Approximate fluoroptic probe locations in the sagittal plane 5 mm lateral to the central plane (left) and central axial plane (right) in the digital swine model when the swine trunk was placed in the isocenter of a 3T birdcage body coil. Material (Mat.) 0¼external air, 1¼internal air, 2¼blood (not shown), 3¼skin, 4¼fat, 5¼muscle, 6¼bone, 7¼lungs.