| ObjectiveThe aim of this study is to explore a new mode in order to reduce the dose of CTscan in patients with congenital heart disease (CHD). Surgical operations orangiocardiography was used as reference standard.Materials and MethodsFrom August2010to December2011,60cases of congenital heart disease werecollected, all patients were scanned by dual-source spiral computed tomograghy, whichhad echocardiography examination first.60patients were randomly divided into twogroups. Retrospective ECG-gated spiral CT scan combined with non-ionic contrast agentwere applied in30patients of group A. Prospective ECG-triggering high-pitch spiralacquisition was applied in another30patients of group B. In group A, tube voltage of thetwo balls both were80~120Kv based on their BMI. Control of current was done duringreal time. Tube rotation cost0.28s. The pitch adjusted the heart rate automatically:0.2~0.5. Thickness was0.6mm. Contrast dose and injection speed was in accordancewith the actual situation of the children. Scan sections were taken from thoracic inlet to5cm below the left subphrenic region. In group B, the tube voltage of the two balls are both80~120Kv based on their BMI too. Tube rotation was0.28s. The pitch was fixed at3.4.Thickness was0.6mm too. Contrast dose and injection speed were same as group A. Afterthe scan, data was transferred to the workstation for the image reconstruction based ondifferent angle and different thickness, for example: multi-plane reformation (MPR),volume rendering (VR), maximum intensity projection (MIP), surface shadow display(SSD), and so on, which would help to show the complex three-dimensional relationship.To standardize the interpretation of image and image quality, two experienced radiologistsinterpreted the image and made a diagnosis, if they had different views, they woulddiscuss and made a last decision, and at the same time evaluated the imagine quality. Analysis the imagine quality and radiation dose of the two groups. Summary up all thedefects of inside or outside heart, surgical operations or angiocardiography was used asreference standard. Compare the imagine quality and accuracy between A and B groups.Results1. The youngest child was4months old, no serious adverse events were recorded, nodifference in clinical manifestation before and after the check.2. The average imagine quality score of group A was4.3±0.7, and group B was4.1±0.8. The images in the two groups both met the need of diagnosis.3. The range of heart rate in group A is72~143bmp, the average scan length is18.6cm, and the average radiation dose was2.03±0.95mSv. In group B, the range of heartrate was55~133bmp, the average scan length was17.8cm. There was no significantdifference of heart rate and scan length between the two groups, the result is:t=3.425, p＜0.05, the radiation dose in group B was much lower than in group A,4.48cases were confirmed by surgery or angiocardiography, most of which werecomplex congenital heart disease, including atrial septal defect, ventricular septal defect,persistent ductus arteriosus, tetralogy of Fallot, coronary arteries abnormality, largevessel-ventricular connection abnormalities and so on. Sum up all the defections. In groupA,26cases are confirmed by surgery or angiocardiography,133deformities arediagnosed by CT, but136deformities were confirmed, so the accuracy was97.8%. Wemissed three cases of patent foramen ovale.22cases are confirmed by surgery orangiocardiography in group B,101deformities were diagnosed by CT, but106deformities were confirmed, and the accuracy was95.3%, we missed two cases of patentforemen ovale, one case of mitral crack, and two cases of small perimembranousventricular septal defect. Compare the accuracy between group A and B, the result is:x~2=1.175, p＞0.05, there was no significant difference between them.ConclusionProspective ECG-triggering high-pitch spiral acquisition of the new siemensdual-source spiral CT was a valuable tool in the routine clinical evaluation of patientswith congenital heart disease, The radiation does was much lower than that of thetraditional retrospective ECG-gated mode. It can provide a comprehensivethree-dimensional evaluation of the heart, there was no significant difference between thetwo modes in image quality, the diagnosis was accurate, and it is safe. |
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