Serena Virdi, Abstract Co-Author: Nothing to Disclose

Davide Prezzi FRCR, Presenter: Nothing to Disclose

Maria Lewis MS, Abstract Co-Author: Nothing to Disclose

Catherine Grierson MD, FRCR, Abstract Co-Author: Nothing to Disclose

David John Breen MD, Abstract Co-Author: Nothing to Disclose

Vicky Joo-Lin Goh MBBCh, Abstract Co-Author: Research Grant, Siemens AG

To prospectively assess the effect of adaptive statistical iterative reconstruction (ASIR) on image quality and quantified CT perfusion parameters in primary colorectal cancer.

Institutional review board approval and informed consent was obtained for this prospective study. To date 20 consecutive patients (17male, 3 female, mean age 69.6 years) with a primary colorectal adenocarcinoma have undergone CT perfusion (Discovery 750HD, GE Healthcare: 100kV, 150mA, axial mode, 0.5s rotation time, 64x0.625mm detectors, 1s interscan delay, reconstructed slice thickness 5mm, z-axis coverage 40mm). Tumor regional blood flow, blood volume, mean transit time, and permeability surface area product (Distributed parameter analysis, Perfusion 4.0, GE Healthcare) were assessed by the same observer using identical regions of interests for the following ASIR percentages: 0%, 20%, 40%, 60%, 80% and 100%, and compared using analysis of variance with statistical significance at 5%. Tumor contrast-to-noise ratios (CNRs) were also measured at the different ASIR percentages.

Tumors were located within the rectum (10), sigmoid colon (2), descending colon (1), splenic flexure (1), ascending colon (3) and cecum (3). Mean (SD) tumor size was 4.31(1.79) cm. Mean (SD) of BF, BV, MTT and PS was 70.72 (16.87)mL/min/100g tissue, 7.57 (2.17) mL/min, 7.68 (1.94) seconds and 32.7 (7.60) mL/min/100g tissue respectively. Mean tumor BF, BV, MTT and PS varied by less than 3%, 7%, 6% and 2% respectively. Tumor CNR increased with increasing ASIR, with values of 2.47 and 3.74 at 0% and 100% ASIR respectively, an increase of 51%.

ASIR does not alter quantified tumor CT perfusion values significantly yet improves the contrast to noise ratio. ASIR enables lower dose CT perfusion techniques to be applied with adequate image quality and no significant changes to quantification.

Iterative reconstruction techniques such as ASIR enable lower dose CT perfusion techniques to be applied in clinical practice, maintaining adequate image quality with no significant changes in quantification of CT perfusion parameters.

Virdi, S, Prezzi, D, Lewis, M, Grierson, C, Breen, D, Goh, V, The Effect of Adaptive Statistical Iterative Reconstruction (ASIR) on Image Quality and CT Perfusion Parameters in Primary Colorectal Cancer.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009290.html