title: Low-Iodine-Load and Low-Tube-Voltage CT Angiographic Imaging of the Kidney by Using Bolus Tracking with Saline Flushing.
abstract: OBJECTIVE
  To prospectively determine the feasibility of low-iodine-load and low-tube-voltage computed tomographic (CT) angiographic imaging of the kidney and to evaluate the opacification and image quality compared with moderate-iodine-load and high-iodine-load techniques.
  
  
  METHODS
  Institutional review board approval and written informed consent was obtained. One hundred thirteen consecutive patients randomly underwent three protocols for dual-phase renal CT angiographic imaging: high-iodine-load (600 mg iodine per kilogram of body weight at 120 kVp); moderate-iodine-load (400 mg iodine per kilogram of body weight at 80 kVp); and low-iodine-load (contrast agent injection initially prepared at 400 mg iodine per kilogram of body weight but stopped immediately after bolus-tracking trigger at 80 kVp) scanning. CT numbers of vessels and kidneys were measured. CT numbers and signal-to-noise ratio (SNR) were compared with one-way analysis of variance and posthoc Tukey-Kramer test and depiction of vessels and image noise, with Kruskal-Wallis test and pair-wise Mann-Whitney test with Bonferroni correction.
  
  
  RESULTS
  Mean iodine weight administered was significantly reduced in order of low- (16.4 g), moderate- (23.5 g), and high-iodine-load (33.7 g) protocols (P < .001). Mean CT numbers of abdominal aorta, renal artery, and renal cortex in first phase were significantly lower with high-iodine-load protocol (308, 274, and 132 HU, respectively) than with moderate- (347, 334, and 156 HU, respectively; P = .001-.006) or low-iodine-load (362, 316, and 161 HU, respectively; P = .001-.003) protocol. Mean CT number of renal vein in second phase was significantly lower with low-iodine-load protocol (223 HU) than with moderate- (299 HU; P < .001) or high-iodine-load (258 HU; P = .020). Mean SNR of renal medulla in second phase was significantly lower (P = .019) with moderate-iodine-load protocol (mean SNR, 7.2) than with high-iodine-load protocol (mean SNR, 10.0). No significant difference in image quality grades was found between high-iodine-load (mean grade, 2.6-2.9), moderate-iodine-load (mean grade, 2.6-3.0), and low-iodine-load (mean grade, 2.6-2.9) protocols (P = .018-.31).
  
  
  CONCLUSIONS
  Combined application of low-iodine-load, bolus tracking with saline flushing, and low-tube-voltage scanning is feasible and resulted in substantial reduction of iodine dose for renal CT angiographic imaging without compromising image quality.
authors.affiliation: From the Departments of Radiology (M.K., S.G., N.K., H.K., H.W., Y.N., Y.T.) and Radiology Services (M.K., T.M.), Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan; and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (K.T.B.).
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Goshima
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondo
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Miyoshi
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Noda
authors.forename: Yukichi
authors.initials: Y
authors.lastname: Tanahashi
authors.forename: Kyongtae T
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D004560:Electricity; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage*; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012965:Sodium Chloride / Q000008:administration & dosage*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D012965:Sodium Chloride; D007455:Iodine