Ultrasound accurately estimates organ volume. In order to ensure that ultrasound measurements reflected actual measurements, lymph node volumes from CBA-lpr^cg mice at death (calculated as 4/3π × radius height × radius width × radius length of lymph node using caliper) were compared with volume calculated on Vevo 660 ultrasound. Linear regression analysis demonstrated a statistically significant correlation. Dotted lines indicate 95% confidence intervals.