Hepatic Function Estimated From HIDA SPECT for Assessment of Liver Response to Radiation Therapy
H Wang1*, M Feng1, K Frey1,2,3, J Balter1, R Ten Haken1, T Lawrence1, Y Cao1,2, (1) Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, (2) Department of Radiology, University of Michigan, Ann Arbor, MI, (3) Department of Neurology, University of Michigan, Ann Arbor, MIWE-A-217A-4 Wednesday 8:00:00 AM - 9:55:00 AM Room: 217A
Purpose: To investigate the dose response of the hepatic extraction fraction derived from HIDA SPECT for assessment of hepatic function in response to radiation therapy (RT).
Methods: Eleven patients with intrahepatic cancers were treated by fractionated conformal RT (30-65 Gy), and underwent HIDA SPECT/CT scans before, during and 1 month after the therapy. Voxel-by-voxel hepatic extraction fraction (HEF) was estimated from HIDA SPECT by the deconvolution method. The dose distributions were mapped on the HEF images via co-registration with the treatment planning CT. The liver voxels, excluding gross tumor volumes and vessels, were segregated into subvolumes based upon the accumulated biologically-corrected doses at the end of RT for analysis of response of hepatic function to radition.
Results: The HEF 1 month after RT decreased compared to pre RT. The averaged regional decreases in the HEF from the 11 patients were correlated linearly with the doses accumulated to the end of RT (R2=0.87). Substantial individual responses of the HEF to doses were observed 1 month after RT.
Conclusions: Our study shows dose-dependent hepatic function changes in local liver regions. There is substantial individual variability in the sensitivity of hepatic function to irradiation. The quantitative HEF images as a measure of spatial hepatic function may be a valuable tool for preserving liver function and avoiding injury after irradiation. The work is supported in part by RO1CA132834.