Development and validation of a rapid and robust method to determine visceral adipose tissue volume using computed tomography images

<div><p>Background</p><p>Visceral adiposity is a risk factor for many chronic diseases. Existing methods to quantify visceral adipose tissue volume using computed tomographic (CT) images often use a single slice, are manual, and are time consuming, making them impractical for large population studies. We developed and validated a method to accurately, rapidly, and robustly measure visceral adipose tissue volume using CT images.</p><p>Methods</p><p>In-house software, Medical Executable for the Efficient and Robust Quantification of Adipose Tissue (MEERQAT), was developed to calculate visceral adipose tissue volume using a series of CT images within a manually identified region of interest. To distinguish visceral and subcutaneous adipose tissue, ellipses are drawn through the rectus abdominis and transverse abdominis using manual and automatic processes. Visceral and subcutaneous adipose tissue volumes are calculated by counting the numbers of voxels corresponding to adipose tissue in the region of interest. MEERQAT’s ellipse interpolation method was validated by comparing visceral adipose volume from 10 patients’ CT scans with corresponding results from manually delineated scans. Accuracy of visceral adipose quantification was tested using a phantom consisting of animal fat and tissues. Robustness of the method was tested by determining intra-observer and inter-observer coefficients of variation (CV).</p><p>Results</p><p>The mean difference in visceral adipose tissue volume between manual and elliptical delineation methods was -0.54 ± 4.81%. In the phantom, our measurement differed from the known adipose volume by ≤ 7.5% for all scanning parameters. Mean inter-observer CV for visceral adipose tissue volume was 0.085, and mean intra-observer CV for visceral adipose tissue volume was 0.059.</p><p>Conclusions</p><p>We have developed and validated a robust method of accurately and quickly determining visceral adipose tissue volume in any defined region of interest using CT imaging.</p></div

Phantom scanning protocols and calculated adipose volumes.

<p>Phantom scanning protocols and calculated adipose volumes.</p

Contouring methods for the separation of subcutaneous and visceral adipose tissue.

<p>(a) In MEERQAT (our program), elliptical contours, shown in blue, were used to divide VAT and SAT regions within each slice. (b) In Pinnacle³ (typical program used to delineate VAT and SAT regions), two manual contours, shown in red and green, were drawn on each slice to separate the VAT region from the SAT region.</p

Graphic interface of MEERQAT.

<p>Axial, coronal, and sagittal views of the computed tomography (CT) image series are displayed on the left. Ellipses are drawn on axial slices (blue line), and interpolated ellipses are visible on the coronal and sagittal displays. Visceral and subcutaneous adipose tissue volumes are shown on the right, along with a plot of visceral adipose tissue volume per slice.</p

Intra-observer CV for VAT volume and SAT volume.

<p>Intra-observer CV for VAT volume and SAT volume.</p

VAT volume from elliptical interpolation & manual delineation.

<p>VAT volume from elliptical interpolation & manual delineation.</p

Comparison between phantom and patient Hounsfield unit (HU) distribution.

<p>(a) The HU histogram of the phantom. (b) The HU histogram of an obese patient.</p

Inter-observer CV for VAT volume and SAT volume.

<p>Inter-observer CV for VAT volume and SAT volume.</p