Figure 2From: Characterization of the ultra-short echo time magnetic resonance (UTE MR) collagen signal associated with myocardial fibrosisHistology and UTE results in canine heart tissue. (a) Histological slice of heart tissue, stained with Picrosirius Red. The 781.2 μm x 781.2 μm region-of-interest (ROI) used for analysis is delineated. The collagen area fraction in the ROI was determined to be 4 ± 2 %, based on a pixel threshold algorithm. (b) Corresponding UTE MR image at TE = 0.02 ms, with the ROI delineated. (c) T2* decay within the ROI. T2*long denotes the long T2* of cardiac muscle. TEs ≤ 2 ms were finely sampled to determine the collagen T2* and resonance frequency, where the T2* model is accurate. Based on the calibration plot in Figure 1a, the collagen signal fraction of 1.2 ± 0.2 % was equivalent to a collagen concentration of 2.3 ± 0.9 %. Hence, there was agreement between the collagen area fraction determined from histology (4 ± 2 %) and the collagen concentration.Back to article page