compare the difference of the image quality between the two heart rate groups, in which they are under the bestsyst phase and bestdiast phase respectively. Moreover, the image quality between these two best phase groups was examined by using the paired samples t test. Using the Bivariate Spearman's correlation analysis test the relationship between the image quality of best phase group and heart rate group. P <0.05 is considered statistically significant difference.5.2 DSCT pulmonary vein anatomy type150 cases of the left atrium and pulmonary veins image data were analyzed by two experienced radiologists, respectively. To observe the pulmonary vein and the left atrial connection, the number of pulmonary vein and pulmonary vein ostium, with or without the additional pulmonary vein and common ostium of pulmonary vein were recorded. On the classification of pulmonary veins were dissected.5.2.1 Confirmation of the additional pulmonary vein and common ostium of pulmonary veinIn most situations, human have four pulmonary veins which open in the left atrium. Variation appeared in rare cases, the number of pulmonary vein is manifested to be more or less than four. The extra pulmonary vein pulmonary veins are called vice pulmonary veins. When the distance between ipsilateral upper and lower pulmonary vein is≤5 mm, it is defined as pulmonary vein common ostium.5.2.2 Classification and definition of pulmonary vein typeSpecifically divided into four types, as follows:①Standard:Four pulmonary veins separately import left atrium, the distance between the ipsilateral pulmonary vein is> 0.5cm;②Pulmonary vein common ostium type:the common pulmonary vein opening is formed under the standard basis, which is according to the ipsilateral pulmonary veins before opening the left atrium is divided into three subtypes with or without convergence, ie the common opening (not converged), long common trunk (has been converged, the openings from the pulmonary vein bifurcation> 1.0cm), a short common trunk (have been converged, openings from the pulmonary vein bifurcation≤1.0cm); the group is also divided into 3 subtypes according to the location of the common opening, which are the left, right and bilateral pulmonary vein common ostium type;③Vice pulmonary veins type:in the standard basis there's a new one or more vice-pulmonary vein, according to deputy pulmonary veins to appear is divided into three subtypes, named as left vice pulmonary veins, right vice pulmonary vein-type and the upper pulmonary veins;④Mixed variant:The pulmonary vein common ostium and vice pulmonary vein are existed together.5.2.3 The definition and recognition of the ahead of the right branch of pulmonary vein ostiaThe right pulmonary veins in the lower right pulmonary vein of the upper right, or when, as the right pulmonary veins in the department of the distance between the left atrium (the upper right or lower right of left atrial pulmonary vein import openings)≤1.0cm, the definition of the branch in advance; if> 1.0 cm, was not ahead of the branch.All statistical analysis was analyzed using SPSS 13.0 version. Recording the pulmonary veins and left atrium anatomical connection type, subtype and the statistical combination of different type of occurrence. Using the X2 test to analyse the differences between the existiong of the vice pulmonary vein and pulmonary vein common ostium with gender. P<0.05 considered significant difference. And record the right middle pulmonary vein (RMPV) whether the branch in advance, and the statistics in all cases, and the typing of occurrence, and RMPV opening position.5.3 DSCT of the pulmonary vein orifice diameter of the Department of Measurement The two experienced images physician independently completed the Department of the pulmonary vein orifice diameter of the measurement, recorded the best systolic and diastolic period best each with pulmonary vein (LSPV, LIPV, RSPV and RIPV) openings in all measurements (maximum diameter, minimum diameter, the average diameter, cross-sectional area and the opening index) and whichever is the average. All statistical analysis was conducted using SPSS 13.0 version. The average measurements of the results in each pulmonary vein for both groups are valued at the mean±standard deviation. The best of systolic and diastolic reconstruction in the pulmonary vein openings resulting comparative measurements using paired sample T test. P<0.05 considered significant difference.Result1. DSCT Automation Best of phase selection in coronary artery imaging sequence quality evaluation of pulmonary veins and the relationship of heart rate150 cases were included in the analysis of the pulmonary vein of 600, four veins of the quality of each case the integrated score of 150.In the best systolic group,114 cases (76.0%) of the pulmonary vein up to the outstanding level of quality integrated video, imaging can be fully evaluated 149 cases (99.3%) of the image quality up to good (3 to 4 points) level; only 1 (0.7%) in the can still～Good (2 to 3 minutes) levels within the imaging evaluation can be conducted.In the best diastolic group,104 cases (69.3%) of the pulmonary vein achieved excellent image quality level of comprehensive, fully carry out imaging evaluation, 144 patients (96.0%) of the image and the quality of good (3 to 4 points) level,5 (3.3%) in the can still～Good (2 to 3 points) levels, and imaging evaluation may be conducted; only one case (0.7%) of the image quality score of less than 2 minutes level;Optimal systolic images at low and high heart rate in the group image quality score was 3.84±0.35 min (n= 88) and 3.91±0.17 min (n=62), are in excellent image quality level, the two heart rate groups no significant difference between (t=-1.716, P value= 0.089); the best diastolic images at low and high heart rate in the group image quality score was 3.86±0.39 min (n= 88) and 3.74±0.40 min (n= 62), also in excellent image quality level, the two heart rate groups no statistically significant difference between the (t= 1.922, P value= 0.057);Low heart rate group, between the best systolic and diastolic best image quality score was no significant difference (t=-0.612, P value= 0.542); in the high heart rate group, between the best and most systolic good video quality score diastolic had statistically