The gradient and homogeneity thresholds were estimated by the histogram of the gradient and homogeneity images, respectively.
Homogeneity: 0: good homogeneity, 1: almost homogeneous images, 2: minor heterogeneity close to skull base and in temporal lobes, 3: heterogeneous signal at multiple locations, 4: high number of heterogeneous areas, 5: highly heterogeneous images, no valid analysis possible.
Three experienced readers, blinded to the imaging protocols, independently scored the overall quality of all images (contrast heart to lung and heart to liver, homogeneity, and image statistics/noise) on a 5-point scale as very poor (1), poor (2), moderate (3), good (4) or very good (5); individual results were finally concluded in a consensus reading.
One advantage of such a prospective initiative is that the homogeneity of images and metadata is better than for retrospectively disclosed repositories, with often only partly overlapping data dictionaries.
In our case, it measures the spatial/spectral image homogeneity.
Considerable improvement of the B1 homogeneity and EPR image quality in comparison with reflection loop-gap resonator of similar size and volume was observed.
Both discriminator thresholds can be adjusted individually for good image homogeneity and a circuit has been designed to avoid threshold drift.
Second-order statistics based on a co-occurrence matrix (GLCM) include entropy (randomness of the matrix), energy/angular second moment (pixel repetition/orderliness and measures the homogeneity of an image), homogeneity (uniformity of co-occurrence matrix), dissimilarity (measurement of how different each element in the matrix is), and correlation (measurement of gray-tone linear dependencies).
Since the region parameters can better represent the values of the evolving regions due to the better image homogeneity, the proposed method can more accurately segment various types of images.
