MRI,SPECT Study And Pathologic Analysis Of Early Radiation-Induced Hepatic Injury In Rabbits

PURPOSE: (1) To investigate the manifestation of MR imaging and its pathologic basis of early radiation-induced hepatic injury, and to study the value of different MR sequences in early radiation-induced hepatic injury detecting. (2) To investigate the manifestation of SPECT with Tc-99m-PHY and MR imaging with SPIO enhancement in early effects of radiation-induced hepatic injury, moreover, to analyze their pathologic features.MATERIAL AND METHODS: (1) 24 rabbits with left liver irradiated by 40 Gy single-dosed X-ray, were divided into two groups to observe changes of 3rd and 10th day post-irradiation respectively, each group consisted 12 rabbits. MR imaging with or without SPIO enhancement and pathologic study, were implemented in each group according the schedule. (2) 12 rabbits with left liver irradiated same to the first part, before irradiation and 3rd day post-irradiation, SPECT with Tc-99m-PHY were implemented, and Tc-99m-PHY administration 24 hours later, a delayed imaging were made in 3 rd day post-irradiation. In the 5th day post-irradiation, MR imaging before and after SPIO administration, and pathologic study were carried.RESULT: (1) the rabbits of two groups (3rd and 10th day post-irradiation), the Kupffer cell which having swallowed SPIO, decreased dramatically in radiated liver; 5 rabbits in the 10th day post-irradiation group (accounted 41.7%) showed occlusive injury of liver vessel, secondary sinusoidal congestion and atrophy of hepatic cell beside the Kupffer cell injury even more serious. TFE-T1WI is very sensitive to Kupffer cell dysfunction in radiation-induced hepatic injury with a good SNR and high CNR after SPIO administration; Enhanced TSE-TIWI showed particular value in detecting the occlusive injury of liver vessel and secondary sinusoidal congestion. (2) In this studying group, 9 of 12 rabbits have showed the positive appearance in MR imaging and SPECT. 3 rabbits positive in early-enhanced MRI, the signal contrast became weak in 60min delayed-enhanced MRI:The irradiated liver of the positive rabbits in SPECT, demonstrated nuclear isotope hold-upin 24-hour delayed observation. In 5days post-irradiation the Kupffer cell having swallowed SPIO in radiated liver showed less dramatically than non- irradiated region.CONCLUSION: (1) the earliest effect of liver injury post-irradiation is Kupfifer eell dysfunction: both the swallowing and clearing ability of Kupffer cell have decreased; Occlusive injury of liver vessek secondary sinusoidal congestion and atrophy of hepatic cell occur some days later(10th day in our study). (2) TFE-T1WI is the most sensitive sequence in evaluating dysfunction of Kupffer cell, can be as the routine sequence in radiation-induced hepatic injury. Enhanced TSE-T1WI showed particular value in detecting the occlusive injury of liver vessel. (3) Bom SPECT and MRI are effective i in evaluating dysfunction of Kupffer cell in radiation-induced hepatic injury.