Armin Michael Huber MD, Abstract Co-Author: Nothing to Disclose

Franziska Dorn, Abstract Co-Author: Nothing to Disclose

Reinhard Meier MD, Presenter: Nothing to Disclose

Daniela Muenzel MD, Abstract Co-Author: Nothing to Disclose

Thomas Liebig MD, PhD, Abstract Co-Author: Nothing to Disclose

Holger Poppert, Abstract Co-Author: Nothing to Disclose

Ernst J. Rummeny MD, Abstract Co-Author: Nothing to Disclose

To evaluate if the order of a CT stroke protocol (CT-perfusion before or after CT-angiography) has an impact on image quality.

40 consecutive patients with clinical suspicion of an acute cerebral infarct underwent a CT stroke protocol including non-enhanced CT (NECT), CT angiography (CTA) and CT perfusion (CTP). NECT was performed first in all patients. Twenty examinations were performed with CTP before CTA (group 1) and 20 in reversed order (group 2). Image quality was quantified by measuring the mean density (Houndsfield Units, HU) in small ROIs in the basilar and middle cerebral artery, in the transverse Sinus, Sinus sagittalis superior and in cortical grey and white matter on baseline and peak enhancement of the CTP, as well as on source images of the CTA. Image quality of CTA was rated concerning contrast of extra- and intracranial arteries and veins according to a 5-point-scale, respectively (1=excellent, 5=poor). CT-perfusion maps were assessed by determining the mean transit time (MTT), cerebral blood flow (CBF) and blood volume (CBV) in non-pathological affected regions.  

Mean density between group 1 and 2 were not significantly different for CTA concerning all measurement points, as well as for CTP at peak enhancement. HU between group 1 and 2 were significantly different for all points except for GM and WM at baseline. Mean delta, defined as the difference between baseline and peak enhancement, was not significantly different between group 1 and 2. Mean values for MTT (4.8+-2.1 vs. 5.9+-2.7sec, p=0.4), CBV (8.0+-4.1 vs. 9.5+-5.7ml/100g, p=0.6) and CBF (109.0+-56.5 vs. 106.2+-54.3ml/100mg/min, p=0.9) were not significantly different between group 1 and 2. Subjective evaluation of image quality was only different for the extracranial vein contrast in group 2, however not for all other criteria.

Reversal of CT stroke protocol had no significant influence on quantitative parameters of the CTP. Subjective rating of image quality was different between the two groups only for extracranial venous contrast.

Performing CTA before CTP may increase image quality of CTA by avoiding extracranial venous preload without reducing the quality of CTP and allow for individual planning of the perfusion volume.

Huber, A, Dorn, F, Meier, R, Muenzel, D, Liebig, T, Poppert, H, Rummeny, E, Order of CT Stroke Protocol (CTA before or after CTP): Impact on Image Quality.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11014422.html