SU-E-J-199: A Novel Method to Evaluate Local Control and Recurrence Using 18F-FDG PET After Lung SBRT.

Area of Science:

• Nuclear Medicine
• Oncology
• Radiotherapy

Background:

• Lung cancer stereotactic body radiosurgery (SBRT) requires accurate follow-up imaging to assess treatment effectiveness.
• 18F-FDG Positron Emission Tomography (PET) is used for monitoring, but interpretation of tumor uptake values can be challenging.
• Standardized Uptake Value maximum (SUVmax) is a common metric, but its accuracy in predicting outcomes after SBRT needs refinement.

Purpose of the Study:

• To evaluate a novel method using background-corrected SUVmax (cSUVmax) for predicting local control and recurrence in lung cancer patients post-SBRT.
• To compare the predictability of cSUVmax against the conventional SUVmax method.
• To establish the reliability of cSUVmax in interpreting follow-up 18F-FDG PET scans after lung SBRT.

Main Methods:

• A cohort study included 20 patients with single lung malignant lesions treated with SBRT.
• Pre- and post-treatment 18F-FDG PET scans were analyzed.
• Tumor SUVmax was corrected using the mean SUV from the descending aorta (cSUVmax) to assess local control or recurrence, and compared with SUVmax alone.

Main Results:

• The mean SUV of the aorta was 1.821±0.364.
• At pre-treatment PET, cSUVmax (threshold 1.52) showed 65% positivity, compared to 70% for SUVmax (threshold 2.50).
• At ≥29 weeks post-SBRT, cSUVmax accurately identified both locally controlled and recurrent groups, while SUVmax showed a 5% false positive and one possible false negative.

Conclusions:

• Background-corrected SUVmax (cSUVmax) is a more reliable parameter than SUVmax alone for predicting local control and recurrence in follow-up PET scans after lung SBRT.
• A low cSUVmax strongly correlates with local control following lung SBRT.
• Elevated cSUVmax suggests a potential for local recurrence.