[Follow-up after lung stereotactic radiotherapy].

Area of Science:

• Oncology
• Radiotherapy
• Medical Imaging

Background:

• Bronchopulmonary stereotactic body radiotherapy (SBRT) is a standard curative-intent treatment for medically inoperable lung cancer patients.
• Post-SBRT computed tomography (CT) lung density changes are common and can mimic or obscure tumor recurrence.
• Radiation-induced CT lung changes differ from those seen with conventional radiotherapy, necessitating distinct interpretation criteria.

Purpose of the Study:

• To review and describe imaging findings on CT and positron emission tomography (PET) after SBRT for lung cancer.
• To identify imaging characteristics predictive of tumor recurrence following SBRT.
• To propose a standardized follow-up algorithm to differentiate tumor progression from radiation-induced pneumonitis.

Main Methods:

• Comprehensive literature review of studies reporting on post-SBRT imaging findings in lung cancer.
• Analysis of CT and PET imaging characteristics associated with SBRT-treated lung lesions.
• Synthesis of data to identify patterns indicative of recurrence versus radiation effects.

Main Results:

• Common post-SBRT CT findings include ground-glass opacities, consolidation, and atelectasis, which evolve over time.
• PET avidity can be present in both recurrence and radiation pneumonitis, requiring careful temporal and spatial assessment.
• Specific imaging patterns and temporal changes can help differentiate tumor progression from benign radiation effects.

Conclusions:

• Standardized interpretation of post-SBRT imaging is crucial for accurate recurrence detection in lung cancer.
• Distinguishing radiation-induced changes from tumor progression requires a multimodal approach integrating clinical, radiological, and functional data.
• The proposed follow-up algorithm aims to improve diagnostic accuracy and optimize patient management after SBRT.