Sonja Kandel MD, Presenter: Nothing to Disclose

Henning Meyer MD, Abstract Co-Author: Nothing to Disclose

Markus Boehnert MD, Abstract Co-Author: Nothing to Disclose

Hatem Mehrez PhD, Abstract Co-Author: Employee, Toshiba Corporation

Patrik Rogalla MD, Abstract Co-Author: Nothing to Disclose

To analyse the impact of contrast material bolus length on perfusion values based on maximum slope method in a swine model.

18 healthy pigs (weight 63-77 kg) underwent a dynamic volume CT of the kidneys during suspended breathing. Prior to the CT examination, a miniature cuff-shaped ultrasound flow probe was surgically implanted at the right kidney artery in each pig. Two sequential perfusion CT series (Series I, II) each comprising of 80 volumes with identical parameters (100 kV, 200 mAs, 0.5 rotation time) were obtained. The contrast media bolus (volume: 0.5 ml/kg BW) lasted for 3 s in Series I and 11.5 s in Series II, injection flow was adapted accordingly. Cortical kidney volume was determined using the volume with the highest cortical enhancement. Perfusion values were calculated for both series using maximum slope method, statistically compared and correlated to the normalised flow values (true perfusion) gained from the flow probe. 

Mean true perfusion and CT perfusion values (min-1) for Series I/II were 2.02/2.1 (p=0.22) and 2.01/1.86 (p=0.12), respectively. CT perfusion in Series I and II correlated well to the true perfusion (r=0.79 and r=0.71, respectively). On average, CT perfusion values were overestimated by 4.3% in Series I and underestimated by 4.4% in Series II.

CT perfusion values are influenced by the contrast media bolus length. Therefore, the bolus length should remain unaltered on serial CTs to avoid perfusion value misinterpretation.

Our results suggest that the injection protocol for perfusion CT should be kept unaltered for longitudinal perfusion value interpretation.  

Kandel, S, Meyer, H, Boehnert, M, Mehrez, H, Rogalla, P, How Influential Is the Length of Contrast Material Bolus in Perfusion CT? Evaluation in a Swine Model.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034188.html