title: Revival of monophasic contrast injection protocols: superiority of a monophasic injection protocol compared to a biphasic injection protocol in high-pitch CT angiography.
abstract: BACKGROUND
  Biphasic injection protocols are frequently used because they yield homogenous contrast enhancement. We hypothesize that with faster scanners and shorter scan times, biphasic injection protocols are no longer necessary.
  
  
  OBJECTIVE
  To evaluate whether a monophasic injection protocol is equivalent to a biphasic protocol in terms of contrast enhancement and homogeneity.
  
  
  METHODS
  Repeated high-pitch CTA (pitch 3) and conventional standard-pitch computed tomography angiography (CTA) (pitch 1.2) from the cervical region to the symphysis was performed in seven beagles (11.2 ± 2.5 kg) in a cross-over study design. Arterial contrast enhancement was measured along the z-axis in the ascending, descending, and abdominal aorta and the iliac arteries. The z-axis is the longitudinal axis of the human body and at the same time the direction in which the CT table is moving. The data were analyzed using repeated measures ANOVA with a post-hoc t-test and visual assessment of the scans.
  
  
  RESULTS
  In high-pitch CTA, monophasic injection protocols were superior to biphasic injection protocols in enhancement levels (P < 0.05) and enhancement homogeneity along the z-axis (P < 0.05). In conventional CTA, enhancement levels did not differ. Contrast homogeneity was better for biphasic protocols.
  
  
  CONCLUSIONS
  High-pitch CTA monophasic injection protocols are superior to biphasic injection protocols, due to a higher and more homogeneous contrast enhancement with the same amount of contrast medium used.
authors.affiliation: UKGM Marburg University Hospital, Diagnostic and Interventional Radiology, Marburg, Germany jonasapitzsch@gmail.com.
authors.forename: Jonas
authors.initials: J
authors.lastname: Apitzsch
authors.affiliation: Bayer Healthcare, MR and CT Contrast Media Research, Berlin, Berlin, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Jost
authors.affiliation: Department of Radiology, Giessen University Hospital, Giessen, Hessen, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bonifer
authors.affiliation: UKGM Marburg University Hospital, Diagnostic and Interventional Radiology, Marburg, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Keulers
authors.affiliation: Bayer Healthcare, MR and CT Contrast Media Research, Berlin, Berlin, Germany.
authors.forename: Hubertus
authors.initials: H
authors.lastname: Pietsch
authors.affiliation: UKGM Marburg University Hospital, Diagnostic and Interventional Radiology, Marburg, Germany.
authors.forename: Andreas Horst
authors.initials: AH
authors.lastname: Mahnken
mesh_terms: D000818:Animals; D002985:Clinical Protocols; D000072226:Computed Tomography Angiography; D003287:Contrast Media / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004285:Dogs; D007275:Injections, Intravenous; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide
keywords: Computed tomography angiography (CTA); animal investigations; aorta; contrast agents; image manipulation/reconstruction