title: Optimization of scan timing for aortic computed tomographic angiography using the test bolus injection technique.
abstract: BACKGROUND
  With fast computed tomography (CT), it is possible for the scanning to outpace the contrast medium bolus during aortic CT angiography (CTA).
  
  
  OBJECTIVE
  To evaluate the effectiveness of a new method for reducing the risk of outpacing in which the scan start timing (ST) and speed can be estimated from the peak enhancement time measured at the femoral artery using a single test-bolus injection (femoral artery test injection method [FTI method]).
  
  
  METHODS
  In 30 cases of aortic CTA, we measured the time to peak enhancement at the femoral artery (TPF) and the ascending aorta (TPA) with test-bolus injection performed twice in each examination. From the resultant linear relationship between TPF and transit time (TT = TPF - TPA), we developed a method for determining the ST and TT from TPF. One hundred patients were assigned to two groups: FTI and bolus tracking (BT), each with 50 patients. CT values were measured in main vessels (ascending aorta, descending aorta, femoral artery). The CT values of the vessels and the rate of cases with more than 300 HU (good cases) were compared between the two groups.
  
  
  RESULTS
  The enhancement in the FTI method was significantly higher than that of the BT method (average CT values: FTI, 388.3 ± 52.4; BT, 281.2 ± 59.1; P < 0.001). The rates of good cases for FTI and BT were 86.0% and 46.0%, respectively.
  
  
  CONCLUSIONS
  The FTI method was very effective in reducing the risk of outpacing of the contrast medium transit in aortic CTA without the need for an additional contrast medium dose.
authors.affiliation: Department of Radiology, Ishinkai Yao General Hospital, Osaka, Japan Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa, Japan hoshi0311@hera.eonet.ne.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hoshino
authors.affiliation: Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Ichikawa
authors.affiliation: Department of Medical Technology, Nakatsugawa Municipal General Hospital, Nakatsugawa, Gifu, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Hara
authors.affiliation: Department of Radiology, Osaka City General Hospital, Osaka, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Terakawa
authors.affiliation: Department of Radiology, Ishinkai Yao General Hospital, Osaka, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hosomi
authors.affiliation: Department of Radiology, Ishinkai Yao General Hospital, Osaka, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Nishimura
authors.affiliation: Department of Radiology, Ishinkai Yao General Hospital, Osaka, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Takayama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D000072226:Computed Tomography Angiography; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D005260:Female; D005263:Femoral Artery; D006801:Humans; D007479:Iopamidol / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D013997:Time Factors
chemical_list: D003287:Contrast Media; D007479:Iopamidol
keywords: CT angiography; Computed tomography (CT); bolus tracking; test-bolus injection; vascular