Quantitative image quality analysis
CNR, biceps femoris muscle
For a quantitative comparison of image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all images acquired for this study (conventional, accelerated, and DNN-reconstructed). The femoral bone marrow signal shown in the representative center slice in each image was calculated from a circular region of interest (ROI) placed in the same location for all images, and the mean standard deviation (SD) of the background noise was used for SNR calculation. For CNR, three different imaging plane-landmark combinations were considered—(1) for axial T1-weighted and T2-weighted fat saturated images, marrow-to-muscle signal difference (medial femoral condyle and biceps femoris muscle) and mean SD of background noise were used; (2) for coronal T2-weighted fat saturated images, marrow-to-meniscus signal difference (medial femoral condyle and medial meniscus) and mean SD of background noise were used; (3) for sagittal T2-weighted images, marrow-to-tendon signal difference(distal femur and patellar tendon) and mean SD of background noise were used to calculate the CNR.