Figure 3. Non-invasive measurement of IOSPM NP biodistribution in mice.

a, Transverse cross-sections display mouse anatomy from pelvis to head (slice position relative to the mouse shown in adjacent graphic). External jugular vein was used as the blood ROI (yellow) due to low vessel pulsatility and minimal respiratory artifact in the surrounding tissues. Hamstrings provided the largest area for muscle ROIs (black). Femur provided a consistent, cylindrical compartment for bone marrow (light blue). ROIs are also shown in the renal cortex (purple), renal pelvis (orange, inset), spleen (green), liver (red), and brain (dark blue). Dashed outlines indicate borders of the liver (red) and spleen (green). Water phantom can be seen below the abdomen and above the head, with differences in phantom brightness indicative of the shorter TE used in structural imaging of the abdomen. b, T2*-weighted signal change from pre-injection baseline (expressed as percent), after normalization of each value with corresponding signal produced by the water phantom. Excellent correspondence is seen over time in signal behavior between individual animals (grey). Average normalized signal change between animals is displayed as the colored line. T2*-W signal change after NP injection could not be reliably determined in the liver due to low T2*-W signal at baseline. c, Quantitative T2 imaging provides trends for the blood, muscle, renal cortex, and renal pelvis consistent with T2*-W data. Spin-echo refocusing allows visualization of signal change in the liver.