RT Journal Article SR Electronic T1 Effects of Increased Image Noise on Image Quality and Quantitative Interpretation in Brain CT Perfusion JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A3448 A1 K. Juluru A1 J.C. Shih A1 A. Raj A1 J.P. Comunale A1 H. Delaney A1 E.D. Greenberg A1 C. Hermann A1 Y.B. Liu A1 A. Hoelscher A1 N. Al-Khori A1 P.C. Sanelli YR 2013 UL http://www.ajnr.org/content/early/2013/04/04/ajnr.A3448.abstract AB BACKGROUND AND PURPOSE: There is a desire within many institutions to reduce the radiation dose in CTP examinations. The purpose of this study was to simulate dose reduction through the addition of noise in brain CT perfusion examinations and to determine the subsequent effects on quality and quantitative interpretation. MATERIALS AND METHODS: A total of 22 consecutive reference CTP scans were identified from an institutional review board–approved prospective clinical trial, all performed at 80 keV and 190 mAs. Lower-dose scans at 188, 177, 167, 127, and 44 mAs were generated through the addition of spatially correlated noise to the reference scans. A standard software package was used to generate CBF, CBV, and MTT maps. Six blinded radiologists determined quality scores of simulated scans on a Likert scale. Quantitative differences were calculated. RESULTS: For qualitative analysis, the correlation coefficients for CBF (−0.34; P < .0001), CBV (−0.35; P < .0001), and MTT (−0.44; P < .0001) were statistically significant. Interobserver agreements in quality for the simulated 188-, 177-, 167-, 127-, and 44-mAs scans for CBF were 0.95, 0.98, 0.98, 0.95, and 0.52, respectively. Interobserver agreements in quality for the simulated CBV were 1, 1, 1, 1, and 0.83, respectively. For MTT, the interobserver agreements were 0.83, 0.86, 0.88, 0.74, and 0.05, respectively. For quantitative analysis, only the lowest simulated dose of 44 mAs showed statistically significant differences from the reference scan values for CBF (−1.8; P = .04), CBV (0.07; P < .0001), and MTT (0.46; P < .0001). CONCLUSIONS: From a reference CTP study performed at 80 keV and 190 mAs, this simulation study demonstrates the potential of a 33% reduction in tube current and dose while maintaining image quality and quantitative interpretations. This work can be used to inform future studies by using true, nonsimulated scans. Abbreviations ALARAas low as reasonably achievableCTDI-volCT dose index volumePABAKprevalence-adjusted bias-adjusted κ values