Patrik Rogalla MD, Presenter: Nothing to Disclose

Sonja Kandel MD, Abstract Co-Author: Nothing to Disclose

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

To evaluate the effect of iterative reconstruction in dynamic volume CT on regional perfusion values and perfusion pixel noise.

13 patients with focal renal tumors underwent a dynamic volume 320-slice CT of the kidneys before surgical treatment planning. The study had IRB approval. Following intravenous injection of 60 ml of iodined contrast material at a flow rate of 10 ml/s, the imaging protocol consisted of 17 sequential low-dose scans at every 2-8 s (decreasing frequency) covering both kidneys. Scanning parameters were 100 kV, 20-40 mAs (depending on body habitus), 0.5 s gantry revolving time, 16 cm detector coverage, and 0.5 mm slice thickness for all dynamic scans. Raw data were reconstructed using conventional filtered back projection (FBP) and true iterative reconstruction (IR) and used for perfusion analysis. ROIs were placed in the aorta as the reference and within 10 levels in each kidney cortex. Both postprocessing techniques (maximum slope and Patlak-plot) were applied for calculation of perfusion maps, regional perfusion and perfusion pixel noise values were statistically compared between both reconstruction methods.

No difference in regional perfusion values was found between FBP and IR (2.59 and 2.73 in normal cortex, 1.93 and 1.78 in renal neoplasia (n.s.), respectively), independent of the postprocessing method used. Standard deviation of perfusion pixel noise was 42 and 18 (p=0.01) in normal tissue, and 45 and 21 in renal tumours (p=0.001) for FBP and IR, respectively.

Iterative reconstruction leads to significant reduction in perfusion pixel noise while maintaining regional perfusion values, therefore potentially improving reproducibility and allowing for radiation dose reduction during data acquisition.

Iterative reconstruction may reduce radiation dose without changing results from perfusion imaging of renal tumours.

Rogalla, P, Kandel, S, Meyer, H, Iterative Reconstruction Using 320-Slice Computed Tomography in Abdominal Perfusion Imaging: Initial Results.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9016264.html