MRI Image Appearance of Different Phase of Radiation-induced Hepatic Injury

Objective : To evaluate the plain and dynamic enhanced MRI appearance of radiation-induced hepatic injury after three-dimensional conformal radiotherapy(stereotactic operation). Methods : The plain and dynamic enhanced MRI images of 36 patients with hepatocellular carcinomas after hepatic irradiation were retrospectively reviewed.The T₁WI,T₂WI intensity and dynamic enhanced patterns of hepatic irradiation were observed,the interval between completion of radiotherapy and the appearance of different types of MR findings was calculated and compared the statistical difference. Results : The irradiatied area of the liver was hypointense on T₁WI images in 53 cases and isointense on T₁WI images in 9 cases,the mean interval was 85 ±32,26±14 days respectively.The irradiated area of the liver was hyperintense on T₂WI images in 50 cases and isointense in 8 cases,the mean interval was 98 ±43,28 ±18days respectively.In contrast enhanced dynamic studies,no enhancement in arterial and portal phase(typeⅠ)was 12 cases,slight enhancement in arterial phase and slight or intense enhancement(typeⅡ)was 15cases,intense enhancement in arterial and portal phase(typeⅢ)was 35cases,the interval between completion of radiotherapy and the appearance of different types of dynamic enhancement images was32± 18,92± 35,110 ±72 days.The difference in interval between typeⅠand typeⅡ,typeⅢ was significant,The difference in interval between type Ⅱ and type Ⅲ findings was not significant. Conclusion : Dynamic enhanced and unenhanced MR imaging can reflect the pathological background of radiation-induce hepatic injuries in every phases and have important value in thedifferentiation of different phases of radiation-induce hepatic injuries.