Ernst Klotz PhD, Presenter: Employee, Siemens AG

Ulrike Haberland, Abstract Co-Author: Employee, Siemens AG

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

Axial coverage of traditional perfusion computed tomography is limited to the width of the detector. Using continuous periodic table movement coverage can be increased beyond this limit. We compared tissue flow values determined from periodic spiral scans with variable pitch with ones determined from standard dynamic scan modes.

A biological flow phantom was scanned with periodic spirals (adaptive 4D spiral, Siemens, Germany ) with ranges between 100 and 148 mm and a temporal sampling of 1.5 s. Additionally the whole phantom was scanned with the standard dynamic mode (temporal sampling 1.0 s) at various overlapping positions as a reference. Scan parameters were selected similar to a typical brain perfusion study. All scans were repeated 5 times. Tissue flow was calculated with a dedicated deconvolution algorithm. In six center and off center slices flow values were recorded in a total of 126 regions of interest (ROI). Reproducibility was determined from the variation of the repeat scans. Agreement between periodic spiral and standard mode was determined by Bland Altman plots and correlation analysis.

The reproducibility of the tissue flow determination ranged from 2.7 to 4.4 ml/100ml/min and was similar for all scan modes (coefficient of variation 3.9 % to 6.1 %). Mean tissue flow ranged from 35 to 121 ml/100ml/min. There was excellent correlation between both periodic spiral ranges and the standard dynamic mode with a Pearson correlation coefficient of r = 0.97. The regression slope (intercept 0) for the 100 mm range was 1.01, for the 148 mm range it was 0.97. The absolute differences per ROI varied between 1.5 and 4.1 ml/100ml/min (1.9 to 6.5 %) and did not depend on the slice location.

Periodic spiral scan modes with variable pitch and a sampling rate of 1.5 s can be used for the quantitative determination of tissue flow. Their performance is equivalent to equidistant sampling with standard dynamic scan modes. The ranges of 100 and 148 mm investigated allow coverage of the whole brain or an entire organ for perfusion imaging.

Periodic spiral scan modes allow coverage of the whole brain or an entire organ for quantitative perfusion imaging.

Klotz, E, Haberland, U, Schmidt, B, Perfusion Computed Tomography Using Dynamic Spiral Scan Modes with Variable Pitch: Quantitative Flow Determination in Comparison to Standard Dynamic Modes.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008595.html