CT angiography of the renal arteries: comparison of lower-tube-voltage CTA with moderate-concentration iodinated contrast material and conventional CTA.
OBJECTIVE
The objective of our study was to investigate the feasibility of an 80-kVp protocol using a moderate-concentration contrast medium (CM) for CT angiography of the renal arteries by comparison with a conventional 120-kVp protocol using a high-concentration CM.


METHODS
Attenuation values and signal-to-noise ratios (SNRs) were determined in a phantom for the 120-kVp protocol with a high-concentration CM and the 80-kVp protocol with a moderate-concentration CM. In addition, 50 patients were prospectively enrolled in the study: 25 were scanned with 120 kVp and 200 effective mAs (mAs(eff)) after the administration of 110 mL of high-concentration CM (370 mg I/mL), and the other 25 were scanned with 80 kVp and 585 mAs(eff) after the administration of 110 mL of moderate-concentration CM (300 mg I/mL). Images of the two groups were compared in terms of arterial attenuation, SNR, contrast-to-noise ratio (CNR), and subjective degree of arterial enhancement and image quality.


RESULTS
The mean attenuation of the main renal artery was significantly higher (p < 0.001) in the 80-kVp group who received moderate-concentration CM (mean ± SD, 370.0 ± 65.0 HU) than in the 120-kVp group who received high-concentration CM (269.9 ± 27.8 HU) without significant differences in SNR and CNR values. The 80-kVp protocol had significantly higher quality scores for arterial enhancement, sharpness of the artery, and overall diagnostic quality compared with the 120-kVp protocol. The effective dose of the 80-kVp protocol (4.5 mSv) was 8.2% lower than that of the 120-kVp protocol (4.9 mSv).


CONCLUSIONS
The use of 80 kVp with moderate-concentration CM could improve arterial enhancement and provide superior image quality with a smaller amount of iodine and a lower radiation dose.
Department of Radiology, Yonsei University College of Medicine, Gangnam Severance Hospital, 211 Eonjuro, Gangnam-gu, Seoul 135-720, Republic of Korea.
Eun-Suk
ES
Cho
Jeong-Sik
JS
Yu
Jhii-Hyun
JH
Ahn
Joo Hee
JH
Kim
Jae-Joon
JJ
Chung
Hyeon-Kyeong
HK
Lee
Kyung Hee
KH
Lee
D000328:Adult; D000792:Angiography / Q000379:methods*; D003287:Contrast Media; D004305:Dose-Response Relationship, Drug; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage; D008297:Male; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D012016:Reference Values; D012077:Renal Artery / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
D003287:Contrast Media; D007455:Iodine