Objective: This study aimed to evaluate the image quality and apparent diffusion coefficient (ADC) values of single-shot turbo spin echo (TSE) diffusion-weighted (DW) images obtained using a parallel imaging (PI) technique. Methods: All measurements were performed on a 3.0-T whole-body MRI system and 32-channel phased-array coil. Signal-to-noise ratio (SNR) and ADC values were measured with a DW imaging (DWI) phantom comprising granulated sugar and agar. The SNRs were calculated using a subtraction method and compared among TSE-DW images at acceleration factors (AFs) of 1-4. Image blur was visually assessed on TSE-DW images of a pin phantom at AFs of 1-4. The ADC values were calculated using DW images with b 5 0 and 1000 s mm

The purpose of our study was to investigate the validity of a spatial resolution measuring method that uses a combination of a bar-pattern phantom and an imageaveraging technique, and to evaluate the spatial resolution property of iterative reconstruction (IR) images with middle-contrast (50 HU) objects. We used computed tomography (CT) images of the bar-pattern phantom reconstructed by the IR technology Adaptive Iterative Dose Reduction 3D (AIDR 3D), which was installed in the multidetector CT system Aquilion ONE (Toshiba Medical Systems, Otawara, Japan). The contrast of the bar-pattern image was set to 50 HU, which is considered to be a middle contrast that requires higher spatial resolution clinically. We employed an image-averaging technique to eliminate the influence of image noise, and we obtained averaged images of the bar-pattern phantom with sufficiently low noise. Modulation transfer functions (MTFs) were measured from the images. The conventional wire method was also used for comparison; in this method, AIDR 3D showed MTF values equivalent to those of filtered back projection. For the middle-contrast condition, the results showed that the MTF of AIDR 3D decreased with the strength of IR processing. Further, the MTF of AIDR 3D decreased with dose reduction. The imageaveraging technique used was effective for correct evaluation of the spatial resolution for middle-contrast objects in IR images. The results obtained by our method clarified that the resolution preservation of AIDR 3D was not sufficient for middle-contrast objects.

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