PET/CT-Based Absorbed Dose Maps in ⁹⁰Y Selective Internal Radiation Therapy Correlate with Spatial Changes in Liver...

Area of Science:

• Nuclear Medicine
• Hepatology
• Radiotherapy

Background:

• Selective internal radiation therapy (SIRT) using ⁹⁰Y can damage functional liver parenchyma.
• Evaluating parenchymal changes and developing absorbed dose (AD)-toxicity models are crucial for managing patients undergoing SIRT.
• Understanding the spatial relationship between AD and liver function is key for personalized treatment.

Purpose of the Study:

• To determine the correlation between ⁹⁰Y PET AD voxel maps and spatial changes in nontumoral liver (NTL) function.
• To assess liver function changes using dynamic gadoxetic acid-enhanced MRI before and after SIRT.
• To develop an AD-toxicity model for predicting localized liver damage.

Main Methods:

• Dynamic gadoxetic acid-enhanced MRI and ⁹⁰Y PET/CT scans were acquired from 11 patients before and after SIRT.
• Liver function (k₁ maps) and absorbed dose (AD maps) were quantified and coregistered.
• Spearman correlation coefficients evaluated the relationship between k₁ loss and AD; logistic function modeled average k₁ loss.

Main Results:

• Significant positive correlations between k₁ loss and AD were observed in most patients (8/11).
• Average k₁ loss showed a strong correlation with AD (ρ ≥ 0.92).
• A logistic model indicated approximately 25% k₁ loss at 100 Gy; higher k₁ loss was noted in specific patient subgroups.

Conclusions:

• Multimodality imaging demonstrated a correlation between ⁹⁰Y SIRT AD and spatial functional liver parenchymal degradation.
• Higher AD is associated with greater local hepatocyte function loss.
• PET-derived AD maps can prospectively identify localized liver damage and enhance treatment strategies.