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The Prediction of Radiation-Induced Liver Dysfunction Using a Local Dose and Regional Venous Perfusion Model

Reviewer: John P. Plastaras, MD, PhD
Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 7 de noviembre del 2006

Presenter: Y. Cao
Presenter's Affiliation: University of Michigan, Ann Arbor, MI
Type of Session: Plenary

Background

• High-dose conformal radiation therapy with chemotherapy can prolong the survival of patients with unresectable liver tumors.
• Radiation-induced liver disease (RILD) limits the ability to safely deliver high doses.
• ?Classic? RILD is characterized by anicteric ascites, hepatomegaly, elevation in transaminases (dominated by alkaline phosphatase over other tranaminases), and venous occlusion.
• This study sought to characterize liver venous perfusion as a possible predictor of RILD, before, during, and after radiation of liver tumors.

Materials and Methods

• Imaging:
  • Diffusion contrast-enhanced CT scanning was used to determine venous perfusion of liver tissue on a voxel by voxel basis: 8 slices in 2-cm slabs were collected using a breathing control device with coached breathing.
  • Hepatic arterial and portal venous perfusion components could be resolved.
  • Serial studies were performed both prior to and after radiotherapy, as follows: after 15 fractions, after 30 fractions, and 1 month after the end of treatment.
• Radiation:
  • Median dose was 67.5 Gy.
  • Dose-dependent effects were modeled by drawing volumes of interest (VOI) based on isodose curve to establish dose gradients.

Results

• Over the course of time, liver venous perfusion decreased in irradiated regions. The magnitude of this effect varied among individuals.
• Dose-dependence:
  • After 15 fractions, there was no significant correlation between dose and perfusion.
  • After 30 fractions, there was a significant correlation between dose and perfusion (1.6 mL/100 g/min/Gy).
  • One month after the end of treatment, the significant correlation between dose and perfusion increase with a steepening of the effect (2.5 mL/100 g/min/Gy).

Author's Conclusions

• There was a 1.1% reduction in the venous perfusion of the liver 1 month after RT.
• The venous perfusion changes after 30 fractions showed individual patient sensitivity to the radiation and a time-delay effect.

Clinical/Scientific Implications

• This study showed that there was a time- and dose-dependent decrease in liver venous perfusion in the irradiated liver as shown by dynamic contrast-enhanced CT.
• This effect did vary among the patients, but it only showed up after 30 fractions, making it difficult to change radiation treatment plans in enough time to avoid toxicity.
• However, it is unknown whether these well-quantified differences in liver perfusion will translate into clinically-apparent RILD.