TY - JOUR T1 - Cranial CT with Adaptive Statistical Iterative Reconstruction: Improved Image Quality with Concomitant Radiation Dose Reduction JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 609 LP - 615 DO - 10.3174/ajnr.A2826 VL - 33 IS - 4 AU - O. Rapalino AU - Shervin Kamalian AU - Shahmir Kamalian AU - S. Payabvash AU - L.C.S. Souza AU - D. Zhang AU - J. Mukta AU - D.V. Sahani AU - M.H. Lev AU - S.R. Pomerantz Y1 - 2012/04/01 UR - http://www.ajnr.org/content/33/4/609.abstract N2 - BACKGROUND AND PURPOSE: To safeguard patient health, there is great interest in CT radiation-dose reduction. The purpose of this study was to evaluate the impact of an iterative-reconstruction algorithm, ASIR, on image-quality measures in reduced-dose head CT scans for adult patients. MATERIALS AND METHODS: Using a 64-section scanner, we analyzed 100 reduced-dose adult head CT scans at 6 predefined levels of ASIR blended with FBP reconstruction. These scans were compared with 50 CT scans previously obtained at a higher routine dose without ASIR reconstruction. SNR and CNR were computed from Hounsfield unit measurements of normal GM and WM of brain parenchyma. A blinded qualitative analysis was performed in 10 lower-dose CT datasets compared with higher-dose ones without ASIR. Phantom data analysis was also performed. RESULTS: Lower-dose scans without ASIR had significantly lower mean GM and WM SNR (P = .003) and similar GM-WM CNR values compared with higher routine-dose scans. However, at ASIR levels of 20%–40%, there was no statistically significant difference in SNR, and at ASIR levels of ≥60%, the SNR values of the reduced-dose scans were significantly higher (P < .01). CNR values were also significantly higher at ASIR levels of ≥40% (P < .01). Blinded qualitative review demonstrated significant improvements in perceived image noise, artifacts, and GM-WM differentiation at ASIR levels ≥60% (P < .01). CONCLUSIONS: These results demonstrate that the use of ASIR in adult head CT scans reduces image noise and increases low-contrast resolution, while allowing lower radiation doses without affecting spatial resolution. ACRAmerican College of RadiologyASIRAdaptive Statistical Iterative ReconstructionCNRcontrast-to-noise ratioCTDIvolvolume CT dose indexDLPdose-length productEDeffective doseFBPfiltered back-projectionGMgray matterHUHounsfield unitlpline pair ER -