Low-dose multidetector computed tomography of the cervical spine: optimization of iterative reconstruction strength levels

Background Iterative reconstruction (IR) techniques reduce image noise in multidetector computed tomography (MDCT) imaging. They can therefore be used to reduce radiation dose while maintaining diagnostic image quality nearly constant. However, CT manufacturers offer several strength levels of IR to choose from. Purpose To determine the optimal strength level of IR in low-dose MDCT of the cervical spine. Material and Methods Thirty consecutive patients investigated by low-dose cervical spine MDCT were prospectively studied. Raw data were reconstructed using filtered back-projection and sinogram-affirmed IR (SAFIRE, strength levels 1 to 5) techniques. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured at C3–C4 and C6–C7 levels. Two radiologists independently and blindly evaluated various anatomical structures (both dense and soft tissues) using a 4-point scale. They also rated the overall diagnostic image quality using a 10-point scale. Results As IR strength levels increased, image noise decreased linearly, while SNR and CNR both increased linearly at C3–C4 and C6–C7 levels (P