title: Radiation reduction with prospective ECG-triggering acquisition using 64-multidetector Computed Tomographic angiography.
abstract: Current 64-multidetector Computed Tomographic scanners (MDCT) utilize retrospective overlapping helical acquisition (RS-OHA) which imparts a higher than desired radiation dose. Although the radiation burden of computed tomographic angiography (CTA) can be efficiently reduced by dose modulation and limiting field of view, a further decrease in radiation without compromising diagnostic image quality would be indeed very desirable. An alternative imaging mode is the axial prospective ECG-triggering acquisition (prospective gating). This study was done to compare the effective radiation dose and the image quality with two techniques to reduce radiation doses with CTA studies utilizing 64-MDCT scanners. The study included 149 consecutive patients (48 females and 101 males) 64-MDCT (mean age = 67 +/- 11 years, 72.2% male). Patients underwent CT coronary angiography using one of three algorithms: retrospective triggering with dose modulation; prospective triggering with padding (step and shoot acquisition with additional adjacent phases); and prospective triggering without padding (single phase acquisition only). Based on body habitus, two different voltages were utilized: 100 kVp (<85 kg) or 120 kVp (>85 kg). Radiation doses and image quality (signal to noise ratio) was measured for each patient, and compared between different acquisition protocols. The signal to-noise ratio of the ascending aorta (SNR-AA) was calculated from the mean pixel values of the contrast-filled left ventricular chamber divided by the standard deviation of these pixel values. Use of 100 kVp reduced radiation dose 41.5% using prospective triggering and 39.6% using retrospective imaging as compared to 120 kVp (P < 0.001). Use of prospective imaging reduced radiation exposure by 82.6% as compared to retrospective imaging (P < 0.001). Using both prospective imaging and 100 kVp without padding (single phase data, no other phases obtained), radiation dose was reduced by 90% (P < 0.001). In terms of image quality, the coefficient of variation of ascending aortic contrast enhancement between kVp of 120 and kVp of 100 was 6% (1.05, 95 CI 0.93-1.17), and 7.8% (0.9, 95% CI 0.7-1.2) at the pulmonary artery. The prospective ECG-Triggered acquisition and 100 kVp images were of diagnostic quality, allowing adequate assessment in all patients. CTA using PA and 100 kVp reduced the radiation dose by up to 90% without compromising the image quality.
authors.affiliation: Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, CA, 90502, USA.
authors.forename: Ambarish
authors.initials: A
authors.lastname: Gopal
authors.forename: Song S
authors.initials: SS
authors.lastname: Mao
authors.forename: Daniel
authors.initials: D
authors.lastname: Karlsberg
authors.forename: Emily
authors.initials: E
authors.lastname: Young
authors.forename: Joshua
authors.initials: J
authors.lastname: Waggoner
authors.forename: Naser
authors.initials: N
authors.lastname: Ahmadi
authors.forename: Raveen S
authors.initials: RS
authors.lastname: Pal
authors.forename: John
authors.initials: J
authors.lastname: Leal
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Karlsberg
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Budoff
mesh_terms: D000368:Aged; D000465:Algorithms; D016009:Chi-Square Distribution; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D040242:Risk Reduction Behavior; D036542:Tomography, Spiral Computed / Q000379:methods*