Whole-body MRI-based fat quantification: a comparison to air displacement plethysmography.

PURPOSE: To demonstrate the feasibility of an algorithm for MRI whole-body quantification of internal and subcutaneous fat and quantitative comparison of total adipose tissue to air displacement plethysmography (ADP). MATERIALS AND METHODS: For comparison with ADP, whole-body MR data of 11 volunteers were obtained using a continuously moving table Dixon sequence. Resulting fat images were corrected for B1 related intensity inhomogeneities before fat segmentation. RESULTS: The performed MR measurements of the whole body provided a direct comparison to ADP measurements. The segmentation of subcutaneous and internal fat in the abdomen worked reliably with an accuracy of 98%. Depending on the underlying model for fat quantification, the resultant MR fat masses represent an upper and a lower limit for the true fat masses. In comparison to ADP, the results were in good agreement with ρ ≥ 0.97, P < 0.0001. CONCLUSION: Whole-body fat quantities derived noninvasively by using a continuously moving table Dixon acquisition were directly compared with ADP. The accuracy of the method and the high reproducibility of results indicate its potential for clinical applications.

Sliding multislice MRI for abdominal staging of patients with pelvic malignancies: a pilot study.

PURPOSE: To integrate SMS (sliding multislice imaging technique for acquiring axial images during continuous table motion) into a high-resolution pelvic MRI protocol for additional staging of the entire abdomen within one examination. MATERIALS AND METHODS: Axial two-dimensional images were acquired during continuous table motion using a fat-saturated contrast-enhanced T1-weighted gradient echo sequence. Patients held their breath during the first 20 s of the examination and breathed normally afterward while data acquisition continued. Measurement parameters were adjusted to optimize image quality throughout the total field of view. The method was investigated in 22 patients with pelvic malignancies. Two readers independently compared SMS image quality to conventional abdominal MR images, generated by a stationary multi-breath-hold gradient echo sequence. RESULTS: Qualitative evaluation yielded high diagnostic value of SMS data in body regions with no or minor breathing motion, and in those acquired during the initial breath-hold. Image quality in the upper abdomen, retroperitoneum, and pelvis is reproducible and equivalent to stationary MRI. Interfering artifacts are related to the intestine in the mid-abdomen. CONCLUSION: SMS is a promising technique that may have the potential for a first-line abdominal staging tool in patients with pelvic malignancies.