Impact of Contrast Media Concentration and kVp settings on Image Quality in CT Angiography of the Intracranial…

Impact of Contrast Media Concentration and kVp settings on Image Quality in CT Angiography of the Intracranial Vessels

Birgitta Ramgren MDBirgitta Ramgren MDRoger Siemund MD, PhDRoger Siemund MD, PhDIsabella Björkman-Burtscher MD, PhDIsabella Björkman-Burtscher MD, PhD

Department of NeuroradiologyDepartment of NeuroradiologyCenter for Medical Imaging and Center for Medical Imaging and

Physiology Physiology Skåne University Hospital, LundSkåne University Hospital, LundSwedenSweden

DisclosureDisclosureThe study has been supported by grants The study has been supported by grants

from Bracco Imaging S.p.A.from Bracco Imaging S.p.A.

PurposePurpose

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

PurposePurposeQuantify the effect on intracranial vessel Quantify the effect on intracranial vessel

enhancement:enhancement:

Increase of the contrast media Increase of the contrast media concentration from 300 mgI/ml to 400 concentration from 300 mgI/ml to 400 mgI/ml mgI/ml

Decrease of the tube voltage from 120 kVp Decrease of the tube voltage from 120 kVp to 90 kVpto 90 kVp

MethodMethodConsecutive inclusion, retrospective analyse Consecutive inclusion, retrospective analyse

including 63 patients including 63 patients referredreferred for clinical for clinical examinationexamination

16 slice scanner (Philips MX 8000 IDT 16)16 slice scanner (Philips MX 8000 IDT 16)

Iomeprol (Iomeron®, Bracco Iomeprol (Iomeron®, Bracco Imaging, ItalyImaging, Italy)) 300 300 mgI/ml or 400 mgI/ml.mgI/ml or 400 mgI/ml.

Contrast volume 80 ml, injection rate 5 ml/s and Contrast volume 80 ml, injection rate 5 ml/s and test bolus based scan delaytest bolus based scan delay

Scan parameters and Scan parameters and patientspatients

Group 1Group 1 Group 2Group 2 Group 3Group 3

Contrast mediaContrast media 300 mgI/ml300 mgI/ml 400 mgI/ml400 mgI/ml 400 mgI/ml400 mgI/ml

Tube voltageTube voltage 120 kVp120 kVp 120 kVp120 kVp 90 kVp90 kVp

Tube currentTube current 229 mAs229 mAs 229 mAs229 mAs 564 mAs564 mAs

CTDICTDIvolvol 32,7 mGy32,7 mGy 32,7 mGy32,7 mGy 36,8 mGy36,8 mGy

Patients (female)Patients (female) 15 (6)15 (6) 15 (7)15 (7) 33 (17)33 (17)

Age mean (years)Age mean (years) 54 (21-78)54 (21-78) 51 (25-74)51 (25-74) 59 (17-87)59 (17-87)






CTDICTDIvolvol 32.7 mGy32.7 mGy 32.7 mGy32.7 mGy 36.8 mGy36.8 mGy








CTDICTDIvolvol 32.7 mGy32.7 mGy 32.7 mGy32.7 mGy 36.8 mGy36.8 mGy



MeasurementsMeasurements

Below the top of the ICA M1 and M2 segments

Image quality gradingImage quality grading

Grading 1-4(poor-excellent)

257 HU (Grade 2)300 mgI/ml, 120 kV

683 HU (Grade 4)400 mgI/ml, 90 kV

360 HU (Grade 2 M1, Grade 3 M2)300 mgI/ml, 120 kV

690 HU (grad 4 M1&M2)400 mgI/ml, 90 kV

MeasurementsMeasurements HUMean HU ± SDMean HU ± SD Group difference, p valueGroup difference, p value

(Welch two sample t-test)(Welch two sample t-test)

mgI/ml/mgI/ml/

kVkVGroup 1Group 1300/120300/120

Group 2Group 2400/120400/120

Group 3Group 3400/90400/90

Group 1 Group 1 versusversus

Group 2Group 2

Group 2 Group 2 versusversus

Group 3 Group 3

Group 1 Group 1 versus versus

Group 3 Group 3

ICA ICA 360 ± 75360 ± 75 424 ± 82424 ± 82 579 ± 157579 ± 157 0.030.03** < 0.01< 0.01** < 0.01< 0.01**

M1 M1 333 ± 68333 ± 68 382 ± 84382 ± 84aa 525 ± 133525 ± 133 0.100.10 < 0.01< 0.01** < 0.01< 0.01**

M2M2 306 ± 66306 ± 66 354 ± 82354 ± 82aa 465 ± 127465 ± 127 0.090.09 < 0.01< 0.01** < 0.01< 0.01**

a One patient excluded because of coilartefacts * significans at p ≤ 0.05

Image quality gradingImage quality gradingImage quality gradingImage quality gradingMean valuesMean values

Group difference, p valueGroup difference, p value (Wilcoxon rank sum test)(Wilcoxon rank sum test)

mgI/ml/kVmgI/ml/kV Group Group 1 1 300/12300/1200

Group Group 2 2 400/12400/1200

Group 3 Group 3 400/90400/90

Group 1 Group 1 versus versus Group 2 Group 2



M1M1 3.003.00 3.433.43aa 3.453.45 0.120.12 0.860.86 0.050.05**M2M2 3.003.00 3.363.36aa 3.553.55 0.210.21 0.430.43 0.020.02**Volume Volume renderingrendering

3.003.00 3.143.14aa 3.523.52 0.570.57 0.070.07 0.010.01**

General General impressioimpressionn

2.802.80 2.862.86aa 3.213.21 0.830.83 0.110.11 0.060.06

a One patient excluded because of coilartefacts * significans at p ≤ 0.05

ResultsResults Contrast media with 400 mgI/ml instead 300 mgI/ml Contrast media with 400 mgI/ml instead 300 mgI/ml

increases intracranial vessel enhancement with increases intracranial vessel enhancement with 18%.18%.

The decrease of tube voltage from 120 kVp to 90 The decrease of tube voltage from 120 kVp to 90 kVp increases intracranial vessel enhancement with kVp increases intracranial vessel enhancement with 37%. 37%.

The combined effect of both parameters yields an The combined effect of both parameters yields an increase of the enhancement with 61%. increase of the enhancement with 61%.

ConclusionConclusion The use of highly concentrated contrast media in The use of highly concentrated contrast media in

combination with low tube voltage are easily combination with low tube voltage are easily performed measures to improve the image quality performed measures to improve the image quality on slice images and 3D reconstructions.on slice images and 3D reconstructions.

Both measures can be recommended for Both measures can be recommended for optimization of intracranial CTA. optimization of intracranial CTA.

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Impact of Contrast Media Concentration and kVp settings on Image Quality in CT Angiography of the Intracranial…