significant differences (t= 3.974, P value= 0.000), can be considered the best in the group with high heart rate systolic score in the best video quality for high-diastole.There is no correlation between the heart rate classification and the best systolic image quality (r value= 0.002, P value= 0.984). There is negative correlation between the heart rate classification and the best diastolic image quality (r value= 0.278, P value= 0.001), can be considered as increased heart rate classification, the best image quality in diastole are decreased, but still in excellent image quality level.2. DSCT pulmonary vein anatomy typePulmonary vein Statistics:150 patients were enrolled and a total of 621 pulmonary vein, LSPV, LIPV the 150, RSPV, RIPV the 150, a total of 21 vice pulmonary vein (20 cases);Statistics of common pulmonary vein ostium and vice pulmonary veinCommon pulmonary vein openings there was 34.7%(52/150), male common pulmonary vein openings there was 29.8%(31/104), female 45.7%(21/46), pulmonary vein openings appear together in the sex ratio was not statistically difference (χ2= 3.535, P value= 0.060).Vice pulmonary veins was 13.3%(20/150); of which 19 cases of the pulmonary veins appear a vice,1 patient had two vice pulmonary vein. Male vice pulmonary veins was 11.5%(12/104), female 17.4%(8/46), Vice-rate pulmonary veins were no significant differences in gender (χ2= 0.945, P value=0.331).Pulmonary vein typeIn accordance with the pulmonary vein in the left atrium of the opening number, pulmonary vein common openings and Deputy pulmonary vein cases were divided into four types, named as:Standard, Pulmonary vein common open type, Vice pulmonary vein, mixed variant of each type. There were 56.7%(85/150),30.0% (45/150),8.7%(13/150) and 4.7%(7/150).Open type in the common pulmonary vein, according to whether the opening at the confluence of the left front of the house is divided into three subtypes, named as:a common opening (not convergence, accounting for 57.8%), length of dry (have convergence, accounting for 33.3%), short of dry (has been convergence, accounting for 8.9%), to jointly open subtypes have a high probability; another position under the common opening into three subtypes, namely, opening the left side of the common type (66.7%), the right side of the common open-type (13.3%), bilateral common open type (20%) to the left of the common open subtypes have a high probability.In the vice pulmonary veins, according to Deputy pulmonary veins to appear is divided into three subtypes, named as the left vice pulmonary veins (7.7%) and the right vice pulmonary veins (69.2%), most on the pulmonary veins (15.4%), there is one case occurred two vice pulmonary vein, open position in the left atrium and the right "at the top" (7.7%); to the right pulmonary veins was the most common vice.The right branch of pulmonary vein and its opening position in advanceThe right branch of pulmonary vein appeared earlier rate of 18%(27/150). Pulmonary vein anatomy in the typing of occurrence was:standard (14.1%,12/85), pulmonary vein common open type (24.4%,11/45), Vice-pulmonary vein-type (23.1%,3/1.3), mixed variant (14.3%,1/7). RMPV openings in the RSPV, RIPV, RSPV and PIPV and the ratio of the left atrium were 89.3%,2.7%,1.3% and 6.7%, to open at the RSPV are most welcome.3. The evaluation of pulmonary vein ostiums diameter measurement by the DSCT Best phase softwareIn 85 cases of "standard type" pulmonary vein,340 pulmonary vein ostiums are measured, with 85 ostiums of upper left pulmonary vein, left inferior pulmonary vein, right superior pulmonary vein and right lower pulmonary vein each.Among the results of CT pulmonary vein orifice diameter measurements, except the lower right pulmonary vein opening index, during the two phases of best systolic period and best diastolic period, the difference of maximum diameter, minimum diameter, average diameter, cross-sectional area and opening index of each pulmonary vein opening were statistically significant (all t values and P values are detailed in Table 3-2), that is, apart from the opening index of right inferior vein, all values measured during the best systolic are larger than those measured during the best diastolic, suggesting that when the heart is in systolic period, the opening of pulmonary vein become circular and the diameter increases, while in diastolic period, pulmonary vein openings become oval or flat, and the diameter decreases. The opening index of right lower pulmonary vein does not have statistic significance since the difference in the two groups (t=-0.115, P value 0.909), suggesting that the morphology of lower right pulmonary vein opening does not change significantly during the two optimal periods.Conclusion1. Among the DSCT coronary imaging sequence which is under the premise of guaranteeing the image quality, the pulmonary vein morphology, size, diameter measurement and its relationship with the left atrium can be observed. Through the application of the best automatic software with the best systolic and diastolic phase, the good image quality of pulmonary vein and left atrium can be obtained.2. When the heart rate≤75bpm, we can choose the best systolic and best diastolic phase to reconstruct the pulmonary vein images. However, when the heart rate is> 75bpm, the quality of image reconstruction with the best systolic phase are better than the best diastolic phase. It is because of the increased speed of the heart rate, best diastolic image quality will gradually decline. Therefore, both fast and slow heart rate, in clinical work to identify pulmonary vein, choosing the best systolic phase to reconstruct image is better.3. DSCT with a variety of three-dimensional reconstruction can clearly demonstrate the pulmonary vein, associated with good classical anatomy. On the basis, the four pulmonary vein anatomic classifications were proposed; it can be provided the basis to understand patterns of left atrial and pulmonary vein before radiofrequency ablation or surgery.4. On the basis of DSCT three-dimensional reconstruction images, measuring the diameter of pulmonary vein ostiums in "standard type" can contribute and provide evidence before radiofrequency ablation and postoperative assessment of whether or not of pulmonary vein stenosis. |
