title: Aortoiliac enhancement during computed tomography angiography with reduced contrast material dose and saline solution flush: influence on magnitude and uniformity of the contrast column.
abstract: OBJECTIVE
  To compare the magnitude and uniformity of aortoiliac contrast enhancement obtained from uniphasic contrast material injections versus contrast material injections with reduced iodine dose followed by a saline flush in aortoiliac multislice CT angiography (CTA).
  
  
  METHODS
  Twenty-nine patients with abdominal aortic aneurysms underwent aortoiliac CTA using protocols A and B. With protocol A, 120 mL contrast material (300 mgI/mL), and with protocol B, 100 mL contrast material followed by a 40-mL saline solution flush were administered at a flow rate of 4 mL/s. Quantitative analysis was performed by calculating mean aortoiliac attenuation, mean plateau deviation, and mean difference between maximum and minimum attenuation value for both groups. Qualitative analysis was performed by visual assessment of vascular enhancement using 2-dimensional and 3-dimensional postprocessing techniques.
  
  
  RESULTS
  The mean aortoiliac attenuation with protocol A was 291 +/- 62 HU, and with protocol B it was 285 +/- 61 HU. The difference of 6 HU was not statistically significant (P = 0.27). Mean plateau deviation was significantly smaller using protocol A than protocol B (16 +/- 9 HU vs. 20 +/- 10 HU, P = 0.03). In addition, the mean difference between maximum and minimum attenuation value was significantly smaller with protocol A than with protocol B (59 +/- 29 HU vs. 72 +/- 32 HU, P = 0.01). Visual analysis showed no difference in contrast material magnitude and homogeneity between the protocols.
  
  
  CONCLUSIONS
  In aortoiliac CTA, a saline solution flush after contrast material bolus allows an iodine dose reduction of approximately 20 mL without impairing the magnitude of contrast enhancement but degrades the uniformity of the contrast column. However, the degradation does not affect visual analysis.
authors.affiliation: Department of Radiology, University Hospital of Graz, Austria. helmut.schoellnast@uni-graz.at
authors.forename: Helmut
authors.initials: H
authors.lastname: Schoellnast
authors.forename: Manfred
authors.initials: M
authors.lastname: Tillich
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Deutschmann
authors.forename: Hannes A
authors.initials: HA
authors.lastname: Deutschmann
authors.forename: Gottfried J
authors.initials: GJ
authors.lastname: Schaffler
authors.forename: Horst R
authors.initials: HR
authors.lastname: Portugaller
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging*; D001027:Aortography; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007455:Iodine / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D012965:Sodium Chloride / Q000008:administration & dosage; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D012965:Sodium Chloride; D007455:Iodine