Together with CT scan, MRI is considered the most accurate method for the measurement ofin vivo body composition at the tissue-organ level. Its advantages include the lack of exposure toionizing radiation and therefore safety for use in children and pregnant women. It is the best methodfor multiple-image protocols and whole body and serial measurements. However, its high costs andneed for high technical skill precludes widespread use in research or clinical settings. Image qualityis also affected by respiratory motion, which becomes an issue for participants unable to hold theirbreath for a long period. An additional limitation includes the size of the participant as those withobesity (usually body-mass index [BMI] > 35 kg/m2) may not fit in the scan.