Visceral fat measurement
View Patent ↗Dual-energy absorptiometry is used to estimate visceral fat metrics and display results, preferably as related to normative data. The process involves deriving x-ray measurements for respective pixel positions related to a two-dimensional projection image of a body slice containing visceral fat and subcutaneous fat, at least some of the measurements being dual-energy x-ray measurements, processing the measurements to derive estimates of metrics related to the visceral fat in the slice, and using the resulting estimates. Processing the measurements includes an algorithm which places boundaries of regions, e.g., a large “abdominal” region and a smaller “abdominal cavity” region. Two boundaries of the “abdominal cavity” region are placed at positions associated with the left and right innermost extent of the abdominal muscle wall by identifying inflection of % Fat values. The regions are combined in an equation that is highly correlated with VAT measured by quantitative computed tomography in order to estimate VAT.
1. A method comprising:
acquiring x-ray measurements using a dual-energy x-ray absorptiometry (DXA) system for respective pixel positions related to a two-dimensional projection image of a portion of a subject's abdomen, wherein the x-ray measurements are dual-energy x-ray measurements;
placing a plurality of regions of the image, wherein said placing includes placing a first region of the image which extends from a first side of the abdomen to a second side of the abdomen, and placing a second region on or within the first region, wherein each of the plurality of regions of the image is a two-dimensional region, and wherein the second region is automatically placed based on fat mass values obtained from DXA measurements;
computer processing to combine the plurality of regions to provide an estimate of visceral fat (VAT) in which said estimate of visceral fat is distinguishable from subcutaneous fat (SAT); and
displaying at least one of said estimate of visceral fat and a metric based on said estimate of visceral fat.
2. The method of claim 1 wherein the placing of the second region is based on an inflection of % total fat values obtained from DXA measurements of two consecutive pixel positions.
3. The method of claim 2 wherein the placing of the second region is based on computer processing the first region.
4. The method of claim 1 wherein the second region has a first side and a second side, wherein the first side of the second region is spaced inwardly from the first side of the abdomen, and wherein the second side of the second region is spaced inwardly from the second side of the abdomen.
5. The method of claim 1 wherein the plurality of regions is combined using polynomial expansion.
6. The method of claim 1 wherein the second region extends across an inner abdominal cavity from the first side to the second side between innermost extents of an abdominal muscle wall.
7. The method of claim 1 wherein the placing further comprises placing a third region of the image, wherein the third region is on or within the first region and is placed where bone is present and percent fat cannot be directly measured, and wherein the second region extends across an inner abdominal cavity from the first side to the second side between innermost extents of an abdominal muscle wall but is exclusive of the third region.
8. The method of claim 1 wherein the placing of at least two regions of the plurality of regions of the image comprises computer processing at least some of the x-ray measurements.
9. The method of claim 1 wherein the placing of the first region of the image comprises using an anatomical landmark and a preselected region of interest line.
10. The method of claim 1 wherein the second region extends across an inner abdominal cavity from the first side to the second side between innermost extents of an abdominal muscle wall and wherein the second region is placed by identifying a left and a right innermost extent of abdominal muscle wall by identifying inflection of adipose tissue values.
11. A method comprising:
acquiring x-ray measurements for respective pixel positions related to a two-dimensional projection image of a portion of a subject's abdomen, wherein the x-ray measurements are dual-energy x-ray measurements;
placing a plurality of regions of the image, wherein each of the plurality of regions of the image is a two-dimensional region and wherein at least one of the plurality of regions is automatically placed based on fat mass values obtained from DXA measurements;
computer processing to combine the plurality of regions to provide an estimate of visceral fat, wherein combining the plurality of regions uses polynomial expansion; and
displaying at least one of said estimate of visceral fat and a metric based on said estimate of visceral fat.
12. A method comprising:
acquiring x-ray measurements for respective pixel positions related to a two-dimensional projection image of a portion of a subject's abdomen, wherein the x-ray measurements are dual-energy x-ray measurements;
placing a plurality of regions of the image, wherein the placing includes placing a first region of the image which extends from a first side of the abdomen to a second side of the abdomen and placing a second region which extends across an inner abdominal cavity from the first side to the second side between innermost extents of an abdominal muscle wall, and wherein said placing of said second region includes identifying a left and a right innermost extent of abdominal muscle wall by identifying inflection of adipose tissue values obtained from DXA measurements, wherein each of the plurality of regions of the image is a two-dimensional region;
computer processing to combine the plurality of regions to provide an estimate of visceral fat, wherein the computer processing includes computer processing at least some of the x-ray measurements for placing the second region of the image; and
displaying at least one of said estimate of visceral fat and a metric based on said estimate of visceral fat.