DOI:10.2214/AJR.07.2996
AJR 2007; 189:W386
© American Roentgen Ray Society
Total Body Fat, Visceral Fat, Subcutaneous Fat, Bone Marrow Fat? What Is Important to Measure?
Michael Mantatzis and
Panos Prassopoulos
University Hospital of Alexandroupolis, Medical School of Thrace,
Alexandroupolis, Greece
WEB—This is a Web exclusive article.
We have read the important article by Brennan and colleagues
[1] regarding the estimation of
total body fat distribution on MRI using an automated method. A number of
common diseases are closely related to obesity and, because current methods of
fat assessment are inaccurate, MRI might become a powerful tool for accurate
and reproducible body fat measurement both in clinical practice and for
research purposes. The authors have used a combination of meticulous
segmentation of the voxels with signal intensity values corresponding to fat
and computer-assisted diagnosis (CAD) techniques to measure total body fat on
MR images. However, this type of automated measurement also incorporates the
bone marrow adipose tissue. As it is noticed in Figure 1 of the article, the
bone marrow within the femoral head, distal tibia, and humerus head is labeled
as fat tissue and consequently is included in the measurements
[1].
Bone marrow adipose tissue has a considerable volume in the body. It
differs in composition and function from subcutaneous or visceral fat and has
not been related with diseases linked to obesity. Therefore, the utility of
the proposed automated system might be compromised if bone marrow adipose
tissue is measured along with the subcutaneous and visceral fat. We would like
to propose anatomic segmentation as a possible solution to overcome this
drawback.
Furthermore and as stated by the authors
[1], it is well known that the
distribution of adipose tissue in the body is by far more clinically relevant
than the increased total body adipose tissue per se
[2,
3]. Visceral adiposity has been
related to hypertension and cardiovascular disease, cerebrovascular disease,
insulin resistance and type 2 diabetes, and others
[2,
3]. Measurements of the
visceral fat could be performed using the authors' proposed automated system,
broadening the utility of their work in clinical practice or for research
purposes. To differentiate visceral from subcutaneous fat, these measurements
would require an intervening step concerning anatomic segmentation in the
authors' process. Assessment of the visceral fat, in addition to the total
body fat, will allow evaluation of regional fat distribution, which is
important in defining disease risk.
References
- Brennan DD, Whelan PF, Robinson K, et al. Rapid automated
measurement of body fat distribution from whole-body MRI.
AJR 2005; 185:418
-423[Abstract/Free Full Text]
- Ross R, Aru J, Freeman J, Hudson R, Janssen I. Abdominal adiposity
and insulin resistance in obese men. Am J Physiol Endocrinol
Metab 2002; 282:E657
-E663[Abstract/Free Full Text]
- Snijder MB, van Dam RM, Visser M, Seidell JC. What aspects of body
fat are particularly hazardous and how do we measure them? Int J
Epidemiol 2006; 35:83
-92[Free Full Text]
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