Radiation Dose, Image Quality, Stenosis Measurement, and CT Densitometry Using ECG-Triggered Coronary 64-MDCT Angiography: A Phantom Study

• Published in: American journal of roentgenology (1976) Vol. 190; no. 2; pp. 315 - 320
• Main Authors: Horiguchi, Jun, Kiguchi, Masao, Fujioka, Chikako, Shen, Yun, Arie, Ryuichi, Sunasaka, Kenichi, Ito, Katsuhide
• Format: Journal Article
• Language: English
• Published: Leesburg, VA Am Roentgen Ray Soc 01.02.2008; American Roentgen Ray Society
• Subjects: Applied radiobiology (equipment, dosimetry...); Biological and medical sciences; Biological effects of radiation; Cardiovascular system; Coronary Angiography - methods; Coronary Stenosis - diagnostic imaging; Electrocardiography - methods; Fundamental and applied biological sciences. Psychology; Humans; Image Enhancement - methods; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Phantoms, Imaging; Radiation Dosage; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Radiographic Image Enhancement - methods; Sensitivity and Specificity; Tissues, organs and organisms biophysics; Tomography, X-Ray Computed - methods; Radiodiagnosis; Stenosis; Coronary arteriography; Image quality; Electrodiagnosis; Radiation dose; Multidetector scanner; Radiobiology; Electrocardiography; Medical imagery; Computerized axial tomography; Dosimetry; Densitometry
• ISSN: 0361-803X; 1546-3141
• DOI: 10.2214/AJR.07.2191

The purpose of this study was to compare prospective ECG-triggered and retrospective ECG-gated coronary 64-MDCT angiography as to radiation dose, image quality, accuracy of stenosis measurement, and CT densitometry. Coronary artery models (n = 3) with different plaque densities (approximately 50, approximately 110, and approximately 1,000 H) on a cardiac phantom were scanned in variable heart rate sequences (n = 14) with both prospective ECG-triggered and retrospective ECG-gated scanning. Radiation dose, image quality graded by motion and stairstep artifacts (grade 1, excellent, to grade 4, poor, with grades 1 and 2 defined as satisfactory), accuracy of stenosis measurement (area; 18%, 50%, and 82%), and CT densitometry of plaques (soft, approximately 50; and intermediate, approximately 110 H) were compared between the two protocols using the Mann-Whitney U test and repeated measures. The radiation dose of prospective ECG-triggered CT angiography (CTA) (3.0 mSv) was lower than that of retrospective ECG-gated CTA (11.7-13.0 mSv) when the same tube current (mA) and voltage (kVp) were used in both methods. Prospective ECG-triggered CTA images were assigned a satisfactory quality rating in stable heart rate up to 75 beats per minute (bpm) when using the minimal X-ray exposure time. In this range, there were no significant differences in stenosis measurement (p = 0.17) and CT densitometry (p = 0.93) between the two protocols. Prospective ECG-triggered coronary 64-MDCT has the potential to reduce radiation exposure while maintaining the diagnostic performance of retrospective ECG-gated coronary 64-MDCT.