Seventy-Peak Kilovoltage High-Pitch Thoracic Aortic CT Angiography without ECG Gating: Evaluation of Image Quality and Radiation Dose

• Published in: Academic radiology Vol. 22; no. 7; p. 890
• Main Authors: Zhang, Long Jiang, Zhao, Yan E, Schoepf, U Joseph, Mangold, Stefanie, Felmly, Lloyd M, Li, Xie, Tang, Chun Xiang, Zhou, Chang Sheng, Qi, Li, Lu, Guang Ming
• Format: Journal Article
• Language: English
• Published: United States 01.07.2015
• Subjects: Aorta, Thoracic - diagnostic imaging; Aortic Diseases - diagnostic imaging; Aortography - methods; Cardiac-Gated Imaging Techniques; Contrast Media - administration & dosage; Feasibility Studies; Female; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Iohexol - administration & dosage; Iohexol - analogs & derivatives; Male; Middle Aged; Radiation Dosage; Radiation Protection - methods; Reproducibility of Results; Sensitivity and Specificity; Tomography, X-Ray Computed - methods; Aorta; radiation dose; X-ray computed tomography; high pitch; angiography; contrast agent
• DOI: 10.1016/j.acra.2015.03.007

To assess the feasibility of 70-kVp high-pitch non-ECG-gated thoracic aortic computed tomography angiography (CTA) with 40-mL contrast agent compared to 100-kVp standard-pitch CTA with 60-mL contrast agent. Sixty-seven patients (51 men and 16 women; mean age, 55 ± 14 years) received non-ECG-gated aortic CTA at 70 kVp, high pitch of 3.4, and 40-mL contrast agent (group A, n = 31) or CTA at 100-kVp, pitch of 1.2, and 60-mL contrast agent (group B, n = 36). Iterative reconstruction was used in all patients. For image quality assessment, CTA images were evaluated on a three-point scale and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated and compared. Furthermore, computed tomography (CT) dose index was recorded. Mean CT values and noise levels were higher in group A compared to group B (all P < .001), whereas SNR and CNR were lower than those in group B (all P < .001). Furthermore, the image quality of the aorta at the level of the diaphragm was lower in group A than that in group B (P < .05). However, image quality was graded as diagnostic in all patients, and motion artifacts of the aortic arch were significantly decreased in group A (P <.05). Interreader agreement was good or excellent for image quality assessment (k = 0.625-0.835). The 70-kVp CTA protocol, which allows dose reduction of 85%, was considered diagnostic in all instances by two readers. Our proposed thoracic aortic CTA protocol provides diagnostic information with substantial reduction of both radiation and contrast agent doses compared to standard-pitch CTA at 100 kVp.