Epicardial and thoracic subcutaneous fat texture analysis in patients undergoing cardiac CT

Abstract

Introduction: The aim of our study was to evaluate the feasibility of texture analysis of epicardial fat (EF) and thoracic subcutaneous fat (TSF) in patients undergoing cardiac CT (CCT).

Materials and methods: We compared a consecutive population of 30 patients with BMI ≤25 kg/m² (Group A, 60.6 ± 13.7 years) with a control population of 30 patients with BMI >25 kg/m² (Group B, 63.3 ± 11 years). A dedicated computer application for quantification of EF and a texture analysis application for the study of EF and TSF were employed.

Results: The volume of EF was higher in group B (mean 116.1 cm³ vs. 86.3 cm³, p = 0.014), despite no differences were found neither in terms of mean density (-69.5 ± 5 HU vs. -68 ± 5 HU, p = 0.28), nor in terms of quartiles distribution (Q1, p = 0.83; Q2, p = 0.22, Q3, p = 0.83, Q4, p = 0.34). The discriminating parameters of the histogram class were mean (p = 0.02), 0,1st (p = 0.001), 10_th (p = 0.002), and 50_th percentiles (p = 0.02). DifVarnc was the discriminating parameter of the co-occurrence matrix class (p = 0.007).The TSF thickness was 15 ± 6 mm in group A and 19.5 ± 5 mm in group B (p = 0.003). The TSF had a mean density of -97 ± 19 HU in group A and -95.8 ± 19 HU in group B (p = 0.75). The discriminating parameters of texture analysis were 10_th (p = 0.03), 50_th (p = 0.01), 90_th percentiles (p = 0.04), S(0,1)SumAverg (p = 0.02), S(1,-1)SumOfSqs (p = 0.02), S(3,0)Contrast (p = 0.03), S(3,0)SumAverg (p = 0.02), S(4,0)SumAverg (p = 0.04), Horzl_RLNonUni (p = 0.02), and Vertl_LngREmph (p = 0.0005).

Conclusions: Texture analysis provides distinctive radiomic parameters of EF and TSF. EF and TSF had different radiomic features as the BMI varies.

Keywords: Cardiac computed tomography; Cardiovascular risk; Epicardial fat; Texture analysis.

Fig. 1

Quantification of EF with semiautomatic dedicated software. A plane obtained at a four-chamber cardiac view was selected to detect EF displayed in red colour. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

Maps comparing quartiles density distribution: Q1 (−175 HU, −136 HU), red (a); Q2 (−135 HU, −96 HU), blue (b); Q3 (−95 HU, −56 HU), yellow (c); Q4 (−55 HU, −15 HU), green (d). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

Radiomic analysis: ROIs in the right atrioventricular groove (red), in the anterior interventricular groove (green), in the left atrioventricular groove (dark blue), and in the thoracic subcutaneous fat (light blue) (a). Histograms representing the intensity values of pixels within the four ROIs: each histogram has the same colour of the relative ROI (b). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4

Plot describing the p values of radiomic features in epicardial fat with bar of significance set at p < 0.05.

Fig. 5

Plot describing the p values of radiomic features in thoracic subcutaneous fat with bar of significance set at p < 0.05.