A feasibility study on monitoring the evolution of apparent diffusion coefficient decrease during thermal ablation.

Area of Science:

• Biomedical Engineering
• Radiology
• Oncology

Background:

• Prostate thermal ablation is a key treatment for localized prostate cancer.
• Accurate assessment of tissue viability during thermal ablation is crucial for treatment efficacy and minimizing side effects.
• Diffusion-weighted imaging (DWI) offers a non-invasive method to monitor tissue changes.

Purpose of the Study:

• To evaluate if a decrease in apparent diffusion coefficient (ADC), indicative of loss of tissue viability (LOTV), can be detected during prostate thermal ablation.
• To correlate ADC changes with temperature and thermal dose during the procedure.

Main Methods:

• A canine prostate model underwent transurethral high-intensity ultrasound ablation.
• Diffusion-weighted images and gradient-echo images were interleaved to measure ADC and temperature.
• Apparent diffusion coefficient difference (ADCDIFF) was calculated and analyzed in relation to thermal dose (CEM43).
• Receiver operator characteristic (ROC) analysis determined the threshold for LOTV detection.

Main Results:

• The in vivo temperature-ADC relationship (2.2%/°C) was consistent with phantom studies.
• A mean decrease of 25% in ADC was observed 60 minutes post-treatment in regions with sufficient thermal dose (CEM43 > 240).
• A 2.25% decrease in ADCDIFF over three time points was identified as a reliable indicator of LOTV.
• ADCDIFF decreased rapidly (1-2 min) or slowly (10-20 min) post-thermal dose, depending on heating patterns.

Conclusions:

• Simultaneous monitoring of ADC and temperature during prostate thermal ablation can enhance tissue viability assessment.
• Decreases in ADCDIFF during treatment serve as a potential indicator of LOTV, improving treatment monitoring and outcomes.