[Evaluation of Low-contrast Detectability of Iterative Reconstruction Algorithm in High-speed CT Technology for Head]

The purpose of this study was to assess the feasibility of high-speed CT technology for head without deterioration of low-contrast detectability using the brain LCD (Canon Medical Systems) of iterative reconstruction.

System performance (SP) function analysis, low-contrast object specific contrast-to-noise ratio (CNR_LO) analysis, and visual evaluation using Scheffe's paired comparison were performed. Additionally, analysis of the correlation of CNR_LO and visual scores was performed. SP was performed with the self-made phantom. CNR_LO was calculated with the catphan 504 phantom (CTP 515). Visual evaluation was performed using the brain phantom which simulated such as cerebral infarction and investigated on a fivepoint scale. All images were acquired with pitch factor of 0.61 (low pitch) and 1.40 (high pitch). All images were reconstructed with filtered back projection (FBP), brain LCD standard (LCD STD) and strong (LCD STR).

SP of brain LCD improved compared with FBP. CNR_LO of FBP decreased in high pitch compared with low pitch. CNR_LO of brain LCD images acquired by low- and high pitch were improved compared with FBP. Visual scores denoted similar trends to that of CNR_LO and there was high correlation with CNR_LO.

It was suggested that using brain LCD can achieve the high speed CT technology for head without deterioration of low-contrast detectability.