Representative sagittal FIESTA images of the left and right thighs and sciatic nerve of rats with neuropathic pain obtained 7 days following spared nerve injury (SNI). White arrows indicate location of sciatic nerve proximal to the nerve injury. +MINO indicates the animal received daily intraperitoneal minocycline injections. +USPIO indicates the animal received an intravenous dose of USPIOs immediately after peripheral nerve injury and on the day prior to MRI. This dose and timing of administration has been shown to label macrophages. The low signal at the distal truncated end of the nerve corresponds to the site of ligature. A) SNI rat that received neither minocycline nor USPIOs. The sciatic nerve demonstrates increased signal intensity relative to the surrounding muscle. The injured nerve was enlarged compared to the uninjured side (data not shown). B) SNI rat that received USPIOs but not minocycline. There is iron-induced signal loss, as the sciatic nerve is nearly isointense to the surrounding muscle. C) SNI rat that received both minocycline and USPIOs. The signal intensity in the sciatic nerve is higher than with USPIOs alone, suggesting that minocycline retards the migration of USPIO-laden macrophages to the site of injury.