1. Impact of Contrast Media Concentration and kVp settings on Image Quality in CT Angiography of the Intracranial Vessels
Birgitta Ramgren MD
Roger Siemund MD, PhD
Isabella Björkman-Burtscher MD, PhD
Department of Neuroradiology
Center for Medical Imaging and Physiology
Skåne University Hospital, Lund
Sweden

2. Disclosure
The study has been supported by grants from Bracco Imaging S.p.A.

3. Purpose
Contrast media concentration and kVp setting are two important parameters with impact on the intensity of vessel enhancement in CTA.

4. Purpose Quantify the effect on intracranial vessel enhancement:
Increase of the contrast media concentration from 300 mgI/ml to 400 mgI/ml
Decrease of the tube voltage from 120 kVp to 90 kVp .

5. Method
Consecutive inclusion, retrospective analyse including 63 patients referred for clinical examination
16 slice scanner (Philips MX 8000 IDT 16)
Iomeprol (Iomeron®, Bracco Imaging, Italy) mgI/ml or 400 mgI/ml.
Contrast volume 80 ml, injection rate 5 ml/s and test bolus based scan delay
All examinations were performed on a

6. Scan parameters and patients
Group 1
Group 2
Group 3
Contrast media
300 mgI/ml
400 mgI/ml
Tube voltage
120 kVp
90 kVp
Tube current
229 mAs
564 mAs
CTDIvol
32,7 mGy
36,8 mGy
Patients (female)
15 (6)
15 (7)
33 (17)
Age mean (years)
54 (21-78)
51 (25-74)
59 (17-87)

7. Scan parameters and patients
Group 1
Group 2
Group 3
Contrast media
300 mgI/ml
400 mgI/ml
Tube voltage
120 kVp
90 kVp
Tube current
229 mAs
564 mAs
CTDIvol
32.7 mGy
36.8 mGy
Patients (female)
15 (6)
15 (7)
33 (17)
Age mean (years)
54 (21-78)
51 (25-74)
59 (17-87)

8. Scan parameters and patients
Group 1
Group 2
Group 3
Contrast media
300 mgI/ml
400 mgI/ml
Tube voltage
120 kVp
90 kVp
Tube current
229 mAs
564 mAs
CTDIvol
32.7 mGy
36.8 mGy
Patients (female)
15 (6)
15 (7)
33 (17)
Age mean (years)
54 (21-78)
51 (25-74)
59 (17-87)

9. Measurements
Below the top of the ICA
M1 and M2 segments

10. Image quality grading Grading 1-4 (poor-excellent)
360 HU (Grade 2 M1, Grade 3 M2)
300 mgI/ml, 120 kV
690 HU (grad 4 M1&M2)
400 mgI/ml, 90 kV
Grading 1-4
(poor-excellent)
257 HU (Grade 2)
300 mgI/ml, 120 kV
683 HU (Grade 4)
400 mgI/ml, 90 kV

11. Measurements HU Mean HU ± SD Group difference, p value
(Welch two sample t-test)
mgI/ml/kV
Group 1
300/120
Group 2
400/120
Group 3
400/90
Group 1 versus
Group 2 versus
versus Group 3
ICA
360 ± 75
424 ± 82
579 ± 157
0.03*
< 0.01* M1
333 ± 68
382 ± 84a
525 ± 133
0.10 M2
306 ± 66
354 ± 82a
465 ± 127
0.09
a One patient excluded because of coilartefacts
* significans at p ≤ 0.05

12. Image quality grading Image quality grading Mean values
Group difference, p value
(Wilcoxon rank sum test)
mgI/ml/kV
Group /120
Group 2 400/120
Group 3 400/90
Group 1 versus Group 2
Group 2 versus Group 3
Group 1 versus Group 3 M1
3.00
3.43a
3.45
0.12
0.86
0.05* M2
3.36a
3.55
0.21
0.43
0.02*
Volume rendering
3.14a
3.52
0.57
0.07
0.01*
General impression
2.80
2.86a
3.21
0.83
0.11
0.06
a One patient excluded because of coilartefacts
* significans at p ≤ 0.05

13. Results
Contrast media with 400 mgI/ml instead 300 mgI/ml increases intracranial vessel enhancement with 18%.
The decrease of tube voltage from 120 kVp to 90 kVp increases intracranial vessel enhancement with 37%.
The combined effect of both parameters yields an increase of the enhancement with 61%.
When measuring in the ICA….

14. Conclusion
The use of highly concentrated contrast media in combination with low tube voltage are easily performed measures to improve the image quality on slice images and 3D reconstructions.
Both measures can be recommended for optimization of intracranial CTA.