Comparison of Low-Dose CT and MR for Measurement of Intra-Abdominal Adipose Tissue:1

Rationale and Objectives

The aim of this study was to determine the accuracy and reproducibility of low-dose computed tomography (CT) and magnetic resonance (MR) for abdominal adipose tissue quantification on phantom and human studies.

Materials and Methods

An adiposity phantom (with known internal/external oil volumes) was scanned at three different tube voltages (140, 120, and 90 kVp) using a 16-detector row CT scanner and was imaged using a T1-weighted spin echo MR sequence. For human studies, whole-volume coverage of the abdomen was obtained using CT (at 140 and 90 kVp) and T1-weighted spin echo MR imaging from five obese male volunteers (mean age, 40.6 years; mean body mass index, 30.2). The volumes of total, visceral, and subcutaneous adipose tissues (TAT, VAT, and SAT, respectively) were calculated independently by two radiologists for each CT scan and MR imaging using a computer-aided semiautomatic program.

Results

The estimated radiation dose could be reduced by approximately 75% with a 90-kVp protocol as compared with the 140-kVp protocol. Phantom studies showed that there was no statistically significant difference between the four methods in estimating the percentage predicted of the true volumes (measurement errors <4% for all methods, P > .05). In human studies, we found no statistically significant difference between the three methods in TAT, VAT, and SAT volumes (P > .05). Inter- and intraobserver reproducibilities of the CT volume estimates using the 90-kVp protocol were better than those obtained from MR imaging (κ > 0.9 versus 0.4–0.5; coefficient of variation < 1% versus 15–22%).

Conclusion

Low-dose CT provides accurate and reproducible measurement of abdominal adipose tissue volumes with a relevant dose reduction.

Key Words: Computed tomography (CT), magnetic resonance imaging (MRI), fat quantification, dose reduction, phantom study