Abstract
ObjectiveTo evaluate the feasibility of quantifying visceral adipose tissue (VAT) on computed tomography (CT) and magnetic resonance imaging (MRI) scans, using freeware, as well as calculating intraobserver and interobserver reproducibility.Materials and MethodsWe quantified VAT in patients who underwent abdominal CT and MRI at our institution between 2010 and 2015, with a maximum of three months between the two examinations. A slice acquired at the level of the umbilicus was selected. Segmentation was performed with the region growing algorithm of the freeware employed. Intraobserver and interobserver reproducibility were evaluated, as was the accuracy of MRI in relation to that of CT.ResultsThirty-one patients (14 males and 17 females; mean age of 57 ± 15 years) underwent CT and MRI (mean interval between the examinations, 28 ± 12 days). The interobserver reproducibility was 82% for CT (bias = 1.52 cm2; p = 0.488), 86% for T1-weighted MRI (bias = −4.36 cm2; p = 0.006), and 88% for T2-weighted MRI (bias = −0.52 cm2; p = 0.735). The intraobserver reproducibility was 90% for CT (bias = 0.14 cm2; p = 0.912), 92% for T1-weighted MRI (bias = −3,4 cm2; p = 0.035), and 90% for T2-weighted MRI (bias = −0.30 cm2; p = 0.887). The reproducibility between T1-weighted MRI and T2-weighted MRI was 87% (bias = −0.11 cm2; p = 0.957). In comparison with the accuracy of CT, that of T1-weighted and T2-weighted MRI was 89% and 91%, respectively.ConclusionThe program employed can be used in order to quantify VAT on CT, T1-weighted MRI, and T2-weighted MRI scans. Overall, the accuracy of MRI (in comparison with that of CT) appears to be high, as do intraobserver and interobserver reproducibility. However, the quantification of VAT seems to be less reproducible in T1-weighted sequences.
Highlights
In the human body, the main function of white adipose tissue is to contribute to energy homeostasis by absorbing and storing lipids, as well as by preventing ectopic lipid deposition
The computed tomography (CT) and magnetic resonance imaging (MRI) examinations were performed for a variety of reasons: hepatic lesion (n = 4); pancreatic lesion (n = 5); tumor of the genitourinary tract (n = 7); liver metastases (n = 5); Crohn’s disease (n = 5); diverticulitis (n = 1); endometriosis (n = 1); aortic aneurysm (n = 1); gastrointestinal stromal tumor (n = 1); and small bowel lymphoma (n = 1)
CT scans were available for all 31 patients; T1-weighted MRI scans were available for 26 patients; T2-weighted MRI scans were available for 23 patients; and T1- and T2-weighted MRI scans were both available for 20 patients
Summary
The main function of white adipose tissue is to contribute to energy homeostasis by absorbing and storing lipids, as well as by preventing ectopic lipid deposition. White adipose tissue deposits are found mainly in the subcutaneous compartments of the upper and lower body, as well as in the visceral compartment[1]. Ultrasound has proven to be an accurate means of evaluating the thickness of subcutaneous fat[7], its performance continues to be suboptimal for the quantification of VAT[8]. To address these issues, some authors have used other tools, such as dual-energy X-ray absorptiometry[9] and body impedance analysis[10], which provide data on lean and fat tissue. Quantitative evaluation of body fat distribution is still difficult to perform
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