Purpose: Functional Liver Image-Guided Hepatic Therapy (FLIGHT) SBRT planning was used in treatment of liver malignancy, sparing higher functioning regions in liver with the assist of Hepabobiliary Iminodiacetic Acid (HIDA) scans. In this study, the global and regional liver function was assessed using HIDA scans acquired in pre, during, and post treatment and the dose distribution from the treatment plan.
Methods: HIDA scans and blood chemistry were or would be obtained for eligible patients before treatment, during treatment, at 3, 6, and 12 months post treatment. Available 3-month and 6-month post-treatment HIDA scans together with the pre-treatment HIDA and 3D dose matrix were analyzed both globally and at voxel-level. The responses of liver functional units at different functional levels to different doses were evaluated.
Results: Among 7 out of the 13 patients treated got both 3 and 6 months HIDA scans. The average global HIDA scores at pre-treatment, post-3months, and post-6months were 3.73, 3.14 (15.73% drop), and 3.72 (0.3% drop). Global HIDA increased by 15.4% from 3months to 6months after treatment. From the analysis at voxel level, a threshold dose was identified for each patient. Above the threshold, all the functional units in liver couldnâ€™t recover. The threshold dose for these patients ranges from 0 to 14Gy at 3months and from 0 to 35.2Gy at 6months. All patients with 3-months threshold dose above 6Gy had global HIDA recovered at 6months. It also showed that for liver functions recovered at 6months, the percentage contribution of functional units in region irradiated <5Gy increased 8.4% (4.4%-12.1%), compared to a 2.6% increase (1.4%-3.5%) for those not recovered at 6months.
Conclusion: threshold dose above 6Gy and the percentage functional contribution in region <5Gy might predict the recovery of liver function.