Influence of undersampling on magnetic resonance imaging measurements of intra-abdominal adipose tissue.

OBJECTIVE: Single-slice magnetic resonance imaging (MRI) and computed tomography (CT) are finding increasing use as methods to estimate visceral fat content in human studies. To assess the validity of this approach, we have compared single- and multi-slice MRI methods for the measurement of intra-abdominal adipose tissue content. MEASUREMENTS: Multi-slice whole-body MR images and single-slices at the level of L2-L3 and L4-L5 were obtained from 59 healthy female volunteers chosen to cover a wide range of body size, and from 17 healthy female volunteers before and after a 6-month exercise intervention.
RESULTS: Taking the group as a whole, significant correlation between multi-slice and single-slices was observed (L2-L3: r=0.56; P<0.01; L4-L5: r=0.76; P<0.01). However, the ranking of subjects according to their intra-abdominal fat content was significantly altered by the choice of MRI strategy, especially using L2-L3 methodology. Whole-body (-23.8+/-20.0%; P<0.01) and single-slice (L2-L3: -31.03+/-35.0%; P<0.01; L4-L5: -22.1+/-37.24%; p<0.05) MRI methods also detected a significant decrease in intra-abdominal fat following the exercise protocol, although the latter techniques gave rise to increased spreading of the data from the mean. These results suggest that the use of single-slice imaging techniques can lead to inconsistencies in the estimation of intra-abdominal fat content, which in turn can have significant effects on data interpretation.
CONCLUSION: Single-slice MRI appears to be suitable for assessing changes in intra-abdominal fat content in interventional studies, especially in large cohort of subjects, where each subject can serve as its own control. However, for accurate determination of an individual's intra-abdominal fat content, and intersubject comparison, only multi-slice imaging will give precise results.