title: Compact-bolus dynamic CT protocol with a test bolus technique in 64-MDCT coronary angiography: comparison of fixed injection rate and duration protocol.
abstract: OBJECTIVE
  We compared the fixed injection rate protocol (P2) with the fixed injection duration protocol (P1) for coronary CT angiography using the test bolus technique.
  
  
  METHODS
  We randomly assigned 100 patients to one of two protocols. In P1, they received 0.7 mL/kg Iohexol-350 in an injection duration of 9 s, and we selected a delay of 3 s after peak enhancement of test bolus scan. In P2, they received 0.7 mL/kg Iohexol-350 at an injection rate of 5 mL/s, and we selected a delay after peak enhancement of test bolus scan using the following formula: TID/2-2 s, where TID is the injection duration of full bolus. We compared attenuation values in the ascending aorta and coronary arteries and patient-to-patient enhancement variability at each segment.
  
  
  RESULTS
  At all segments, CT attenuations of P2 were significantly greater than those of P1 (ascending aorta 400 ± 64 vs. 368 ± 60, P = 0.01; left main trunk 399 ± 67 vs. 369 ± 55, P = 0.02; proximal-RCA 393 ± 66 vs. 363 ± 56, P = 0.01). There was no significant difference in patient-to-patient enhancement variability at all segments between the two groups (P > 0.05).
  
  
  CONCLUSIONS
  P2 yielded superior vessel enhancement and comparable patient-to-patient enhancement variability compared with P1 in thin patients.
authors.affiliation: Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan. masafkidoh@yahoo.co.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Naritsugu
authors.initials: N
authors.lastname: Sakaino
authors.forename: Kazunori
authors.initials: K
authors.lastname: Harada
authors.forename: Shouzaburou
authors.initials: S
authors.lastname: Uemura
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007472:Iohexol