ABSTRACT
OBJECTIVE: To compare radiation doses between conventional and chest pain protocols using dual-source retrospectively electrocardiography (ECG)-gated cardiothoracic computed tomography (CT) in children and adults and assess the effect of tube current saturation on radiation dose reduction. MATERIALS AND METHODS: This study included 104 patients (16.6 ± 7.7 years, range 5–48 years) that were divided into two groups: those with and those without tube current saturation. The estimated radiation doses of retrospectively ECG-gated spiral cardiothoracic CT were compared between conventional, uniphasic, and biphasic chest pain protocols acquired with the same imaging parameters in the same patients by using paired t tests. Dose reduction percentages, patient ages, volume CT dose index values, and tube current time products per rotation were compared between the two groups by using unpaired t tests. A p value 0.05); the groups with tube current saturation showed significantly higher volume CT dose index values (p < 0.01) and tube current time product per rotation (p < 0.001) than the groups without tube current saturation in all protocols. CONCLUSION: The radiation dose of dual-source retrospectively ECG-gated spiral cardiothoracic CT can be reduced by approximately 15% by using the biphasic chest pain protocol instead of the conventional protocol in children and adults if radiation dose parameters are further optimized to avoid tube current saturation.
Subject(s)
Adult , Child , Humans , Chest Pain , Cone-Beam Computed Tomography , Electrocardiography , Methods , Retrospective Studies , ThoraxABSTRACT
PURPOSE: We proposed a multi-physiological signals based real-time intelligent triggering system(MITS) for Cardiac MRI. Induced noise of the system was analyzed. MATERIALS AND METHODS: MITS makes cardiac MR imaging sequence synchronize to the cardiac motion using ECG, respiratory signal and second order derivative of SPO2 signal. Abnormal peaks due to arrhythmia or subject's motion are rejected using the average R-R intervals and R-peak values. Induced eddy currents by gradients switching in cardiac MR imaging are analyzed. The induced eddy currents were removed by hardware and software filters. RESULTS: Cardiac MR images that synchronized to the cardiac and respiratory motion are acquired using MITS successfully without artifacts caused by induced eddy currents of gradient switching or subject's motion or arrhythmia. We showed that the second order derivative of the SPO2 signal can be used as a complement to the ECG signals. CONCLUSION: The proposed system performs cardiac and respiratory gating with multi-physiological signals in real time. During the cardiac gating, induced noise caused by eddy currents is removed. False triggers due to subject's motion or arrhythmia are rejected. The cardiac MR imaging with free breathing is obtained using MITS.
Subject(s)
Arrhythmias, Cardiac , Artifacts , Complement System Proteins , Electrocardiography , Magnetic Resonance Imaging , Noise , RespirationABSTRACT
Objective To compare the image quality and radiation dose between prospective ECG-trigering and retrospective ECG gating technique in coronary artery imaging. Methods 33 patients suspected coronary artery disease were included in this study and divided into experimental group (prospective ECG-triggering coronary artery imaging, heart rate < 65 bpm, 16 patients)and control group (retrospective ECG gating coronary artery imaging, heart rate < 75 bpm, 17 patients). Radiation dose was recorded for statistical analysis. At the same time, image quality was evaluated. Results There were no significant differences in image quality 3.2 msy. Effective dose reduced 76.47 %. Conclusions Prospective ECG gating coronary artery imaging can obtain the similar image quality compared with prospective ECG gating coronary artery imaging but the effective dose reduced 76.47 %. Prospective ECG gating coronary artery imaging has clinical value to peoples who are able to not accept high radiation dose and with low heart rate.
ABSTRACT
Objective To establish the database of diameter and length of the pulmonary artery branches in different phase of cardiac cycle in healthy adult chest MDCT.Methods Normal enhanced chest MDCT with ECG-gating was selected and slab thin slice maximaun intensity projection(STS MIP) reconstruction were performed in different periods on ECG represent systole and diastole respectively.The diameter and length of pulmonary artery on the plane which showed the whole length of the aim artery were measured.Doppler UCG with ECG-gating was performed in healthy adults to measure the inner diameter of pulmonary trunk and right and left pulmonary artery in different phases of the cardiac cycle as contrast method.Results Normal enhanced chest MDCT with ECG-gating showed the diameter in systole period of the main pulmonary artery was larger than that in diastole period,while it went conversely to that of the proximal part of two pulmonary arteries,distal part of the right pulmonary artery,right media-lobe artery,both S10 segmental arteries and the difference were statistic significantly,only the length in diastole period of the right upper lobe artery was larger than that in systole period.The distance between the measured point of the main artery and the right one showed larger in diastole than systole period.On ECG-gating UCG,in addition to that the diameter change of the main pulmonary artery during the two periods were coincident with MDCT,the two pulmonary artery had no significant difference during the two periods.Conclusion It is necessary using branching geometry data of the main artery to segmental arteries in different period of the cardiac cycle with normal enhanced chest MDCT for flowing model building of pulmonary artery.
ABSTRACT
In multilayer spiral CT heart and coronary artery imaging, image data are acquired by ECG gating technology when heart beats slowest so as to restrain pulsation pseudo-image. ECG gating technology includes foresight ECG gating and retrospective ECG gating. The principle, methods and mutual image reconstruction are introduced in this paper.